Breech Presentation

Etiology

Clinical conditions associated with breech presentation may increase or decrease fetal motility or affect the vertical polarity of the uterine cavity. Prematurity, multiple gestations, aneuploidies, congenital anomalies, Mullerian anomalies, uterine leiomyoma, and placental polarity as in placenta previa are most commonly associated with a breech presentation. Also, a previous history of breech presentation at term increases the risk of repeat breech presentation in subsequent pregnancies.[4][5] These are discussed in more detail in the pathophysiology section.

Epidemiology

Breech presentation occurs in 3% to 4% of all term pregnancies. A higher percentage of breech presentations occurs with less advanced gestational age. At 32 weeks, 7% of fetuses are breech, and 25% are breech at 28 weeks or less.

Specifically, following 1 breech delivery, the recurrence rate for the second pregnancy was nearly 10%, and for a subsequent third pregnancy, it was 27%. Some have also described prior cesarean delivery as increasing the incidence of breech presentation twofold.

Pathophysiology

As mentioned previously, the most common clinical conditions or disease processes that result in breech presentation affect fetal motility or the vertical polarity of the uterine cavity.[6][7] Conditions that change the vertical polarity or the uterine cavity or affect the ease or ability of the fetus to turn into the vertex presentation in the third trimester include:

• Mullerian anomalies: Septate uterus, bicornuate uterus, and didelphys uterus 
• Placentation: Placenta previa as the placenta occupies the inferior portion of the uterine cavity. Therefore, the presenting part cannot engage
• Uterine leiomyoma: Larger myomas are mainly located in the lower uterine segment, often intramural or submucosal, and prevent engagement of the presenting part.
• Prematurity
• Aneuploidies and fetal neuromuscular disorders commonly cause hypotonia of the fetus, inability to move effectively
• Congenital anomalies:  Fetal sacrococcygeal teratoma, fetal thyroid goiter
• Polyhydramnios: The fetus is often in an unstable lie, unable to engage
• Oligohydramnios: Fetus is unable to turn to the vertex due to lack of fluid
• Laxity of the maternal abdominal wall: The Uterus falls forward, and the fetus cannot engage in the pelvis.

The risk of cord prolapse varies depending on the type of breech. Incomplete or footling breech carries the highest risk of cord prolapse at 15% to 18%, complete breech is lower at 4% to 6%, and frank breech is uncommon at 0.5%.

History and Physical

During the physical exam, using the Leopold maneuvers, palpation of a hard, round, mobile structure at the fundus and the inability to palpate a presenting part in the lower abdomen superior to the pubic bone or the engaged breech in the same area, should raise suspicion of a breech presentation.

During a cervical exam, findings may include the lack of a palpable presenting part, palpation of a lower extremity, usually a foot, or for the engaged breech, palpation of the soft tissue of the fetal buttocks may be noted. If the patient has been laboring, caution is warranted as the soft tissue of the fetal buttocks may be interpreted as caput of the fetal vertex. Any of these findings should raise suspicion, and an ultrasound should be performed.

Evaluation

An abdominal exam using the Leopold maneuvers in combination with the cervical exam can diagnose a breech presentation. Ultrasound should confirm the diagnosis. The fetal lie and presenting part should be visualized and documented on ultrasound. If a breech presentation is diagnosed, specific information, including the specific type of breech, the degree of flexion of the fetal head, estimated fetal weight, amniotic fluid volume, placental location, and fetal anatomy review (if not already done previously), should be documented.

Treatment / Management

Expertise in the delivery of the vaginal breech baby is becoming less common due to fewer vaginal breech deliveries being offered throughout the United States and in most industrialized countries. The Term Breech Trial (TBT), a well-designed, multicenter, international, randomized controlled trial published in 2000, compared planned vaginal delivery to planned cesarean delivery for the term breech infant. The investigators reported that delivery by planned cesarean resulted in significantly lower perinatal mortality, neonatal mortality, and serious neonatal morbidity. Also, the 2 groups had no significant difference in maternal morbidity or mortality. Since that time, the rate of term breech infants delivered by planned cesarean has increased dramatically. Follow-up studies to the TBT have been published looking at maternal morbidity and outcomes of the children at 2 years. Although these reports did not show any significant difference in the risk of death and neurodevelopmental, these studies were felt to be underpowered.[8][9][10][11](B2)

Since the TBT, many authors have argued that there are still some specific situations in that vaginal breech delivery is a potential, safe alternative to a planned cesarean. Many smaller retrospective studies have reported no difference in neonatal morbidity or mortality using these criteria.

The initial criteria used in these reports were similar: gestational age greater than 37 weeks, frank or complete breech presentation, no fetal anomalies on ultrasound examination, adequate maternal pelvis, and estimated fetal weight between 2500 g and 4000 g. In addition, the protocol presented by 1 report required documentation of fetal head flexion and adequate amniotic fluid volume, defined as a 3-cm vertical pocket. Oxytocin induction or augmentation was not offered, and strict criteria were established for normal labor progress. CT pelvimetry did determine an adequate maternal pelvis.

Despite debate on both sides, the current recommendation for the breech presentation at term includes offering an external cephalic version (ECV) to those patients who meet the criteria, and for those who are not candidates or decline external cephalic version, a planned cesarean section for delivery sometime after 39 weeks.

Regarding the premature breech, gestational age determines the mode of delivery. Before 26 weeks, there is a lack of quality clinical evidence to guide the mode of delivery. One large retrospective cohort study recently concluded that from 28 to 31 6/7 weeks, there is a significant decrease in perinatal morbidity and mortality in a planned cesarean delivery versus intended vaginal delivery, while there is no difference in perinatal morbidity and mortality in gestational age 32 to 36 weeks. Of note is that no prospective clinical trials examine this issue due to a lack of recruitment.

Differential Diagnosis

The differential diagnoses for the breech presentation include the following:

• Face and brow presentation
• Fetal anomalies
• Fetal death
• Grand multiparity
• Multiple pregnancies
• Oligohydramnios
• Pelvis Anatomy
• Preterm labor
• Primigravida
• Uterine anomalies