Premature Rupture of Membranes (PROM)

Definition and Classification

• PROM at term (≥37 weeks) - rupture before labor onset
• Preterm PROM (PPROM) - rupture before 37 weeks' gestation
• Previable PROM - rupture before approximately 22-23 weeks
• The latent period = time from membrane rupture to onset of labor

Predisposing Factors

• Short cervix
• Prior history of PROM or preterm delivery
• Genital tract infection (Chlamydia, gonorrhea, Trichomonas vaginalis, bacterial vaginosis)
• Non-genital infections (pyelonephritis, pneumonia, appendicitis, periodontal disease)
• Multiple gestation / polyhydramnios
• Uterine overdistention
• Smoking
• Placental abruption

Diagnosis

Complications

Maternal Complications

• Chorioamnionitis: 9% with term PROM; rises to 24% after >24 hours of rupture; 13-35% with PPROM remote from term; up to 25-77% with second-trimester PROM on conservative management
• Endometritis: 2-13%
• Placental abruption: 4-12%
• Maternal sepsis: 0.8% (death: 0.14%) - more likely with very early preterm PROM

Fetal Complications

• Umbilical cord compression (from oligohydramnios - FHR decelerations common)
• Umbilical cord prolapse (especially with malpresentation)
• Fetal death: ~1-2% with conservatively managed PROM; 12-71% (avg ~30%) with PROM <24 weeks
• Intrauterine infection

Neonatal Complications

• Gestational age at delivery is the primary determinant of severity
• Neonatal sepsis is twice as common after PPROM versus preterm labor
• Infection can manifest as congenital pneumonia, sepsis, meningitis
• Long-term: chronic lung disease, developmental disabilities, cerebral palsy, periventricular leukomalacia, visual/hearing deficits
• Long-term morbidities are uncommon with delivery after ~32 weeks

Management (Gestational Age-Based)

Term PROM (≥37 weeks)

• Induce labor - usually with oxytocin infusion
• No substantial fetal benefit to expectant management at term
• Reduces risk of chorioamnionitis (rises with prolonged rupture)
• Allow adequate time for latent phase; minimize digital vaginal exams until active phase

Preterm PROM at 34-36 weeks (Late Preterm)

• Conservative management prolongs pregnancy by only a few days (mean ~71-78 hours) while significantly increasing chorioamnionitis risk (16% vs 2%)
• PROMEXIL trials: conservative management doubled chorioamnionitis (5.6% vs 2.3%)
• Delivery is generally recommended - active management reduces RDS (5.2% vs 8.3%), ventilator need, and NICU stay
• Antenatal corticosteroids: administer if not previously given

Preterm PROM at <34 weeks (Remote from Term)

1. Antibiotics - broad-spectrum (e.g., ampicillin + erythromycin; ACOG recommends GBS prophylaxis); prolong latency and reduce infection
2. Antenatal corticosteroids - single course (betamethasone or dexamethasone) to accelerate fetal lung maturation
3. Tocolytics - short-term, to allow time for corticosteroids to act; not for prolonged use
4. Magnesium sulfate for neuroprotection - at 24-32 weeks to reduce risk of cerebral palsy
5. GBS prophylaxis - if colonization status unknown or positive
6. Continuous fetal monitoring - assess for cord compression, infection signs
7. DVT prophylaxis - leg exercises, compression stockings (prolonged bed rest increases DVT risk)

Previable PROM (<22-23 weeks)

• Particularly high fetal jeopardy
• Survival with conservative management at ≤24 weeks: ~44% overall (14% for PROM before 22 weeks; 58% for PROM at 22-24 weeks)
• Immediate delivery → neonatal death
• Requires detailed counseling; decisions individualized

Chorioamnionitis (Complication of PROM)

• Fever >38°C
• Maternal and fetal tachycardia
• Uterine tenderness
• Foul-smelling or purulent amniotic fluid
• Elevated CRP (>2 mg/dL); WBC unreliable (normally elevated in labor)

Summary Algorithm

Confirmed PROM
    ↓
Assess: gestational age, labor status, infection signs, fetal well-being
    ↓
≥37 weeks → Induce labor (oxytocin)
34-36 weeks → Active delivery (steroids if not given)
24-33 weeks → Conservative management:
              Antibiotics + Steroids + MgSO4 (24-32wks) + Tocolysis + Monitoring
<22-23 weeks → Individualized counseling; consider viability/prognosis

Malpresentation

Key Definitions

Incidence (Order of Decreasing Frequency)

1. Breech Presentation

Types

Predisposing Factors

• Prematurity (24% at 18-22 wks; 8% at 28-30 wks; 3-4% at term)
• Fundal-cornual placental implantation
• Uterine anomalies / polyhydramnios
• Multiple gestation
• Fetal neuromuscular disorders (diminished motor tone/activity)
• Prior breech presentation

Risks During Labor & Delivery

• Umbilical cord prolapse - especially footling breech (incomplete cervical occlusion)
• Head entrapment - after-coming head trapped by incompletely dilated cervix (especially prematurity <1500 g or CPD)
• Trauma from extension of the head or nuchal arms
• Fetal asphyxia - ~1/3 of breech fetal deaths considered preventable

Diagnosis

• Leopold maneuvers (globular hard head palpable at fundus)
• Speculum: soft, irregular presenting part
• Ultrasound - confirms type and fetal position

Management

• ACOG recommends planned CS if ECV fails or is not possible
• The landmark Term Breech Trial (Hannah et al., 2000, n=2088) showed statistically significant increase in perinatal morbidity and mortality with planned vaginal delivery vs. planned CS

• Success rate ~60%; should be attempted at ≥36 weeks (before this, spontaneous version may still occur)
• Requires: ultrasound, electronic fetal monitoring, tocolytic agents, readiness for emergency CS
• Factors predicting failure: engaged breech, oligohydramnios, posterior placenta, fetal spine anterior, nulliparity
• Neuraxial anesthesia increases ECV success rate
• Contraindications: placenta previa, oligohydramnios, non-reassuring CTG, prior uterine scar (relative), multiple gestation

• Frank or complete breech (not footling)
• Estimated fetal weight 2000-3800 g
• Normal gynecoid pelvis with adequate measurements (AP inlet ≥11 cm, widest transverse ≥12 cm, interspinous ≥9 cm)
• Flexed fetal head
• Qualified obstetrician present
• Continuous fetal monitoring throughout labor
• Membranes kept intact as long as possible (hydraulic cord protection)

2. Transverse Lie / Shoulder Presentation

• Fetal long axis perpendicular to uterine axis; presenting part is the shoulder
• Incidence: ~1 in 300 deliveries
• Common causes: prematurity (38%), high parity (87%), uterine anomaly, placenta previa, polyhydramnios, pelvic obstruction
• Oblique lie is unstable and typically converts to longitudinal or transverse during labor

Management

• <36-37 weeks, not in labor: await spontaneous version; do not attempt external version (risk of cord entanglement)
• ≥36-37 weeks, intact membranes, no placenta previa/CPD: external version → induction of labor at 38 weeks
• Unstable lie at ≥37 weeks: admit to hospital; evaluate for etiology; ECV + induction if no contraindication
  • Awaiting spontaneous labor in unstable lie → high cord prolapse rate (10 cord prolapses and 4 perinatal deaths in 50 unmanaged cases vs. 1 cord prolapse and 0 deaths in 102 actively managed cases)
• Labor with transverse lie + ruptured membranes or placenta previa: Cesarean section mandatory
  • Back-up transverse: low transverse uterine incision often adequate
  • Back-down shoulder presentation: classical (vertical) uterine incision usually required

3. Face and Brow Presentations (Deflection Abnormalities)

Engaging Diameters

• Vertex (normal): smallest - suboccipitobregmatic (~9.5 cm)
• Face: ~0.8 cm larger than vertex
• Brow: ~1.5 cm larger than vertex (mento-occipital diameter - the largest diameter of the fetal head)

Causes

• Cephalopelvic disproportion (CPD) - most important
• Increased parity, prematurity, PROM
• Anencephaly (almost always produces face presentation)

Face Presentation

• Reference landmark: chin (mentum)
  • Mentum anterior: usually delivers vaginally
  • Mentum transverse: frequently rotates to anterior
  • Mentum posterior: cannot deliver vaginally at term → CS
• Clinical rule: "If a face presentation is progressing, leave it alone"
• 70-90% of face presentations result in spontaneous delivery

Brow Presentation

• Head partially extended; mento-occipital diameter must negotiate the pelvic inlet
• Most spontaneously convert to face or vertex (>50% of cases)
• If brow fails to convert → labor arrest → CS required
• Associated with CPD in ~10.9% (vs. 2.7% with vertex)
• If labor progresses normally without CPD, oxytocin augmentation may be cautiously tried

Management of Both

• Recognize abnormality on vaginal exam (inability to centrally palpate posterior fontanelle; palpation of anterior fontanelle, orbital ridges, or nose)
• Suspect if lambdoid sutures cannot be identified centrally
• If labor arrested + CPD suspected → Cesarean section
• Persistent mentum posterior (face) or failed conversion (brow) → Cesarean section
• Labor arrest + poor contractions + no CPD: cautious oxytocin augmentation

4. Compound Presentation

• An extremity (usually hand/arm) enters the birth canal alongside the head or breech
• Small/premature fetuses usually proceed to vaginal delivery without incident
• Do NOT attempt to reduce the hand/arm - manipulation increases cord prolapse risk
• Cord prolapse rate: 10-20% even without manipulation
• CS indicated for labor arrest or cord prolapse

Summary Table