Breech Presentation

1. Incidence and Etiology

• Fundal-cornual placental implantation (occurs in only 7% of all pregnancies but strongly associated with breech)
• Uterine anomalies (septate, bicornuate uterus)
• Prematurity and multiple gestation
• Polyhydramnios or oligohydramnios
• Pelvic tumors or structural abnormalities
• Fetal neuromuscular disorders (reduced fetal movement/tone - infants with neuromuscular disorders have disproportionately high rates of breech at delivery)
• Hydrocephaly or other major fetal anomalies

2. Classification

A. Frank Breech (Extended Breech)

• Hips flexed, knees extended - legs lie alongside the trunk
• Most common: 60-65% of all breech presentations
• Buttocks act as a good dilating wedge
• Cord prolapse risk: ~0.5% (lowest of the three types)

B. Complete Breech (Flexed Breech)

• Hips and knees both flexed - fetus in a "squatting" posture
• Least common: ~5% of all breech presentations
• Buttocks still act as a reasonable dilating wedge
• Cord prolapse risk: 5-6%

C. Incomplete (Footling) Breech

• One or both feet (or knees) are lowermost in the canal; incomplete hip flexion
• Frequency: 25-35% of all breech presentations
• Poor cervical dilating wedge
• Highest cord prolapse risk: 15-18%

3. Diagnosis

Clinical Methods

• First maneuver: the hard, ballotable fetal head is felt in the fundus (instead of the softer breech)
• Third maneuver (Pawlik's): the presenting part above the symphysis is soft, irregular, and does not ballot as sharply as the head
• Fourth maneuver: the back is identified on one side, the small parts on the other

• The presenting part is soft and irregular
• The sacrum, ischial tuberosities, anus, and genitalia may be palpable
• Key differentiating clue: the anus is flanked by bony prominences on only two sides, whereas the face and skull have a complete circle of bone around them
• Whenever a fontanel cannot be identified on examination, breech presentation should be suspected

Ultrasound

• Type of breech (frank, complete, footling)
• Gestational age and estimated fetal weight
• Position of fetal arms and neck - hyperextension of the fetal neck is a contraindication to vaginal delivery (high risk of spinal cord injury)
• Placental location
• Amniotic fluid volume
• Fetal anomalies

4. Course of Labor

First Stage

• The buttocks are a less effective dilating wedge (especially incomplete breech)
• Fetal monitoring is essential throughout - because the fetal abdomen and umbilical cord insertion are in the lower uterine segment during late first stage and second stage, significant variable decelerations are more likely than with cephalic presentation
• Membranes should be left intact as long as possible to provide hydraulic protection against cord compression

Second Stage - Mechanism of Labor

1. Engagement - bitrochanteric diameter engages in an oblique diameter of the pelvic inlet
2. Descent - the anterior hip descends more rapidly than the posterior hip
3. Internal rotation - bitrochanteric diameter rotates to assume the anteroposterior (AP) diameter of the outlet
4. Lateral flexion - the anterior hip catches beneath the symphysis pubis, allowing the posterior hip to be born first, then the anterior hip
5. Shoulder engagement - the fetal body rotates so the shoulders engage obliquely; they descend and rotate to the AP diameter; the anterior shoulder follows lateral flexion, and the posterior shoulder is born first
6. Delivery of the after-coming head - the head engages in the same diameter as the shoulders; flexion, descent, and rotation bring the posterior neck under the symphysis; the head is born in flexion

Risks Inherent in Labor

• Prolapse of the umbilical cord - especially in footling breech
• Trapping of the after-coming head by an incompletely dilated cervix - particularly dangerous in preterm infants (<1500 g) and with CPD
• Trauma from extension of the fetal head or nuchal position of the arms
• Fetal acidosis - breech labors are more often associated with significant fetal acidosis than cephalic presentations; fetal blood sampling from the buttock is possible if the heart rate pattern is ominous

Prognostic Scoring (Zatuchni-Andros Index)

Criteria for Allowing a Trial of Labor (Vaginal Breech Delivery)

• Frank or complete breech presentation (not footling)
• Estimated fetal weight 2000-3800 g
• Normal gynecoid pelvis with adequate measurements (AP inlet ≥11 cm, widest transverse inlet ≥12 cm, interspinous diameter ≥9 cm)
• Flexed fetal head (not hyperextended)
• Experienced obstetrician present

Types of Vaginal Breech Delivery

• Spontaneous breech: infant delivers without manipulation - rare at term, minimal traumatic morbidity
• Partial (assisted) breech extraction: spontaneous to the umbilicus, then body is extracted
• Total breech extraction: entire body extracted by clinician - rarely indicated except for second twin in emergency

5. Indications for Cesarean (Abdominal) Delivery

Absolute / Standard Indications Relating to Breech

General Indications for Cesarean That Apply to All Presentations (from Morgan & Mikhail)

• Increased risk of uterine rupture (previous classic cesarean section, previous extensive myomectomy)
• Central or partial placenta previa
• Abruptio placentae

• Fetopelvic disproportion (CPD)
• Abnormal fetal presentation (transverse/oblique lie, breech)
• Dysfunctional uterine activity

• Fetal distress
• Umbilical cord prolapse with fetal bradycardia
• Maternal hemorrhage
• Active genital herpes with ruptured membranes
• Impending maternal death

The Hannah Trial (Term Breech Trial, 2000)

Summary