Membrane stripping, often called a membrane sweep, is a common technique used near the end of pregnancy to encourage the onset of labor. This manual intervention is performed by a healthcare provider during a standard pelvic examination. The goal is to stimulate the body to begin the labor process without using medications. The procedure is only possible if the cervix has already begun to soften and open slightly.
How the Procedure Works
The healthcare provider inserts a gloved finger through the cervical opening and sweeps it in a circular motion around the lower uterus. This action gently separates the thin membranes of the amniotic sac from the uterine wall. The physical separation creates localized irritation at the junction of the amniotic sac and the cervix.
This mechanical separation triggers the release of natural compounds known as prostaglandins. These hormone-like substances play a significant role in preparing the body for labor. Prostaglandins soften and ripen the cervix, a process called effacement, and stimulate the uterine muscle to begin contracting.
During the brief procedure, the patient typically experiences a sensation similar to a rough or deep cervical check. They may feel momentary discomfort, pressure, or cramping as the sweeping motion occurs. Mild cramping that persists for a few hours afterward is common.
Timing and Effectiveness
Healthcare providers generally offer membrane stripping when a patient is near or past their due date, typically around 39 or 40 weeks of gestation. The procedure is only an option if the cervix is already partially dilated enough to permit finger insertion. It is often attempted before moving to more formal medical induction techniques, such as synthetic oxytocin.
Research indicates that membrane stripping can increase the likelihood of spontaneous labor starting, particularly within 24 to 48 hours. It can increase the chance of labor beginning spontaneously by more than 20% within a week compared to having no intervention. However, it is not a guaranteed method, and some patients may require multiple attempts or other induction methods.
Following the sweep, it is normal to experience some light spotting or a small amount of dark, bloody discharge, as the cervix is highly vascular. Patients may also notice irregular contractions or increased cramping that does not immediately develop into sustained labor. These symptoms are generally seen as a sign that the procedure has had a physical effect.
Safety Considerations and Contraindications
Membrane stripping is considered a relatively safe procedure for individuals with uncomplicated, full-term pregnancies. The potential risks are minor, but include the possibility of accidental rupture of the membranes, commonly called the water breaking. This risk is why the procedure is performed only near term.
Another potential concern is the risk of introducing infection, though this risk is low. It is also possible to experience bleeding heavier than simple spotting, or to have persistent, painful contractions that do not progress to true labor.
The procedure should not be performed in certain circumstances, which are known as contraindications. These include any situation where a vaginal delivery is unsafe, such as placenta previa, where the placenta covers the cervix, or vasa previa. It is also generally avoided if the patient has an active infection in the genital area, such as active genital herpes.
Patients should seek immediate medical attention if they experience heavy, bright red bleeding, a sudden gush of fluid indicating ruptured membranes, or severe, unrelenting abdominal pain. While mild cramping and spotting are common, any concerning symptoms should be promptly discussed with a healthcare provider.