Cervical insufficiency (CI), also known as incompetent cervix, is an obstetric complication in which the cervix is unable to support a full-term pregnancy. This condition is characterized by a history of recurrent pregnancy losses in the second or early-third trimester with no other cause. The prevalence of cervical insufficiency has been estimated to affect 0.5% of the general obstetric population and 8% of patients with a history of previous midtrimester miscarriages (approximately 16-24 weeks gestational age).1
The pathophysiology of CI is not well-understood, although all causes are related to compromise in the structure or function of the cervix. Congenital causes of CI include Müllerian anomalies, collagen and elastin deficiencies (eg, Ehlers-Danlos or Marfan syndrome), other uterine malformations, and diethylstilbestrol (DES) exposure.1 Acquired causes include cervical trauma sustained during a previous delivery, loop electrosurgical excision procedure (LEEP), cervical conization, and mechanical dilation during uterine evacuation procedure.1,2
Another risk factor for CI is polycystic ovarian syndrome (PCOS). The mechanism of hyperandrogenism and its effect on cervical ripening is not fully understood. However, patients with PCOS and associated insulin resistance are at an increased risk for negative pregnancy outcomes including development of CI early in pregnancy and termination of pregnancy at an earlier gestational age.3 Individuals with PCOS may need increased cervical monitoring in the second trimester of pregnancy.4,5
History and Physical Examination
Patients with CI typically present with a history of 1 or more pregnancy losses characterized by early cervical dilation without uterine contractions, pain, or other labor signs. A connective tissue disorder or history of cervical trauma supports the diagnosis.1
Symptoms of CI are abdominal pressure or cramping, backache, pelvic pressure, increased volume of vaginal discharge (mucous, watery, light bloody discharge), or bleeding.1,6 Physical examination should include a manual and speculum examination to inspect for cervical dilation, prolapse of the fetus or membranes, and purulent discharge indicative of infection.
Diagnosis of Cervical Insufficiency
Previously, diagnosis of CI was challenging because of a lack of defined diagnostic criteria.1,2 Based on a more contemporary approach, Roman et al noted that patients with or without prior pregnancy loss may be diagnosed with CI.8 Based on their criteria, diagnosis of CI can be made using history, physical examination, or ultrasonography findings7:
- History: painless cervical dilation resulting in recurrent midtrimester births in the absence of other causes.
- Physical examination: dilated cervix of ≥1 cm at 16 to 23 weeks on manual or speculum examination.
- Transvaginal ultrasonography: short cervical length (<25 mm) before 24 weeks’ gestation with a history of 1 or more spontaneous preterm births (PTBs).
Short cervical length is an important finding on ultrasound and is characteristic of CI. However, Brown et al noted that a finding of short cervix on ultrasonography should not be used alone to diagnose CI as a short cervix is also predictive of preterm labor in general.8 Other sonographic findings predictive of CI and preterm labor include cervical effacement (funneling) and protrusion of the amniotic membranes greater than or equal to 5 mm into the internal orifice (OS).9 Mancuso et al also noted that a U-shaped funnel was associated with earlier delivery than a V-shaped funnel.9
Workup of Cervical Insufficiency
A thorough medical history should be taken at the initial pregnancy evaluation to identify any risk factors for CI (Table).10-13 This is important particularly if this is the patient’s first pregnancy. At the first obstetric appointment, urinalysis and vaginal cultures should be performed. People with a history of CI are at higher risk for infection because of compromised cervical integrity.10 Bacterial vaginosis (an overgrowth of normal vaginal bacteria) has been linked to PTB and may increase the risk for preterm delivery. The 2020 guidelines from the United States Preventative Task Force (USPSTF) state that “screening for asymptomatic bacterial vaginosis in pregnant persons not at increased risk for preterm delivery has no net benefit in preventing preterm delivery.… For pregnant persons at increased risk for preterm delivery, the evidence is conflicting and insufficient, and the balance of benefits and harms cannot be determined.”11 In the second trimester, cervical length screening is recommended for pregnant persons with a singleton pregnancy and history of prior spontaneous preterm birth.12
Treatment of Cervical Insufficiency
Treatment options are aimed at preventing PTB and can be divided into surgical intervention (cervical cerclage) and conservative management (restriction of physical activity, vaginal pessary, or vaginal progesterone).
A cerclage is a suture placed around the cervix to reinforce its structural integrity in the second trimester. The American College of Gynecology (ACOG) recommends cerclage for persons with shortened cervical length before 24 weeks of gestation during their current singleton pregnancy and in those with a history of spontaneous PTB at less than 34 weeks of gestation.2 Brown et al recommended that persons with a history of 3 or more second-trimester pregnancy losses be offered elective cerclage at 12 to 14 weeks of gestation.8,13
There are 2 surgical techniques for cervical cerclage: the Shirodkar and McDonald approaches. The primary difference between these methods is the location of the sutures on the cervix, and the choice is usually dependent upon the preference of the surgeon.8,13 The sutures can also be placed either vaginally or transabdominally. Transabdominal cerclage may be used if the conventional transvaginal cerclage fails, or very little vaginal tissue is found following a cervical surgery.8,13
Conservative options proposed for prevention of PTB in individuals with CI include activity restriction, vaginal pessary, and vaginal progesterone. Activity restriction was previously recommended for patients considered at high risk for PTB, however, evidence that bed rest or pelvic rest improves birth outcomes or prevents preterm labor is lacking.2,8 Pessary is a less invasive option that provides support to the cervix with a silicone ring. Multiple small studies have shown that pessary may be an effective alternative or adjunct to cerclage, however, further studies are necessary.2,14 Vaginal or intramuscular progesterone is currently recommended for treating short cervix in the second trimester and has been considered as an alternative to cervical cerclage in persons at risk for PTB.8 Despite these recommendations, less evidence is available suggesting that vaginal progesterone should be used in addition or as an alternative treatment option to cerclage for CI.8
Cervical Insufficiency and Trauma Caused by Conization
Acquired causes of CI include trauma from procedures such as conization or cone biopsy. Conization is indicated for diagnosis and treatment of cervical intraepithelial neoplasia (CIN) and neoplastic sections of the cervix are excised with an electrified wire loop (LEEP) or scalpel (cold knife conization, CKC). In 2016, an estimated 196,000 cases of CIN (≥ grade 2) were diagnosed, 36% of which were in individuals aged 18 to 29 years.15
Mean cervical length is shorter in pregnant persons with a history of prior LEEP or cone biopsy.16 These individuals are also at increased risk for CI, PTB, perinatal mortality, and other negative birth outcomes.17 Multiple factors may impact development of CI following conization and increased risk for PTB. These factors include stage of CIN, size and depth of the conization, and patient age during the procedure. Patients who have LEEP before the age of 25 years are also at increased risk for preterm labor and other negative obstetrical outcomes.18 Understanding the risks for CI and PTB following a traumatic cervical procedure is important information for persons considering future pregnancies. For those who had conization via LEEP or CKC, optimal timing of pregnancy was found to be 6 months and 9 months after the procedures, respectively.19
Cervical insufficiency is a complication of pregnancy that should be considered in patients with specific risk factors, particularly a history of unexplained PTB or miscarriage in the second or early third trimester. Persons with a history of connective tissue disorder, PCOS, LEEP, or conization may require additional monitoring because of their increased risk for PTB. Transvaginal ultrasonography can detect cervical changes associated with CI and PTB, making it an important diagnostic tool. Ultrasonography has also been integral in understanding the effects of traumatic cervical procedures such as conization and the importance of monitoring cervical length. Ultimately, taking an accurate gynecologic and obstetric history is important, especially for guidance of future pregnancies.
Jillian Lam, MS, PA-S, is a second-year physician assistant student at Augusta University in Augusta, Georgia. Ms Lam is also a Certified Health Education Specialist. Stevie Redmond, PA-C, is an associate professor in the Physician Assistant Department at Augusta University. She serves as the Director of Education for the program.
1. Thakur M, Mahajan K. Cervical Incompetence. In: StatPearls [Internet]. StatPearls Publishing; 2022. Accessed February 7, 2023. https://www.ncbi.nlm.nih.gov/books/NBK525954/
2. ACOG Practice Bulletin No.142: Cerclage for the management of cervical insufficiency. Obstet Gynecol. 2014;123(2 Pt 1):372-379. doi:10.1097/01.AOG.0000443276.68274.cc
3. Wang Y, Gu X, Tao L, Zhao Y. Co-morbidity of cervical incompetence with polycystic ovarian syndrome (PCOS) negatively impacts prognosis: a retrospective analysis of 178 patients. BMC Pregnancy and Childbirth. 2016;16(1):308. doi:10.1186/s12884-016-1094-6
4. Wu Y, Cai M, Liang X, Yang X. The prevalence of cervical insufficiency in Chinese women with polycystic ovary syndrome undergone ART treatment accompanied with negative prognosis: a retrospective study. J Obstet Gynaecol. 2021;41(6):888-892. doi:10.1080/01443615.2020.1819212
5. Feigenbaum SL, Crites Y, Hararah MK, Yamamoto MP, Yang J, Lo JC. Prevalence of cervical insufficiency in polycystic ovarian syndrome. Hum Reprod. 2012;27(9):2837-2842. doi:10.1093/humrep/des193
6. Chau CT, Wei LS. Cervical insufficiency. In: Butler JR, Amin AN, Fitzmaurice LE, Kim CM, eds. OB/GYN Hospital Medicine: Principles and Practice. McGraw-Hill Education; 2019.
7. Roman A, Suhag A, Berghella V. Overview of cervical insufficiency: diagnosis, etiologies, and risk factors. Clin Obstet Gynecol. 2016;59(2):237-240. doi:10.1097/GRF.0000000000000184
8. Brown R, Gagnon R, Delisle MF. Cervical insufficiency and cervical cerclage. J Obstet Gynaecol Can. 2013;35(12):1115-1127. doi:10.1016/s1701-2163(15)30764-7
9. Mancuso MS, Szychowski JM, Owen J, et al. Cervical funneling: effect on gestational length and ultrasound-indicated cerclage in high-risk women. Am J Obstet Gynecol. 2010;203(3):259.e1-5. doi:10.1016/j.ajog.2010.07.002
10. Tantengco OAG, Menon R. Breaking down the barrier: the role of cervical infection and inflammation in preterm birth. Front Glob Womens Health. 2022;2:777643. doi:10.3389/fgwh.2021.777643
11. US Preventive Services Task Force; Owens DK, Davidson KW, Krist AH, et al. Screening for bacterial vaginosis in pregnant persons to prevent preterm delivery: US Preventive Services Task Force Recommendation Statement. JAMA. 2020;323(13):1286-1292. doi:10.1001/jama.2020.2684
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13. Brown R, Gagnon R, Delisle MF. No. 373—Cervical insufficiency and cervical cerclage. J Obstet Gynaecol Can. 2019;41(2):233-247. doi:10.1016/j.jogc.2018.08.009
14. Timofeev J. Use of cervical pessary in the management of cervical insufficiency. Clin Obstet Gynecol. 2016;59(2):311-319. doi:10.1097/grf.0000000000000196
15. McClung NM, Gargano JW, Park IU, et al. Estimated number of cases of high-grade cervical lesions diagnosed among women — United States, 2008 and 2016. MMWR Morb Mortal Wkly Rep. 2019;68(15):337-343. doi:10.15585/mmwr.mm6815a1
16. Fischer RL, Sveinbjornsson G, Hansen C. Cervical sonography in pregnant women with a prior cone biopsy or loop electrosurgical excision procedure. Ultrasound Obstet Gynecol. 2010;36(5):613-617. doi:10.1002/uog.7682
17. Kindinger LM, Kyrgiou M, MacIntyre DA, et al. Preterm birth prevention post-conization: a model of cervical length screening with targeted cerclage. PLoS One. 2016;11(11):e0163793. doi:10.1371/journal.pone.0163793
18. Chevreau J, Mercuzot A, Foulon A, et al. Impact of age at conization on obstetrical outcome: a case-control study. J Low Genit Tract Dis. 2017;21(2):97-101. doi:10.1097/lgt.0000000000000293
19. Zhang X, Tong J, Ma X, et al. Evaluation of cervical length and optimal timing for pregnancy after cervical conization in patients with cervical intraepithelial neoplasia: a retrospective study. Medicine (Baltimore). 2020;99(49):e23411. doi:10.1097/md.0000000000023411