The cervix is the lower part of the uterus. Normally, the cervix is firm and closed. During early pregnancy, the cervix provides important physical support for the developing baby and forms a mucus plug that shields the baby from bacteria. Towards the end of pregnancy, after week 37, the cervix becomes softer and gradually dilates, so that it starts to open to the vagina. If the cervix opens too early during gestation, the pregnancy may be at risk. This situation, a condition called cervical insufficiency or incompetent cervix, occurs in about 1% of pregnancies (1). Cervical insufficiency can result in premature birth or miscarriage. In contrast to most first trimester losses, which are due to fetal genetic defects, one out of every four pregnancy losses during the second trimester is believed to be due to an incompetent cervix (2).
Most women who develop cervical insufficiency will not show specific symptoms, but some may experience increased vaginal pressure, bleeding, pain, or discharge. A transvaginal ultrasound can provide a diagnosis if cervical insufficiency is suspected or can be performed to monitor high-risk situations, such as in women with previous second-trimester pregnancy losses. Ultrasound examines the cervical length, dilation, and displacement of fetal membranes into the cervical area as criteria needed to diagnose cervical insufficiency (3). The causes of cervical insufficiency are not completely known, but these may be related to previous structural damage or biochemical changes (3). For example, cervical trauma from difficult past deliveries or a dilation and curettage may lead to long-term cervical weakness. Certain genetic conditions can also weaken the cervix, as can prior in utero exposure to diethylstilbestrol, an estrogenic compound (1, 3). A history of multiple second-trimester losses is considered a reliable risk factor requiring monitoring and proactive prevention of future cervical insufficiency. The main approach for managing cervical insufficiency is cerclage, which is a surgical procedure to stitch the cervix closed. This procedure is believed to prevent almost 90% of cervical insufficiency-associated premature births. In most women who have repeat losses during the second trimester, cerclage is recommended before week 14 to help prevent another premature birth (2, 4).
Although premature birth and miscarriage are well-known concerns associated with cervical insufficiency, maternal sepsis is another, albeit extremely rare complication. Sepsis may happen because the widening cervix permits the mucus plug to escape and no longer serve as a protective barrier to infection. This may allow the genital tract and uterus to be exposed to harmful bacteria. Many cases of maternal sepsis are associated with infection by streptococcus bacteria (5, 6), which can be controlled by systemic antibiotics during early stages. However, an uncontrolled infection could lead to fever with rapid progression to sepsis, resulting in severe organ dysfunction and shock (6). Although sepsis was once a common cause of maternal death, advances in contemporary prenatal care have made maternal sepsis exceedingly rare in developed countries. However, the World Health Organization cites maternal sepsis as an ongoing problem (7), primarily within less developed countries, where routine prenatal care may be lacking. Management of cervical insufficiency is important for preventing the more common consequences of premature delivery and miscarriage, but also for reducing risk of the extremely rare, but life-threatening complication of maternal sepsis.
- Mayo clinic. Incompetent cervix.
- American Pregnancy Association. Incompetent cervix: weakened cervix.
- Merck manual. Dulay A. Cervical insufficiency.
- American Pregnancy Association. Cervical cerclage.
- NSW Government. Maternal sepsis fact sheet.
- Sinha P and Otify M. The Obstetrician & Gynaecologist. 2012;14:106-114.
- World Health Organization. Statement on Maternal Sepsis.