Prelabor rupture of membranes means the amniotic sac breaks before labor starts; when it happens before 37 weeks it is called preterm. The main risks are infection, cord prolapse and preterm birth.
Key symptoms
- Sudden gush or steady leak of clear fluid from the vagina
- Wet underwear that keeps coming back
- Contractions that may or may not follow
- Fever or foul-smelling fluid if infection develops
What you find on exam
- Sterile speculum exam: fluid pooling in the vagina
- No digital cervical exam unless in labor
- Temperature, maternal and fetal heart rate
- Uterine tenderness suggests intraamniotic infection
Tests
- Nitrazine test (paper turns blue) and ferning under the microscope
- Ultrasound for amniotic fluid volume and fetal position
- Group B Streptococcus culture if status is unknown
- Continuous fetal heart rate monitoring
Treatment basics
- 37 weeks or more: induce labor, usually with oxytocin
- 34 to 36 weeks: delivery or careful watchful waiting after shared decision
- Under 34 weeks: watchful waiting with antibiotics (ampicillin plus azithromycin or erythromycin) and betamethasone
- Magnesium sulfate for fetal brain protection under 32 weeks
- Penicillin for GBS prophylaxis when indicated
Red flags
- Fever, uterine tenderness or foul fluid (intraamniotic infection)
- Cord seen or felt in the vagina: cord prolapse, an emergency
- Abnormal fetal heart rate or vaginal bleeding
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.