Cesarean birth: Management of the deeply impacted head and the floating head

INTRODUCTION — Fetal extraction is difficult in a small proportion of cesarean births, and such cases are associated with increased maternal and neonatal morbidity [1]. Causes of difficult extraction include:

●Deeply impacted fetal head

●Floating fetal head

●Extremely low birth weight fetus

●Breech or transverse fetal lie

●Low anterior placenta

●Uterine constriction ring (Bandl's ring)

Surgical preparation for cesarean birth should include anticipating potential difficulties with fetal extraction, taking steps to prevent these difficulties from occurring, and having a plan for managing them if they do occur. This involves mobilization of the proper resources, both personnel and equipment, prior to initiation of the procedure.

Although much has been written about techniques for managing difficult vaginal births, there is a paucity of literature to assist obstetricians with a difficult cesarean birth. The best available information is from case reports, small case series, expert opinion, and clinical experience.

This topic will focus on methods for managing two difficult clinical scenarios when fetal extraction may be difficult at cesarean birth: the deeply impacted fetal head and the floating fetal presenting part. Approaches to other causes of potentially difficult fetal extraction are reviewed separately:

●Breech birth (see "Delivery of the singleton fetus in breech presentation", section on 'Cesarean breech birth')

●Transverse lie (see "Transverse fetal lie", section on 'Procedure for cesarean birth')

●Uterine constriction ring (see "Cesarean birth: Surgical technique", section on 'Bandl's ring')

●Preterm low birth weight (see "Delivery of the low birth weight singleton cephalic fetus", section on 'Techniques for atraumatic cesarean birth')

Management of uncomplicated fetal extraction is also discussed separately. (See "Cesarean birth: Surgical technique", section on 'Fetal extraction'.)

GENERAL PRINCIPLES — Atraumatic fetal extraction is facilitated by adequate incisions in the skin, abdominal wall, and uterus and uterine relaxation.

Adequate incision — The skin, abdominal wall, and hysterotomy should be opened adequately to allow for atraumatic fetal delivery.

●Skin – While there are limited data on what is an adequate skin incision size, most experts suggest approximately 15 cm (the size of an Allis clamp) for the cesarean birth of a term fetus. (See "Cesarean birth: Surgical technique", section on 'Skin incision'.)

●Abdominal wall – A Pfannenstiel-Kerr incision the same length as the skin incision is most commonly used for opening the abdominal wall in patients who are not obese and may be enlarged quickly and substantially by transverse incision of the rectus muscles (called a Maylard incision), if required. (See "Cesarean birth: Surgical technique", section on 'Opening the abdomen'.)

In patients with obesity, body habitus, including weight distribution and panniculus size, should be carefully assessed before deciding upon the appropriate incision. The type of incision may affect ease of infant delivery, as well as exposure, postoperative pain and respiratory effort, wound strength, and wound complication rates. (See "Cesarean birth: Overview of issues for patients with obesity", section on 'Abdominal wall incision'.)

●Hysterotomy – The uterine incision is usually transverse but may be vertical; no randomized trials have compared the two techniques with respect to ease of fetal extraction. Although lateral sharp extension of a low transverse uterine incision may be adequate to facilitate a difficult fetal extraction, a T-shaped or J-shaped hysterotomy may be required to avoid injury to the uterine vasculature and possibly the ureters [2], with an increased risk of uterine rupture in a future pregnancy. Therefore, the position and size of the fetus, location of the placenta, presence of leiomyomas, development of the lower uterine segment, and future pregnancy plans should be considered before choosing a transverse rather than a vertical incision. (See "Cesarean birth: Surgical technique", section on 'Hysterotomy' and 'Reverse breech extraction ("pull method")' below.)

Uterine relaxation

●In patients receiving neuraxial anesthesia, uterine relaxation can be achieved quickly with nitroglycerin. Onset of action is immediate, and relaxation lasts three to five minutes. We suggest 50 micrograms of nitroglycerin administered intravenously, followed by up to four additional doses of 50 micrograms every 60 seconds, as needed, to achieve adequate uterine relaxation [3]. Beginning with the minimal effective dose may decrease the risk of maternal hypotension, compared with using an initial bolus of 100 to 200 micrograms, but the higher initial dose may be more appropriate when urgent fetal extraction is required [4,5].

Most patients achieve adequate uterine relaxation with a total dose of ≤250 micrograms. The only randomized trial comparing nitroglycerin versus placebo to facilitate fetal extraction during planned repeat cesarean birth did not demonstrate any benefit [6]; however, the surgeons considered only 16 of the 97 fetal extractions as difficult (10/66 in the nitroglycerin group and 6/31 in the placebo group), so the possibility of a modest benefit cannot be excluded. It is also possible that nitroglycerin would be more effective for intrapartum cesarean births since myometrial tone might be higher in the laboring uterus.

●In patients receiving general anesthesia for cesarean birth, inhalational anesthetic agents, such as sevoflurane, desflurane, and isoflurane, are commonly used for maintenance and produce dose-dependent uterine relaxation. This feature can be leveraged when greater relaxation is needed. (See "Anesthesia for cesarean delivery".)

DEEPLY IMPACTED FETAL HEAD

Epidemiology — An impacted fetal head was noted in approximately 1.5 percent of all cesarean births in one study [1] and 16 percent of second stage cesarean births in another study [7]. It is most likely to occur following a prolonged second stage or after failed attempts at operative vaginal delivery.

Overview of pathophysiology and management — When the fetal head descends into the vagina and does not progress further, the vaginal tissues conform to the head, resulting in a suction cup-like effect that can make elevating the head back up to the uterine incision challenging at cesarean. The deeply impacted fetal head is considered impacted if it cannot be gently moved out of the pelvis during a vaginal examination between contractions or if there is insufficient space between the fetal head and symphysis pubis to permit delivery with standard fetal extraction maneuvers.

Forceful use of standard fetal extraction maneuvers in this setting may cause extensive maternal trauma (eg, laceration of the lower uterine segment, uterine vessels, cervix, vagina, and/or urinary tract) and may severely injure the fetus (eg, intracranial and subgaleal hemorrhage, skull fracture, nerve injury, neck fracture, death) [7-9]. Postpartum hemorrhage, broad ligament hematoma, injury to the ureters during repair, and postpartum infection are additional concerns. However, it can be difficult to determine whether these adverse effects are attributable to disengagement maneuvers or to a prolonged second stage or a failed trial of operative vaginal birth or a combination of factors.

The procedures described in the sections below have been used for delivering the fetus with a deeply impacted fetal head. A well-placed uterine incision; adequate uterine relaxation; slow, careful, and deliberate placement of the operator's hand around the head; and, possibly, use of adjunctive devices/instruments will allow controlled atraumatic extraction of the head and reduce the likelihood of uterine extension.

Common pitfalls to avoid include the following:

●Making the hysterotomy too low and inadvertently incising the vagina, which may be quite challenging to repair. The appropriate area for incising the lower uterine segment in a second stage cesarean birth, particularly if the second stage is prolonged, can be higher than expected in other circumstances.

●Acting too hastily and forcefully. Even in the setting of acute fetal bradycardia, taking an extra few seconds to assess anatomy and initiate gentle maneuvers will likely not contribute to any additional fetal compromise. Generally, the operator has up to five minutes to deliver a previously well-oxygenated term infant before an increased risk of asphyxial injury occurs [10-12]. (See "Umbilical cord blood acid-base analysis at delivery".)

●Flexing the wrist against the lower uterine segment between the incision and cervix. Using this area as a fulcrum to dislodge the head can result in cervical lacerations. Instead, the fetal head is cupped with the delivering hand and then pressure is applied in the cephalic direction to elevate both the head and body. Once the fetal head is in the abdomen it can then be elevated to the abdominal incision.

●Not having a plan. If plan/intervention A for delivering the deeply impacted fetal head is not successful, the clinician should be prepared to expeditiously move on to plan/intervention B, and if necessary plan/intervention C (algorithm 1).

Patient and team preparation

When a decision is made to perform a cesarean birth in a patient in whom a deeply impacted fetal head is suspected:

●A member of the delivery team should explain to the patient the challenges with delivery that can arise due to a deeply impacted fetal head. This will allow the patient to be emotionally prepared if events during the cesarean birth require additional positioning or personnel.

●Prior to proceeding to the operating room, the obstetric team should discuss their plan for extraction of a suspected deeply impacted fetal head with anesthesia and nursing colleagues.

When the fetal head is impacted at cesarean:

●Nursing, anesthesia, obstetric, and pediatric staff should be called to the operating room, if not already available, to provide assistance as needed.

●The delivering obstetrician should clearly and calmly inform the team as each technique to manage fetal head impaction is performed.

●A team member should be recording time and announcing each minute that has passed after hysterotomy.

●If an abdominovaginal delivery is planned (ie, placing a hand in the vagina to assist abdominal delivery of the fetus), the patient should be frog-legged as quickly as possible while trying to maintain a sterile field.

Prophylactic use of disimpacting systems — One approach to preventing complications associated with a deeply impacted fetal head is to prophylactically intervene to minimize impaction of the head prior to beginning the cesarean birth, although high-quality information to support that the use of these systems meaningfully improves outcomes is limited. We have adopted the use of the fetal pillow and are assessing how it affects our outcomes.

The fetal pillow is a variation on the fetal head elevator. The disposable device has a balloon that is inserted into the vagina just below the fetal scalp when the patient is being prepared for cesarean. Prior to the start of the cesarean birth, the balloon is inflated with 180 mL saline, which is meant to gently lift the fetal head 2 to 3 cm from its original position. After the newborn is delivered, the device is deflated and removed. A video of the procedure is available online [13].

In a meta-analysis comparing second-stage cesarean birth with versus without use of a fetal pillow in 1326 patients across 10 studies, the intervention was associated with reductions in the following maternal outcomes [14]:

●Time from hysterotomy to delivery (mean difference -52.26 seconds, 95% CI -55.2 to -34.94)

●Hospital stay (mean difference -0.88 hours, 95% CI -1.07 to -0.70)

●Estimated blood loss (mean difference -130.82 mL, 95% CI -130.1 to -381.0)

●Uterine incision extension (odds ratio [OR] 0.50, 95% CI 0.3-0.9)

●Need for blood transfusion (OR 0.39, 95% CI 0.2-0.7)

●Operative complications (OR 0.44, 95% CI 0.2-0.9)

For newborns, the intervention was associated with:

●Higher arterial pH values (mean difference 0.62, 95% CI 0.43-0.88)

●Lower risk of neonatal sepsis (OR 0.10, 95% CI 0.01-0.99)

●Lower risk of admission to the neonatal intensive care unit (OR 0.63, 95% CI 0.5-0.9)

These findings should be interpreted cautiously given the small number of cases and studies, bias related to the observational design of most of the studies, and heterogeneity in outcome assessment and definitions. Adequately powered randomized trials are needed to understand if there is any role of fetal elevation devices for improving maternal and newborn outcomes at second-stage cesarean birth. NICE concluded that the fetal pillow should only be used with special arrangements for clinical governance and audit or research [15].

An alternative to the fetal pillow is to gently elevate the fetal head manually before making the skin incision.

Maneuvers for fetal extraction

Initial approach — Typically, clinicians place their hand in the midline between the pubic symphysis and the fetal cranium to elevate the head into the abdomen for delivery. However, this is often not possible when the head is tightly impacted. In this scenario, we suggest placing the hand laterally before a rescue maneuver is employed. This is an easy intervention that can be implemented quickly. The transverse diameter of the maternal pelvis is wider than the anterior-posterior diameter; therefore, when there is no space anteriorly, space may still be available laterally to place a hand and disengage an impacted fetal head. It is important to maintain a straight wrist while keeping the arm in the midline and avoiding pressure on the uterine angles. Starting with the operator's hand lateral to the fetal head, the hand is swept over the face or occiput and the head flexed into the palm of the hand. From this position, the head is elevated towards the mother's head, not the ceiling, while keeping the arm straight and in the midline parallel to the mother's body. With the head now elevated, the delivery can be completed in routine fashion.

Choosing a rescue maneuver — Several maneuvers have been proposed to help extract the deeply engaged, impacted fetal head. There is no consensus for the best practice as available data have many limitations, resulting in uncertainty of best practice [16,17].

Our preferred approach for dealing with an impacted fetal head at cesarean is reverse breech extraction ("pull method") because this maneuver is best supported by available, but limited, evidence. We encourage physicians to seek training and develop skill in this maneuver if they are not already trained and skilled in its use. Regardless, providers should develop their skills to ensure that they are comfortable performing at least two of the following maneuvers so they are appropriately equipped to safely deliver the fetus with a deeply impacted head when this emergency when it arises.

Reverse breech extraction ("pull method") — Clinicians who intend to use this method as their first approach for addressing a deeply impacted fetal head should be comfortable with the technique, having practiced it in nonemergency situations.

We suggest a low vertical hysterotomy for planned reverse breech extraction to avoid the possible need to perform a T or J extension of a low transverse incision. The operator's hand is inserted into the uterus toward the fundus to grasp the feet, which are then pulled to perform a footling breech extraction (figure 1) [18]. When grasping and pulling the feet, care must be taken to only apply traction parallel to the axis of the legs to avoid fracturing the tibia and/or fibula. Once the feet are through the hysterotomy incision, the delivery is accomplished as a typical breech extraction, with care taken to avoid hyperextension of the neck (eg, use the Mauriceau-Smellie-Veit maneuver). (See "Delivery of the singleton fetus in breech presentation", section on 'Head'.)

In a meta-analysis of randomized trials comparing reverse breech extraction with abdominovaginal delivery ("push method," discussed below) for the deeply impacted head, reverse breech extraction generally resulted in better outcomes [17]. The vaginal push method significantly increased maternal operative blood loss >1000 mLs (RR 2.21), duration of surgery (generally by 10 to 15 minutes), and risks of postpartum hemorrhage (RR 2.21), blood transfusion (RR 2.75), uterine incision extension (RR 3.45), and maternal infection (endometritis [RR 1.54], urinary tract [peto OR 10.26], postpartum pyrexia/sepsis [RR 3.64]). Differences in risks for low Apgar score at five minutes, low umbilical artery pH, and neonatal intensive care unit (NICU) admission were not statistically significant. A major limitation of the analysis was inclusion of only seven small trials (total of 739 participants) that were all at high risk of bias.

A Society of Obstetricians and Gynaecologists of Canada guideline that reviewed the most effective clinical approaches to disengage an impacted fetal head during cesarean delivery concluded that the pull technique is associated with fewer complications than pushing upward from below, but both approaches are acceptable [19].

Abdominovaginal delivery ("push method") — Abdominovaginal delivery refers to a procedure in which an assistant places their gloved, cupped hand into the vagina to gently disengage and push the impacted fetal head up into the uterus for extraction via cesarean birth (figure 2) [20]. Three or four fingers are separated and spread over a large area of fetal skull to avoid exerting excessive focal pressure, which can be traumatic. The operating obstetrician also assists from above by providing steady upward traction on the fetal shoulders and by attempting to flex the fetal head or at least prevent further deflexion. To facilitate vaginal access, the mother's legs are abducted into the "Whitmore" or "frog" position on the operating room table, or stirrups can be used to place the patient in dorsal lithotomy for delivery. We identify the assistant who will perform this maneuver prior to proceeding to the operating room for delivery.

Although the use of an assistant's hand transvaginally is the preferred method to accomplish this maneuver, the primary obstetrician can also perform this task but should change gloves before resuming transabdominal procedures. In the absence of an assistant, the primary obstetrician uses their transabdominal hand to prevent further deflexion and places their other hand in the vagina to push up the head [21,22].

This technique is generally successful in dislodging the deeply impacted fetal head and creating a space between the bony pelvis and fetal skull so abdominal delivery can be completed in the usual manner. However, it also increases the risk of extension of the uterine incision, potentially resulting in laceration of local anatomic structures [1,23]. Additionally, it has been associated with serious fetal morbidity, including skull fracture [24,25], so care must be taken to avoid excessive pressure on the fetal skull when pushing up from below or when the operator places their fingers between the fetal skull and the maternal pelvic bones.

If abdominovaginal delivery is anticipated, both the abdomen and perineum should be prepped preoperatively. Despite thorough surgical preparation and antibiotic prophylaxis, the risk of postpartum endometritis appears to be increased [26], presumably because of contamination of the operative field by vaginal flora.

As described above, limited data from randomized trials suggest that use of reverse breech extraction rather than this technique reduces the risk of uterine incision extension. (See 'Reverse breech extraction ("pull method")' above.)

Patwardhan technique ("shoulders first method") — A fetal shoulder that appears in the hysterotomy as soon as the incision is made is a sign that the fetal head is deeply impacted. Having an assistant gently push the shoulder cephalad (toward the mother's head) while the primary obstetrician tries to extract the fetal head in the standard manner may facilitate delivery. If this is ineffective, the Patwardhan shoulders first technique has been used successfully for difficult fetal extraction at cesarean in India [27].

The step-by-step procedure is as follows:

●The anterior shoulder is delivered along with the anterior arm by hooking a finger in the elbow, if required.

●With gentle traction on this shoulder, the posterior shoulder is then delivered.

●Next, the surgeon holds the trunk of the baby gently with both thumbs parallel to spine, and, with fundal pressure given by the assistant, the buttocks are delivered, followed by legs.

●Finally, the baby's head, which is the only part still inside the uterus, is gently lifted out of the uterus.

A meta-analysis of observational studies comparing techniques used to deliver a deeply impacted fetal head at full dilation cesarean noted that the abdominovaginal delivery (pooled studies of push and pull techniques) was associated with a higher rate of uterine extension than the shoulders first (Patwardhan) technique (odds ratio [OR] 30.95, 95% CI 5.95-160.86, three studies, 279 participants) [26]. Separate analyses of the shoulders first (Patwardhan) technique versus push and versus pull techniques were not performed. Another meta-analysis (three studies, 838 participants) that compared abdominovaginal delivery with Patwardhan technique for managing an impacted fetal head at cesarean found no significant differences between the two approaches for any of six outcomes: extension of the uterine incision, blood transfusion, bladder injury, postpartum hemorrhage, NICU admission, and Apgar score <7 at five minutes [28]. It is difficult to make any practice recommendations based on these data given the limitations of the included studies (eg, differences in study design, outcome parameters, baseline patient characteristics, operator ability, and low statistical power).

Fetal head elevators — Fetal head elevators function as fetal shoe horns. Because they take up less space than the obstetrician's hand, they are easier to get around a tightly impacted head.

Several variations of these instruments are available, including the Coyne spoon (figure 3) and the Sellheim spoon (figure 4). For each instrument, the smooth, rounded edge is carefully slipped into the uterus, between the fetal head and the anterior lower uterine segment, and gently positioned below the fetal head. Using the handle, the instrument and fetal head are then carefully elevated out of the pelvis, and the delivery is completed in the usual manner. With this technique, care must be taken to lift the handle vertically or cephalad relative to the mother, rather than forcing it caudad (like a shoe horn), to avoid injury to the maternal bladder and to minimize extension of the incision.

T or J incision — If all of the maneuvers that the obstetrician is comfortable performing have not resulted in the delivery of the infant within five minutes from making the uterine incision, the incision should be extended vertically (T or J incision if the initial incision was transverse) to facilitate delivery of the infant's body and then the head. (See 'Adequate incision' above.)

Techniques to avoid

●Vacuum extractor – Some authors have described using the vacuum extractor to assist in delivering a deeply impacted fetal head during cesarean [29,30]. However, no one has described the technique clearly, specifically where the vacuum cup should be applied. Furthermore, severe fetal injuries, such as intracranial hemorrhage, have been reported [31,32]. Given the difficulty of safely placing the vacuum cup on a deeply impacted fetal head (which is not accessible from the uterus) and the potential for both maternal and fetal trauma from this approach, we and others (eg, the Royal College of Obstetricians and Gynaecologists [17]) suggest not using this technique.

●Single forceps blade or bladder filling – The Royal College of Obstetricians and Gynaecologists also caution against using a single forceps blade or bladder filling to assist delivery of an impacted fetal head as neither of these practices is supported by evidence [17].

FLOATING FETAL HEAD

Overview of pathophysiology and management — As with the impacted fetal head, management of the floating fetal head (which can be defined as -3/5 station or above) is a difficult problem. In contrast to the deeply impacted fetal head, where maternal anatomy actually impedes access to the head, the floating head is easily accessed. However, it is difficult to grasp and establish traction to guide it through the incision.

This is because, in an uncomplicated cesarean, the head typically has advanced beyond the site of the hysterotomy and, when the head is gently elevated and flexed toward the incision, uterine forces naturally push it along the path of least resistance, which is through the hysterotomy. The obstetrician's hand also acts as a guide. By comparison, when the head is floating above the hysterotomy incision, the uterus has already accommodated to the position of the fetus; therefore, uterine forces do not push the head through the incision. Applying fundal pressure is often inadequate and has a tendency to push the head laterally, rather than toward, the hysterotomy.

Choosing an approach — There are two relatively safe and easy options to manage the floating head at cesarean. We prefer internal podalic version followed by breech extraction, but cephalic extraction with a vacuum, Coyne spoon, or forceps are other acceptable options when operators are uncomfortable with the technique of internal podalic version.

In a trial that randomly assigned 150 patients with a high floating head during cesarean to internal podalic version, vacuum, or Wrigley forceps, internal podalic version decreased time from hysterotomy to delivery and reduced neonatal and maternal complications [33]. Although definitive conclusions cannot be made as to the overall safety and efficacy of one technique over the other based on this one small trial, these data present a compelling argument for obstetricians to be familiar and comfortable with the internal podalic version technique.

Internal podalic version followed by breech extraction — Internal podalic version with breech extraction is different from reverse breech extraction of the impacted head (see 'Reverse breech extraction ("pull method")' above) because the fetus is internally verted from cephalic to breech presentation before extracting most of the body. The obstetrician reaches into the uterus with one hand, grasps one or both fetal feet, and pulls the foot or feet through the hysterotomy while guiding the head to the fundus with their other external hand. This technique causes the fetus to rotate from a cephalic presentation to a footling breech presentation. Breech extraction is then performed. (See "Delivery of the singleton fetus in breech presentation", section on 'Cesarean breech birth'.)

This technique is also often used for vaginal delivery of a second twin with an unengaged cephalic presentation. (See "Twin pregnancy: Labor and delivery", section on 'Cephalic presentation'.)

Extraction with vacuum, obstetric spoon, or forceps

●Vacuum – For the vacuum procedure, after entry into the uterus and rupture of the membranes, an obstetric vacuum extractor is placed over the flexion point (figure 5) to deliver the fetal head, which should be accessible in this setting [30,34]. Use of a soft, bell vacuum cup minimizes the risk of fetal injury. Not much traction is needed since there is minimal anatomic resistance to extraction through the hysterotomy.

●Spoon – An equally simple method, preferred by the authors, involves slipping a Coyne spoon into the uterus, beneath the infant's cheek, and using the leverage of the spoon to draw the head into the hysterotomy (movie 1).

●Forceps – Forceps can also be used in this situation, depending on operator comfort and experience. Wrigley forceps have short stems and blades, which make them ideal for this setting.

SUMMARY AND RECOMMENDATIONS

●Basic approach – Atraumatic fetal extraction is facilitated by adequate incisions in the skin, abdominal wall, and uterus and uterine relaxation. (See 'General principles' above.)

●Approach to the deeply impacted head

•For delivery of the deeply impacted fetal head, we start by attempting traditional midline hand placement. If this is not possible, we then attempt placing the hand lateral to the head to disimpact it, as there may be more room laterally than in the midline. (See 'Initial approach' above.)

•For patients in whom the head cannot be disimpacted with the operator's abdominal hand, we suggest reverse breech extraction ("pull method") for obstetricians trained in the maneuver (Grade 2C). This is the rescue maneuver best supported by available literature. (See 'Choosing a rescue maneuver' above and 'Reverse breech extraction ("pull method")' above.)

•For clinicians who are not trained or not comfortable with reverse breech extraction, abdominovaginal delivery is an alternative familiar to most obstetricians (algorithm 1). (See 'Abdominovaginal delivery ("push method")' above.)

•Other interventions have not been studied as extensively. Extending the incision into a T or J is a last resort and should be employed within five minutes of making the hysterotomy. (See 'Patwardhan technique ("shoulders first method")' above and 'Fetal head elevators' above and 'T or J incision' above.)

●Approach to the floating head

•For delivery of the floating fetal head, we suggest internal podalic version for obstetricians trained in the maneuver (Grade 2C) (see 'Internal podalic version followed by breech extraction' above).

•For those who are not trained or not comfortable with this technique, use of vacuum, Coyne spoon, or forceps are reasonable alternatives, depending on the operator's skill set and comfort with each technique. Available literature is very limited. (See 'Extraction with vacuum, obstetric spoon, or forceps' above.)