Prelabour Rupture of Membranes at Term

Prelabour rupture of membranes at term is rupture of the membranes at 37 weeks or later before contractions have begun. It results from membrane weakening, infection or physical stress. It matters because most women go into labour within 24 hours, but waiting too long raises the risk of intrauterine infection and neonatal sepsis.

• Most women labour within 24 hours.
• Risk factors: smoking, genital tract infection, previous preterm rupture, polyhydramnios, multiple pregnancy.
• Waiting is safe for well women for up to 24 hours, after which induction lowers infection.

Women have sudden leakage of fluid with no pain, and normal fetal movements. Examination shows fluid in the vagina, a soft uterus, and a normal temperature and pulse.

• No contractions at presentation.
• Fluid is usually clear.
• Differential diagnosis: urine leakage, vaginal discharge, loss of mucus plug, bacterial vaginosis, cervicitis, early labour.
• Complications: chorioamnionitis, cord prolapse, abruption, fetal distress, neonatal sepsis, caesarean section, postpartum infection.

The approach is history and a sterile speculum examination, without digital examination.

• Speculum examination: pooling of fluid, nitrazine paper blue (pH above 6.5), ferning on microscopy.
• Placental alpha microglobulin 1 or insulin-like growth factor binding protein 1 test where available.
• Ultrasound for presentation, amniotic fluid index and cord; cardiotocography for 20 minutes; maternal temperature and pulse.
• Rectovaginal swab for group B streptococcus.

The principle is to offer induction at presentation or expectant care for up to 24 hours, then induce, with antibiotics when indicated.

• Supportive: explain choices; admit or home review every 4 to 6 hours if well and near the facility with a clean pad check; temperature 4-hourly; avoid baths and intercourse; return at once for fever, foul fluid, reduced movements, or contractions.
• Pharmacological: misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) for induction in an unscarred uterus, or oxytocin starting at 2 mU/minute and doubling every 30 minutes to a maximum of 32 mU/minute; benzylpenicillin 5 million units IV then 2.5 million units 4-hourly in labour for group B streptococcus carriage or rupture of 18 hours or more; ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily for chorioamnionitis; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours); oxytocin 10 IU IM at birth.
• Procedures: induction within 24 hours of rupture; Foley catheter with a 30 mL balloon if the uterus is scarred; continuous cardiotocography once induction starts; caesarean section for obstetric reasons or cord prolapse.
• Special groups: penicillin allergy of low risk uses cefazolin 2 g IV then 1 g 8-hourly, and severe allergy uses clindamycin 900 mg IV 8-hourly; HIV positive women continue tenofovir 300 mg, lamivudine 300 mg and dolutegravir 50 mg oral once daily and are induced early; newborns of mothers who had fever or incomplete antibiotic cover have a sepsis screen and benzylpenicillin 50 mg/kg IV 12-hourly plus gentamicin 5 mg/kg IV 24-hourly for 48 hours pending culture.
• Red flags: temperature above 38 degrees Celsius, maternal pulse above 100 per minute, fetal heart rate above 160 beats per minute, foul liquor, meconium, bleeding, cord felt in the vagina.
• Follow-up: newborn observation for 12 to 24 hours; maternal temperature 4-hourly for 24 hours after birth; review at 6 weeks.