Evaluation and management of preterm premature rupture of membranes

Algorithmic management approach Assess stability of fetal presentation.

After confirming the diagnosis of PPROM, the clinician should assess gestational age on the basis of history, physical examination, and ultrasound. The fetal presentation and estimated fetal weight should be determined, and the fetal heart rate should be monitored for evidence of recurrent variable decelerations. The mother should be evaluated for chorioamnionitis, primarily by assessment of temperature and maternal and fetal heart rate.

If the fetal presentation is unstable, thus predisposing to umbilical cord prolapse, or if the fetal heart rate tracing is worrisome, the patient should be delivered. If the gravida initially is admitted to a facility with only a level 1 nursery and maternal transfer is impractical, neonatal transfer should take place immediately after the birth.

Assess fetal lung maturity. At a gestational age of less than 32 weeks, lung maturity is very unlikely, and testing is not cost-effective. However, at 32 to 34 weeks, testing should be performed routinely. Amniotic fluid may be obtained by transabdominal amniocentesis or by aspiration of fluid pooled in the vaginal vault. Edwards et al³ recently confirmed the reliability of this sampling method. Lung maturity may be assessed by means of the lecithin:sphingomyelin ratio, lamellar body count, or fetal lung maturity test.

If the fetal presentation is unstable or the fetal heart rate tracing is worrisome, the patient should be delivered.

The decision to deliver. If the gestational age is 32 weeks or more, fetal lung maturity is confirmed, and a neonatal intensive care unit is available, both mother and baby usally will fare better if delivered.

Patients should be treated intrapartum with antibiotics to prevent perinatal transmission of group B streptocol infection. Appropriate regimens include penicillin, then 2.5 million units IV every 4 hours; or ampicillin, 2 g IV initially, then I g every 4 hours.

A recent study confirmed the value of this treatment plan.⁴ In it, 164 patients at 32 to weeks’ gestation with confirmed fetal lung maturity were randomly assigned to delivery or expectant management. The mean gestational ages in the two groups were similar: 34.1 weeks in the former and 34.3 weeks in the latter group. The expectant management group had a longer duration of hospitalization for the mother and baby, and an increased rate of maternal infection and fetal heart rate abnormalities. In addition, the infants in this group received more frequent, prolonged antibiotic therapy.

Expectant management is appropriate for some patients. If gestational age is less than 32 weeks and the mother and fetus are stable, expectant management is appropriate.

If the patient is at 32 to 34 weeks’ gestation and amniotic fluid cannot be obtained, she should be managed expectantly until 34 weeks. At 34 weeks, she should be delivered.

A recent study by Naef et al⁵ confirmed the value of delivery at 34 weeks or more. In this investigation, 120 patients at 34 to 36 6/7 weeks’ gestation were randomly assigned to oxytocin induction (n = 57) or expectant management (n = 63). Fetal lung maturity studies were not done. In the expectant management group, chorioamnionitis occurred more often (16% versus 2%, P = .007), maternal hospitalization was prolonged (5.2±6.8 days versus 2.6±1.6 days, P = .006), and there was a trend toward an increased rate of neonatal infection.

• Corticosterioids. A single course of corticosteroids should be administered to reduce the risk of neonatal RDS, IVH, and NEC.² Dosage regimens include 2 intramuscular (IM) doses of betamethasone, 12 mg, at 24-hour intervals, or 4 IM doses of dexamethasone, 6 mg, at 12-hour intervals. Tocolytics should be administered to delay delivery for 48 hours, thus permitting administration of corticosteroids.³ Prolonged administration of tocolytics is not justified.
  
• Testing for infection. The patient should be tested for gonorrhea, chlamydia, bacterial vaginosis, and group B streptococcal colonization. If the test for bacterial vaginosis is positive, the patient should be treated with metronidazole, 250 mg orally, 3 times daily, for 7 days. If gonorrhea is present, she should receive either cefixime, 400 mg orally in a single dose, or ceftriaxone, 125 mg IM in a single dose.⁶
  

• Prophylactic antibiotics. Even in the absence of obvious lower genital tract infection, patients with PPROM benefit from antibiotic prophylaxis. Many studies investigating the role of prophylactic antibiotics in women with PPROM have been published.⁷