A cervical cerclage is a minor surgical procedure in which the opening to the uterus (the cervix) is stitched closed in order to prevent a miscarriage or premature birth.
Approximately 10% of pregnancies end in preterm delivery, defined as a delivery that occurs before week 37 of pregnancy (the average pregnancy lasts 40 weeks). Premature birth is a major cause of serious health problems in neonates (newborn babies), including respiratory distress, difficulty regulating body temperature, and infection. More than 85% of long-term disabilities in otherwise healthy babies and 75% of deaths among newborns occur as a result of preterm delivery.
A woman with an incompetent cervix is 3.3 times more likely to deliver prematurely. The cervix is the neck-shaped opening at the lower part of the uterus and is normally closed tight during pregnancy until the baby is ready to be delivered, at which point it expands (dilates) to roughly 4 in (10 cm) in diameter. An incompetent cervix is prone to dilating and/or effacing (shortening) prematurely during the second trimester. The growing fetus subsequently places too great a strain on the cervix, leading to miscarriage (loss before week 20 of pregnancy) or premature delivery (loss after week 20). Approximately 1% of women will be diagnosed with an incompetent cervix (one in 500–2,000 pregnancies). It is the cause of 25% of losses during the second trimester.
A doctor might recommend a cerclage be performed if a woman has one or more of the following risk factors:
Racial and socioeconomic factors influence a woman's risk of delivering prematurely: African-American women are at more risk (16–18%) than white women (7–9%); women under 18 and over 35 are also at greater risk. Less educated women are more likely to deliver prematurely. Smoking during pregnancy is associated with a 20–30% greater risk of delivering prematurely. Male fetuses are more likely to be born prematurely and have a higher rate of fetal death than female fetuses (a difference of 2.8–9.8%).
Elective cervical cerclage is a minor surgical procedure that is generally performed between 12 and 14 weeks of pregnancy (at the beginning of the second trimester) before symptoms of premature labor begin. Emergent cerclages are those placed later in pregnancy when cervical changes have already begun.
The patient will usually receive regional (epidural or spinal) anesthesia during the procedure, although general anesthesia is sometimes used. Spinal anesthesia involves inserting a needle into a region between the vertebrae of the lower back and injecting numbing medications. An epidural is similar to a spinal except that a catheter is inserted so that numbing medications may be administered as needed. Some women experience a drop in blood pressure when a regional anesthetic is administered; this effect can be countered with fluids and/or medications.
While there are numerous techniques for performing cerclage, the McDonald and Shirodkar techniques are the most common. The McDonald cerclage involves stitching the cervix with a 0.2 in (5 mm) band of suture. The cerclage is placed high on the cervix when the lower part has already started to efface. The stitch is usually removed around week 37 of pregnancy. The classic Shirodkar procedure involves a permanent "purse-string" stitch around the cervix; because it will not be removed, a cesarean section will be necessary to deliver the baby. Most Shirodkar cerclages are now performed with a modified technique that allows the sutures to be later removed.
Some less common methods of cerclage include:
Diagnosis of an incompetent cervix is usually done by medical history and/or by examination (manually during a pelvic exam or using ultrasound technology). Some symptoms of an incompetent cervix used to decide if a cerclage is necessary are:
Women who are more than 1.5 in (4 cm) dilated, who have already experienced rupture of membranes, or whose fetus has died are ineligible for cerclage.
Before the procedure may be performed, there are a number of preparatory steps that must be taken. A complete medical history will be taken. A cervical exam will be necessary to assess the state of the cervix; usually a transvaginal (through the vagina) ultrasound will be performed. No food or drink will be allowed after midnight before the day of surgery to avoid nausea and vomiting during and after the procedure. The patient will also be instructed to avoid sexual intercourse, tampons, and douches for 24 hours before the procedure. Before the procedure is performed, an intravenous (IV) catheter will be placed in order to administrate fluids and medications.
After the cerclage has been placed, the patient will be observed for at least several hours (sometimes overnight) to ensure that she does not go into premature labor. The patient will then be allowed to return home, but will be instructed to remain in bed or avoid physical activity for two to three days. Follow-up appointments will usually take place so that her doctor can monitor the cervix and stitch and watch for signs of premature labor.
While cerclage is generally a safe procedure, there are a number of potential complications that may arise during or after surgery. These include:
The success rate for cervical cerclage is approximately 80–90% for elective cerclages, and 40–60% for emergent cerclages. A cerclage is considered successful if labor and delivery is delayed to at least 37 weeks (full term).
Approximately 1–9% of women will experience premature labor after cerclage. The risk of chorioamnionitis is 1–7%, but increases to 30% if the cervix is dilated greater than 1.2 in (3 cm). The risks associated with premature delivery, however, are far greater. Babies born between 22 and 25 weeks of pregnancy are at significant risk of moderate to severe disabilities (46–56%) or death (approximately 10–30% survive at 22 weeks, increasing to 50% at 24 weeks, and 95% by 26 weeks).
Depending on her specific condition, a woman may have some alternative therapies available to her to avoid or delay premature labor. These include:
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American Academy of Family Physicians. 8880 Ward Parkway, Kansas City, MO 64114. (816) 333-9700. http://www.aafp.org .
American Board of Obstetrics and Gynecology. 2915 Vine Street, Dallas, TX 75204. (214) 871-1619. http://www.abog.org .
American College of Obstetricians and Gynecologists. 409 12th St., SW, PO Box 96920, Washington, DC 20090-6920. http://www.acog.org .
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Stephanie Dionne Sherk
A cervical cerclage is generally performed in a hospital operating room by an obstetrician/gynecologist who specializes in the areas of women's general health, pregnancy, labor and childbirth, prenatal testing, and genetics. Anesthesia will be administered by an anesthesiologist.