PROM dilemmas: Choosing a strategy, knowing when to call it quits

Are prophylactic antibiotics warranted?

The fact that infection is the most commonly identified cause of PROM prompts the question: Does treatment with IV antibiotics improve outcomes and prolong latency even in the absence of clinically apparent infection? Mercer and colleagues³² reported a significant reduction in chorioamnionitis, endometritis, and neonatal infection, including sepsis and pneumonia, in pregnancies treated with prophylactic antibiotics, compared with expectant management alone. In that study, latency also increased significantly following antibiotic therapy. Other meta-analyses confirm the benefits of prophylactic antibiotics, demonstrating a lower rate of neonatal sepsis and IVH following treatment.^33,34

One large multicenter randomized trial found a reduced rate of IVH and RDS after treatment with IV erythromycin and ampicillin for 48 hours, followed by a 5-day course of amoxicillin and erythromycin.³⁵ A Cochrane review of the use of prophylactic antibiotics in the setting of PROM included 19 studies with various antibiotic regimens.³⁶ It concluded that antibiotic therapy prolongs latency (at both 48 hours and 7 days), decreases maternal infection, and reduces the incidence of neonatal complications, including infection, need for oxygen, IVH, and periventricular leukomalacia.

No superior regimen, but avoid amoxicillin-clavulanate. Although no single antibiotic regimen is clearly superior to the others, erythromycin has been associated with benefits most consistently. The most common dosage for erythromycin is 250 mg every 6 hours for a total of 48 hours and then an additional 5 days of oral treatment. Amoxicillin-clavulanate has been associated with an increased risk of NEC in at least two trials, and should probably be avoided. A Cochrane review confirms these conclusions.³⁶

Choice of delivery route is flexible

Once the need for delivery arises, choose the route according to normal obstetric indications. In the setting of PROM with malpresentation, cesarean delivery is probably the best approach. However, in very-low-birth-weight infants, the best mode of delivery remains unclear.³⁷ If the fetus is in cephalic presentation, an attempt at vaginal delivery does not appear to have a worse neonatal outcome.

If spontaneous labor does not occur or if induction is not indicated for maternal or fetal reasons, one may choose to deliver the patient at 32 weeks’ gestation or continue expectant management until 34 weeks’ gestation. This decision is discussed in more detail in the next section.

ALGORITHM

Management of PROM varies with gestational age

PROM at 32 to 34 weeks’ gestation

Although it is generally accepted that the fetus benefits from expectant management in pregnancies complicated by PROM before 32 weeks’ gestation, the management of PROM that arises between 32 and 34 weeks remains controversial and a focus of ongoing research. Because most neonatal morbidity is caused by prematurity, and the rate of prematurity-related complications decreases with increasing gestational age, some argue that the potential benefit of prolonging latency after 32 weeks’ gestation does not outweigh the risk of chorioamnionitis.

Continue the gestation? Or deliver?

Mercer and colleagues randomized 97 women with PROM between 32 and 36 weeks’ gestation and a mature lung profile to expectant management or immediate induction.³⁸ Although expectant management did prolong pregnancy, no neonatal benefit was observed, and the rate of chorioamnionitis was higher with expectant management, with a longer hospital stay.

Cox and associates found a higher rate of chorioamnionitis among 68 women with PROM between 30 and 34 weeks’ gestation who were managed expectantly, compared with 61 women assigned to immediate induction.³⁹ Neonatal morbidity was similar in both groups.

These studies suggest that expectant management after 32 weeks leads only to an increased rate of chorioamnionitis and longer maternal and neonatal hospitalization, without any demonstrable neonatal benefit. However, one significant limitation of these studies is the fact that patients managed expectantly received neither corticosteroids nor prophylactic antibiotics.

Are corticosteroids appropriate at this gestational age?

We lack sufficient evidence to support the routine use of corticosteroids after 32 weeks in pregnancies complicated by PROM. The NIH consensus panel suggested that they may be an option in patients without contraindications up to 34 weeks’ gestation.³¹

Some experts recommend testing for fetal lung maturity when PROM occurs between 32 and 34 weeks’ gestation. In this group, the rate of fetal lung maturity is between 50% and 60%.^40,41 There is no clear benefit in prolonging a pregnancy when fetal lung maturity can be documented. However, in the setting of immature fetal lungs, expectant management may be appropriate following treatment with corticosteroids and a prophylactic antibiotic regimen. Patients who present at 34 weeks’ gestation or beyond are likely to benefit most from immediate delivery.

When expectant management is chosen between 32 and 34 weeks, inpatient hospitalization with daily monitoring is also recommended. The mode of delivery depends on the usual obstetric indications.