When is cervical cerclage necessary?
Cervical cerclage is done in women with a history of a short cervix or cervical incompetence, which is a condition where the cervix is at risk of opening before the baby is ready to be born. This can result in pregnancy loss or premature birth.
The cervix is the canal at the base of the uterus that connects the uterus to the vagina. When the cervix is short or incompetent, it begins to dilate (widen) and efface (thin) before the pregnancy has reached term, usually in the second trimester (16-24 weeks) or early in the third trimester.
If you have a short cervix and a history of preterm labor, progesterone supplementation may be recommended to help reduce the risk of another premature birth. However, cervical cerclage is not appropriate for everyone at risk of premature birth. Like any procedure, cerclage carries some risks.
What causes cervical incompetence?
Several conditions can cause an incompetent cervix, including:
How is cervical incompetence diagnosed?
Tests to help diagnose an incompetent cervix during the second trimester include:
- Transvaginal ultrasound: Evaluates the length of the cervix and be used to check if membranes are protruding through the cervix.
- Pelvic exam: Assesses whether the amniotic sac has begun to protrude through the opening (prolapsed fetal membranes). If the fetal membranes are in the cervical canal or vagina, this indicates cervical incompetence.
- Lab tests: If fetal membranes are visible and an ultrasound shows signs of inflammation, a sample of amniotic fluid (amniocentesis) is taken to diagnose or rule out an infection of the amniotic sac and fluid (chorioamnionitis).
How is a cervical stitch done?
Cervical stitch can be done through the vagina (transvaginal cervical cerclage) or the abdomen (transabdominal cervical cerclage). It may also be done as an outpatient procedure under regional or general anesthesia.
- Transvaginal cervical cerclage: During transvaginal cerclage, there is no surgical incision. A speculum is inserted into the vagina. The cervix is grasped using ring forceps and a suture is made through the vagina to shut the cervix. Different techniques of transvaginal cerclage include:
- McDonald cerclage: This is the most common and essentially done using a purse-string stitch to cinch the cervix shut. It involves a band of sutures at the upper part of the cervix, as the lower part has already started to efface.
- Shirodkar cerclage: This is less common but involves the use of ring forceps to pull the cervix downward. Then sutures are done as close as possible to the internal opening of the cervix. Small incisions are made in the cervix and the tissue is tied together.
- Transabdominal cerclage: This is done when other procedures to close the cervix have failed. It is done by making an incision in the lower abdomen and stitching the cervix together.
What are the risks of cervical stitch?
Though rare, possible risks associated with cervical cerclage include:
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Thakur M, Mahajan K. Cervical Incompetence. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021. https://www.ncbi.nlm.nih.gov/books/NBK525954/