Previable Rupture of Membranes

Previable rupture of membranes is rupture before the gestation at which a baby can survive, usually before 24 weeks, and in facilities without neonatal intensive care often before 28 weeks. It follows infection, cervical weakness, bleeding or unknown causes. It matters because survival is low, the risk of infection and pulmonary hypoplasia is high, and parents need clear counselling on expectant care or delivery.

• Survival is low even when the pregnancy continues to viability.
• Risk factors: previous preterm rupture, cervical surgery, short cervix, cerclage, bleeding, genital infection, smoking.
• Pulmonary hypoplasia is likelier with rupture before 20 weeks and oligohydramnios beyond 14 days.

Women have sudden leakage of fluid, often with a small uterus for dates, and may have no pain at first. Fever, uterine tenderness and foul discharge signal infection.

• Fundal height smaller than dates.
• Contractions may start within days.
• Differential diagnosis: urinary incontinence, vaginal discharge, threatened miscarriage, cervical insufficiency with bulging membranes, bacterial vaginosis.
• Complications: chorioamnionitis, maternal sepsis, placental abruption, cord prolapse, pulmonary hypoplasia, limb contractures, fetal death, extremely preterm birth.

The approach is to confirm rupture and gestation and to exclude infection.

• Sterile speculum: pooling of fluid, nitrazine paper blue (pH above 6.5), ferning; placental alpha microglobulin 1 or insulin-like growth factor binding protein 1 test where available.
• Ultrasound: gestation, amniotic fluid index and deepest vertical pocket, fetal growth, presentation, cervical length; avoid digital examination.
• Temperature, pulse, full blood count, C-reactive protein, high vaginal and rectovaginal swab, urine culture.
• Cardiotocography only after viability.

The principle is to counsel on options, give antibiotics, deliver for infection, and give steroids once viability is reached.

• Supportive: counselling with the family on outlook; offer expectant care or delivery within the law, including delivery where the mother's life or health is in danger; admit for at least 1 week then consider outpatient care if stable; temperature twice daily; remove any cerclage in the presence of infection or labour; pelvic rest.
• Pharmacological: amoxicillin 500 mg oral 8-hourly plus erythromycin 250 mg oral 6-hourly for 7 days (azithromycin 1 g oral once if erythromycin is unavailable); betamethasone 12 mg IM twice, 24 hours apart, from 24 weeks to 34 weeks and 6 days; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks; chorioamnionitis: ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily; for termination of pregnancy where indicated: mifepristone 200 mg oral then misoprostol 400 micrograms vaginal or sublingual 3-hourly (maximum 5 doses) 24 to 48 hours later, or misoprostol alone 400 micrograms vaginal 3-hourly (maximum 5 doses); paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours).
• Procedures: induction of delivery or evacuation for infection, bleeding or abruption at any gestation; amnioinfusion with sodium chloride 0.9 percent is considered only in specialist units; caesarean section for obstetric reasons after viability.
• Special groups: RhD negative women give anti-D immunoglobulin 500 IU IM within 72 hours of bleeding; HIV positive women continue tenofovir 300 mg, lamivudine 300 mg and dolutegravir 50 mg oral once daily.
• Red flags: temperature above 38 degrees Celsius, foul liquor, uterine tenderness, bleeding, maternal pulse above 100 per minute, fetal tachycardia, contractions.
• Follow-up: full blood count and C-reactive protein every 2 to 3 days in hospital; amniotic fluid index weekly; delivery by 34 weeks if the pregnancy reaches viability; postnatal counselling on recurrence.