Is membrane stripping appropriate in modern obstetrics?

OB/GYN News,  Nov 1, 2004  by Amy Rouse,  James A. McGregor

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YES

Membrane stripping is an intervention sometimes performed in the obstetric office setting. This technique involves a digital exam followed by gently sweeping the presenting membrane, separating the membrane from its neighboring lower uterine segment. The intent of the procedure, also known as membrane sweeping, is to stimulate local prostaglandin release, leading to cervical ripening.

The safety of membrane stripping has been called into question. A detailed review of the literature, however, suggests that this method is safe at term with regard to maternal and neonatal morbidity.

A 2004 Cochrane Database Systematic Review examined this technique and evaluated outcomes with regard to shortening of pregnancy duration, need for induction of labor, risk of cesarean section, maternal and neonatal infection, and maternal side effects (The Cochrane Library [3];2004[CD000451]). The review included results of 19 clinical trials, with the majority comparing membrane stripping with prostaglandin use, and one study comparing membrane stripping with OxyContin (oxycodone) use.

The results of this review suggested that membrane stripping is relatively safe. There was no demonstrated increase in either maternal or neonatal infection in patients whose membranes were stripped at 38 weeks or greater. Using membrane stripping as part of routine prenatal care led to an overall decrease in pregnancies lasting beyond 41 and 42 weeks, but this difference was not clinically significant. Risk of cesarean section was not clinically different among patients whose membranes were stripped and those patients in whom no intervention was performed. Finally, as one would expect, patients who underwent membrane stripping noted an increased rate of bleeding and irregular contractions over those patients who were not treated.

Another study not included in this review specifically evaluated the risks associated with membrane stripping and group B streptococcus colonization (Am. J. Obstet. Gynecol. 2002;187[suppl. 6]:S221). The study randomized patients to membrane stripping at 38 weeks vs. no stripping. All patients with negative routine group B streptococcus (GBS) cultures were cultured again at 40 weeks. The resultant data suggested that membrane stripping does not increase GBS colonization.

With regard to the efficacy of membrane stripping as a means to avoid formal induction of labor, there does not appear to be a substantial benefit. The Cochrane review concluded that seven patients would need to undergo membrane stripping to prevent one formal induction of labor, and the studies that would provide the most logical comparison--those that assessed membrane stripping vs. prostaglandin ripening--enrolled too few patients to provide evidence of benefit. However, there is no evidence to suggest an increased risk of infection, nor is there an apparent increase in GBS colonization. Membrane stripping can be considered a reasonable option in a term patient who is otherwise a good candidate for outpatient ripening.

Dr. Amy Rouse is a maternal-fetal medicine fellow at the University of Southern California, Los Angeles.

NO

Accumulated evidence and clinical common sense tell us that membrane stripping is marginally effective, always painful, and sometimes dangerous; it should be abandoned by today's pregnancy care providers. If membrane stripping is actually considered to be indicated, there should be written, informed patient consent so as to ensure patient knowledge and reduce professional liability.

This once widely taught procedure entails digitally entering the cervix and physically "sweeping" or separating fetal amniochorion from the maternal decidua, with the consequent release of potentially pharmacologic concentrations of prostaglandins. Where membrane stripping is still practiced, putative reasons include. "prevention of postdates," "impending macrosomia," or patient or practitioner preference for hastening labor.

Despite well-reasoned concerns, some practitioners continue to serially strip membranes even in the presence of GBS, a well-known perinatal pathogen. Instances of electively stripping membranes before term is reached are documented.

We and others have taken note of severe intrauterine infections subsequent to membrane stripping. Stillbirth, observed intrapartum death, overwhelming neonatal sepsis, and meningitis and/or encephalitis with permanent brain injury are all "low-frequency" but catastrophic consequences of invasive membrane stripping.

How are potentially virulent cervicovaginal microbes transported into the child's intrauterine environment? Simple: The inserted finger directly transports cervicovaginal microbes into the lower uterine space and inoculates the fetal membranes and maternal decidua with potentially massive numbers of microflora. Subsequent cervical bleeding is often regarded as proof of a "good job." In fact, bleeding signifies tissue trauma and necrosis. Blood is a prime nutrient for most pathogens. Chopped meat liquid broth remains the preferred culture media for anaerobic bacteria.