|Classification and external resources|
Cervical incompetence is a medical condition in which a pregnant woman's cervix begins to dilate (widen) and efface (thin) before her pregnancy has reached term. Internal os opening more than 1 cm is abnormal and cervical length less than 2 cm is considered diagnostic. Cervical incompetence may cause miscarriage or preterm birth during the second and third trimesters.
In a woman with cervical incompetence, dilation and effacement of the cervix may occur without pain or uterine contractions. In a normal pregnancy, dilation and effacement occurs in response to uterine contractions. Cervical incompetence occurs because of weakness of the cervix, which is made to open by the growing pressure in the uterus as pregnancy progresses. If the responses are not halted, rupture of the membranes and birth of a premature baby can result.
According to statistics provided by the Mayo Clinic, cervical incompetence is relatively rare in the United States, occurring in only 1–2% of all pregnancies, but it is thought to cause as many as 20—25% of miscarriages in the second trimester.
Risk factors for premature birth or stillbirth due to cervical incompetence include:
- diagnosis of cervical incompetence in a previous pregnancy,
- previous preterm premature rupture of membranes,
- history of conization (cervical biopsy),
- diethylstilbestrol exposure, which can cause anatomical defects, and
- uterine anomalies.
Cervical incompetence is not generally treated except when it appears to threaten a pregnancy. Cervical incompetence can be treated using cervical cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal.
Cerclage procedures usually entail closing the cervix through the vagina with the aid of a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. Cerclages are usually performed between weeks 14 and 16 of the pregnancy. The sutures are removed between weeks 36 and 38 to avoid problems during labor. The complications described in the literature have been rare: hemorrhage from damage to the veins at the time of the procedure; and fetal death due to uterine vessels occlusion.
No significant differences in pregnancy outcomes were found in the study where performing cerclage was compared to not having it performed. As cerclage can induce preterm contractions without preventing premature delivery, makes the recommendation that it be used sparingly in women with a history of conization.
- Althuisius SM, Dekker GA, Hummel P, Bekedam DJ & van Geijn HP (Nov 2001). "Final results of the Cervical Incompetence Prevention Randomized Cerclage Trial (CIPRACT): therapeutic cerclage with bed rest versus bed rest alone.". American Journal of Obstetrics & Gynecology (Academic Press) 185 (5): 1106–1112. doi:10.1067/mob.2001.118655. PMID 11717642.
- "Cervical Incompetence – Protocol for Management". PROTOCOL #41. Maternal Fetal Medicine, University of New Mexico. 2012-03-03.
- Armarnik, S; Sheiner, E, Piura, B, Meirovitz, M, Zlotnik, A, Levy, A (2011 Apr). "Obstetric outcome following cervical conization.". Archives of gynecology and obstetrics 283 (4): 765–9. doi:10.1007/s00404-011-1848-3. PMID 21327802.
- Zeisler, H; Joura, EA, Bancher-Todesca, D, Hanzal, E, Gitsch, G (1997 Jul). "Prophylactic cerclage in pregnancy. Effect in women with a history of conization.". The Journal of reproductive medicine 42 (7): 390–2. PMID 9252928.
- The first revision of this article was adapted from material from the public domain source "Summary Report: ICD-9-CM coordination and maintenance committee", published at http://www.cms.hhs.gov/paymentsystems/icd9/icd111700.pdf.