Here is a quick summary of some key aspects of PPROM that I have learned over the last week.
What is PPROM?
Preterm Premature Rupture of the Membranes, or PPROM, is the rupture of the amniotic sac in a pregnant woman. Premature refers to the rupture occurring prior to the onset of labor. Normally, spontaneous rupture occurs after labor contractions begin. Preterm PROM occurs when the rupture is prior to 37 weeks of gestation, which is considered less than full term. (Note: technically speaking, Nanette experienced PPROM with Samuel since her water broke at week 36 and labor had not yet begun.)
The exact cause of PPROM is unknown. Infection and repeated pelvic examinations are the leading explanations.
Why is PPROM a problem?
The two major concerns with PPROM are infection and the onset of labor, which are interrelated. The onset of labor is of great concern for extremely preterm pregnancies. Chorioamnionitis (inflammation caused by infection of the chorion and amnion membranes) can lead to sepsis in the mother and fetus. Chorioamnionitis has been shown in several studies to be the cause of the rupture of membranes. Bacterial infection of the amnion has also been shown to increase the production of the labor-inducing hormone prostaglandin. A more likely inducer of labor may be the bacterial production of cytokines, which, in addition to triggering production of prostaglandin, also induce labor themselves. Thus, infection can trigger PPROM and subsequently lead to the onset of labor and delivery.
Other concerns with PPROM are abruptio placenta (detached placenta) and umbilical cord prolapse (cord exiting the uterus). Both are very serious but are less common than premature delivery and infection.
How is PPROM treated?
PPROM patients are treated with bedrest and a prophylactic antibiotic. To accelerate lung development in the fetus, a corticosteriod (usually betamethasone) is administered no sooner than two days before fetal viability and less than 34 weeks. A single corticosteriod has been shown to be very effective to reduce the incidence of neonatal respiratory distress syndrome, intracranial bleeding, and mortality. However, a second dose has been shown to provide no additional benefits.
In rare cases (<10%) ruptured membranes will spontaneously seal. These cases are almost always in PPROM cases that resulted subsequent to amniocentesis.
Tocolytic agents (which slow or halt contractions) are sometimes given to midtrimester patients with PPROM. Tocolytes can delay delivery for 24-48 hours so that corticosteriod treatment becomes effective and the patient may have time to be transferred to a NICU. However, since labor may be the results of infection, tocolytes can be unsafe for both the mother and fetus by prolonging infection and endangering both for sepsis.
What are the outcomes of PPROM?
The implications of PPROM are largely dependent on the stage of the pregnancy. Midterm PPROM and subsequent premature delivery lead to much higher fetal mortality and morbidity rates than late term PPROM. Fetal lung development is hampered by oligohydramnios (low amniotic fluid) cause by ruptured membranes. For midtrimester patients, the fetal mortality and morbidity rates are very high but decrease with each week of gestation. Here is a link to some informative graphs.
Finally, of interest to expectant women in this situation is the latency from PPROM to delivery. A 1996 study showed that for PPROM between 28-34 weeks, labor begins within 24 hours in 50% of cases and within 1 week in 80% of cases; for PPROM between 24-26 weeks, labor begins within 1 week in 50% of cases and delayed at least 4 weeks in 22% of cases. A more recent (and more applicable) 2006 study showed that less than 40% of midtrimester PPROM women deliver in the first week and more than 30% stay pregnant for more than 5 weeks.
If you want to go to learn more, I recommend reading this excellent emedicine summary.
Some of my sources
"Pathology of the Placenta", Harold Fox and Neil James Sebire
"Maternal and perinatal outcome of expectant management of premature rupture of membranes in the midtrimester", Moretti M., Sibai BM.
http://www.merckmanuals.com/professional/index.html
http://emedicine.medscape.com/article/261137-overview
