Management of preterm premature rupture of membranes (PPROM) is the most controversial of all obstetric problems. This article describes an algorithmic approach (FIGURE) to evaluation and treatment.
PPROM refers to rupture of membranes before onset of contractions at a gestational age less than 37 weeks. Approximately 30% to 40% of preterm deliveries are associated with PPROM.1 In turn, preterm delivery is responsible for approximately 75% of all neonatal deaths, excluding infants with anomalies incompatible with life.2
PPROM is multifactorial and complex
PPROM may occur in patients with an incompetent cervix, which can result from previous genital tract surgery or laceration. PPROM occurs with increased frequency in women who smoke or who have multiple gestation, polyhydramnios, or antepartum hemorrhage. Some women with PPROM also appear to have inherent deficiencies in collagen synthesis, which may predispose to weakening of the membranes.1
Infection link confirmed. Of greatest interest in recent years has been the confirmation that PPROM is associated with lower and upper genital tract infection; there are 3 major lines of supporting evidence:
- Many of the bacteria that inhabit the lower genital tract can produce phospholipase A, an enzyme that can trigger the arachidonic acid cascade that leads to the synthesis of prostaglandins. These same bacteria also are able to produce a variety of proteolytic enzymes that can degrade the collagen matrix of the chorioamniotic membranes.
- Compared to women with uncomplicated gestation, those with PPROM are more likely to have lower genital tract infections (such as group B streptococcal colonization or bacterial vaginosis).
- Compared to women with preterm labor and intact membranes, women with PPROM are more likely to have clinical and subclinical chorioamnionitis and inflammatory cytokines in the amniotic fluid.2
Evidence-based conclusions
The following conclusions are based on good and consistent evidence (level A recommendations) on management of patients with PPROM.
- As a rule, at a gestational age of less than 32 weeks, the greatest threat to the fetus is preterm delivery.
- If the gestational age is 32 weeks or more and fetal lung maturity is confirmed, the risks of expectant management usually exceed the risks of delivery.
- Outpatient management is appropriate only in a highly select group of women.
- In properly selected patients, the benefits of a single course of corticosteroids outweigh the risks.
- Tocolytics are effective in delaying delivery for 48 hours—a critical interval for the administration of corticosteroids.
- Prophylactic antibiotics prolong the latent period and reduce maternal and neonatal infection. These benefits clearly outweigh any risks such as allergic drug reaction or development of resistant organisms.
Direct observation is the best diagnostic test
Patients with PPROM usually note a sudden “gush” of fluid from the vagina. They also may experience a “constant leakage” of fluid or a sensation of “wetness” in the vagina or on the perineum.
The single best test to confirm the diagnosis is direct observation of amniotic fluid in the vaginal vault. Demonstration of severe oligo-hydramnios by ultrasound in a patient with a suggestive history also is helpful.
Although widely used, both the fern test and nitrazine test have pitfalls. The former may be falsely positive in the presence of highly estrogenized cervical mucus or extraneous saline on the glass side (e.g., from a fingerprint). The nitrazine test may be falsely positive in the presence of blood or seminal fluid.
Neonatal and maternal factors guide the management plan
The most important of several factors that must be considered in developing a management plan for PPROM are gestational age and availability of neonatal intensive care. For most patients at less than 36 weeks’ gestation, the prudent course at a hospital with only a level 1 nursery is transfer to a tertiary care facility. If a level 2 nursery is available, the clinician may have sufficient support from neonatology staff to manage patients at 34 weeks’ gestation.
Other important considerations include:
- the presence or absence of labor
- the presence of overt or subclinical infection,
- the stability of the fetal presentation and heart-rate tracing,
- the degree of fetal lung maturation, and
- the degree of cervical effacement and dilation.
- Expectant management. The principal hazards are the risks of ascending infection, umbilical cord prolapse, umbilical cord compression due to oligohydramnios, and abruptio placentae.
- Immediate delivery. The major risks are the well-recognized complications of prema-turity, including respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH), sepsis, necrotizing enterocolitis (NEC), thermal instability, metabolic derangements, apnea and bradycardia, patent ductus arteriosus, and poor feeding. Of these, the 4 most likely to result in neonatal death are RDS, IVH, sepsis, and NEC, all of which are significantly more likely at gestational ages below 32 weeks than at 32 weeks or more.