Anesthesia for cesarean delivery

INTRODUCTION — Goals for anesthesia for cesarean delivery (CD) must include the comfort and safety of the parturient, and the well-being of the fetus and neonate. This topic will discuss the management of regional and general anesthesia for CD. Anesthesia for CD in patients with preeclampsia and neuraxial labor analgesia are reviewed separately.

●(See "Anesthesia for the patient with preeclampsia", section on 'Anesthesia for cesarean delivery'.)

●(See "Neuraxial analgesia for labor and delivery (including instrumental delivery)".)

PREOPERATIVE ASSESSMENT — We agree with the American Society of Anesthesiologists (ASA) Practice Guidelines for Obstetric Anesthesia, which recommend that parturients undergoing CD should have a focused history and physical examination by an anesthesia provider [1].

●History and physical examination – Gestational history, past medical history, allergies, and anesthetic history should be reviewed. At a minimum, the physical exam should include an assessment of the vital signs, airway, cardiac and respiratory systems, and lower back (for possible neuraxial anesthesia). For patients who will undergo a scheduled and non-urgent, non-emergency CD, adequate preoperative fasting should be verified. (See "Preoperative fasting in adults", section on 'Pregnant patients' and "Airway management for the pregnant patient", section on 'Fasting and aspiration prophylaxis'.)

The preoperative assessment for emergency CD should be as comprehensive as time permits.

●Antenatal anesthesia consultation – It is reasonable to schedule an antenatal consultation with an anesthesiologist for patients at risk of complications due to preexisting conditions, even if CD is not planned. Each parturient should be viewed as a potential candidate for operative delivery during labor, possibly on an emergency basis. Some of the indications for antenatal anesthesia consultation are shown in a table (table 1).

●Laboratory testing – Preoperative laboratory testing should be individualized, based on patient factors and institutional norms. Pregnant women generally have a blood type and antibody screen performed as part of routine prenatal care; repeat preoperative type and screen should be performed for patients at high risk of severe bleeding, and for those with red blood cell antibodies. Baseline hemoglobin, platelet count, and coagulation testing may be indicated for specific conditions. (See "Cesarean birth: Preoperative planning and patient preparation", section on 'Laboratory testing'.)

PREPARATION FOR ANESTHESIA — Preparation for anesthesia includes the administration of aspiration prophylaxis, placement of one or more intravenous (IV) catheters, and standard American Society of Anesthesiologists monitors.

●Aspiration prophylaxis – The obstetric patient is at increased risk of aspiration of gastric contents, especially in cases of difficult or failed intubation, when mask ventilation may be required. Guidelines for preoperative fasting and pharmacologic aspiration prophylaxis are based on gastric physiology and expert opinion, as there is limited evidence that interventions improve outcomes. Because worse outcome may be associated with aspiration of particulate matter, acidic material, and of large volumes, goals for aspiration prophylaxis are to eliminate particulate gastric contents and to decrease the volume and acidity of stomach contents at the time of induction of anesthesia.

•Preoperative fasting – Gastric emptying is not changed by pregnancy [2-4], and preoperative fasting guidelines are the same for elective CD as for other surgical procedures (ie, two hour fast for clear liquids, six hours for solids, eight hours for fatty meals). (See "Preoperative fasting in adults", section on 'Pregnant patients'.)

•Pharmacologic prophylaxis – Practice varies with respect to administration of pharmacologic agents prior to scheduled and emergency CD. We agree with the American Society of Anesthesiologists Practice Guidelines for Obstetric Anesthesia, which state that the timely administration of nonparticulate antacids, H2 receptor antagonists and/or metoclopramide should be considered before surgical procedures (eg, CD) [1]. The guidelines for preoperative fasting from the American Society of Anesthesiologists also list proton pump inhibitors for consideration [5].

Options for pharmacologic prophylaxis include nonparticulate antacids (ie, sodium citrate-citric acid 30 mL orally), H2 receptor blockers (eg, famotidine 20 mg IV), proton pump inhibitors (eg, pantoprazole 40 mg IV), and prokinetic agents (eg, metoclopramide 10 mg IV over one to two minutes). Metoclopramide promotes stomach emptying and also increases lower esophageal sphincter tone, which may be particularly helpful in parturients who typically have lower esophageal sphincter dysfunction due to hormonal and anatomical factors. Sodium citrate and citric acid oral solution increases stomach pH immediately and for approximately one hour [6], while the other prophylactic medications require 30 to 40 minutes to be maximally effective. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Premedication'.)

A combination of prophylactic agents may be more effective than single medications. This was demonstrated by a meta-analysis of 22 randomized studies involving pharmacologic aspiration prophylaxis for women who had general anesthesia for CD [7]. The combined administration of antacids with H2 antagonists was more effective at reducing gastric acidity (ie, pH <2.5) than antacids alone, and more effective than placebo.

●Premedication – Unlike many other surgical procedures, sedatives are not generally administered as premedication prior to CD, as these medications cross the placenta and also may result in some degree of amnesia for the baby's birth. Reassurance and verbal support by the anesthesia clinician provide sufficient anxiolysis for most patients.

However, for particularly anxious patients, premedication may be required and may be safely administered, to allow placement of a neuraxial anesthetic, or to help the patient tolerate surgery while awake with neuraxial anesthesia. In one randomized trial, the administration of midazolam (0.02 mg/kg IV) plus fentanyl (0.1 mcg/kg IV) prior to spinal anesthesia for CD resulted in similar neonatal Apgar scores, pulse oximetry, and neurobehavioral scores when compared with placebo [8]. There was also no difference in the ability of the mother to recall the birth. In our practice, a single dose of IV midazolam (1 to 2 mg) given prior to CD is often sufficient for severe maternal anxiolysis, and the addition of fentanyl is not necessary. In patients who may be particularly anxious about neuraxial placement for a planned CD, 30 to 50% nitrous oxide by a patient-controlled mask may be an appropriate adjunct during neuraxial placement [9].

●IV access – We place one 16- to 18-gauge intravenous (IV) catheter in preparation for routine elective CD. We place additional IV catheters as indicated by the risk of hemorrhage, or to allow administration of magnesium when indicated.

●Monitoring – Standard American Society of Anesthesiologists monitors include pulse rate, blood pressure measurement, electrocardiography, oxygen saturation via pulse oximetry, and temperature monitoring when significant changes in body temperature are expected. If sedatives are administered, end-tidal carbon dioxide (ETCO₂) should be monitored as well.

The fetal heart rate should be documented prior to CD. If possible, laboring patients who were monitored in the labor room should continue to be monitored after transfer to the operating room when surgery is significantly delayed or when clinically indicated. (See "Cesarean birth: Preoperative planning and patient preparation", section on 'Fetal heart rate monitoring'.)

●Preoperative antibiotics – A single intravenous dose of a narrow spectrum antibiotic should be administered preoperatively within 60 minutes of incision to all women undergoing planned CD (table 2). Choice of antibiotic and dosing are discussed separately. (See "Cesarean birth: Preoperative planning and patient preparation", section on 'Antibiotic prophylaxis'.)

ENHANCED RECOVERY AFTER CESAREAN DELIVERY — Enhanced recovery protocols have been developed for CD, similar to other types of surgery. Such protocols consist of multidisciplinary best practices and include components that are used throughout the perioperative period [10-12]. The optimal elements of ERAS have not been determined, and protocols are institution specific. Our ERAS protocols are similar to the enhanced recovery after cesarean (ERAC) protocol published by the Society for Obstetric Anesthesia and Perinatology [13]. Common anesthesia-related components of ERAC protocols are shown in a table (table 3).

CHOICE OF ANESTHETIC TECHNIQUE — Options for anesthesia for CD include neuraxial anesthesia (ie, spinal anesthesia, combined spinal-epidural anesthesia (CSE), and epidural anesthesia) and rarely, general anesthesia. The choice of anesthetic technique should be based on maternal and fetal status, comorbidities, expected duration and difficulty of the procedure, and the presence (or absence) of an in situ epidural or spinal catheter. If a working epidural catheter is in place, the epidural catheter is used to achieve surgical anesthesia. An overall approach to the choice of anesthetic technique for CD is shown in an algorithm (algorithm 1). (See 'Epidural drugs for CD' below and 'Failed or inadequate neuraxial block' below.)

Although not recommended for first-line use, in very rare circumstances (eg, for patients with relative or absolute contraindications to both neuraxial and general anesthesia), peripheral nerve blocks (eg, transverse abdominis plane blocks together with ilioinguinal block) have been used for anesthesia for CD [14,15]. Supplementation with sedatives, opioids, and local anesthetic infiltration by the surgeon may be required with these techniques.

General versus neuraxial anesthesia — For most patients who undergo CD, we recommend using neuraxial anesthesia (NA) rather than general anesthesia (GA). There are exceptions for which GA is more appropriate as detailed below. While maternal and neonatal outcomes are not clearly improved with NA, most patients prioritize being awake for the birth of the infant. Other theoretical advantages favor NA. NA is used for >95 percent of CDs in the United States and Canada [16].

●Advantages of NA for CD

•The mother can be awake for the birth and a partner can be present.

•NA avoids the need for airway instrumentation, which may be more challenging in the parturient. (See "Airway management for the pregnant patient", section on 'Incidence and consequences of airway problems'.)

•NA minimizes the use of systemic medication and transfer of medication to the fetus.

•NA allows the use of neuraxial opioids for postoperative analgesia, thereby minimizing the need for systemic opioids. (See "Post-cesarean delivery analgesia".)

•Blood loss during CD may be lower with NA, though the difference is likely clinically insignificant, without a difference in transfusion [17-19].

•NA may be associated with a reduced incidence of perioperative venous thromboembolism and surgical site infection compared with general anesthesia [20].

•NA may be associated with a reduced risk of severe postpartum depression. In a retrospective database study including over 400,000 cesarean deliveries in the State of New York, the use of general anesthesia was associated with increased risks of postpartum depression requiring hospitalization, suicidal ideation, and self-inflicted injury [21]. However, as the circumstances requiring the choice for general anesthesia may confound these results (ie, emergency versus urgent CD, or fetal distress), further research is required to define this association.

●Catheter techniques – We use catheter NA techniques (ie, CSE, epidural, dural puncture epidural) rather than single-shot spinal when there is time to perform the procedure and achieve surgical anesthesia, in the following scenarios:

•Expected prolonged surgery, due to complicated repeat CD, previous abdominal or uterine surgery, multiple procedures planned, high risk of hemorrhage, severe patient obesity, or cesarean hysterectomy

•Patients with increased risks for general anesthesia (eg, predicted difficult airway, history of malignant hyperthermia, prior complications from general anesthesia, full stomach)

•Patients with prior or expected difficult neuraxial techniques, or in those that the spinal technique proves to be difficult to perform

●General anesthesia – General anesthesia may be indicated for CD in the following scenarios:

•Emergency CD, with insufficient time to perform neuraxial anesthesia or to achieve a surgical level of anesthesia via labor epidural catheter [22]

•Maternal refusal of, or inability to cooperate with, neuraxial anesthesia

•Failed neuraxial technique (see 'Failed or inadequate neuraxial block' below)

•Anticipated massive hemorrhage or highly complex surgery (see "Anesthesia for the patient with peripartum hemorrhage", section on 'General concerns')

•Some maternal cardiac comorbidities (see "Anesthesia for labor and delivery in high-risk heart disease: General considerations")

•Relative or absolute contraindications to NA (eg, coagulopathy, severe hypovolemia, infection at the site of epidural or spinal placement, some intracranial pathology) (see "Overview of neuraxial anesthesia", section on 'Preoperative evaluation' and "Obstetric and nonobstetric anesthesia for patients with neurologic disorders", section on 'Choice of analgesic or anesthetic technique')

For urgent or emergency CD, spinal anesthesia may be appropriate, particularly for patients who have increased risks associated with general anesthesia (ie, known difficult airway, recent oral intake of food, or malignant hyperthermia susceptibility). A single-shot spinal anesthetic by an experienced provider does not take much longer than general anesthesia induction. The anesthesia and obstetric providers should collaborate to determine the degree of urgency so the appropriate anesthetic plan can be formulated.

Maternal mortality — Anesthesia-related mortality during CD is very rare. Based on data from the Pregnancy Mortality Surveillance System, anesthesia-related maternal case fatality rates have changed over time; fatality with general anesthesia has decreased, while fatality associated with regional anesthesia increased from 1979 to 2002 [23]. A review of data from 1997 to 2002, which included 56 deaths, reported a nonsignificant difference in case fatality rates for general anesthesia compared with regional anesthesia during CD (6.5 deaths per million versus 3.8 death per million, risk ratio 1.7, 95% CI 0.6-4.6).

Neonatal effects — The literature on the differences in neonatal outcome associated with the choice of anesthetic technique for CD is inconclusive, but the overall effect is likely small. Apgar scores and umbilical acid base status may be affected by variables unrelated to the choice of anesthetic, including the indication for the CD, vasopressors administered during anesthesia (ie, phenylephrine versus ephedrine), surgical technical issues, and others. A meta-analysis of 22 randomized studies including 1800 patients who underwent CD reported no difference in umbilical artery or vein pH during non-urgent CD between patients with neuraxial versus general anesthesia [17]. Mean Apgar scores at one minute were higher with epidural than with general anesthesia, with no differences in five-minute Apgar score between general and any type of neuraxial anesthesia.

Neonatal exposure to anesthetic drugs during induction and maintenance of general anesthesia can cause early neonatal depression. The neonatal resuscitation team should be notified of all medications administered to the mother during induction of general anesthesia, and prior to delivery.

NEURAXIAL ANESTHESIA — For CD, a sensory level from sacral dermatomes to T4 is required.

Choice of neuraxial technique — Options for neuraxial anesthesia (NA) include single-shot or continuous spinal, epidural, and combined spinal-epidural (CSE). Comparison of these techniques is shown in a table (table 4).

●Spinal anesthesia – Spinal anesthesia is the most commonly used NA technique for CD. Spinal anesthesia is usually performed more quickly than epidural anesthesia and provides rapid onset of dense, bilateral, reliable anesthesia, using a very low dose of drug with minimal risk of maternal toxicity or fetal drug transfer. The duration of anesthesia is limited after single injection spinal, without the ability to extend anesthesia for unforeseen circumstances.

Continuous spinal anesthesia (CSA) may be performed to allow slow titration of spinal anesthesia for parturients with some comorbidities (eg, significant cardiac lesions), or for patients in whom epidural placement may be difficult or ineffective for anatomic reasons (eg, patients who have had extensive spinal surgery). CSA is also a reasonable option after an unintentional dural puncture during attempted epidural catheter placement. In obstetric patients, the risk of post dural puncture headache (PDPH) is high when large gauge continuous spinal catheters (18 g or 19 g) are used; this limits the routine use of a continuous spinal. (See "Spinal anesthesia: Technique", section on 'Continuous spinal'.)

●Epidural anesthesia – Epidural anesthesia is a catheter based, continuous technique, such that the onset can be titrated and the duration extended with incremental dosing. Labor epidural analgesia can be converted to a surgical level of epidural anesthesia if necessary and is the preferred technique with a properly working epidural. Epidural anesthesia tends to be less dense and reliable than spinal anesthesia, is less likely to adequately anesthetize sacral levels, and the onset is slower. This technique requires larger doses of drugs, increasing the risk of fetal drug exposure, also increasing the risk of maternal and fetal systemic toxicity if intravascular injection occurs. Therefore, spinal anesthesia is preferred in elective circumstances when a labor epidural is not in place.

Some clinicians use dural puncture epidural for anesthesia for CD, particularly in patients with obesity, to help verify the location of the epidural needle tip in the epidural space. (See "Neuraxial analgesia for labor and delivery (including instrumental delivery)", section on 'Dural puncture epidural analgesia'.)

●Combined spinal–epidural anesthesia – Combined spinal-epidural (CSE) anesthesia provides the rapid onset and other advantages of spinal anesthesia and in addition, the option to extend and prolong anesthesia with the epidural catheter. With this technique, functionality of the epidural catheter is not verified until it is used. However, epidural catheters placed as part of CSE may be at least as reliable, or more so, than standalone epidural catheters [24].

Spinal anesthesia — The techniques for single-shot and continuous spinal anesthesia are described separately. (See "Spinal anesthesia: Technique".)

Spinal drugs for CD — A combination of local anesthetic (LA) and opioid is usually administered for spinal anesthesia for CD.

●Local anesthetics – Bupivacaine is the most commonly used LA for spinal anesthesia for CD in the United States because of its duration of action appropriate for most CDs, a low incidence of transient radicular irritation, low cost, and wide availability. Other options include ropivacaine, levobupivacaine (outside the United States), and chloroprocaine (table 5). (See "Spinal anesthesia: Technique", section on 'Local anesthetics'.)

•Bupivacaine – Our LA of choice for CD is bupivacaine (hyperbaric 0.75% in 8.25% dextrose), with a usual dose 11 to 12 mg when combined with an opioid (eg, fentanyl and morphine). The onset time of bupivacaine is five to eight minutes [25].

-Dose range – The dose range for bupivacaine for spinal anesthesia for CD is from 8 to 12 mg. The 95 percent effective dose (ED95) of intrathecal hyperbaric bupivacaine for CD spinal anesthesia is 11.2 mg [25].

Obesity does not seem to affect the ED95 of hyperbaric bupivacaine for spinal anesthesia for CD [26,27]. However, the ED95 of bupivacaine in extremely obese parturients (ie, with a body mass index [BMI] greater than 50 kg/m²) has not been extensively studied. In our practice, we use a CSE technique in patients with a BMI greater than 50 kg^/m2 with a starting intrathecal dose of 9 mg of bupivacaine.

-Baricity – We prefer hyperbaric bupivacaine because of its rapid onset and the option to modify the spinal level by changing the position of the operating table. Plain bupivacaine (ie, slightly hypobaric, prepared in saline) may also be used for spinal anesthesia for CD. The literature comparing safety and efficacy of hyperbaric with isobaric bupivacaine for CD is inconclusive [28,29].

-Duration of action – By 1.5 hours, the midthoracic sensory level will have receded, although total duration of action extends beyond 2.5 hours.

•Ropivacaine – Ropivacaine is available only in an isobaric formulation. Thus, if a hyperbaric solution is desired, dextrose (5 to 8.25%) must be added. Ropivacaine is approximately 40 percent less potent than bupivacaine [30]. The duration of surgical anesthesia is shorter than bupivacaine [31].

-Dose range – For spinal anesthesia for CD, the typical dose range for ropivacaine is from 15 to 20 mg. In a comparative dose finding study, the ED50 (effective dose for 50 percent of patients) and ED90 of intrathecal ropivacaine in patients with singleton pregnancies were 11.2 (95% CI 10.2 - 12.0) mg and 15.7 (95% Ci 14.4 t- 18.3) mg, respectively [32].

-Duration of action – Clinically, at equipotent doses ropivacaine provides sensory block equivalent to bupivacaine for CD and may result in more rapid recovery from motor block [33].

•Chloroprocaine – Chloroprocaine is a short-acting ester LA used at a dose of 45 to 60 mg for spinal anesthesia of short duration (30 to 50 minutes) [34]. Chloroprocaine is of limited use for CD because of its short duration of action [35,36]. (See "Spinal anesthesia: Technique", section on 'Local anesthetics'.)

•Lidocaine – Lidocaine (60 to 100 mg) is rarely used for spinal anesthesia for CD because of the relatively high risk of transient neurologic symptoms (TNS) in the nonobstetric population. Although there is some evidence that pregnancy and the postpartum period protect against lidocaine-induced TNS [37,38], lidocaine is usually avoided for spinal anesthesia.

●Intrathecal opioids – Opioids may be added to the LA solution used for spinal anesthesia to improve intraoperative analgesia and for postoperative analgesia. The addition of a lipophilic opioid is particularly helpful for blocking the discomfort of visceral manipulation (eg, manipulation of the uterus during CD). A meta-analysis including over 800 patients who had spinal anesthesia for CD with and without various intrathecal opioids found the need for intraoperative analgesia supplementation decreased from 24 to 4 percent with the addition of opioid to the LA [39].

•Lipophilic opioids (fentanyl and sufentanil) – Lipid-soluble opioids such as fentanyl (10 to 25 mcg) and sufentanil (2.5 to 10 mcg) are commonly added to intrathecal LA to improve intraoperative analgesia [39]. We routinely add fentanyl 15 mcg to bupivacaine for spinal anesthesia for CD. Sufentanil is less commonly used in the United States than in Europe because the concentrated solution (50 mcg/mL) makes accurate measurement of low doses difficult. Lipid-soluble opioids provide minimal postoperative analgesia because of their short duration of action and are not associated with delayed respiratory depression. Pruritus is a common dose-related side effect of intrathecal fentanyl and sufentanil [40].

A 2020 meta-analysis of 14 randomized trials (700 patients) of the effects of adding fentanyl to bupivacaine for spinal anesthesia for CD found that intrathecal fentanyl (10 to 15 mcg) reduced the need for supplemental intraoperative analgesia (4.5 percent versus 29.6 percent, RR 0.18, 95% CI 0.11-0.27) and reduced the incidence of intraoperative nausea and vomiting (10 percent versus 25.8 percent, RR 0.41, 95% CI 0.24-0.74) [41]. The incidence of pruritus was increased sixfold with the addition of fentanyl. The results were similar when fentanyl was added to a combination of bupivacaine and morphine, based on two small trials. The optimal dose of intrathecal fentanyl could not be determined, though doses between 10 and 12.5 mcg reduced the need for intraoperative analgesia and resulted in low rates of intraoperative nausea and vomiting and pruritus. The overall quality of data was judged to be moderate, based on a high risk of bias in some studies.

•Hydrophilic opioids (morphine and hydromorphone) – Hydrophilic opioids (eg, preservative-free morphine 75 to 200 mcg or hydromorphone 75 mcg) are commonly added to LA for spinal anesthesia for CD, primarily to provide postoperative analgesia as a component of multimodal opioid sparing postoperative analgesia. Use of neuraxial opioids for post CD analgesia is discussed in detail separately. (See "Post-cesarean delivery analgesia".)

●Adjuvants – Additional drugs that may be added to the spinal drug solution include the following:

•Epinephrine – Epinephrine (100 to 200 mcg intrathecal) may be added to intrathecal drugs to prolong the duration of action. In patients who may require longer duration of action in their spinal anesthetic, 100 to 200 mcg of epinephrine can be added. The authors use 100 mcg of intrathecal epinephrine, which extends the surgical block time by 30 to 50 minutes [42].

•Clonidine – Although not commonly used, intrathecal clonidine may be of benefit in obstetric patients. Clonidine may be used in addition to or in place of intrathecal opioids in patients with a history of an allergy to opioids, a history of pruritus, substance use disorders or adverse reactions to intrathecal opioids. The addition of clonidine (75 mcg) to hyperbaric bupivacaine improves early postoperative analgesia [43-45], while larger doses (150 mcg) have been reported to decrease hyperalgesia postoperatively [46]. Overall 24-hour opioid consumption does not differ when clonidine is used intrathecally compared with short-acting opioids (eg, sufentanil and fentanyl [47].

•Neostigmine – The use of neostigmine in spinal anesthesia has been associated with significant increases in maternal nausea and vomiting and is not advised [48].

Drugs for continuous spinal anesthesia — The drugs used for CSA for CD are the same ones used for single-shot spinal. However, dosing must take into account the dead space of the catheter (approximately 0.3 mL, but may vary), and may be reduced if the spinal catheter has been used for labor analgesia.

Importantly, inadvertent administration of epidural doses of medications through a spinal catheter can result in high or total spinal anesthesia, severe hypotension, and cardiac arrest. The doses of drugs used for CSA are approximately 10 percent of those that are administered for epidural anesthesia. All members of the nursing, obstetric, and anesthesiology teams must be notified that the catheter is in the intrathecal space, and the catheter should be labeled appropriately.

●Spinal catheter placed de novo for CD – If a de novo spinal catheter is placed, we incrementally administer the spinal bupivacaine to effect (anticipating the same total dose as for a single-shot spinal). We administer the intrathecal adjuncts as a bolus to ensure adequate dosing.

●Spinal catheter initially placed for labor analgesia – When surgical anesthesia is necessary for patients with an in situ spinal catheter for labor analgesia, the initial doses of LA for surgery must be reduced, depending on the labor analgesic infusion, and the patient’s sensory level. Spinal drugs should be administered slowly and titrated to effect. Each labor floor should have a protocol for dosing spinal catheters for emergency CD.

The same LA/opioid combination solution used for epidural analgesia may be used for continuous spinal analgesia (eg, bupivacaine 0.0625 to 0.1% or ropivacaine 0.08 to 0.1%, either with 2 mcg/mL fentanyl). The drug delivery mode most commonly used for spinal infusions is the continuous infusion, but the rate must be decreased to 1 to 3 mL/hour, depending on the concentration (eg, 1 mL/hour 0.1% bupivacaine, 3 mL/hour 0.0625% bupivacaine). (See "Neuraxial analgesia for labor and delivery (including instrumental delivery)", section on 'Continuous spinal analgesia'.)

For emergency CD for these patients, we administer 7.5 mg (1 mL) of 0.75% hyperbaric bupivacaine through the IT catheter. This bolus typically results in adequate anesthesia for surgery; further doses of bupivacaine may be titrated in 1.5 mg increments, to effect. Since in this setting patients have received lipophilic opioid (ie, fentanyl or sufentanil) as part of the infusion for labor analgesia, no additional lipophilic opioid is required for surgical anesthesia. Intrathecal morphine or hydromorphone should be administered as a bolus for postoperative analgesia. (See "Post-cesarean delivery analgesia", section on 'Hydrophilic opioids (morphine and hydromorphone)'.)

When using an intrathecal catheter, we establish an operative level of anesthesia and then test sensory dermatomes roughly every hour to ensure adequate coverage. If the level is receding prior to the closure of the fascia, we administer incremental supplemental doses of spinal local anesthetic (eg, 3.75 mg or 0.5 mL of hyperbaric 0.75% bupivacaine) to maintain a T4-T6 level.

Epidural anesthesia — The technique for epidural catheter placement is discussed separately. (See "Epidural and combined spinal-epidural anesthesia: Techniques", section on 'Epidural anesthesia technique'.)

Epidural drugs for CD

●Local anesthetics – The epidural local anesthetics (LA) commonly used for CD include lidocaine, bupivacaine, ropivacaine, and in the United States, chloroprocaine (table 6)

•Choice of LA – The choice of epidural LA is usually based on the speed of onset required for the clinical situation, and the possibility of systemic toxicity. Our practice is as follows:

-For scheduled and non-urgent CD, we typically use 2% lidocaine with epinephrine. One contributor uses bicarbonated 2% lidocaine with epinephrine in this scenario.

-For urgent CD we use bicarbonated 2% lidocaine with epinephrine.

-For emergency CD requiring maximal speed of onset of surgical anesthesia, practice varies among contributors to this topic; one uses bicarbonated 3% 2-choloroprocaine, and another uses bicarbonated 2% lidocaine with epinephrine. Prior to any rapid epidural medication administration, providers should aspirate the catheter and quickly assess catheter function in an attempt to identify both intrathecal and intravascular migration.

The most rapid onset of epidural surgical anesthesia may be achieved by using bicarbonated 3% 2-chloroprocaine; bicarbonated lidocaine may produce faster onset of epidural anesthesia than 3% 2-chloroprocaine without bicarbonate [49].

In a network meta-analysis of 24 randomized trials that evaluated speed of onset of various epidural local anesthetics for CD, the fastest onset of surgical anesthesia was with bicarbonated 2% lidocaine [49]. Bicarbonated 3% 2-chloroprocaine was not evaluated. The speed of onset, from fastest to slowest, was with bicarbonated 2% lidocaine > 3% 2-chloroprocaine > 2% lidocaine > 0.75% ropivacaine > 0.5% bupivacaine. The mean onset after bupivacaine 0.5% was 19.8 (95% CI 17.3-22.4) min; compared with bupivacaine, onset after bicarbonated 2% lidocaine, 3% 2‐chloroprocaine and 2% lidocaine were 6.4 (95% CI 3.3-9.6), 5.7 (95% CI 3.0-8.3) and 3.9 (95% CI 1.8-6.0) min faster, respectively. Onset after 0.75% ropivacaine was similar to 0.5% bupivacaine. None of the study mixtures contained epinephrine or opioids.

In the network meta-analysis above, the comparison between bicarbonated lidocaine and chloroprocaine was indirect. In a subsequent randomized trial that compared 3% 2-chloroprocaine with a mixture of 2% lidocaine with epinephrine, bicarbonate, and 100 mcg fentanyl, mean time to onset of surgical anesthesia was modestly faster with the lidocaine mixture, 9.3 versus 10.9 minutes, mean difference 97 seconds (90% CI -10.6 to 204) [50].

•Lidocaine – 2% lidocaine with epinephrine (1:200,000 dilution) is the most commonly used epidural LA for CD. For scheduled cesarean deliveries, and for laboring patients without an epidural catheter in place, 15 to 25 mL of 2% lidocaine with epinephrine (1:200,000) is injected via 5 mL aliquots, after a 3 mL 1.5% lidocaine with epinephrine test dose. (See "Neuraxial analgesia for labor and delivery (including instrumental delivery)", section on 'The epidural test dose in obstetrics'.)

Approximately 10 to 20 percent less volume and dose of drug are required when converting an existing labor epidural to surgical anesthesia.

Onset of anesthesia typically occurs over approximately 5 to 10 minutes; speed of onset can be increased by addition of sodium bicarbonate [51] and/or fentanyl [52]. In one study, alkalinization of epidural lidocaine with epinephrine for patients with in situ labor epidural catheters decreased the time from epidural bolus to surgical anesthesia for CD from 9.7 to 5.2 minutes [51].

•Chloroprocaine – 3% 2-chloroprocaine is an LA with the fastest onset and shortest duration of action of LAs available for epidural administration. 2-chloroprocaine is metabolized very rapidly by plasma esterases, and is therefore less likely to cause local anesthetic systemic toxicity than alternative LAs in the event of a catheter inadvertently placed into a blood vessel.

Chloroprocaine is mainly used for the most urgent cesarean deliveries. The onset of anesthesia with a rapid bolus of 3% 2-chloroprocaine through an existing labor epidural catheter occurs in approximately eight minutes [53] and can be reduced to approximately three minutes with the addition of sodium bicarbonate to the solution [54]. The duration of action, measured as two dermatome regression of sensory block, is approximately 40 to 60 minutes. Therefore, we administer 2% lidocaine with epinephrine 15 to 20 minutes after chloroprocaine to maintain surgical anesthesia, and administer 5 mL of the lidocaine solution as required at 35 to 50 minute intervals.

Chloroprocaine may reduce the efficacy of analgesia from subsequently administered epidural morphine [55,56]. However, we still administer the epidural morphine towards the end of the CD and find it to be clinically effective.

•Bupivacaine – Bupivacaine is not routinely used for epidural anesthesia for CD because of the risk of cardiac sequelae with intravascular injection, and because of its slow onset. Onset of block occurs in approximately 20 minutes, and the duration of action (two dermatome regression) is 120 to 240 minutes [52]. (See "Local anesthetic systemic toxicity", section on 'Amide local anesthetics'.)

•Ropivacaine – Ropivacaine is also rarely used for CD. Epidural ropivacaine is approximately 40 percent less potent than bupivacaine, with a similar onset, and slightly shorter duration of action. Therefore, higher doses of ropivacaine than bupivacaine may be required for equivalent anesthesia [57-59]. Ropivacaine may have a higher margin of safety than bupivacaine. However, animal and human studies that have compared cardiotoxicity of the two drugs have reported conflicting results, with some showing cardiac conduction abnormalities at lower doses of bupivacaine than ropivacaine [60-62], and others showing no difference between the two LAs [61,63].

●Epidural opioids – Opioids may be administered epidurally to speed the onset of anesthesia, improve the quality of the anesthetic, and/or to provide postoperative analgesia [64-66]. Lipophilic opioids (fentanyl or sufentanil) are administered primarily for intraoperative analgesia and are administered during initiation of epidural anesthesia. Hydrophilic opioids (ie, morphine and hydromorphone) are used for postoperative analgesia and are administered after the fetus is delivered. (See "Post-cesarean delivery analgesia", section on 'Hydrophilic opioids (morphine and hydromorphone)'.) Doses for the commonly used opioids are as follows:

•Fentanyl – 50 to 100 mcg [64,65].

•Sufentanil – 20 to 30 mcg [66].

•Morphine – Preservative-free morphine (1 to 3 mg) should be administered for postoperative analgesia in patients without contraindication during CD. Typical epidural doses range from 1 to 3 mg, with lower doses providing adequate postoperative analgesia for 18 to more than 24 hours with lower incidence of side effects compared with higher doses, when administered as part of a multimodal pain control regimen [67,68].

•Hydromorphone – Epidural hydromorphone (0.6 to 1.0 mg) may be a useful alternative for postoperative analgesia when epidural morphine is not available [69,70].

●Other adjuvants – Other medications may be added to epidural LA and opioid solutions to improve the anesthetic or speed the onset.

•Epinephrine – Epinephrine (1:400,000 to 1:200,000) is often added to the epidural local anesthetic solution to increase the density of block, reduce systemic absorption of LA, and to prolong the duration of anesthesia [71]. In most cases, a commercially prepared solution of lidocaine with epinephrine 1:200,000 is used for epidural anesthesia for CD.

•Neostigmine – Epidural administration of neostigmine may reduce the required dose of LA for CD, and may modestly enhance postoperative analgesia, without significant maternal or fetal side effects [48]. Unlike intrathecal neostigmine, epidural administration does not seem to cause nausea and vomiting.

Neostigmine is not widely used as an adjunct for epidural anesthesia in the United States and is not used by the authors. Further study is required before recommending the routine use of neostigmine in this setting.

•Sodium bicarbonate – Sodium bicarbonate 8.4% may be added to the epidural local anesthetic solution to speed the onset and improve the quality of the block (usually 2 mL/20 mL of local anesthetic). Faster speed of onset with addition of sodium bicarbonate to lidocaine and to chloroprocaine is discussed above. Sodium bicarbonate can be added to bupivacaine only in very small doses (0.1 mL/20 mL); otherwise it will cause precipitation.

Combined spinal-epidural anesthesia — The technique for CSE is discussed separately. (See "Neuraxial analgesia for labor and delivery (including instrumental delivery)", section on 'CSE technique'.)

The drugs used for CSE mimic those used for spinal anesthesia and, if necessary, epidural anesthesia. Opioids are added to the spinal drugs (eg, fentanyl and preservative-free morphine) to directly deliver the drugs to their relevant receptors in the spinal cord.

There are various options for management of a CSE placed for a scheduled CD, including administration of a full dose of spinal drug, followed by epidural medication as necessary, or administration of a partial spinal dose (ie, sequential CSE) with epidural administration to achieve adequate surgical anesthesia. The authors typically use a full dose spinal technique for CSE.

●Full spinal dose CSE – In most cases, the same initial doses and combinations of spinal drugs are administered as for single-shot spinal anesthesia. The first dose of epidural medication is then administered when the sensory level recedes below T4. At that point, after negative aspiration of the catheter for blood and CSF, we administer a test dose of 3 mL of 1.5 or 2% lidocaine with epinephrine 1:200,000. In this setting, this bolus acts as a test dose for intravascular injection (ie, tachycardia would occur with intravascular injection of epinephrine). Since the patient already has a spinal block with motor block, the bolus does not test for intrathecal injection. (See "Neuraxial analgesia for labor and delivery (including instrumental delivery)", section on 'The epidural test dose in obstetrics'.)

Therefore, it is always a good practice to fractionate the total dose of local anesthetic (ie, administer 3 to 5 mL at a time).

The test dose often reestablishes a level of surgical anesthesia above T4. We then test the sensory level every 20 minutes, and administer aliquots of 3 to 5 mL of 2% lidocaine with epinephrine, based on the level of the block.

●Sequential CSE – A CSE may be managed by injection of a portion of the usual single-shot spinal dose, usually half (eg, 5 to 6 mg bupivacaine), followed by subsequent epidural injections (eg, 3 to 5 mL of 2% lidocaine with epinephrine), titrated to achieve adequate surgical anesthesia.

Sequential techniques result in less hypotension [72-74] than single-shot or full-dose spinal CSE, and may indicate that the epidural catheter is well positioned at the start of the anesthetic.

Intraoperative management

Intraoperative positioning — Patients should be positioned with left uterine displacement (LUD) for CD, to minimize the chance of aortocaval compression. (See "Cesarean birth: Preoperative planning and patient preparation", section on 'Uterine displacement'.)

Traditionally, 15 degrees of LUD has been recommended for any pregnant patient with a visibly gravid uterus or at greater than 20 weeks gestational age. The need for and efficacy of LUD for healthy parturients have been questioned [75]. Two studies have examined the cardiovascular effects of a 15 degree tilt in patients receiving spinal anesthesia [76,77]. Although these studies failed to demonstrate a difference in neonatal acidosis, both studies utilized aggressive fluid and vasopressor administration, which may have impacted the outcome. In addition, these were healthy parturients without signs of fetal compromise. Therefore, little is known about the effects of 15 degree tilt in parturients whose fetuses may have uteroplacental insufficiency. Both authors of this topic continue to tilt patients when feasible and may employ more aggressive tilting strategies if fetal heart rates are compromised.

●In one study, 100 healthy term parturients with singleton pregnancies were randomly assigned to either a 15 degree left lateral tilt or supine positioning for elective CD with spinal anesthesia [76]. Maternal blood pressure was maintained with intravenous fluid co-loading and phenylephrine infusion targeted at maintaining systolic blood pressure at baseline. There was no difference in neonatal acid base status between the groups. Systolic blood pressures and cardiac output were significantly lower in the supine group, despite increased phenylephrine administration.

●In another trial, noninvasive cardiac output monitoring was used during spinal anesthesia for CD in 80 healthy parturients who were randomly assigned to supine or 15 degree left lateral tilt positioning [77]. There were no differences in systolic blood pressure, mean arterial pressure, cardiac index, nausea and vomiting, or neonatal Apgar scores between the groups.

●A small study compared magnetic resonance imaging (MRI) images of inferior vena cava (IVC) volume during 15 and 30 degrees of left and right lateral tilt in pregnant patients between 31 and 39 weeks gestation [78]. IVC compression was consistently relieved by 30 degrees of left lateral tilt, but not with 15 degrees of left lateral tilt, or with either 15 or 30 degrees of right lateral tilt.

●MRI examination of aortic and IVC volumes in pregnant and nonpregnant peers has shown that IVC volume, but not aortic volume, is influenced by patient position; specifically, a left-lateral tilt of at least 30 degrees is needed to improve vena cava volume [79]. A lateral tilt of 30 degrees is impractical during CD, and further study is required before changing practice.

Supplemental oxygen — Most healthy parturients do not require supplemental oxygen during neuraxial anesthesia for uncomplicated CD. We administer supplemental oxygen via facemask or nasal cannulae to parturients with worrisome fetal heart rate tracings and other evidence of fetal compromise, and to parturients with decreased oxygen saturation.

Preventing nausea and vomiting — Nausea with or without vomiting occurs commonly during CD with neuraxial anesthesia. We routinely administer prophylaxis for intraoperative and postoperative nausea and vomiting. We administer ondansetron 4 mg IV for prophylaxis for postoperative nausea and vomiting and for hemodynamic benefits in the setting of spinal anesthesia (see 'Ondansetron' below). Other options include metoclopramide to facilitate stomach emptying, a scopolamine patch (1.5 mg transdermal), and dexamethasone (4 to 8 mg IV). (See "Postoperative nausea and vomiting", section on 'Antiemetics'.)

Several etiologies for nausea and vomiting during CD are possible, including the following:

●Hypotension is the most common cause of nausea, and it usually resolves with restoration of normal blood pressure with vasopressors (ie, phenylephrine or ephedrine). Prophylactic ondansetron may reduce the incidence of both hypotension and nausea and vomiting induced by spinal anesthesia [80,81]. (See 'Vasopressors' below.)

●Visceral manipulation (eg, uterine exteriorization or reinsertion) may cause nausea despite otherwise adequate neuraxial anesthesia. A small dose of fentanyl (eg, 25 to 50 mcg IV) often relieves nausea while waiting for completion of surgery.

●Uterotonic medication, especially when administered rapidly, can cause nausea. (See "Cesarean birth: Surgical technique", section on 'Prevention of postpartum hemorrhage'.)

Hemodynamic management — Dense neuraxial blockade at the sensory level required for CD (ie, fourth thoracic dermatome) causes sympathetic block and vasodilation, which can result in hypotension if not appropriately treated with vasopressor [82] (figure 1).

Goal blood pressure — We aim to maintain blood pressure within 10 to 20 percent of baseline blood pressure unless the patient has severe hypertension (see "Anesthesia for the patient with preeclampsia", section on 'Goal blood pressure'). We use a prophylactic phenylephrine infusion as described below, and administer boluses of vasopressors to patients who drop below 20 percent of their baseline blood pressure, to patients who become symptomatic with nausea, vomiting, or lightheadedness, or if the fetus shows signs of distress following placement of spinal anesthesia. (See 'Vasopressors' below.)

While recommendations are usually to maintain systolic blood pressure at ≥100 mmHg or ≥80 percent of baseline for healthy parturients, the optimal goal for blood pressure management has not been defined [83]. A study of approximately 75 parturients who had spinal anesthesia for CD randomly assigned patients to have systolic blood pressure maintained at 80 percent, 90 percent, or 100 percent of baseline value [84]. Blood pressure was controlled by the use of a titrated infusion of phenylephrine, starting at 100 mcg/min IV, without intravenous preload. Patients whose systolic blood pressure was maintained at 100 percent had significantly less nausea or vomiting compared with the other two groups, and umbilical artery pH was higher, though none of the values were truly acidotic.

Vasopressors — Our primary strategy for preventing spinal anesthesia-induced hypotension involves prophylactic, titrated administration of low dose phenylephrine infusion (ie, starting at 25 to 50 mcg/min IV) started around the time of injection of the spinal drug. We administer phenylephrine rescue boluses, aiming for a maternal blood pressure close to baseline. This strategy is largely consistent with the 2017 International Consensus Statement on the Management of Hypotension with Vasopressors During Cesarean Section Under Spinal Anesthesia [85]. A network meta-analysis of 109 randomized trials involving various methods for prevention of spinal hypotension at CD found that vasopressors were more effective than fluid loading, leg compression, or other types of medications [86]. One measure that can be used to temporarily increase venous return while administering vasopressors is to elevate both legs while the patient is in the supine position, with left uterine displacement.

●Phenylephrine versus ephedrine – Phenylephrine, a direct, primarily alpha adrenergic agonist and ephedrine, an indirect acting alpha and beta adrenergic agonist, are both effective for treating hypotension resulting from spinal anesthesia for healthy parturients at CD [87-91]. Phenylephrine is typically the preferred vasopressor in this situation, although ephedrine may be preferable in some cases (eg, maternal bradycardia). Commonly used doses of vasopressors for treatment of hypotension include phenylephrine (50 to 100 mcg IV bolus, or 25 to 100 mcg/min IV infusion) and ephedrine (5 to 10 mg IV boluses, or infusion, 1 to 5 mg/min IV infusion).

Phenylephrine is associated with a lower incidence of intraoperative nausea and vomiting, and a small but statistically significant increase in umbilical artery pH at delivery, while ephedrine may be associated with increased risk of fetal acidosis [88,92-96].

It has been suggested that the relative fetal acidosis occurs because ephedrine crosses the placenta, increasing fetal metabolic rate. In addition, ephedrine has a delayed onset compared with phenylephrine, which may result in a longer period of hypotension [88].

However, phenylephrine can cause reflex maternal bradycardia; thus, the choice of vasopressor therapy for spinal hypotension is often guided by the resulting maternal heart rate. Profound bradycardia (40 to 50 beats per minute) during phenylephrine infusion should be treated by reducing or stopping the infusion, unless it is accompanied by hypotension. Bradycardia with associated hypotension can be treated with ephedrine and may require the use of an anticholinergic medication (glycopyrrolate, 0.2 to 0.4 mg IV).

In cases of fetal compromise, it is not clear which, if either, vasopressor would be preferable. Most of the studies cited above included healthy parturients undergoing scheduled CD. A retrospective study of approximately 380 high-risk parturients who underwent CD under spinal anesthesia reported no difference in umbilical artery pH in patients who received ephedrine, phenylephrine, or required no vasopressor during the anesthetic [97]. Similarly, a retrospective review of patients with preeclampsia who underwent CD found no difference in umbilical artery pH between patients who received ephedrine and phenylephrine to treat spinal hypotension [98]. In another study in which preeclamptic patients were randomly assigned to prophylactic infusion of phenylephrine or ephedrine during spinal anesthesia for CD, there was no difference in umbilical artery pH between groups [99]. In that study, the range of patients’ baseline systolic blood pressure was from 136 to 162 mmHg. Clinicians should administer prophylactic vasopressors cautiously in patients with preeclampsia, as significant blood pressure elevation may result.

●Dose of vasopressors – The optimal doses and method of administration of phenylephrine and ephedrine are not clear. Treatment of hypotension with bolus administration of phenylephrine may be associated with more hypotension and intraoperative nausea and vomiting compared with prophylactic infusion, but prophylactic infusion at higher doses (75 to 100 mcg/min) is associated with a higher incidence of bradycardia and hypertension [87,100-103]. Infusions of phenylephrine in patients with hypertensive comorbidities (such as preeclampsia) should be used cautiously. (See "Anesthesia for the patient with preeclampsia", section on 'Vasopressors during neuraxial analgesia'.)

In a 2014 systematic review, administration of a prophylactic phenylephrine infusion (with a fluid load) to parturients having spinal anesthesia decreased the incidence of hypotension by approximately 60 percent before and after delivery (RR = 0.36), and decreased the incidence of nausea and vomiting (RR = 0.39) compared with no prophylaxis or ephedrine infusion [104]. There were no differences in other maternal or fetal endpoints or outcomes. Studies available for analysis were limited and included variable dosing regimens.

●Norepinephrine – We do not routinely use norepinephrine to prevent or treat spinal anesthesia induced hypotension. Limited data suggest that norepinephrine may be as effective as phenylephrine and may cause overall less maternal bradycardia [105-108]. Existing studies have used varied doses and administration protocols; further study is required before recommending routine use of norepinephrine in this setting.

•A 2019 meta-analysis of three trials (294 patients) that compared norepinephrine to phenylephrine for prevention of hypotension after spinal anesthesia for CD found similar hypotension and Apgar scores between groups, and a lower incidence of bradycardia with norepinephrine [107].

•In a subsequent trial involving 82 parturients who were randomly assigned to receive prophylaxis for spinal induced hypotension with either fixed dose norepinephrine 4 mcg/minute or phenylephrine 50 mcg/minute, the incidence of bradycardia was lower (4.8 versus 31.7 percent), and fetal pH was slightly higher in the norepinephrine group (7.35 [95% CI 7.33-7.37] versus 7.34 [95% CI 7.26-7.36]) [108]. Apgar scores, the incidence of hypotension, and the use of rescue vasopressors were similar.

•In a randomized dose finding study of 99 patients who received intrathecal bupivacaine 10 mg with sufentanil 5 mcg for spinal anesthesia for elective CD, the effective norepinephrine infusion dose in 50 percent of patients (ED 50) and ED95 for preventing hypotension were 0.029 (95% CI 0.008-0.042) mcg/kg/minute and 0.105 (95% CI 0.082-0.172) mcg/kg/minute, respectively [105].

If used, a reasonable starting dose would be 2.5 to 4 mcg/minute, titrated to effect [109]. Before administration of norepinephrine, patency of the intravenous catheter should be verified, as extravasation of the drug can result in significant tissue damage.

Fluid management — A rapid bolus of IV crystalloid is usually administered at the time of induction of spinal anesthesia (co-loading), in conjunction with prophylactic and as needed vasopressors. We typically administer a fluid bolus of 500 to 1000 mL IV during the neuraxial procedure, depending on the patient's comorbidities and volume status [82]. Further fluid administration should be based on an accurate estimate of blood loss. In patients with preeclampsia with severe features, a limited fluid bolus should be administered. (See "Anesthesia for the patient with preeclampsia", section on 'Intravenous fluid management'.)

Crystalloid solutions are used more commonly than colloid solutions for CD because they are less expensive and more readily available. Furthermore, the available data do not indicate an absolute benefit of colloids over crystalloids [110-114].

Glucose-free solutions should be used to prevent hypoglycemia in the fetus. Excessive placental glucose transfer can result in compensatory release of fetal insulin (fetal hyperinsulinemia), resulting in neonatal hypoglycemia after delivery [115,116].

Ondansetron — Ondansetron administered at the time of spinal injection may reduce the incidence of spinal hypotension and related symptoms. Two meta-analyses of randomized trials reported that ondansetron administered prophylactically during spinal anesthesia for CD reduced the incidence of hypotension, the dose of vasopressors administered, and the incidence of bradycardia, although the included studies were small with high heterogeneity [80,81]. A randomized trial including 60 patients who underwent elective CD with combined spinal epidural anesthesia found that a single dose of ondansetron 4 mg IV reduced the ED₅₀ (ie, effective dose in 50 percent of subjects) of phenylephrine infusion by approximately 26 percent [117]. In this study, phenylephrine was administered to maintain blood pressure within 20 percent of baseline.

Maintaining normothermia — Similar to other patients having surgical procedures, patients who undergo CD are at risk for hypothermia due to prolonged skin exposure and fluid shifts. Providers should attempt to maintain normothermia in both the mother and the neonate by keeping the room temperature at 22 to 23°C, and using warmed fluids. We cover the mother with warm blankets for routine cesarean deliveries with neuraxial anesthesia of less than an hour duration, and use an active warming device (eg, forced-air warming) for longer procedures and for patients who have general anesthesia. We routinely monitor temperature for patients who have general anesthesia or blood transfusion, and for patients who have neuraxial anesthesia for longer procedures. In non-obstetric patients, intraoperative hypothermia is associated with coagulopathy, infection, prolonged drug effects, and myocardial ischemia, though these outcomes have not been studied in obstetric patients. (See "Perioperative temperature management", section on 'Consequences'.)

The optimal methods (eg, prewarming and active intraoperative forced air warming, warmed fluids, increased ambient temperature) for preventing hypothermia during CD are unclear; available literature involves varied interventions and duration of surgery.

●In one study of 30 patients who underwent epidural anesthesia for CD, patients randomly assigned to prewarming and intraoperative warming with an upper body forced air blanket maintained higher core temperature after two hours of surgery than patients who were not actively warmed (37.1 ± 0.4°C versus 36.0 ± 0.5°C) [118]. Newborns of the warmed mothers had higher core temperatures (37.1 ± 0.5 versus 36.2 ± 0.6°C) and higher umbilical vein pH (7.32 ± 0.07 versus 7.24 ± 0.07). Intravenous fluid was warmed to 37°C, and the operating room temperature was kept at 23°C.

●In contrast, in a randomized trial that included 30 patients who underwent spinal anesthesia for CD, lower extremity forced air warming did not reduce the incidence of intra- or postoperative hypothermia, defined as core temperature ≤35.5°C (8 of 15 warmed patients, versus 10 of 15 unwarmed) [119]. There were no differences in cord blood gases or neonatal Apgar scores.

The mechanisms for perioperative hypothermia, consequences, and preventive measures are discussed in detail separately. (See "Perioperative temperature management".)

Neonatal effects of hypothermia are also discussed separately. (See "Neonatal resuscitation in the delivery room", section on 'Temperature control'.)

Administration of uterotonics — Uterine contraction is the main mechanism for reduction of uterine bleeding after delivery. The uterus is massaged, and oxytocin is administered as the first-line uterotonic medication.

Protocols for infusion of oxytocin vary by institution, but should include either administration of small, slow bolus doses (ie, <3 units intravenous [IV]) or controlled infusion. At one author's institution, oxytocin 18 milliunits/minute IV is started after cord clamping, administered by controlled infusion, and titrated as needed for bleeding up to 36 milliunits/minute.

Rapid administration of oxytocin can result in hypotension, nausea and vomiting, and chest pain with electrocardiogram changes [120], and can cause cardiovascular collapse [121,122]. The incidence of side effects is directly related to the rate of administration. Therefore, the lowest effective dose of oxytocin should be used.

The optimal dose and route of administration (ie, bolus dose versus infusion) of oxytocin at CD are unclear. A prospective, double blinded trial randomly assigned 60 patients to receive bolus doses of oxytocin, 3 units over 15 seconds IV, or wide open infusion of oxytocin, during elective CD with spinal anesthesia [123]. Uterine tone was assessed at three minute intervals by the obstetrician, and with additional boluses of oxytocin administered upon request. Patients in the bolus group received less oxytocin to achieve adequate uterine tone compared with those in the infusion group (mean 4 versus 8.4 IU), although there was no difference in systolic or diastolic blood pressure, heart rate, side effects, or blood loss between the two groups.

If a bolus injection is given after CD, some studies suggest that the addition of an oxytocin infusion reduces delayed blood loss and the need for blood transfusion and/or additional uterotonic agents compared with bolus injection alone [124,125].

Parturients who receive oxytocin during labor may become desensitized, and require higher doses of oxytocin for a uterotonic effect. In one study, the bolus dose of oxytocin required to achieve adequate uterine tone at CD in 90 percent of patients (ED90) who had received 10 hours of oxytocin in labor was 2.99 (95% CI )2.32-3.67 [126] , compared with an ED90 of 0.35 (95% CI 0.18-0.52) units in patients who underwent elective CD [127]. Similarly, the ED90 for oxytocin infusion is approximately 15 units/hour for elective cesarean deliveries, but this may increase to 44 units/hour in previously laboring patients with oxytocin supplementation [128,129].

Whether bolus or infusion dosing is used, each unit should have a standardized protocol for oxytocin administration as oxytocin is consistently reported as a high-alert medication by the Institute of Safe Medication Practices and has a narrow therapeutic window. Patients at high risk for bleeding may benefit from prolonged infusions in recovery and postpartum units to reduce the risk of a delayed hemorrhage.

Other uterotonic medications including carbetocin (outside the United States) that are used for postpartum hemorrhage are discussed separately. (See "Postpartum hemorrhage: Medical and minimally invasive management", section on 'Administer additional uterotonic medications'.)

Failed or inadequate neuraxial block

●Inadequate block at initiation – For elective cesarean deliveries, the level of sensory block should be assessed before skin preparation and draping to allow for supplementation, or if necessary, repeat neuraxial block. A neuraxial block inadequate for surgery may occur if there is no block, a low spinal level, or a patchy block. Management of inadequate block depends on the degree of urgency and patient factors. In urgent situations, general anesthesia should be induced rather than making further attempts at neuraxial anesthesia.

•Inadequate spinal anesthesia – If time permits, 20 minutes should be allowed for full onset of the spinal block before further intervention.

-Partial spinal block – If there is a low or patchy spinal block, we usually place an epidural catheter and titrate the epidural medication to effect, similar to a sequential combined spinal epidural. Repeat single-shot spinal should be avoided, as the correct dose of drug in this scenario cannot be determined, and either high spinal or inadequate spinal is possible. Placement of an epidural catheter and dosing to effect may avoid low or high levels that can occur with repeat spinal administrations. For urgent CD, without time for epidural placement and dosing, general anesthesia should be considered.

Alternatively, for scheduled CD, repeat spinal may be performed once all evidence of spinal block has worn off.

-No spinal block – If after 20 minutes there is no evidence of spinal anesthesia, it is likely safe to repeat full dose spinal anesthesia.

•Inadequate epidural anesthesia – If epidural anesthesia is inadequate for CD after administration of appropriate doses of epidural medications, we replace the epidural catheter and titrate further epidural medication to effect with the new catheter. Single-shot spinal should not be performed following failed epidural anesthesia. High block associated with single-shot spinal after failed epidural is one of the most common serious complications of obstetric anesthesia and can result in respiratory arrest [130].

●Inadequate block during surgery – If discomfort occurs during surgery, the level of neuraxial block should be promptly assessed. Additional epidural local anesthetic and/or opioid may be administered if a catheter is in place. Small doses of systemic medication may be effective for anxiolysis or to treat visceral stimulation (eg, fentanyl 50 to 100 mcg IV, midazolam 1 to 2 mg IV, ketamine 10 to 30 mg IV with midazolam pretreatment, nitrous oxide by mask). One contributor to this topic uses intraperitoneal local anesthetic in this setting (ie, 20 mL of 3% 2-chloroprocaine, poured sterilely into the surgical field). However, if the neuraxial block is clearly inadequate despite these maneuvers, then general anesthesia should be induced and the airway secured.

The optimal volume and concentration of local anesthetic solution for intraperitoneal instillation and the risk of local anesthetic toxicity have not been determined. In one case series of 32 patients who had pain during CD, 20 to 60 mL of 1% chloroprocaine (mean dose 11.8 mg/kg) was poured into the peritoneal cavity after delivery of the fetus [131]. One to five minutes later, excess LA solution was suctioned away. Approximately one-half of the patients had improved pain scores after intraperitoneal LA, though all patients also received intravenous opioids. None of the patients exhibited signs of local anesthetic systemic toxicity (LAST).

High neuraxial block — High thoracic levels of spinal or epidural blockade often leads to a subjective feeling of dyspnea. For most patients, reassurance that this is a normal sensation is sufficient. Assessment of grip strength is a quick way to determine whether the block involves the cervical nerve roots, and may be reaching a level that requires ventilatory support. Patients with weak grip strength should be assessed continuously for block progression. In the case of ascending spinal anesthesia with hyperbaric solution, the head of the bed should be elevated to prevent further cephalad spread. If the patient is unable to phonate, or to maintain adequate oxygenation, a rapid sequence induction of general anesthesia with intubation should be performed.

High neuraxial block may be the most common anesthesia related serious complication in obstetric patients. It can result in respiratory compromise, hypoxemia, hypotension, and cardiac arrest. The Serious Complications Repository Project from the Society for Obstetric Anesthesia and Perinatology collected data on over 250,000 obstetric anesthetics [130]. High neuraxial block was the most frequently reported anesthesia-related complication, and occurred in 1/4336 anesthetics.

High blocks were associated with both unrecognized intrathecal catheters and with de novo spinal placement following attempted bolusing of an in situ labor epidural catheter that resulted in an inadequate surgical level. Therefore, providers should always aspirate epidural catheters prior to administering medications and bolus catheter medication slowly and incrementally if the clinical situation permits. In addition, if labor epidural catheter fails to adequately provide anesthesia after administration of a large dose of local anesthetics, spinal anesthesia should be avoided as a follow-up technique as this may lead to unusually high or unpredictable levels. (See 'Failed or inadequate neuraxial block' above.)

GENERAL ANESTHESIA — General anesthesia (GA) may be indicated for CD in certain patient and clinical scenarios. (See 'General versus neuraxial anesthesia' above.)

Patient positioning, hemodynamic management, temperature control, and administration of uterotonic agents during general anesthesia are the same as they are during neuraxial anesthesia. (See 'Intraoperative management' above and 'Administration of uterotonics' above.)

Patients who have general anesthesia for CD are at increased risk of difficulty with airway management, and of awareness with recall after anesthesia, compared with non-pregnant patients who undergo other types of surgery.

●Airway concerns – The incidence of airway difficulty and management of the airway for these patients are discussed separately. (See "Airway management for the pregnant patient".)

●Awareness during general anesthesia – Awareness with recall is relatively common during GA for CD. The rate of awareness under anesthesia for obstetric patients may be as high as 1:212, compared with 1:19,600 for all types of surgery [132,133]. The 5^th National Audit Project from the United Kingdom reported that many of these cases of awareness were preventable.

General anesthesia during CD is administered differently than other surgeries due to fetal concerns and maternal physiology; some of the changes in anesthetic technique may contribute to the high incidence of awareness in obstetric patients. Suggested mechanisms for awareness in these patients include the following:

•Underdosing or omission of sedative premedication, induction agents, and opioids to avoid placental transfer to the fetus

•Underdosing of inhalation anesthetics to avoid uterine relaxation and bleeding

•Changes in drug distribution related to physiologic changes of pregnancy (eg, increase in cardiac output)

•Increase in difficulty with airway management, which is associated with awareness in all patients

•High percentage of emergencies among patients who have general anesthesia for CD (see "Accidental awareness during general anesthesia")

To minimize the possibility of awareness, we administer a high concentration of volatile anesthetic after induction of anesthesia leading up to delivery, and routinely administer midazolam and opioids after delivery. (See 'Maintenance of general anesthesia' below.)

Preparation for general anesthesia — Preoperative assessment, intravenous (IV) access, monitoring, and administration of antibiotics are similar whether neuraxial anesthesia or general anesthesia is used. (See 'Preparation for anesthesia' above.)

Prior to general anesthesia, the patient is positioned on the operating table with left uterine displacement, with the head and neck positioned optimally for intubation. The patient's abdomen is typically prepared and draped prior to induction of anesthesia, to minimize the time between induction and delivery and fetal exposure to anesthetics. The surgeon makes an incision only after the anesthesia clinician has the airway secured.

Induction of anesthesia — Rapid sequence induction and intubation (RSII) is the standard induction technique for CD. RSII and airway management for pregnant patients are discussed separately. (See "Airway management for the pregnant patient" and "Rapid sequence induction and intubation (RSII) for anesthesia".)

●Induction agents – Propofol (2 to 2.5 mg/kg IV) or etomidate (0.3 to 0.5 mg/kg IV) are the induction agents of choice, although ketamine may be used for hemodynamically unstable or hypovolemic patients. All intravenous induction medications are lipophilic and therefore transfer across the placenta to the fetus. The choice of induction agent should be determined by maternal factors. Since parturients typically do not receive premedication, and have an increased volume of distribution, full induction doses should be administered for general anesthesia. (See "Induction of general anesthesia: Overview" and "General anesthesia: Intravenous induction agents".)

●Adjunctive medications for induction – For most patients, we avoid administration of intravenous opioids until after the fetus is delivered, though practice varies. In a meta-analysis of 17 randomized placebo controlled studies of the use of alfentanil, remifentanil, or fentanyl during induction of anesthesia for CD, there were no significant differences in Apgar scores at one or five minutes after administration of alfentanil or remifentanil [134]. Based on four studies, fentanyl caused a reduction in five-minute Apgar scores (weighted mean difference [WMD] -0.2), a result that was statistically significant but was likely clinically insignificant. For patients with preeclampsia, opioids and other medications are administered during induction of anesthesia to prevent hypertension with laryngoscopy and intubation. (See "Anesthesia for the patient with preeclampsia", section on 'Induction of anesthesia'.)

We administer adjunct medications, including opioids and vasoactive medications, as indicated by the patient’s medical status. (See "Anesthesia for labor and delivery in high-risk heart disease: General considerations" and "Anesthesia for the patient with preeclampsia".)

●Neuromuscular blocking agents – A neuromuscular blocking agent (NMBA), typically succinylcholine, is usually administered during induction as part of RSII. (See "Rapid sequence induction and intubation (RSII) for anesthesia", section on 'Neuromuscular blocking agents (NMBAs)'.)

NMBAs do not cross the placenta and are therefore not associated with weakness in the neonate. For routine CD, NMBAs are not required for surgery beyond endotracheal intubation.

Maintenance of general anesthesia — After induction and intubation, we administer high-dose volatile anesthetic (eg, sevoflurane, isoflurane, desflurane) with high flows of oxygen to quickly obtain an adequate end-tidal concentration of anesthetic (1 MAC) and minimize the chance of awareness under anesthesia.

Volatile inhalation anesthetics produce dose-dependent uterine relaxation [135], which can result in uterine atony and hemorrhage. After delivery, once fetal transfer of medication is no longer a concern, we administer midazolam (2 mg), a short-acting opioid (eg, fentanyl 100 mcg IV), and N₂O 50 to 70%, to allow a reduced dose of volatile anesthetic to 0.5 to 0.75 MAC or substitute a propofol infusion for the volatile anesthetic.

Ventilation should be controlled or supported to achieve an end-tidal CO₂ of approximately 30 mmHg, which should correlate with the normal partial pressure of carbon dioxide (PCO₂) of 30 to 32 mmHg at the end of pregnancy. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Mechanical ventilation'.)

Emergence from anesthesia — Airway complications in obstetric patients are more common during emergence from anesthesia and the immediate postoperative period than during induction and initial airway management [136]. Emergence and extubation in these patients are discussed separately. (See "Airway management for the pregnant patient", section on 'Extubation'.)

POST-CESAREAN DELIVERY ANALGESIA — Multimodal strategies for postoperative pain control after CD should be used to promote rapid recovery, allow the patient to care for their newborn, and to minimize the need for postoperative opioids. For most patients, the strategy for post-CD pain control should consist of neuraxial opioid and scheduled nonopioid analgesics (acetaminophen and nonsteroidal anti-inflammatory drugs [NSAIDs]), with systemic opioids reserved for breakthrough pain. Alternative plans are required for patients who receive general anesthesia for CD and may be required for patients with risk factors for severe postoperative pain (eg, patients with chronic pain and/or who chronically use opioids). Post-CD analgesia is discussed in detail separately. (See "Post-cesarean delivery analgesia".)

PATIENTS WITH SUSPECTED OR CONFIRMED COVID-19 — UpToDate has added information on many aspects of COVID-19, including infection control, airway and other aspects of anesthetic management, intensive care, and obstetric concerns in topic reviews linked at the end of this section. For patients with suspected or confirmed COVID-19, important considerations specific to obstetric anesthesia include the following:

●For elective procedures, screen patients and support persons by phone the night prior to admission to plan necessary resources.

●Use droplet and contact precautions with eye protection (gown, gloves, mask, face shield) whenever entering a labor room. For operative procedures, regardless of the type of anesthesia, anesthesia clinicians should use droplet, contact, and airborne precautions (gown, gloves, face shield, and N95 mask or powered air purifying respirator [PAPR])

●COVID-19 is not a contraindication to neuraxial anesthesia. Early epidural analgesia may reduce the need for general anesthesia and airway management should emergency CD become necessary.

●Patients with COVID-19 often receive venous thromboembolism prophylaxis. The anticoagulation regimen should be carefully considered so that neuraxial anesthesia techniques may be used. (See "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)

●Consider checking a platelet count prior to neuraxial anesthesia in symptomatic patients as thrombocytopenia has been reported in both pregnant and nonpregnant patients with severe COVID-19 illness. [137-139].

●Although data are limited, performance of an epidural blood patch to treat post dural puncture headache (PDPH) in patients with COVID-19 is likely safe. The theoretical risk of seeding the central nervous system by injecting viremic blood into the epidural space must be weighed against the risk of complications of untreated PDPH, and coagulation status must be considered.

Selected UpToDate topic reviews of COVID-19-related issues include the following:

●(See "COVID-19: Perioperative risk assessment, preoperative screening and testing, and timing of surgery after infection".)

●(See "Overview of infection control during anesthetic care", section on 'Infectious agents transmitted by aerosol (eg, COVID-19)'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Local anesthetic systemic toxicity" and "Society guideline links: Post dural puncture headache" and "Society guideline links: COVID-19 – Index of guideline topics" and "Society guideline links: Obstetric anesthesia" and "Society guideline links: Enhanced recovery after surgery".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Anesthesia for cesarean birth (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Preoperative assessment and preparation

•Parturients undergoing cesarean delivery (CD) should have a focused history and physical examination by an anesthesia provider. Antenatal anesthesia consultation should be considered for patients at risk for complications due to preexisting conditions (table 1). (See 'Preoperative assessment' above.)

•For patients who undergo elective or emergency CD, pharmacologic aspiration prophylaxis should be considered. Options include sodium citrate-citric acid, 30 mL orally immediately prior to anesthesia, an H2 receptor antagonist (eg, famotidine 20 mg IV) or proton pump inhibitor (eg, pantoprazole 40 mg IV) 40 to 60 minutes prior to induction, and metoclopramide 10 mg IV over 1 to 2 minutes, ≥30 minutes prior to induction. (See 'Preparation for anesthesia' above.)

●Enhanced recovery after cesarean delivery – Enhanced recovery after cesarean (ERAC) delivery protocols consist of multidisciplinary best practices throughout the perioperative period. Commonly used anesthesia related components of ERAC protocols are shown in a table. (table 3)

●Choice of anesthetic technique – The choice of anesthetic technique for CD should be based on maternal and fetal status, comorbidities, expected duration and difficulty of the procedure, and the presence (or absence) of an in situ epidural catheter. If a working epidural catheter is in place, the epidural catheter is used to achieve surgical anesthesia (algorithm 1).

For most patients, we recommend neuraxial anesthesia (NA) rather than general anesthesia (GA) for CD (Grade 1B). There are exceptions for which GA is more appropriate. While maternal and neonatal outcomes are not clearly improved with NA, most patients prioritize being awake for the birth of the infant. Other theoretical advantages favor NA. (See 'General versus neuraxial anesthesia' above.)

●Neuraxial anesthesia

•For spinal anesthesia, the spinal solution typically includes local anesthetic (LA) (eg, hyperbaric bupivacaine 10 to 12 mg), lipophilic opioid (eg, fentanyl 10 to 25 mcg) to improve intraoperative anesthesia, and hydrophilic opioid (eg, preservative-free morphine 75 to 200 mcg) for postoperative analgesia. (See 'Spinal drugs for CD' above.)

•For epidural anesthesia, the epidural solution typically includes LA (eg, 2% lidocaine with epinephrine 1:200,000 with or without sodium bicarbonate), lipophilic opioid (eg, fentanyl 50 to 100 mcg) to improve intraoperative anesthesia, and hydrophilic opioid (eg, preservative-free morphine 1 to 3 mg) for postoperative analgesia. For emergency CD bicarbonated 3% 2-chloroprocaine provides the most rapid onset of surgical anesthesia. (See 'Epidural drugs for CD' above.)

•Management of failed or inadequate neuraxial anesthesia depends on the urgency of the situation and patient factors. In emergency situations, general anesthesia should be induced. When time permits, neuraxial anesthesia can be performed, taking precautions to avoid high neuraxial block. (See 'Failed or inadequate neuraxial block' above and 'High neuraxial block' above.).

-Inadequate spinal anesthesia – If possible, 20 minutes should be allowed after spinal injection to assess full onset. For partial block, we typically place an epidural catheter and titrate to effect. If there is no evidence of block, it is likely safe to repeat full dose spinal.

-Inadequate epidural anesthesia – We replace the epidural catheter and titrate epidural medication to effect. Single-shot spinal should not be performed following failed epidural anesthesia, to avoid high neuraxial block.

●General anesthesia – For general anesthesia, our usual strategy is as follows:

•We perform rapid sequence induction and intubation. (See 'Induction of anesthesia' above.)

•After induction, we administer high concentration of volatile anesthetic (eg, sevoflurane, isoflurane, or desflurane) to rapidly achieve 1 MAC end tidal anesthetic and minimize the risk of awareness during anesthesia. (See 'Maintenance of general anesthesia' above.)

•After delivery, we administer opioid (eg, fentanyl 100 mcg IV), midazolam 2 mg IV, and nitrous oxide 50 to 70%, and reduce the concentration of volatile anesthetic to 0.5 to 0.75 MAC or substitute a propofol infusion to reduce the risk of uterine atony and hemorrhage.

●Patient positioning – Patients should be positioned with left uterine displacement to attempt to avoid aortocaval compression and supine hypotension. (See 'Intraoperative positioning' above.)

●Hemodynamic management – We suggest administration of phenylephrine, rather than ephedrine, to prevent and treat neuraxial block-induced hypotension in the absence of maternal bradycardia (Grade 2B). For healthy patients, we administer a prophylactic, low dose, titrated infusion of phenylephrine with phenylephrine rescue boluses, along with intravenous volume expansion (co-loading) with glucose free crystalloid solution, with a goal for maternal blood pressure within 20 percent of baseline, and aiming for lack of nausea and vomiting. (See 'Hemodynamic management' above.)