Obstetric Topic 29. Anomalies of rupture of membranes

I. Definitions and Risk Factors

Definitions

• PROM / prelabor rupture of membranes: rupture of fetal membranes before onset of labor at ≥37 weeks.
• PPROM / preterm prelabor rupture of membranes: rupture before 37 weeks and before labor.
• Prolonged rupture: rupture-to-delivery interval >18 h → increased infection risk.
• Normal rupture: spontaneous rupture during labor, usually in the first stage.

Risk Factors and Etiology

• Previous PROM, PPROM or preterm birth.
• Ascending genital tract infection.
• Uterine overdistension: multiple pregnancy, polyhydramnios.
• Procedures / trauma: amniocentesis, obstetric procedures, abdominal trauma.
• Smoking.
• Mechanism: infection/inflammation or mechanical stretch → membrane weakening → rupture → labor or infection.

II. Clinical Features and Diagnosis

Diagnosis

1. History: sudden gush or continuous leakage of watery vaginal fluid; ask color, odor, contractions, bleeding, fever and fetal movements.
2. Avoid digital vaginal examination unless active labor or delivery is planned → increases infection risk.
3. Sterile speculum examination:
   • Pooling in posterior fornix or leakage from cervical os.
   • Assess fluid color/odor, cervix, bleeding, discharge and possible prolapsed cord/parts.
4. Bedside / biochemical tests if pooling is not clear:
   • Nitrazine: blue = alkaline fluid, pH >6.5; false positive with blood, semen, infection or antiseptic.
   • Fern test: dried amniotic fluid forms fern-like crystals under microscopy.
   • IGFBP-1 / PAMG-1 immunoassay: useful when diagnosis is uncertain.
5. Ultrasound: oligohydramnios / reduced AFI supports PROM; also check presentation and placental status.
6. Fetal assessment: fetal heart monitoring / CTG when viable.

III. Complications

Maternal and Fetal Risks

• Infection: chorioamnionitis → maternal/fetal infection, neonatal sepsis, postpartum endometritis, maternal sepsis.
• Preterm birth: main PPROM consequence.
• Cord prolapse / cord compression → fetal hypoxia, especially with malpresentation or high presenting part.
• Malpresentation.
• Placental abruption and fetal distress.
• Early severe PPROM + oligohydramnios → pulmonary hypoplasia, fetal deformation, fetal loss.

IV. Management

General Principles

• Management depends on gestational age, infection, fetal status, labor, presentation and abruption/cord prolapse.
• Monitor maternal temperature, pulse, BP, uterine tenderness, fetal heart rate and labs if infection is suspected.
• Minimize vaginal examinations.
• GBS: screen if status unknown and give intrapartum prophylaxis when indicated.
• Immediate delivery if chorioamnionitis, placental abruption, cord prolapse, fetal distress or advanced labor.
• Cesarean section: only for obstetric indication, e.g. fetal distress not allowing vaginal delivery, cord prolapse or malpresentation.

Stable Patient by Gestational Age

1. Term PROM ≥37 weeks:
   • Short expectant management about 12-24 h if uncomplicated and no infection.
   • Oxytocin induction if no contractions or according to local protocol.
   • No routine antibiotics solely for term PROM without infection; give GBS prophylaxis if indicated.
2. Late preterm PPROM 34+0-36+6 weeks:
   • Individual risk assessment: induction/delivery vs expectant management.
   • Balance prematurity risk against infection risk; deliver if infection or fetal compromise appears.
   • Consider corticosteroids if delivery is expected within 7 days and no chorioamnionitis.
3. PPROM 24+0-33+6 weeks:
   • Expectant inpatient management if mother and fetus are stable.
   • Latency antibiotics: IV ampicillin + erythromycin, then oral regimen according to protocol.
   • Antenatal corticosteroids: fetal lung maturity.
   • Magnesium sulfate: neuroprotection if delivery before 32 weeks is expected.
   • Tocolysis: controversial; consider short-term only to complete steroids or transfer, if no infection/abruption/fetal compromise.

Chorioamnionitis

• Signs: fever, uterine tenderness, maternal/fetal tachycardia, foul liquor, raised inflammatory markers.
• Treatment: broad-spectrum antibiotics + delivery.
• Typical regimen: ampicillin + gentamicin; add clindamycin at cesarean for anaerobic coverage.
• Route: vaginal delivery preferred if rapid and safe; chorioamnionitis alone is not an automatic cesarean indication.