- A large, prospective, randomized, controlled trial clearly showed that antibiotics decrease neonatal morbidities and prolong the interval between rupture of membranes and delivery.
- Avoid digital cervical examination during testing for rupture of membranes because it may hasten delivery and increase neonatal morbidity.
- Consider giving magnesium sulfate and corticosteroids to patients with preterm premature rupture of membranes at or beyond 23 weeks, provided there is no evidence of infection. After 32 weeks, deliver the infant if either intraamniotic infection or fetal lung maturity is present.
- At delivery, amnioinfusion decreases variable decelerations and improves pH when clinically indicated.
The outlook for preterm premature rupture of membranes (PPROM) has improved considerably since a landmark study showed clear benefits of antibiotics.
Previously, approximately 80% of women with PPROM experienced spontaneous labor within 48 hours with expectant management.
We now know that infection is a major cause of PPROM and that antibiotic therapy decreases neonatal morbidity and increases the interval from rupture of membranes to delivery. These benefits are most evident at early gestational ages.
This article reviews newer studies, as well as that breakthrough 1997 study, and their implications for diagnosis and treatment, including optimal drug regimens. Recommendations for 4 special situations are also discussed:
- presence of cerclage,
- herpes simplex infection,
- bleeding, and
- outpatient management.
Despite progress, research is still needed. For example, because much of our information about clinical interventions for PPROM, such as corticosteroid therapy and use of tocolytics, predates the use of antibiotics, many earlier studies need to be repeated.
A variety of methods confirm the diagnosis
Nitrazine paper test
The most common way to diagnose rupture of membranes involves exposing nitrazine paper to the leaking fluid. If the fluid is alkaline, the paper will turn bright blue.
However, seminal fluid, urine, and blood can also turn nitrazine paper blue. Therefore, a confirmatory method should be used with nitrazine paper testing.
Fern pattern test
When amniotic fluid proteins are allowed to dry and then examined under a microscope, they will exhibit a “fern” pattern.
The combination of nitrazine paper and the fern test has a specificity of over 90%.
Avoid digital cervical examination
Digital examination during testing may diminish latency (the period from rupture of membranes to delivery) and increase neonatal morbidity.3
Testing at early gestational ages
Occasionally, PPROM occurs early in the middle trimester. At such early gestations, amniotic fluid may not fern or produce the classic blue color when exposed to nitrazine paper.
Other tests may be used, however:
- Ultrasound can help in evaluating the quantity of amniotic fluid.
- Indigo carmine dye can be placed in the amniotic cavity, with a tampon inserted in the vagina. If the tampon turns blue when the patient ambulates, rupture of membranes is confirmed.
- Alpha-fetoprotein and human choriogonadotropin. When alpha-fetoprotein is present and human choriogonadotropin is highly concentrated in amniotic fluid, ruptured membranes are confirmed.4
Fortunately, a large majority of patients can be diagnosed using clinical history, nitrazine paper, and the fern pattern test.
Preterm premature rupture of membranes (PPROM) is ruptured membranes before the 37th week of gestation.
PPROM complicates 3% to 4.5% of all pregnancies and is responsible for 30% to 40% of all preterm births.26 This high incidence makes it a major cause of premature birth in the United States.
African-American women appear to have a higher incidence of PPROM than Caucasian women.27
Smoking is strongly correlated with PPROM,28 as it is with most poor perinatal outcomes.
Nutritional deficiencies in hydroxyproline, vitamin C, copper, and zinc also are linked.26
The precise cause is unknown
Ascending infection29 and uterine bleeding1 are both strongly correlated with PPROM. An incompetent cervix is also thought to play a role, as are conditions involving connective tissue abnormalities, such as those found in Ehlers-Danlos syndrome.
Unfortunately, we have yet to identify a factor or factors that could be linked to a specific cause for any given patient. Such knowledge would enable us to abandon empiric treatment in favor of more specific management guidelines.
Infection plays a major role in most cases
Bacteria in the vagina ascend through the intracervical canal and establish subclinical infection in the lower uterine segment.29
This activates macrophages and polymorphoneutrophils as a host defense mechanism. Macrophages release interleukin-6, interleukin-8, and tumor necrosing factors, while lysis of polymorphoneutrophils triggers the release of proteolytic enzymes.
These enzymes not only destroy the invasive microorganisms, but are capable of damaging the chorion and amnion, increasing the likelihood of ruptured membranes.
As we come to understand these mechanisms more fully, we should be able to tailor therapy to specific etiologies, thereby optimizing outcomes.30