Delivery of the singleton fetus in breech presentation

INTRODUCTION — Vaginal breech birth is associated with increased neonatal morbidity and mortality compared with vaginal birth of a cephalic presentation. External cephalic version of a breech fetus is an effective approach to increasing the number of patients who present in labor with cephalic presentation and is the approach that we recommend. (See "Overview of breech presentation" and "External cephalic version".)

For patients who present in labor with a breech fetus, cesarean birth is the preferred approach in many hospitals in the United States and elsewhere. Cesarean is performed for over 90 percent of breech presentations, and this rate has increased worldwide [1,2]. However, even in institutions with a policy of routine cesarean birth for breech presentation, vaginal breech births occur because of situations such as patient preference, precipitous birth, out-of-hospital birth, and lethal fetal anomaly or fetal death. Therefore, it is essential for clinicians to maintain familiarity with the techniques required to assist in a vaginal breech birth.

In addition, some clinicians and patients consider vaginal breech birth preferable to cesarean birth. Recent trends, particularly in central Europe, support vaginal breech birth [3-5]. In selected cases, as described below and depicted in the algorithm (algorithm 1), it is associated with a low risk of complications. The American College of Obstetricians and Gynecologists has opined that "Planned vaginal delivery of a term singleton breech fetus may be reasonable under hospital-specific protocol guidelines for eligibility and labor management" [6].

This topic will focus on vaginal birth of breech singletons, with a brief discussion of breech delivery at cesarean. Choosing the best route of birth for the fetus in breech presentation and delivery of the breech first or second twin are reviewed separately.

●(See "Overview of breech presentation", section on 'Approach to management at or near term'.)

●(See "Twin pregnancy: Labor and delivery", section on 'Diamniotic twins with noncephalic-presenting twin' and "Twin pregnancy: Labor and delivery", section on 'Approach to cephalic/noncephalic presentation'.)

VAGINAL BREECH BIRTH

Criteria for minimizing risk in patients who opt for vaginal breech birth — Cesarean is the preferred route of birth for many patients in labor with breech presentation (see "Overview of breech presentation", section on 'Approach to management at or near term'). However, for patients who would like a trial of labor and have an experienced clinician willing to attempt vaginal breech birth, general criteria have been developed to help identify pregnancies at lowest risk. These criteria, described below, are largely based upon expert opinion and thus vary somewhat among providers [5,7-10]. In a prospective series of over 8000 patients with breech presentation at term, only an approximate 30 percent of patients met similar criteria [11].

Suggested criteria:

●No contraindication to vaginal birth; an obvious example is placenta previa. Although a contracted pelvis with fetal-pelvic disproportion is a contraindication to vaginal birth, making an accurate diagnosis is not possible in most cases. There is no convincing evidence that pelvimetry (clinical or radiographic [magnetic resonance imaging, computed tomography, radiograph]) in patients with breech presentation provides information that leads to better patient selection for a trial of labor and vaginal birth or improved neonatal outcome; however, few data are available from large or randomized trials [12,13].

●No prior cesarean births – Prior cesarean is a relative contraindication, based on expert opinion, since both vaginal breech birth and trial of labor after a previous cesarean are associated with increased risk. Whether the prior cesarean was for a probable recurring indication is a factor in balancing the risks and benefits of a trial of labor. French guidelines do not consider a previous cesarean a contraindication to the trial of labor [10]. (See "Choosing the route of delivery after cesarean birth".)

●Gestational age ≥36 weeks or at the limit of neonatal viability – The preterm fetus has a greater ratio of fetal head circumference to abdominal circumference (HC/AC) than a term fetus, but the gestational age at which the risk of head entrapment by an incompletely dilated cervix is increased is not well defined; <36 weeks is a common threshold for recommending cesarean birth. An observational study of breech births at 32+0 to 36+6 weeks reported more low Apgar scores but less antibiotic use, newborn intensive care unit (NICU) admission, and respiratory distress syndrome among vaginal compared with cesarean births [14], thus suggesting that breech labor and vaginal birth at 32 + 0 to 36 + 6 weeks in selected cases without risk factors for adverse outcomes may be reasonable. This is not the case before 32 weeks, where a meta-analysis of retrospective studies found poorer perinatal outcomes for vaginal than cesarean breech births [15]. (See "Overview of breech presentation", section on 'Approach to management of preterm breech birth'.)

However, for extremely preterm pregnancies at the limit of neonatal viability, the choice of birth route should take into account the likelihood of neonatal survival in the individual clinical setting and the fact that cesarean birth usually requires a classical uterine incision, which has implications for future pregnancies. Thus, it should be a shared decision after parental counseling by the neonatal and obstetric teams. In the author's experience, vaginal breech birth in pregnancies at the limit of viability is typically uncomplicated, particularly if amniotic membranes can be kept intact until the birth.

●Spontaneous labor – Most experts recommend avoiding induction of labor [9,16]. However, in at least three observational studies of pregnancies with breech presentation, maternal and perinatal morbidity and mortality were similar after induced versus spontaneous labor [17-19].

Other studies reported similar neonatal outcomes (mortality, severe morbidity) after induction versus planned cesarean birth of breech presentation [20] and after induction of breech versus cephalic presentation [21].

●Staff skilled in breech birth and immediate availability of resources and facilities for safe emergency cesarean birth (eg, anesthesia, obstetric, and pediatric personnel; surgical facilities and personnel). Because of a shortage of clinicians experienced in vaginal breech birth, a pilot study evaluated a program of planned induction at 37 to 38 weeks on a day when an experienced clinician was scheduled to be in attendance and found the completion rate of vaginal breech birth was 67 percent (48 in 72) with no cases of neonatal asphyxia or respiratory disorders [22].

●Ultrasound examination showing:

•Frank or complete breech presentation (incomplete breech presentation is a contraindication) – With a complete breech, a combination of fetal lower legs, thighs, and trunk is the presenting part; with a frank breech, a combination of the thighs and trunk is the presenting part. In either case, if this large presenting part passes easily through the cervix and pelvis, then subsequent pelvic head entrapment is unlikely. Short-term morbidity appears to be similar for both groups, but manual assistance is more frequently required with a complete breech presentation [23].

In footling presentations, however, the legs and trunk deliver sequentially. The presenting part is smaller than the thighs/trunk combination and can pass through an incompletely dilated cervix or inadequate pelvis. In this setting, the relatively large aftercoming head may become entrapped. Therefore, footling breech delivery/extraction is not performed in singleton pregnancies but may be performed for delivery of a second twin. (See "Twin pregnancy: Labor and delivery", section on 'Approach to cephalic/noncephalic presentation'.)

•Estimated fetal weight ≥2000 and ≤4000 g – This is the range used in the author's practice but either end of the range varies among clinicians who offer vaginal breech birth (eg, ≥2500 and ≤3500 g, ≥1500 and ≤3800 g).

Dystocia related to large fetal size is a major concern in breech presentation since, in contrast to the cephalic presentation, the largest diameters of the fetus deliver last rather than first. On the other hand, with increasing fetal size, the relative size of body to head increases, making it less likely for the body to deliver through an inadequate pelvis (provided the thighs are flexed as mentioned above).

•Absence of growth restriction – Fetal growth restriction is also a concern because approximately half of the perinatal deaths in the Term Breech Trial were in growth-restricted fetuses [9,24]. This may have been due to an increased risk of fetal acidosis related to chronic placental insufficiency compounded by the unavoidable cord compression that occurs during the second stage of labor [9]. However, there are no high-quality data on which to base the optimum weight thresholds or for counseling patients regarding risk for vaginal breech birth [25].

•Absence of a fetal anomaly that may cause dystocia (eg, sacrococcygeal teratoma, macrocephaly).

•No hyperextension of the fetal neck/head (hyperextension is usually defined as a cervical spine extension angle ≥90 degrees; on ultrasound, the axis of the face is a perpendicular line with the axis of the fetal body) – Hyperextension ("star gazing") should be excluded by ultrasound, or radiograph if ultrasound is unavailable.

An increased risk of neurodevelopmental handicap has been observed in young children born vaginally in the breech position with hyperextension of the neck/head [26-28]. In one large series, an extended fetal neck/head was reported in 33 of 445 (7.4 percent) breech presentations [27]. None of the seven fetuses delivered by cesarean had a neurologic abnormality, but 5 of the 26 fetuses born vaginally had neurologic sequelae referable to spinal, supraspinal, and cerebellar injuries.

Some clinicians consider patients with a prior vaginal birth, and thus a tested pelvis, better candidates for planned vaginal breech birth than nulliparous patients. No differences in neonatal outcome after planned vaginal breech birth have been observed for multiparous versus nulliparous patients, but data are limited and at high risk of bias [29-31].

Selected guidelines

●Society of Obstetricians and Gynaecologists of Canada – A clinical practice guideline from the Society of Obstetricians and Gynaecologists of Canada states that patients with breech presentation and a contraindication to a trial of labor (cord presentation, fetal growth restriction or macrosomia, any presentation other than a frank or complete breech with a flexed or neutral head attitude, clinically inadequate maternal pelvis, fetal anomaly incompatible with vaginal delivery) should be advised to have a cesarean delivery [9]. However, patients who choose to labor despite this recommendation "have a right to do so and should not be abandoned. They should be provided the best possible in-hospital care."

●French College of Gynaecologists and Obstetricians – A clinical practice guideline from the French College of Gynaecologists and Obstetricians state that "complete breech presentation, a previous cesarean, nulliparity, and term prelabor rupture of membranes are not, each one by itself, per se contraindications to planned vaginal delivery (professional consensus)" and "term breech presentation is not a contraindication to labor induction when the criteria for planned vaginal delivery are met" [10].

Labor management — The author's approach to management of labor during a vaginal breech birth is described below. The rationale for this approach is based largely on good outcomes in observational studies of vaginal breech birth using strict selection criteria, adhering to an intrapartum protocol, maintaining a low threshold for intervention, and ensuring that an experienced obstetrician or midwife attends the birth.

●Confirm position/presentation – Perform a vaginal examination and/or ultrasound examination on admission to determine whether the fetal hips are flexed (frank or complete breech) or extended (incomplete breech).

●Leave the membranes intact because rupture increases the risk for cord prolapse due to the irregular contour of the presenting part compared with the fetal head [32]. Perform a vaginal examination immediately following spontaneous rupture of membranes to exclude or detect cord prolapse [9]. The frequency of cord prolapse is approximately 1 percent with a frank breech presentation (versus ≥10 percent with a footling breech) [33].

Although cesarean birth is recommended for preterm fetuses in breech presentation, if vaginal birth is attempted, then leaving the membranes intact may be particularly beneficial in this population. Delay in rupturing the membranes until the fetus has passed through the vagina reduces the risk of entrapment of the aftercoming head by an insufficiently dilated cervix and helps protect the fetus from trauma [34-36]. Intact membranes may also help facilitate cervical effacement and dilation.

●Monitor fetal heart rate – Most experts recommend continuous electronic fetal heart rate monitoring, given the increased risk of cord compression, which may cause variable decelerations; however, data on specific fetal heart rate patterns during breech labor and their relationship to fetal hypoxia are limited [37].

Early decelerations are common during labor in breech-presenting fetuses as the uterine contractions start at the fundus and transiently compress the fetal head causing a vagal response. However, it is not always possible to clearly distinguish an early deceleration from a variable deceleration or whether the deceleration is due to head or cord compression.

After membranes have ruptured, a scalp electrode may be attached to the buttocks if external monitoring is inadequate [38].

●Monitor progress – Monitor and record labor progress, as with a cephalic presentation. The fetal position is described relative to the sacrum (eg, right sacrum anterior is a breech presentation in which the fetal sacrum is in the right anterior quadrant of the mother's pelvis and the bitrochanteric diameter of the fetus is in the right oblique diameter of the pelvis).

On vaginal examination, the intergluteal cleft is analogous to the sagittal suture for vertex presentation, and some degree of gluteal "asynclitism" is common.

●Suggest neuraxial analgesia – Neuraxial analgesia is useful because it relieves pain, eliminates the maternal urge to push involuntarily before full cervical dilation, and provides anesthesia if obstetric maneuvers are needed to facilitate birth. Contemporary neuraxial anesthesia methods preserve the ability of the mother to push effectively when the breech descends to the pelvic floor. (See 'Anesthesia' below.)

●Use oxytocin cautiously – For patients with a prolonged latent phase or transient hypocontractile uterine activity related to initiation of neuraxial anesthesia, the author recommends oxytocin administration consistent with standard obstetric practice.

Because poor progress in the active phase unrelated to neuraxial analgesia may be an indicator of fetopelvic disproportion, he does not administer oxytocin once the active phase of labor has begun [9,39,40]. If labor progress is protracted in the active phase, he performs a cesarean birth. Some clinicians use oxytocin augmentation in the active phase of labor, with a low threshold for resorting to cesarean birth if they assess labor progress as inadequate, which is also a reasonable approach.

The normal progress of labor in the breech presentation has not been evaluated as extensively as in cephalic presentation.

•Dilation – As with cephalic presentation, a French study with 77 percent oxytocin augmentation observed a latent and an active phase in breech labors and that cervical dilation from 5 cm to 10 cm was slightly slower in nulliparous (median 1.5 cm/hour) compared with parous patients (2 cm/hour) [41]. The rate of cervical dilation from 3 to 10 cm was similar for complete and frank breech presentation, although median cervical dilatation from 8 to 10 cm appeared to be faster for complete breeches.

•Descent – In the first stage, descent is regarded as adequate if the breech reaches the level of the ischial spines when the cervix is 6 cm dilated and reaches the pelvic floor at full dilation. Engagement of the buttocks at the onset of the second stage can be assessed by ultrasound and appears to be predictive of vaginal birth [42].

In the second stage, a passive approach in which pushing is delayed for up to 90 minutes is acceptable [9]; however, once the patient starts to push, failure of the breech to descend and deliver within 30 to 60 minutes is managed by cesarean birth rather than breech extraction, based on good outcomes with this approach in large studies [7,11,40,43].

The cardinal movements of labor and shown in the table (table 1).

Delivery of the breech fetus

Training aids — With decreasing rates of vaginal breech birth and thus clinical experience, simulation training [44] and other teaching aids, such as illustrations (figure 1A-E) and videos, can be useful [45]. Videos demonstrating live vaginal breech births are available online [46]. The following simulation video illustrates one clinician's approach to vaginal breech birth using Piper forceps to extract the aftercoming head (movie 1).

Anesthesia — Neuraxial anesthesia that provides adequate analgesia without impairing maternal expulsive efforts has several benefits: reduction of rectal pressure can help the patients avoid pushing before the cervix is fully dilated and the anesthetic can be augmented quickly if a denser anesthetic is needed for forceps-assisted birth of the aftercoming head, an urgent cesarean birth, or to facilitate maneuvers to release an entrapped head. The drugs commonly used for neuraxial labor analgesia include a combination of dilute local anesthetic and an opioid, and provide effective maternal analgesia with minimal motor block. Neuraxial anesthesia with high-concentration local anesthetic solutions may increase intervention rates [47,48].

If a neuraxial anesthetic is not in place, a pudendal nerve block may be offered if an episiotomy or forceps-assisted delivery is performed.

Maternal position — The author places the mother in the recumbent or lithotomy position with a wedge under one side of the buttocks and the abdomen well tilted laterally. The best maternal position for vaginal breech birth has not been studied extensively. Although two small studies reported better outcomes (fewer interventions, shorter second stage, and fewer neonatal injuries) when the mother was in an upright (kneeling) or all-fours (hands/knees) position than recumbent [49,50], the author has not adopted use of nonrecumbent positions and awaits more and better data, preferably from a randomized trial, confirming their benefit. Upright active maternal birth position is part of the OptiBreech approach to breech birth being studied in the United Kingdom [51]. Descent is facilitated by the effects of gravity and by spontaneous maternal movement, which can increase the diameters of the maternal pelvis [49,52,53].

Episiotomy — Episiotomy is performed only if required to facilitate birth and only after the fetal anus is visible at the perineum. Although in the past many clinicians routinely performed episiotomy for breech birth [54], no data from randomized trials are available to guide practice, and routine episiotomy is no longer performed for cephalic births. In a retrospective study, the increased use of episiotomy in breech births compared with cephalic births (12.6 versus 5.4 percent) was not associated with a significant reduction in obstetric anal sphincter injury (0.9 versus 1.1 percent) [55].

Timing of clinician assistance — There is a general consensus that spontaneous or assisted breech birth is acceptable, whereas breech extraction should be avoided in singleton pregnancies [9].

A key point is to avoid assisting the birth until maternal bearing-down efforts have resulted in expulsion of the fetus at least to the umbilicus, at which time suprapubic pressure is applied to promote neck/head flexion and descent. Rotation of the trunk and extraction of limbs, when needed to assist this process, is acceptable, but traction on the trunk should be avoided as it is thought to cause extension of the neck and arms, and nuchal arms, which make birth more difficult [56]. Review of 90 obstetric textbooks published between 1960 and 2000 found that recommendations for 'safe' intervals between birth of the umbilicus and the head ranged from 5 to 20 minutes, with very little evidence to substantiate these guidelines [57].

However, if progress is arrested after expulsion to the umbilicus or in the setting of persistent fetal bradycardia, then birth should be expedited, either with oxytocin infusion if uterine contractions are inadequate, or by breech extraction together with suprapubic pressure on the uterine fundus to assist head flexion.

Buttocks, trunk, and lower limbs — Maternal expulsive efforts alone should be adequate to deliver the buttocks, lower trunk, and lower limbs if not extended. The mother is encouraged to bear down until the feet, legs, and buttocks have delivered and the trunk is visible to the level of the scapulae. The trunk is supported by the operator in a plane at or below the horizontal plane of the birth canal. Meconium passage is common.

If the lower limbs are extended when the trunk has delivered to the level of the umbilicus, the operator may use his/her fingers to exert pressure on the back of the knee (Pinard maneuver) and guide the thigh away from the trunk as the trunk is rotated in the opposite direction. This causes the knee to flex and allows extraction of the foot and the leg (figure 1B). The same procedure can be repeated, if needed, to deliver the other leg and foot.

After the legs have delivered, the cord is checked for pulsation, and a small loop is pulled down to prevent traction on the cord.

Arms — After delivery of the trunk and lower limbs, the mother is asked to push again, and the shoulders should present in the anterior-posterior plane and deliver spontaneously, one at a time, along with the arms, which are usually crossed in front of the chest.

Shoulder dystocia with breech presentation is usually due to extension of the arms or nuchal arms. This is typically caused by traction on the fetus early in the delivery because if the trunk is pulled down, the arms can drag behind. If traction is avoided, uterine contractions and maternal expulsive efforts tend to push the entire fetus into the birth canal in its normal flexed arm position.

If the arms do not deliver spontaneously, intervention is required. The fetus is held by the hips or bony pelvis, never by the abdomen because injury to the kidneys/adrenals is possible. The author wraps the legs/pelvis in a towel to provide a good grip and keeps the back upwards. The fetus is rotated through 180 degrees to deliver the first shoulder and arm, then in the opposite direction so the other shoulder and arm deliver under the symphysis pubis (Loveset maneuver) (figure 2A-B). The second rotation may be assisted by gentle traction on the delivered arm in the direction of the rotation. Performance of this maneuver will help prevent a nuchal arm (entrapment of the arm above and behind the head).

Failure of the shoulders and arms to deliver with simple rotation of the trunk is managed by sliding an index finger along the fetal scapula, over the shoulder, and into the antecubital fossa. The elbow and forearm are then swept in front of the face and downward to the chest, at which point the arm can be delivered. This procedure is repeated for the other side. Gentle rotation of the fetal trunk at the same time, keeping the back anterior (ie, toward the symphysis pubis), will assist this maneuver.

If the arms remain trapped behind the neck, the fetus can be rotated so the chest is facing the symphysis pubis. This helps to dislodge the nuchal arm(s) and allows the elbow to be swept down and extracted, as described above.

Extraction rather than spontaneous delivery of the arms can dislocate the shoulder or lead to fracture, but these complications are less morbid than nonintervention resulting in prolonged dystocia, which can lead to asphyxia.

Head — At this stage, the fetal head may appear without any further effort on the clinician's part. Unlike cephalic vaginal births in which the head is delivered by neck extension, in breech vaginal births the head is delivered by neck flexion. As such, the maneuvers used to facilitate delivery of the head are different.

If the hairline is not visible after the shoulders have delivered, the body is turned to face the floor, and suprapubic pressure is applied by an assistant to flex the neck/head and push it down into the pelvis. The combination of encouraging maternal expulsive effort, avoiding operator traction on the fetus, and applying suprapubic pressure to prevent a prolonged expulsion phase has been reported to reduce perinatal mortality from a baseline of 3.2 percent to 0 percent [9].

Once the hairline is visible, the head is delivered. Some obstetricians prefer to use forceps to assist delivery of the aftercoming head. If forceps assisted delivery is not possible or desired, the fetus's legs are swung upwards, keeping the vulva completely covered by the operator's other hand to keep the head from popping out of the vagina. This hand is then released slowly to allow first the face and then the remainder of the head to deliver with maternal expulsive efforts.

The Mauriceau-Smellie-Veit maneuver (figure 3) is favored by the author for routine delivery of the head. The fetal trunk lies along the operator's right forearm, with legs straddling the forearm. The middle finger of the right hand is placed on the maxilla, and the second and fourth fingers on the malar eminences to promote flexion and descent while counterpressure is applied to the occiput with the middle finger of the left hand. Traction on the jaw should be avoided because of the possibility of temporomandibular joint injury [58].

With either forceps-assisted or spontaneous birth, it is essential to support the fetal legs, but the trunk should be no more than 45 degrees above horizontal; this avoids traction on the cervical spine during delivery of the head. If the body is bent backwards too far (eg, over the mother's abdomen), hyperextension of the neck can occlude the vertebral arteries and can lead to necrosis of the cervical cord. Excess weight on the cervical spine from downward traction can have the same effect or dislocate the fetus's neck.

An alternative approach is to allow the body to spontaneously deliver and hang over the end or side of the bed without support until the head is about to emerge from the vagina ("hands-off technique").

In a retrospective case-control study, time from buttocks on the perineum to birth of the head >7 minutes or umbilicus to head birth >3 minutes was associated with poor perinatal outcomes [59]. A review of 90 textbooks observed that recommendations for safe intervals between birth of the umbilicus and the head ranged from 5 to 20 minutes [57].

Use of forceps — As mentioned above, some obstetricians prefer to use forceps to assist delivery of the aftercoming head. The feet are grasped and, using as much traction as required to keep the body straight and take weight off of the neck, the legs are swung upward to no more than 45 degrees above horizontal, where they are held by an assistant using a towel to make certain they do not slip. The operator then applies Piper forceps (picture 1A-B and movie 1). Piper forceps have a backward curve at the shank that makes them more convenient to use than standard forceps because the fetal body does not have to be elevated as high to keep it out of the way of the handles.

The assistant moves the fetal body to the operator's right so the operator, in a kneeling position, can apply the left blade. Initially, the handle of the forceps is held along the mother's right thigh, almost at right angles to the maternal body and to the mother's right. Using two fingers of the right hand as a guide, the toe of the blade is eased into the vagina and directed upward at an angle approximately 45 degrees below the horizontal plane and over the fetal right ear. The left hand gradually moves the handle along a curve, downward and toward midline, while the fingers of the right hand guide the toe and protect the vaginal wall and side of the fetal head.

Unlike a cephalic birth, a breech birth means that the smallest diameter of the fetal cranium appears at the vulva first, with the large parietal diameter at the back of the pelvis. Thus, if the forceps handle is brought to midline too soon after insertion of the blade, the distal part of the blade will dig into the side of the head and it will not be possible to lock the handles. The tip must be kept directed at the maternal sacrum for as long as possible, which means that the guiding hand has to be inserted well into the vagina until the tip has passed around the occiput.

The assistant then moves the fetus to the operator's left, and a similar procedure is performed for insertion of the right blade. The handles are locked when both handles reach midline and the fetal body is above the shank.

Elevating the handles of the forceps and mild traction result in flexion and extraction of the head (figure 4A-B). The mouth can be cleared as soon as it emerges from the vagina.

Head entrapment — Head entrapment is a potentially serious complication of breech birth. The preterm fetus is at high risk because its head-to-abdominal circumference ratio is larger than that of a term or near-term fetus; therefore, the preterm breech head may be caught in a partially dilated cervix, resulting in acute asphyxia from compression of the umbilical cord. This can also happen with a larger fetus, especially if the mother begins to push before full cervical dilation occurs. In both preterm and term fetuses in breech presentation, the skull may not have sufficient time to mold when passing through the bony pelvis. This may also play a role in pelvic head entrapment and can result in damage to the occipital bone during birth.

If the head is entrapped, uterine relaxation may allow the head to be delivered. The patient is placed in the McRoberts position (the patient's knees and hips are flexed so that their anterior thighs are pressed against the abdomen), and the author's preference is to administer either a beta adrenergic agonist (eg, salbutamol in 50 mcg slow intravenous boluses until the maternal heart rate reaches 120 beats/minute [maximum cumulative dose 250 mcg]) or nitroglycerin 50 to 200 mcg intravenously. Terbutaline 250 mcg subcutaneously is another option, as is slow intravenous administration using dosing guided by local protocols. Induction of general anesthesia will also lead to uterine and cervical relaxation but would take too long to administer and be effective in this setting, unless the patient is already in the operating theater with general anesthesia immediately available.

If uterine relaxation alone is unsuccessful, all of the other options below pose significant risk to the fetus and mother and few if any clinicians have the requisite expertise; therefore, we recommend not using these procedures.

●Dührssen incisions – If the head of the (usually preterm) fetus is entrapped and the cervix is effaced, but incompletely dilated, the cervical os can be enlarged surgically. One or two fingers are placed between the cervix and the presenting part to protect the fetus and allow the surgeon to palpate the cervicovaginal junction. Bandage scissors are used to make one to three incisions (Dührssen incisions) extending the full length of the remaining undilated cervix, typically at 6, then 2 and 10 o'clock. The 3 and 9 o'clock positions are avoided to keep away from the descending branches of the uterine arteries.

A major disadvantage of this technique, which is rarely performed, is that the incisions may extend into the lower uterine segment and broad ligament, with potential injury to uterine vessels, ureter, and bladder, and severe hemorrhage.

●Zavanelli maneuver with cesarean birth – If surgical facilities are available, the provider can administer a tocolytic drug and attempt to replace the body of the fetus in the uterus (Zavanelli maneuver) and proceed to cesarean birth [60,61]. Although a review of 11 cases of obstructed aftercoming head of the breech managed with this maneuver reported successful outcomes, the safety of this approach is unclear [62]. It has been used primarily in cephalic presentations complicated by refractory shoulder dystocia; maternal and fetal injury and fetal death have been reported in some of these cases [63].

●Symphysiotomy (surgical division of the cartilage of the symphysis pubis) – Successful delivery of the obstructed aftercoming head by symphysiotomy has been reported in observational studies, primarily in sub-Saharan Africa, where facilities for safe cesarean birth may not be available and some clinicians have experience with this procedure [64-69]. No randomized trials have been performed. A simulated symphysiotomy is demonstrated in the WHO Reproductive Health Library video on breech birth [46]. However, even in regions without adequate facilities for safe cesarean birth, the procedure is very rarely performed under exceptional circumstances because of lack of expertise among providers and the potential for serious maternal morbidity [70].

The fibrocartilaginous area of the symphysis pubis and overlying skin are infiltrated with local anesthetic, and a firm plastic catheter is inserted into the urethra. Two assistants support the mother's legs at no more than 90 degrees abduction. The urethra is displaced laterally using the surgeon's index and middle fingers placed against the posterior aspect of the symphysis (figure 5). Using a scalpel, a small (1 to 3 cm) incision is made through the cartilaginous portion of the symphysis to allow modest separation of the pubic bones, which is permanent [64,71]. The separation enlarges the bony outlet to allow delivery of the head. The skin incision may be left unsutured or closed with a suture if needed for hemostasis.

Postpartum, the mother rests in bed for approximately two days and then is mobilized on crutches until free weight bearing is comfortable. Abduction should be avoided for 7 to 10 days. Complications include lacerations of the bladder, urethra, and/or vagina; urinary incontinence; vesicovaginal fistula; and long-term pelvic pain and instability [72-74]. Rarely, pelvic instability may require delayed orthopedic repair.

CESAREAN BREECH BIRTH — For patients with a breech presentation at term unsuitable for vaginal birth, the author suggests scheduling planned cesarean birth for breech presentation between 39+0 and 41+0 weeks of gestation. The breech presentation should be confirmed immediately prior to surgery, ideally by ultrasound examination, in case spontaneous version has occurred. For patients with a breech presentation in whom preterm birth is indicated for medical or obstetric reasons, the cesarean birth is scheduled or, in patients with spontaneous preterm labor, performed when delivery appears to be inevitable.

The abdominal and uterine incisions should be sufficiently large to allow easy, atraumatic fetal extraction. A low transverse hysterotomy incision is adequate for most term or near-term fetuses. The technique of fetal extraction through the hysterotomy incision is similar to that described above for vaginal breech birth, and likewise, forceps of appropriate size should be available if needed for controlling delivery of the aftercoming head. The fetus must be delivered gently and atraumatically. Care should be taken not to hyperextend or place too much traction on the cervical spine.

In the preterm pregnancy, the lower uterine segment may be very narrow, making delivery through a transverse lower uterine incision difficult. Several solutions have been suggested:

●Make a vertical uterine incision [75,76]. Although a review of 416 breech presentations of various gestational ages delivered by low-transverse or low-vertical incisions found no advantages for the low-vertical incision [77], we cannot conclude that the two incisions were similarly safe and effective since this was an observational series and the patients delivered by low-transverse incisions had different characteristics than those delivered by low-vertical incisions. Case-by-case clinical judgment should guide this decision.

●Administer a uterine relaxant (eg, nitroglycerin, terbutaline) when a difficult delivery is anticipated or encountered [78,79].

SPECIAL SITUATIONS

Delivery of the macrocephalic fetus in breech presentation — Breech presentation is more common when fetal anomalies are present. For this reason, it is important to exclude fetal anomalies, such as hydrocephalus with macrocephaly or large tumors, before choosing the route of birth.

For a viable breech fetus with significant hydrocephalus with macrocephaly, birth should be by cesarean to avoid pelvic head entrapment. Both the uterine and the abdominal incisions should be sufficiently large to accommodate easy extraction of the head. A transverse incision in the lower segment may be too small in this setting, so it is preferable to use a vertical lower segment incision, which may have to be extended into the upper segment.

For a nonviable fetus with hydrocephalus with macrocephaly, vaginal breech birth is preferable since vaginal birth is generally safer for the mother and perinatal asphyxia will not change the outcome when congenital anomalies are lethal or the fetus is already dead. If pelvic head entrapment occurs during spontaneous labor and the mother consents, the calvarium can be decompressed and collapsed by cephalocentesis. The author uses a wide-bore spinal needle, but use of other instruments has been described in case reports. The procedure is easier to perform when the head is fixed at the pelvic brim after delivery of the body, at which stage the fetus usually is no longer alive, than when it is mobile in the upper segment. It may be performed transvaginally but is usually more easily performed transabdominally. In the United States, a deliberate intentional act that results in the death of a partially delivered fetus with a heart rate during an abortion may be unlawful (termed partial birth abortion). It is prudent to consult a hospital attorney and review state and federal regulations before performing cephalocentesis on a live fetus.

Delivery in the absence of skilled assistance and appropriate facilities — The following synopsis describes management of patients during imminent birth of a fetus in breech presentation not occurring on the labor and delivery unit. It is intended for health care providers who do not perform obstetric deliveries as part of their usual practice.

●Call for help. There are two patients in an obstetric delivery, the mother and the fetus; each needs at least one health care provider. An obstetrician and pediatrician or family medicine practitioner should be summoned, if available.

●If no part of the fetus has emerged from the vagina, encourage the mother not to bear down; panting may help the mother to avoid pushing. This provides some time to move the mother to the labor and delivery unit and/or for the arrival of a skilled birth assistant.

A beta sympathomimetic drug (eg, terbutaline 0.25 mg subcutaneously or 2.5 to 10 mcg/minute intravenously) may help to reduce the strength and frequency of uterine contractions. Alternatively, a beta sympathomimetic inhaler may be used.

However, once the fetus is partially born (the buttocks or a leg or legs are visible at or beyond the introitus), it is better to assist with completing the birth. The umbilical cord will usually be compressed during birth, so the fetus should be delivered ideally within 10 minutes. Significant cord compression is common once the buttocks have passed the perineum [80].

●The critical principle is to avoid any traction on the fetus unless there is absolutely no progress over several minutes of maternal bearing-down efforts. Pulling on the fetus tends to cause the neck/head to extend making it impossible to elevate the body and deliver the head by flexion, which makes birth of the head more difficult.

●When the fetal buttocks are visible at the introitus, support the mother in a semi-upright, crouching, or kneeling position (whichever feels best) with the thighs flexed and apart, and encourage them to bear down strongly during contractions. In most cases, the entire fetus will deliver spontaneously, and only gentle support of the body is needed as the head is born.

●If there is delayed progress of the birth, try turning the mother to a kneeling position and have them bear down in this position. Alternatively, apply gentle, steady pressure on the top of the uterus, toward the pelvis, during contractions. Avoid sharp pressure.

●If there is no further progress, attempt the maneuvers described in this topic. (See 'Delivery of the breech fetus' above.)

NEWBORN EVALUATION — All newborns born after abnormal fetal presentations require a thorough pediatric examination. A pediatrician should be present at birth because of the possibility of injury during delivery and the possibility that the malpresentation was due to a fetal abnormality. In addition, the risk of developmental dysplasia of the hip is increased with breech presentation [81].

Neonatal morbidity is common but not necessarily related to mode of birth or obstetric mismanagement in labor [82].

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: Breech presentation and external cephalic version".)

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: Breech pregnancy (The Basics)")

SUMMARY AND RECOMMENDATIONS — The following algorithm illustrates our approach to patients considering singleton breech vaginal delivery (algorithm 1).

●Overview – For patients who present in labor with a breech fetus, the options are cesarean birth or breech vaginal birth. Cesarean birth is the preferred approach in most hospitals. However, a minority of clinicians and pregnant patients opt for vaginal breech birth. In properly selected cases, it is associated with a low risk of complications. (See 'Introduction' above and "Overview of breech presentation".)

●Approach to vaginal birth

•Selection criteria – Our criteria for selecting patients at lower risk of morbidity from vaginal breech birth include (see 'Criteria for minimizing risk in patients who opt for vaginal breech birth' above):

-No contraindication to vaginal birth.

-No prior cesarean births (relative contraindication).

-No fetal anomaly that may cause dystocia.

-Estimated fetal weight within an appropriate range. The optimum range is unclear. The author uses ≥2000 and ≤4000 g, but ≥2500 and ≤3500 g or ≥1500 and ≤3800 g are examples of other reasonable approaches.

-Gestational age ≥36 weeks.

-No hyperextension of the fetal neck/head (ie, an extension angle of greater than 90 degrees).

-Frank or complete breech presentation (incomplete breech presentation is a contraindication).

-Spontaneous labor.

-Staff skilled in breech birth and immediate availability of facilities for safe emergency cesarean birth (eg, anesthesia, obstetric, and pediatric personnel; surgical facilities and personnel).

•Anesthesia – We prefer use of neuraxial rather than parenteral analgesia for management of labor pain. We avoid oxytocin augmentation in the active phase of labor. (See 'Labor management' above.)

•Procedure

-We leave membranes intact. A vaginal examination should be performed immediately upon rupture of membranes to exclude cord prolapse. (See 'Labor management' above.)

-Descent is adequate if the breech reaches the level of the ischial spines when the cervix is 6 cm dilated and reaches the pelvic floor at full dilation. We may delay pushing for up to 90 minutes. If the fetus fails to be born within 60 minutes of maternal pushing, we perform a cesarean birth. (See 'Labor management' above.)

-We do not assist the birth until maternal efforts have resulted in expulsion of the fetus at least to the scapulae. (See 'Buttocks, trunk, and lower limbs' above.)

-Arm dystocia can usually be resolved by rotation of the trunk by 180 degrees in each direction or by sliding an index finger along the scapula, over the shoulder, and into the antecubital fossa. The elbow and forearm are then swept in front of the face and downward to the chest, at which point the arm can be delivered (figure 1C). (See 'Arms' above.)

-It is essential that the trunk not be raised more than 45 degrees above the horizontal plane of the birth canal; this avoids traction on the cervical spine, which can lead to death or severe disability. (See 'Head' above.)

-Suprapubic pressure helps the neck/head to flex and descend. The head can deliver spontaneously or with use of the Mauriceau-Smellie-Veit maneuver or with use of Piper forceps. No method has been proven to be superior to the others. (See 'Head' above.)

-If the head is entrapped, we administer a uterine relaxant. Options include a beta adrenergic agonist (eg, terbutaline 0.25 mg subcutaneously or 2.5 to 10 mcg/minute intravenously) or nitroglycerin (50 mcg once, may repeat at one minute intervals as needed to sufficiently relax the uterus, maximum total dose 250 mcg; an initial bolus of 100 to 200 mcg may also be used but increases the risk of hypotension). General anesthesia is another option but may take too long to administer. The mother should also push effectively.

If maternal pushing, suprapubic pressure, and uterine relaxation are unsuccessful, all other options pose significant risk to the fetus and mother. (See 'Head entrapment' above.)

●Approach to cesarean birth

•At term – For patients with a breech presentation at term, we suggest scheduling planned cesarean birth for breech presentation between 39+0 and 41+0 weeks of gestation. For patients with a breech presentation in whom preterm birth is indicated for medical or obstetric reasons, the cesarean birth is scheduled or, in patients with spontaneous preterm labor, performed when birth appears to be inevitable.

The presentation should be checked immediately prior to surgery in case spontaneous version has occurred.

The technique of fetal extraction through the hysterotomy incision is similar to that for vaginal breech birth. (See 'Cesarean breech birth' above.)

•Preterm – The preterm lower uterine segment may be narrow, making delivery through a transverse lower uterine incision difficult. A vertical incision is made in the lower uterine segment and extended into the upper uterine segment if required. (See 'Cesarean breech birth' above.)