Premature Rupture of Membranes (PROM)
Treatment of PROM depends on the stage of the patient’s pregnancy. In PROM occurring at term, the mother and baby will be watched closely for the first 24 hours to see if labor will begin naturally. If no labor begins after 24 hours, most doctors will use medications to start labor. This is called inducing labor. Labor is induced to avoid a prolonged gap between PROM and delivery because of the increased risk of infection.
Preterm PROM presents more difficult treatment decisions. The younger the fetus, the more likely it may die or suffer serious permanent damage if delivered prematurely. Yet the risk of infection to the mother and/or the fetus increases as the length of time from PROM to delivery increases. Depending on the age of the fetus and signs of infection, the doctor must decide either to try to prevent labor and delivery until the fetus is more mature, or to induce labor and prepare to treat the complications of prematurity. However, the baby will need to be delivered to avoid serious risks to both it and the mother if infection is present, regardless of the risks of prematurity.
Corticosteroids decrease perinatal morbidity and mortality after preterm PROM. A recent meta-analysis found that corticosteroid administration after preterm PROM, versus no administration, reduced the risk of respiratory distress syndrome (20 versus 35.4 percent), intraventricular hemorrhage (7.5 versus 15.9 percent), and necrotizing enterocolitis (0.8 versus 4.6 percent) without an increase in the risk of maternal or neonatal infection. Because corticosteroids are effective at decreasing perinatal morbidity and mortality, all physicians caring for pregnant women should understand the dosing and indications for corticosteroid administration during pregnancy. The most widely used and recommended regimens include intramuscular betamethasone (Celestone) 12 mg every 24 hours for two days, or intramuscular dexamethasone (Decadron) 6 mg every 12 hours for two days. The National Institutes of Health recommends administration of corticosteroids before 30 to 32 weeks’ gestation, assuming fetal viability and no evidence of intra-amniotic infection. Use of corticosteroids between 32 and 34 weeks is controversial. Administration of corticosteroids after 34 weeks’ gestation is not recommended unless there is evidence of fetal lung immaturity by amniocentesis. Multiple courses are not recommended because studies have shown that two or more courses can result in decreased infant birth weight, head circumference, and body length.
Giving antibiotics to patients with preterm PROM can reduce neonatal infections and prolong the latent period. A meta-analysis showed that patients receiving antibiotics after preterm PROM, compared with those not receiving antibiotics experienced reduced postpartum endometritis, chorioamnionitis, neonatal sepsis, neonatal pneumonia, and intraventricular hemorrhage. Another meta-analysis found a decrease in neonatal intraventricular hemorrhage and sepsis. A number of antibiotic regimens are advocated for use after preterm PROM. The regimen studied by the National Institute of Child Health and Human Development trial uses an intravenous combination of 2 grams of ampicillin and 250 mg of erythromycin every six hours for 48 hours, followed by 250 mg of amoxicillin and 333 mg of erythromycin every eight hours for five days. Women given this combination were more likely to stay pregnant for three weeks despite discontinuation of the antibiotics after seven days. It is advisable to administer appropriate antibiotics for intrapartum group B streptococcus prophylaxis to women who are carriers, even if these patients have previously received a course of antibiotics after preterm PROM.
Limited data are available to help determine whether tocolytic therapy is indicated after preterm PROM. As described above, corticosteroids and antibiotics are beneficial when administered to patients with preterm PROM, but no studies of these therapies combined with tocolysis are available. Tocolytic therapy may prolong the latent period for a short time but do not appear to improve neonatal outcomes. In the absence of data, it is not unreasonable to administer a short course of tocolysis after preterm PROM to allow initiation of antibiotics, corticosteroid administration, and maternal transport, although this is controversial. Long-term tocolytic therapy in patients with PROM is not recommended; consideration of this should await further research.
Management Based on Gestational Age
34 TO 36 WEEKS
When preterm PROM occurs at 34 to 36 weeks’ ges-tation, physicians should avoid the urge to prolong pregnancy. Studies have shown that labor induction clearly is beneficial at or after 34 weeks’ gestation. One study showed that conservative management between 34 and 36 weeks’ gestational age resulted in an increased risk of chorioamnionitis and a lower average umbilical cord pH. Another study of 430 women with preterm PROM revealed that there was no improvement in major or minor neonatal morbidity after 34 weeks’ gestation. Although corticosteroids are not indicated after 34 weeks’ gestation, physicians should prescribe appropriate antibiotics for group B streptococcus prophylaxis and should consider maternal transport to a facility skilled in caring for premature neonates, if possible. Preterm PROM is not a contraindication to vaginal delivery.
32 TO 33 WEEKS
For patients with preterm PROM at 32 or 33 weeks’ gestation with documented pulmonary maturity, induction of labor and transportation to a facility that can perform amniocentesis and care for premature neonates should be considered. Prolonging pregnancy after documentation of pulmonary maturity unnecessarily increases the likelihood of maternal amnionitis, umbilical cord compression, prolonged hospitalization, and neonatal infection.
There are few data to guide the care of patients without documented pulmonary maturity. No studies are available comparing delivery with expectant management when patients receive evidence-based therapies such as corticosteroids and antibiotics. Physicians must balance the risk of respiratory distress syndrome and other sequelae of premature delivery with the risks of pregnancy prolongation, such as neonatal sepsis and cord accidents. Physicians should administer a course of corticosteroids and antibiotics to patients without documented fetal lung maturity and consider delivery 48 hours later or perform a careful assessment of fetal well-being, observe for intra-amniotic infection, and deliver at 34 weeks, as described above. Consultation with a neonatologist and physician experienced in the management of preterm PROM may be beneficial. Patients with amnionitis require broad-spectrum antibiotic therapy, and all patients should receive appropriate intrapartum group B streptococcus prophylaxis, if indicated.