Term Rupture of Membranes

Term rupture of membranes is rupture of the amniotic sac at 37 weeks or later, before or during labour. Most women labour spontaneously within 24 hours. It matters because the risk of chorioamnionitis and neonatal sepsis rises with the time from rupture to birth, and group B streptococcus carriage raises the risk further.

• Risk factors: previous preterm rupture, smoking, genital infection, polyhydramnios, multiple pregnancy, low body mass index.
• Group B streptococcus is carried by many healthy women.
• Prompt induction cuts infection without raising caesarean rates.

Women report a gush or continuous trickle of clear fluid that wets the clothing, with or without contractions. Fluid pools in the posterior fornix on speculum examination, and increases with coughing.

• Clear or pale straw liquor.
• Green liquor suggests meconium; bloody or foul liquor suggests abruption or infection.
• Differential diagnosis: urinary incontinence, vaginal discharge, loss of mucus plug, bacterial vaginosis, cervicitis, semen.
• Complications: chorioamnionitis, cord prolapse, placental abruption, fetal distress, neonatal sepsis, caesarean section, postpartum endometritis.

The approach is a clinical history with a sterile speculum examination.

• Sterile speculum examination: pooling of fluid in the posterior fornix, fluid leaking on coughing, nitrazine paper turning blue (pH above 6.5), ferning of dried fluid on a slide.
• Placental alpha microglobulin 1 or insulin-like growth factor binding protein 1 test on vaginal fluid where available.
• Ultrasound for presentation, amniotic fluid index and cord position; cardiotocography; temperature, pulse, blood pressure.
• Rectovaginal swab for group B streptococcus; avoid digital vaginal examination unless in established labour.

The principle is to confirm rupture, check the fetus and the cord and offer induction within 24 hours, with antibiotics for infection or group B streptococcus risk.

• Supportive: confirm presentation and exclude cord prolapse; admit or review at home every 4 to 6 hours if well and near the facility; temperature 4-hourly; sanitary pad checked for colour and smell; avoid baths, tampons and intercourse; fluid intake 2 litres daily.
• Pharmacological: induce within 24 hours with misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) in an unscarred uterus, or oxytocin starting at 2 mU/minute and doubling every 30 minutes to a maximum of 32 mU/minute; for group B streptococcus carriage, rupture of 18 hours or more, or fever, give benzylpenicillin 5 million units IV then 2.5 million units 4-hourly until delivery; for chorioamnionitis give ampicillin 2 g IV 6-hourly plus gentamicin 5 mg/kg IV once daily; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours) for fever; oxytocin 10 IU IM at birth.
• Procedures: Foley catheter with a 30 mL balloon for induction in a scarred uterus; caesarean section for obstetric reasons, cord prolapse or fetal distress; continuous cardiotocography after induction starts.
• 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 have induction without delay (caesarean section is considered for viral load above 1000 copies/mL); newborns of mothers with 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, foul-smelling liquor, fetal heart rate above 160 beats per minute, thick meconium, vaginal bleeding, palpable cord, constant pain.
• Follow-up: newborn observation for 12 to 24 hours with temperature, feeding and breathing checks; maternal temperature 4-hourly for 24 hours after birth; review at 6 weeks.