Preterm Premature Rupture of the Membranes

Preterm Premature Rupture of the Membranes (PPROM) is the rupture of the membranes prior to 37 completed weeks gestation and prior to the onset of labour.

Pre-labour rupture of membranes at term (PROM) is defined as spontaneous rupture of the membranes before the onset of labour at or after 37 weeks gestation. PROM is prolonged when it occurs more than 18 hours before the commencement of labour and is associated with an increased risk of ascending infection.

All women with actual or suspected PPROM should be referred urgently to the Obstetric Unit and observed in hospital for at least 72 hours.

The timing of delivery depends on gestational age, clinical evidence of infection, and the patient’s Group B streptococcus (GBS) status.

History

Traditionally, diagnosis was based on:

Traditional tests

• Alkaline pH of cervicovaginal discharge (nitrazine test)
• Ferning of cervicovaginal discharge
• Diminished amniotic fluid volume on ultrasound

Current test

• Testing for the amniotic fluid protein PAMG-1 (AmniSure)

Pathophysiology

PPROM complicates 2% of pregnancies and accounts for 40% of preterm deliveries.

Risk Factors

1. Previous PPROM
2. Previous preterm labour
3. Low socioeconomic status
4. Smoking
5. Infections (STIs, chorioamnionitis)
6. Cervical surgery
7. Uterine overdistension
8. Cervical cerclage
9. Amniocentesis
10. Antepartum bleeding
11. Placental abruption
12. Abdominal trauma

Complications

1. Infection (mother and fetus)
   • In general terms there is a higher (potential) risk of infection (about 2%)    for the baby and mother if you wait for labour to start, compared to being   induced shortly after the membranes have ruptured (0.5%).
2. Premature labour
   • An inverse relationship exists between gestational age at the time of ROM and latency.
   • In general women with preterm PROM at 24 to 28 weeks of gestation are likely to have a longer latency period than those with preterm PROM closer to term.
   • At term (in the absence of obstetric intervention):
     • 50% of pregnancies complicated by PROM will go into labour spontaneously within 12 hours
     • 70% within 24 hours
     • 85% within 48 hours
     • 95% within 72 hours
   • In women with PPROM remote from term:
     • 50% will go into labour within 24 – 48 hours
     • 70% – 90% within 7 days.
3. Pulmonary hypoplasia (if <22 weeks gestation)

Clinical Assessment

Preterm PROM is a clinical diagnosis based on:

History

• Gush or trickle of vaginal fluid
• Differential diagnoses: urinary incontinence, infection, cervical mucus

Examination

• Vital signs
• Abdominal exam (fundal height, contractions)
• Sterile speculum exam (confirm fluid, take swabs)

Investigations

Blood tests

• FBE
• CRP
• U&Es, glucose

Amniotic fluid testing

• PAMG-1 (AmniSure)
  • When the diagnosis is unclear from clinical assessment, the presence of amniotic fluid can be confirmed by testing for the presence of the protein, PAMG-1 (placental a-1 microglobulin).
  • This protein has a sensitivity of 96% and specificity of 98.9% for amniotic fluid.
• Amnio-dye test (rarely required)

Urine

• MSU for M&C

Swabs

• High vaginal swab for M&C
• Low vaginal and anorectal swab for GBS

Other

• CTG for fetal wellbeing
• Ultrasound for fetal size, well-being, and liquor volume

Management

1. ABC stabilization
2. Steroids
   • Steroids may be required for prophylaxis for neonatal respiratory distress syndrome.All women with PPROM < 34 weeks gestation should be administered corticosteroids
   • Betamethasone 11.4mg IM daily x 2 doses for gestations <34 weeks

3. Cervical suture – Remove if present and send for culture

4. Tocolysis – For gestations <34 weeks with contractions and no infection, to complete steroid course

5. Antibiotics – Antibiotic treatment after PPROM reduces the risk of ascending infection; Chorioamnionitis and delivery within 7 days

Broad-spectrum prophylaxis

• Preferred (for ≤ 32 weeks):
  • Amoxycillin 2g IV 6-hourly + Erythromycin 250mg PO 6-hourly for 48 hrs
  • Then Amoxycillin 250mg PO 8-hourly + Erythromycin 500mg PO 8-hourly for 5 days
• Alternative:
  • Erythromycin 250mg PO 6-hourly for 10 days
• Avoid amoxycillin/clavulanic acid

GBS prophylaxis

• Benzylpenicillin 1.2g IV stat, then 600mg IV 4-hourly x 6 doses
• Alternatives: Clindamycin or Lincomycin 600mg IV TDS

6. Magnesium sulphate
   • Magnesium sulphate should be given to women at risk of imminent, preterm (<30 weeks gestation) birth to provide neuroprotection to the fetus (NHMRC: grade A recommendation)
   • For neuroprotection <30 weeks gestation
   • Start 4 hours before planned delivery if possible

7. Delivery
   • 36 weeks: induce labour if no contraindications
   • GBS positive: consider induction from 32 weeks
   • Conservative management: deliver at 36 weeks or earlier if infection develops

Disposition

Observe in hospital for 72 hours. Outpatient follow-up is possible for stable patients remote from delivery.

Re-present if:

• Temp ≥ 37.2°C
• Fluid becomes green/brown or malodorous
• Vaginal bleeding
• Abdominal pain or contractions
• Concerns about fetal movement
• Feeling unwell
• Any other concerns

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References

Publications

• Caughey AB, Robinson JN, Norwitz ER. Contemporary diagnosis and management of preterm premature rupture of membranes. Rev Obstet Gynecol. 2008 Winter;1(1):11-22