First-trimester pregnancy termination: Uterine aspiration

INTRODUCTION — Termination of pregnancy by uterine aspiration (also known as aspiration curettage, suction curettage, dilation and curettage, or procedural abortion) is a commonly used method of abortion. It is typically used in the first trimester through 13 6/7 weeks of gestation, though it can be performed by some providers through approximately 15 6/7 weeks gestation. Uterine aspiration is an alternative to medication abortion (also referred to as medical abortion or induction abortion).

First-trimester uterine aspiration is reviewed here. An overview of pregnancy termination, including a discussion on how to choose between a medication and aspiration abortion, as well as first-trimester medication abortion and management of second-trimester pregnancy terminations, is discussed elsewhere.

●(See "Overview of pregnancy termination".)

●(See "First-trimester pregnancy termination: Medication abortion".)

●(See "Overview of second-trimester pregnancy termination".)

●(See "Second-trimester pregnancy termination: Induction (medication) termination".)

●(See "Second-trimester pregnancy termination: Dilation and evacuation".)

PATIENT SELECTION — Uterine aspiration is commonly performed through 14 weeks of gestation, though some clinicians offer uterine aspiration in the second trimester.

●Counseling – Patients choosing first-trimester uterine aspiration are counseled about the alternatives (ie, continuing pregnancy with parenting or adoption) and the choice between medication and aspiration abortion, including the risks, benefits, and expected outcomes of each [1-4]. This is discussed in detail separately. (See "Counseling in abortion care" and "Overview of pregnancy termination".)

Many states have regulations and restrictions regarding abortion care [5]. Clinicians should be aware of their state and federal guidelines. (See "Counseling in abortion care".)

●Contraindications – There are few absolute contraindications to first-trimester aspiration abortion, which include inability to obtain informed consent and selected anatomic conditions (eg, fibroids that restrict access to the uterine cavity).

Medical conditions that increase risk of complications with first-trimester abortion also increase the risk of a continued pregnancy. Thus, when abortion is desired in a patient with comorbidities, the relative increased risk of abortion must be compared with the increased risk if pregnancy were to continue.

Low-grade fever (≤100.4°F, or 38°C) and uterine tenderness are not contraindications to aspiration abortion [6-9]. For higher fevers or if clinically significant infection is suspected, the clinician should evaluate for septic abortion. (See "Septic abortion: Clinical presentation and management", section on 'Evaluation'.)

PREPROCEDURE EVALUATION AND PREPARATION

History — Clinicians should elicit a standard medical history. Particular attention should be given to any report of bleeding or clotting disorders, anemia, or uterine/cervical abnormalities.

Physical examination and ultrasound — Physical examination includes:

●Vital signs

●Gestational age estimated by uterine size on pelvic examination

●Uterine flexion assessment by pelvic examination

●Cardiac, pulmonary, and airway assessment for patients in whom moderate or deep sedation is planned

If uterine size on physical examination is inconsistent with the expected gestational age (based on the first day of the last menstrual period), ultrasound may increase the accuracy of the gestational estimation and evaluate uterine anatomy (eg, flexion, fibroids). In settings where ultrasound is readily available, transabdominal ultrasound may be used instead of a pelvic examination to determine gestational age. Transvaginal ultrasound is also used if ectopic pregnancy or early pregnancy loss is suspected. (See "Ectopic pregnancy: Clinical manifestations and diagnosis", section on 'Clinical presentation' and "Pregnancy loss (miscarriage): Ultrasound diagnosis".)

Laboratory testing and alloimmunization prevention — Confirmation of pregnancy typically requires a high-sensitivity urine pregnancy test or ultrasound. Laboratory testing for hemoglobin or hematocrit, chlamydia and/or gonorrhea, and recommendations for RhD testing and administration of anti-D immune globulin are described in detail separately. (See "Overview of pregnancy termination", section on 'Laboratory testing' and "Overview of pregnancy termination", section on 'Alloimmunization prevention'.)

Antibiotic prophylaxis — For patients undergoing first-trimester uterine aspiration abortion, we recommend antibiotic prophylaxis, consistent with guidelines from the Society of Family Planning (SFP), American College of Obstetricians and Gynecologists (ACOG), and Royal College of Obstetricians (RCOG) [6,10,11].

Typical antibiotic regimens include (table 1 and table 2):

●Preferred: Doxycycline (200 mg orally, one dose) one hour prior to the procedure [10].

●Alternatives:

•Metronidazole (500 mg orally, one dose) one hour prior to the procedure. This is a commonly used regimen and is effective based on clinical experience but has not been well studied [12].

or

•Azithromycin (500 mg orally, one dose) one hour prior to the procedure. This is a commonly used regimen and is effective based on clinical experience but has not been well studied [12]. We prefer 500 mg rather than 1000 mg because it causes less nausea.

While prophylactic antibiotics should ideally be given one hour prior to the procedure, they may be given up to 12 hours prior [6].

Randomized trials and meta-analyses have demonstrated that prophylactic antibiotic therapy reduces the risk of genital tract infection after first-trimester uterine aspiration abortion [13,14]. In a meta-analysis of 21 randomized trials including patients undergoing first-trimester uterine aspiration, antibiotic prophylaxis compared with placebo or no antibiotics resulted in lower rates of genital tract infection (4.3 versus 6 percent, relative risk [RR] 0.72, 95% CI 0.58-0.90) [14].

The choice of regimen is guided mostly by susceptibility patterns of likely pathogens, bioavailability of antimicrobials, and clinical experience [6,10,11]. Based on the available limited data, no single agent or regimen appears to be superior to others [13,14]. In the meta-analysis of placebo-controlled trials described above, the benefit of prophylactic antibiotics did not appear to differ according to the type of antibiotic or dosing regimen used [14]. The trials included in the meta-analysis used a wide range of antibiotic regimens; many investigated regimens with two or more antibiotics given in multiple doses, including regimens with both pre- and postoperative administration [13,14]. There have been few studies directly comparing one regimen versus another [13].

Thromboprophylaxis — For most patients, thromboprophylaxis (either pharmacologic or mechanical) is not required as first-trimester uterine aspiration is a minor procedure with a low risk of venous thromboembolism; early ambulation is encouraged. This is in accordance with American College of Chest Physicians guidelines [15]. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

Limited role for cervical preparation — Cervical preparation with osmotic dilators or medications (eg, misoprostol) is not routinely used for most patients undergoing first-trimester aspiration abortion; cervical preparation delays the procedure, is associated with risk of complications and side effects, and does not confer proven benefit.

However, there are some exceptions, and for patients in whom dilation may be more difficult or are at an increased risk of cervical injury, preprocedure cervical preparation may be appropriate. This is discussed in detail separately. (See "Pregnancy termination: Cervical preparation for procedural abortion", section on '12 to <14 weeks'.)

Procedure setting — The vast majority (80 to 90 percent) of first-trimester uterine aspiration procedures in the United States can be performed safely in an outpatient clinical setting (eg, office, ambulatory surgery center) [16,17]. In a study including over 23,000 first-trimester aspiration abortion procedures from a United States private insurance database, those performed at ambulatory surgery centers compared with office-based settings had similarly low rates (2.2 and 2.6 percent) of adverse events [18].

Hospital admission after uterine aspiration is rare and there are no absolute indications for hospital-based terminations. Rather, criteria for a hospital-based procedure depends on patient's history (eg, hemodynamic stability, severity of comorbidities), provider's experience level, resources at their clinic, and available resources for referral. Patients who need an abortion and who are unstable or those already hospitalized for acute illnesses or other medical conditions (eg, decompensated heart failure, severe symptomatic anemia) may be best managed as an inpatient. Some geographic areas have limited access to abortion care and hospital-based care may not be readily available. For patients with medical comorbidities in such areas, outpatient or ambulatory care centers with deep sedation or higher-level staffing (eg, anesthesiologist, certified nurse anesthetist) are appropriate alternatives.

PAIN MANAGEMENT — Pain associated with first-trimester uterine aspiration may be alleviated by a variety of analgesics as well as nonpharmacologic methods. Clinicians may find that an individualized analgesia plan to match patient preferences and expectations is most appropriate for their practice [19].

Basic measures — In many patients, pain is adequately controlled with nonsteroidal antiinflammatory drugs (NSAIDs), local anesthesia, and verbal support.

●NSAID – Ibuprofen is typically administered 30 to 60 minutes before the procedure [20].

Ibuprofen is generally preferred over ketorolac as it is given orally and is equally effective [21].

●Paracervical block – Use of a paracervical block for local anesthesia is nearly universal in first-trimester uterine aspiration (figure 1) [22]. We use 20 mL of buffered 1% lidocaine; an alternative is 1% chloroprocaine. (See 'Paracervical block' below.)

In one randomized trial including 120 patients undergoing first-trimester uterine aspiration, those receiving a paracervical block (20 mL of 1% buffered lidocaine) compared with a sham block had lower pain scores with cervical dilation and aspiration and higher satisfaction scores for pain control and the procedure overall [23]. A cervical block with lidocaine has also been described. In this randomized trial including 50 patients undergoing first-trimester uterine aspiration, those receiving a paracervical block with lidocaine combined with ketorolac compared with oral ibuprofen and a standard lidocaine block had improved pain after cervical dilation (60 versus 75 mm, on a scale of 0 to 100 mm), but not other procedure-related pain [24].

The paracervical block technique and commonly used anesthetic agents are discussed in detail separately. (See "Pudendal and paracervical block", section on 'Gynecologic procedures'.)

●Verbal support – In the awake patient, a designated support person can provide verbal support and reassurance to decrease anxiety, which in turn may decrease pain. This method may include distractions through unrelated conversation or guided breathing and relaxation techniques. The support person may be a friend, partner, trained staff member, or doula who sits close to the patient during the procedure. Randomized trials and qualitative research point to positive outcomes from using abortion doula services, such as a reduced need for additional clinical support staff [25-27].

The use of neutral or nonspecific language during procedures has also been shown in some but not all studies to reduce pain perception [28-30]. Some suggestions for neutral communication for abortion and gynecologic care are outlined in the table (table 3). Also, giving the patient some control (eg, taking a break in the middle of the procedure, requesting additional medication) may also decrease anxiety.

●Other – We view use of an opioid analgesic as optional as it has no proven benefits. In one randomized trial including 120 patients undergoing first-trimester uterine aspiration, hydrocodone/acetaminophen compared with placebo increased postoperative nausea without other benefit [31].

Role of procedural sedation — While many patients have adequate pain control with the above measures (see 'Basic measures' above), procedural sedation may be used, where available, to enhance pain control. Since most first-trimester abortions are performed in the outpatient setting, it is uncommon to administer moderate or deep sedation. Any patient taking oral or IV sedating medications should be instructed that they cannot drive themselves home after the procedure and must have a confirmed person to take them home afterwards. Requiring a driver, particularly for a procedure widely associated with social stigma and potential legal risk, may be a barrier for some patients and should be kept in mind when planning the use of oral or IV sedation.

●IV sedation – IV sedation must be administered by a licensed practitioner (eg, physician, certified nurse midwife, registered nurse), and all patients receiving moderate sedation or deeper must have cardiorespiratory monitoring by a clinician other than the provider performing the procedure. These issues are discussed in detail separately. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications", section on 'Preparation and monitoring'.)

When IV sedation is chosen, we use fentanyl 100 mcg and midazolam 2 mg at the start of the procedure. Additional details of this combination and other options are discussed separately. (See "Procedural sedation in adults in the emergency department: Medication selection, dosing, and discharge criteria", section on 'Coadministration of midazolam and fentanyl' and "Procedural sedation in adults in the emergency department: Medication selection, dosing, and discharge criteria", section on 'Medication choice and dosing when increased risk of complications'.)

IV sedation provides enhanced pain control. In one randomized control trial of 130 patients, those receiving IV sedation (fentanyl 100 mcg and midazolam 2 mg) compared with oral sedation (oxycodone 10 mg and lorazepam 1 mg sublingual), had lower adjusted intraoperative pain scores (36 versus 61 on verbal rating scale of 0 to 100) [32].

●Oral anxiolysis – As the higher level of staffing required for IV sedation is not available in all settings, many providers rely on oral anxiolytics to reduce preprocedural anxiety.

When oral anxiolysis is chosen, we most commonly give lorazepam (0.5 to 2 mg sublingual) 30 minutes prior to the procedure. Some outpatient clinics may have the ability to directly dispense medications, while other providers may prescribe benzodiazepines in advance for patients to bring with them for administration in clinic prior to the procedure.

In a randomized trial involving 124 patients undergoing first-trimester uterine aspiration, those receiving an oral anxiolytic (midazolam) prior to the procedure had less preprocedural anxiety compared with those who received placebo, though pain scores were similar in both groups [33]. Patients in the midazolam group had less nausea and more commonly reported partial amnesia; however, they were also more likely to have postoperative dizziness and sleepiness.

●Nitrous oxide – While nitrous oxide does not appear to be superior to oral or IV sedatives during uterine aspiration, its limited duration of side effects and lack of restriction on driving home afterwards may be advantageous in the outpatient setting for some patients. This is especially true for patients who need to drive long distances to access abortion services due to geographic or legal restrictions.

In one randomized trial including 140 patients undergoing first-trimester uterine aspiration, use of nitrous oxide with oxygen (N₂O/O₂) compared with oral hydrocodone/acetaminophen and lorazepam resulted in similar pain scores and patient satisfaction [34]. However, in another randomized trial evaluating the use of nitrous oxide for pain control during hysteroscopic sterilization, N₂O/O₂ compared with oral medications alone resulted in lower mean pain scores (22.8 versus 54.5 on 100 mm visual analog scale) [35]; the concentration of N₂O/O₂ was titrated up to a maximum of 70:30 more frequently than in the uterine aspiration study.

Further information on patient selection and administration of procedural sedation can be found separately. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications" and "Procedural sedation in adults in the emergency department: Medication selection, dosing, and discharge criteria".)

PROCEDURE

Patient positioning and procedural instruments — The patient is guided into a recumbent position suitable for a pelvic examination.

As in other vaginal procedures, gloves are used, but a vaginal procedure cannot be sterile. Thus, sterile gloves are not required if the clinician utilizes a no-touch technique to maintain sterility of all instruments that pass through the cervical os. (See "Overview of preoperative evaluation and preparation for gynecologic surgery", section on 'Vaginal preparation'.)

The picture shows a typical equipment tray for manual uterine aspiration (picture 1).

Paracervical block — Following a bimanual pelvic examination to assess uterine size and flexion, a vaginal speculum is used to visualize the cervix. Antiseptic solution (eg, povidone-iodine, chlorhexidine) may be used to cleanse the cervix prior to uterine aspiration, though this practice has not been shown to prevent abortion-related infection [6].

Approximately 2 mL of local anesthetic (eg, 1% buffered lidocaine) is injected into the cervical stroma at the planned location of tenaculum placement. Use of a tenaculum with adequate traction will straighten the cervicouterine angle for safer passage of intrauterine instruments during dilation and aspiration. A paracervical block, typically using a total of 20 mL of local anesthetic, is then administered (figure 1). (See 'Basic measures' above.)

Mechanical dilation — For most patients, mechanical cervical dilation is required to accommodate the cannula size that is necessary to remove the pregnancy tissue. Mechanical dilation may not be necessary for patients with gestations less than 7 0/7 weeks.

Cannulas are sized by diameter, and most clinicians choose a diameter equal to the number of weeks of gestation or 1 mm smaller. For example, at seven weeks, the tissue can be aspirated safely and effectively with a 7 mm or a 6 mm cannula. Sequential rigid dilators are passed until adequate dilation is reached to pass the desired cannula. If dilation cannot be achieved, additional cervical preparation may be warranted before proceeding with aspiration. (See "Pregnancy termination: Cervical preparation for procedural abortion".)

Uterine evacuation

Aspiration procedure — Aspiration is performed with a flexible or rigid, curved or straight plastic cannula attached to a manual or electric vacuum aspirator (figure 2). Sharp curettage alone (without aspiration) is not effective to accomplish uterine evacuation, and the World Health Organization strongly recommends against its routine use as a standalone abortion procedure in the first trimester [36,37].

Choice of cannula type is based on provider preference, as they can be used interchangeably with each type of aspirator. Some clinicians prefer to use a flexible, straight cannula with a manual uterine aspirator (MUA) for gestations ≤10 weeks and use a rigid, curved cannula with an electric vacuum aspirator (EVA) for gestations >10 weeks. Extraction forceps may also be needed for later gestational ages (eg, >15 0/7 weeks gestation). (See "Second-trimester pregnancy termination: Dilation and evacuation", section on 'Uterine evacuation'.)

For gestations ≤10 weeks, MUA and EVA have similar rates of successful uterine evacuation, patient acceptability, and major complications [38,39]. By contrast, for gestations ≤50 days, pooled analyses from randomized trials show that MUA had less blood loss and less perceived pain but a longer procedure time than EVA [39]. MUA is also quieter (which may make it preferable for some patients [40,41]), more portable, less expensive, and does not require electricity (which makes it favorable for use in resource-limited settings).

The completion of the procedure is signaled by a gritty sensation of the endometrium at the top of the cannula and the strength of the empty uterus contracting around the cannula.

Role of ultrasound during procedure — Ultrasound guidance during the aspiration procedure may be employed at the discretion of the provider, as there is no evidence for or against its practice in the first trimester. It is most often used if there is suspicion or knowledge of uterine abnormalities (eg, fibroids, bicornuate uterus), multiple gestation, difficult cervical dilation, procedures performed at later gestational ages (eg, ≥12 or 14 weeks), or when teaching uterine aspiration skills.

Tissue evaluation

Expected findings — After uterine aspiration, most clinicians examine the products of conception (POC).

POC findings that confirm a complete abortion vary by gestation (picture 2):

●≤9 weeks of gestation – Identification of the appropriately sized gestational sac is sufficient to confirm completion of procedure.

●10 to <12 weeks – In addition to the gestational sac, fetal parts may begin to be identified.

●≥12 weeks – Four extremities, spine, calvarium, gestational sac, and placenta must all be identified.

Inadequate products of conception — If inadequate POC are suspected at the time of the procedure, the first-line approach is to repeat aspiration immediately. When available, we use intraoperative transabdominal ultrasound guidance to guide re-aspiration and to assure the cannula is reaching the uterine fundus and pregnancy tissue. For retained POC easily identified on transabdominal ultrasound prior to re-aspiration, this intraoperative sonogram is often sufficient to confirm a successful evacuation.

When transabdominal ultrasound does not identify retained POC, transvaginal ultrasound may be performed. If POC are still not identified, a diagnosis of ectopic pregnancy, uterine anomaly (which may be complicating access to the pregnancy), or very early intrauterine gestation (for which tissue may not be easily identified) should be further considered. For such patients, serial laboratory testing of quantitative serum beta human chorionic gonadotropin (hCG) is often required. A serum level is drawn on the day of the aspiration as a baseline, and a repeat hCG is measured in 24 to 48 hours. A fall in hCG of at least 50 percent indicates the pregnancy was intrauterine and the aspiration procedure was successful [37,42,43]. If there is an inadequate decline or a rise in hCG levels, further evaluation (with ultrasound and/or hCG level) for retained POC, ongoing pregnancy, or ectopic pregnancy is needed. (See "Approach to the patient with pregnancy of unknown location", section on 'Hemodynamically stable patients' and "Ectopic pregnancy: Clinical manifestations and diagnosis", section on 'Diagnostic evaluation' and 'Incomplete or failed abortion' below.)

RECOVERY AND FOLLOW-UP — Postprocedure recovery time is typically 20 to 30 minutes for patients who receive minimal or moderate sedation. During recovery, the patient should be assessed for stable vital signs, vaginal bleeding, adequate pain control, and ability to ambulate independently at time of discharge. Postprocedure care and instructions are provided in writing and reviewed verbally (table 4).

While data do not support routine postprocedure visits after uterine aspiration [44], warning signs that indicate need for a postprocedure visit include [45]:

●Vaginal bleeding more than two maxi pads per hour for more than two consecutive hours

●Cramps that are persistent and worsening despite pain medication

●Temperature ≥100.4°F (38°C)

We inform all patients about their ability to get pregnant quickly following pregnancy termination and that contraceptive methods can be placed, dispensed, or prescribed on procedure day, if desired [46]. (See "Contraception: Postabortion", section on 'Initiation of contraception' and "Overview of pregnancy termination", section on 'Plan for contraception'.)

COMPLICATIONS — First-trimester uterine aspiration is a safe and effective procedure for appropriately selected patients [47]; the overall complication rate is approximately 9 per 1000 [48]. Major complications (suspected perforation, missed ectopic pregnancy, hemorrhage, sepsis) are rare (0.71 per 1000) [49].

Maternal mortality — The overall death rate from all legal abortions is far less than the maternal mortality ratio among patients with term pregnancies in the United States. (See "Overview of pregnancy termination", section on 'Maternal mortality'.)

In a systematic review including 57 studies evaluating complications after first-trimester aspiration abortion, no abortion-related deaths were reported (six studies, over 220,000 patients) [50]. One additional study in this review including over 20,000 patients reported four maternal deaths, but none were attributed to complications from the procedure (deaths were from external causes, such as suicide and homicide) [51].

Infection — Postabortal endometritis is uncommon when antibiotic prophylaxis is used (see 'Antibiotic prophylaxis' above). In a 2015 systematic review including five office-based studies in which all patients received antibiotic prophylaxis prior to first-trimester uterine aspiration, <2 percent of patients required outpatient treatment for presumed or diagnosed infection [50].

Management of patients with postabortal endometritis is as follows:

●Patients with suspected postabortion infection who are hemodynamically stable and are not toxic-appearing can be treated with oral antibiotics as an outpatient. We prescribe broad-spectrum antibiotic therapy (with coverage of anaerobes) such as:

•Ceftriaxone 500 mg intramuscularly once plus

•Doxycycline 100 mg orally twice daily for 14 days plus

•Metronidazole 500 mg orally twice daily for 14 days

This regimen is in accordance with Centers for Disease Control and Prevention guidelines for pelvic inflammatory disease [52]. (See "Pelvic inflammatory disease: Treatment in adults and adolescents", section on 'Outpatient therapy'.)

●Patients in whom more severe infection or sepsis is suspected (eg, generalized abdominal tenderness, guarding, tachycardia, high fever, lethargy), or those who fail outpatient management, require aggressive therapy with broad spectrum intravenous antibiotics, assessment for uterine perforation, and inpatient monitoring and support, possibly in an intensive care unit. (See "Septic abortion: Clinical presentation and management", section on 'Management'.)

●Any retained products of conception (POC) or blood clot found on ultrasound in the setting of suspected infection should be evacuated. (See 'Incomplete or failed abortion' below.)

Hemorrhage — Postabortal hemorrhage (eg, bleeding requiring transfusion or admission, bleeding >500 mL) is uncommon with first-trimester uterine aspiration. In the systematic review discussed above (see 'Maternal mortality' above), hemorrhage requiring transfusion occurred in ≤0.1 percent of procedures [50].

When hemorrhage does occur, it usually results from uterine atony, cervical or vaginal lacerations, uterine perforation, or retained tissue. Abnormal placentation (usually a result of prior cesarean birth, endometrial ablation, or other uterine surgery in which there was damage to the endometrial-myometrial interface) may also result in significant bleeding with uterine aspiration but is rare in early gestations.

If abnormal placentation is suspected prior to the procedure, additional precautions (eg, use of intraoperative ultrasound, avoiding direct suction curettage over the uterine scar or area of suspected abnormal implantation, having an electric vacuum aspirator immediately available, advanced notification of back-up providers such as a gynecologic surgeon or interventional radiologist) should be taken. Depending on availability and access, providers may consider using an operating room with blood products available.

Our management approach of such patients is like that of The Society of Family Planning (SFP) guidelines and is discussed in detail separately [53]. (See "Overview of pregnancy termination", section on 'Hemorrhage'.)

Cervical or vaginal laceration — Cervical or vaginal trauma from first-trimester uterine aspiration is rare (≤0.1 percent) [50], but risk can be reduced by appropriate cervical preparation in patients in whom difficult mechanical dilation is anticipated. (See 'Limited role for cervical preparation' above.)

Most cervical or vaginal trauma during first-trimester uterine aspiration can be controlled with direct pressure for one to two minutes. For cervical lacerations, application of silver nitrate or ferric subsulfate (Monsel solution) may be useful. Lacerations that have persistent bleeding are repaired surgically with absorbable sutures; only a single suture is typically needed.

Uterine perforation — For both first- and second-trimester surgical termination procedures, the reported rate of uterine perforation is less than 0.6 percent [50,54-56]. In the systematic review discussed above (see 'Maternal mortality' above), uterine perforation in which additional interventions were necessary occurred in ≤0.1 to 2.3 percent of procedures (seven studies) [50].

When uterine perforation is suspected, the aspiration procedure should be stopped to evaluate the extent of the perforation using ultrasound guidance. If there is no evidence of vascular or visceral injury (eg, excessive bleeding, hypotension, acute onset of hematuria) and the procedure is not complete, the procedure can continue under ultrasound guidance if the remaining pregnancy tissue can be safely reached. Less commonly, the procedure can be postponed for one to two weeks to allow closure of the perforation; the subsequent aspiration is performed under ultrasound guidance. By contrast, immediate surgical intervention is indicated if there are signs of severe uterine bleeding, or vascular or visceral injury are suspected. (See "Uterine perforation during gynecologic procedures", section on 'Management'.)

Post-procedure, the patient is typically monitored in the recovery room for one to two hours for signs of intraperitoneal hemorrhage or visceral injury. While some experts prescribe antibiotics (metronidazole 500 mg by mouth twice daily for one week) for patients with suspected uterine perforation, other experts only administer antibiotics to those with clinical signs of infection (eg, endometritis, peritonitis). This is discussed in more detail separately. (See "Uterine perforation during gynecologic procedures", section on 'Postprocedure monitoring' and "Uterine perforation during gynecologic procedures", section on 'Management'.)

Hematometra — Immediate postoperative pain (eg, dull, aching lower abdominal pain) without overt bleeding from the vagina may indicate development of hematometra. Pain due to hematometra can sometimes be accompanied by tachycardia, diaphoresis, or nausea. The onset is usually within the first hour after completion of the procedure.

On pelvic examination, the uterus is often large, midline, globular and is tense and tender to palpation. Ultrasound examination may reveal an enlarged uterine cavity filled with echogenic material. Treatment requires immediate uterine evacuation, permitting the uterus to contract to a normal postprocedure size. Intramuscular methylergonovine maleate (0.2 mg) may be given to ensure continued contraction of the uterus [57].

Incomplete or failed abortion — All patients will continue to have an elevated level of hCG for a short period following pregnancy termination; a positive urine pregnancy test after an abortion is not diagnostic of ongoing pregnancy. Return of the serum hCG concentration to undetectable following pregnancy termination varies widely from 7 to 60 days [42], and depends primarily on the hCG concentration at the time of termination.

●Incomplete abortion – Incomplete abortion refers to retained POC (ie, placental tissue, fetal fragments, fetal membranes) and is an uncommon complication of first-trimester uterine aspiration. In one series evaluating patients undergoing pregnancy termination and in whom follow-up information was available (80 percent of patients), retained POC were present in 4 of 672 first-trimester procedures [58].

While presentation of retained POC can be similar to that of hematometra or endometritis (lower abdominal or pelvic pain and an enlarged or tender uterus), these entities can often be distinguished by the character and timing of these symptoms. For example, a patient with retained POC typically presents with pain and/or heavy or persistent vaginal bleeding days or weeks after the procedure. By contrast, hematometra is more likely to present with pain immediately postabortion (within one hour) and without heavy vaginal bleeding; endometritis is more likely to be accompanied by fever and pain that is not associated with sonographic evidence of retained tissue in the uterine cavity [59].

Symptomatic patients with suspected retained POC are typically managed with repeat aspiration (to completely empty the uterus). Misoprostol is also an acceptable alternative, and expectant management can be offered to selected patients. By contrast, asymptomatic patients can often be managed expectantly. This is discussed in detail separately. (See "Retained products of conception in the first half of pregnancy", section on 'Management'.)

●Failed abortion – Failed abortion, or an ongoing pregnancy after an attempted pregnancy termination, is rare, but occurs more frequently at early gestational ages (eg, <7 0/7 weeks of gestation when a definitive intrauterine pregnancy may not be seen on ultrasound) [60-62]. Ongoing pregnancy may also rarely result from a multiple gestation in which only one of the sacs was evacuated, or in those with uterine pathology (eg, congenital uterine anomaly, large submucosal fibroid) [62,63].

In a prospective study of 1132 uterine aspiration procedures up to seven weeks of gestation, the failed abortion rate was 15 per 1000; all providers inspected tissue on-site using flotation and backlighting, as is standard practice [64]. A modest reduction in failed abortion (rate of 1.3 per 1000) at <7 weeks was seen in one case series of 2399 patients, in which a resource-intensive protocol included pre- and postabortion transvaginal ultrasonography, a rigid 7 mm cannula for aspiration, and colposcopic magnification for POC examination when needed to confirm procedure completion [65,66].

The type and risk of possible damage to the ongoing pregnancy from an attempted abortion cannot be quantified and direct or indirect injury to the developing embryo could occur.

SPECIAL CONSIDERATIONS

Multiple gestations — Uterine aspiration of multiple gestations in the first trimester can generally be approached like a single gestation of the same duration. For example, a six-week twin pregnancy can be successfully evacuated by manual uterine aspiration through a 6 mm cannula following the same steps as for a six-week singleton pregnancy.

An electric vacuum aspirator (EVA) rather than a manual uterine aspirator (MUA) may better accommodate the increased volume of tissue with multiple gestations, and uterotonics can treat excessive bleeding due to uterine atony. Many providers will also use ultrasound guidance for multiple gestations at an earlier gestational age than for singletons for reassurance of procedure completion as it may be difficult to assess from tissue examination if all gestational products were evacuated. (See 'Expected findings' above.)

Uterine anomalies and abnormalities — Uterine anomalies or abnormalities (eg, congenital uterine anomaly, large fibroids) can pose challenges in uterine aspiration. Ultrasound guidance is extremely helpful in navigating a divided or distorted endometrial cavity. Aspiration of the nonpregnant horn of a didelphic uterus is not necessary, but, if easily accomplished, may decrease postprocedure uterine bleeding.

Adjunctive use of misoprostol for cervical preparation may be useful for gestations <12 weeks when cervical dilation is impaired by fibroids (see 'Limited role for cervical preparation' above). When large fibroids impede placement of the cannula at the fundus to reach the pregnancy, alternate instruments, such as EVA nozzle extenders may be helpful. Some providers anecdotally report modifying flexible cannulas in tandem or inserting a moldable metal uterine sound inside a cannula to navigate placement past fibroids.

Finally, it is important to remember that when uterine aspiration is not successful due to these anatomic challenges, medication abortion is often an alternative.

Suspected molar pregnancy — Molar pregnancy should be considered in any patient with a prior history of hydatidiform mole. Molar pregnancy may also be suspected preprocedure from characteristic ultrasound findings (eg, classic "snowstorm or Swiss cheese pattern" of a central heterogeneous mass in the uterus with numerous discrete anechoic spaces) or a markedly high serum hCG level. Postprocedure, a molar pregnancy may be suspected if hydropic swellings of the chorionic villi are seen during tissue examination.

In the case of suspected molar pregnancy, tissue should be sent for pathology evaluation. In our practice, we also send a serum hCG on the day of uterine evacuation as a baseline in case further monitoring is required. In the event of a confirmed molar diagnosis, protocols for hCG monitoring should be followed. (See "Hydatidiform mole: Treatment and follow-up".)

Future pregnancies — Study results vary regarding uterine aspiration and risks to subsequent pregnancy. This is discussed separately. (See "Overview of pregnancy termination", section on 'Future pregnancies'.)

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: Pregnancy termination".)

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 topic (see "Patient education: Abortion (The Basics)")

●Beyond the Basics topic (see "Patient education: Abortion (pregnancy termination) (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Clinical significance – Termination of pregnancy by uterine aspiration is a commonly used abortion method; most of these are done in the first trimester. (See 'Introduction' above.)

●Counseling – Aspiration abortion and medication abortion are both safe and effective procedures for appropriately selected patients. The choice between the two methods is discussed elsewhere. (See 'Patient selection' above and "Overview of pregnancy termination", section on 'Choice of procedure'.)

●Preprocedure evaluation and preparation

•Role of ultrasound – Ultrasound is useful if uterine size on examination is inconsistent with expected gestational age or if there is a suspicion of an ectopic pregnancy. (See 'Physical examination and ultrasound' above.)

•Laboratories – Laboratory testing for hemoglobin or hematocrit, chlamydia and/or gonorrhea, as well as recommendations for RhD testing and administration of anti-D immune globulin are discussed in detail separately. (See 'Laboratory testing and alloimmunization prevention' above and "Overview of pregnancy termination", section on 'Laboratory testing' and "Overview of pregnancy termination", section on 'Alloimmunization prevention'.)

•Prophylactic antibiotics – For all patients undergoing first-trimester uterine aspiration abortion, we recommend antibiotic prophylaxis (Grade 1B). Antibiotic prophylaxis reduces the risk of postabortion infection. We suggest doxycycline (single dose of 200 mg given orally one hour prior to the procedure) rather than other agents (Grade 2C). However, alternative regimens are also reasonable, as summarized in the table (table 1). (See 'Antibiotic prophylaxis' above.)

•Role of cervical preparation – Cervical preparation with osmotic dilators or cervical ripening medications is typically not required in first-trimester aspiration abortion. Exceptions to this are patients in whom difficult mechanical dilation is anticipated or if there is an increased risk of cervical injury. Guidance on the use of cervical preparation is provided separately. (See 'Limited role for cervical preparation' above and "Pregnancy termination: Cervical preparation for procedural abortion", section on '12 to <14 weeks'.)

●Pain management – Pain control for first-trimester aspiration abortion includes nonsteroidal antiinflammatory drugs (NSAIDs), local anesthesia with a paracervical block (figure 1), and verbal support. While procedural sedation (where available) may enhance pain control, a driver home is required which may be a barrier for some patients. (See 'Pain management' above.)

●Procedure – The aspiration procedure includes a paracervical block, mechanical cervical dilation, and aspiration of uterine contents with a manual or electric aspirator (figure 2). Some suggestions for neutral communication for abortion and gynecologic care are outlined in the table (table 3). After aspiration, the products of conception are examined to confirm complete uterine evacuation (picture 2). (See 'Procedure' above and 'Tissue evaluation' above.)

●Recovery and follow-up – Future pregnancy plans may be discussed, and appropriate guidance given for preconception or contraceptive care. Patients should be counseled to seek medical attention if they have postprocedure symptoms, including excessive vaginal bleeding, persistent pelvic cramps, or temperature ≥100.4°F or 38°C (table 4). (See 'Recovery and follow-up' above.)

●Complications – First-trimester aspiration abortion is a safe procedure and major complications (eg, uterine perforation, hemorrhage, sepsis) are rare. (See 'Complications' above.)

ACKNOWLEDGMENTS — The UpToDate editorial staff acknowledges Frank W Ling, MD, and Lee P Shulman, MD, who contributed to earlier versions of this topic review.