Reproductive · Obstetrics
The facts most likely to be tested
Cervical insufficiency is characterized by painless cervical dilation in the second trimester leading to recurrent second-trimester pregnancy loss.
The classic clinical presentation is a patient reporting pressure, vaginal discharge, or bloody show without associated uterine contractions.
A history of cervical conization, LEEP, or mechanical cervical dilation during prior procedures are major risk factors for structural cervical weakness.
Transvaginal ultrasound showing a cervical length < 25 mm before 24 weeks gestation is diagnostic for cervical insufficiency in high-risk patients.
The definitive management for patients with a history of recurrent second-trimester losses is a prophylactic cerclage placed at 12–14 weeks gestation.
Physical exam-indicated cerclage, or rescue cerclage, is indicated when cervical dilation is noted on physical exam before 24 weeks gestation in the absence of labor or infection.
Patients with a history of preterm birth should be offered serial transvaginal ultrasound surveillance starting at 16 weeks gestation to monitor for cervical shortening.
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A 26-year-old G2P1 woman at 18 weeks gestation presents to the clinic complaining of increased vaginal discharge and pelvic pressure for the past 24 hours. She denies any abdominal pain, contractions, or vaginal bleeding. Her obstetric history is significant for a spontaneous pregnancy loss at 19 weeks gestation last year. On physical examination, the cervix is noted to be 3 cm dilated with visible fetal membranes. The patient is afebrile and fetal heart tones are reactive.
What is the most appropriate next step in management?
Physical exam-indicated (rescue) cerclage
The patient presents with classic signs of cervical insufficiency (painless dilation in the second trimester); because she is currently dilated, a rescue cerclage is indicated to prevent imminent pregnancy loss.
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High yield triage
Etiology / Epidemiology
History of cervical trauma (LEEP, cone biopsy) or DES exposure are primary risk factors.
Clinical Manifestations
Painless cervical dilation in the second trimester with bulging membranes.
Diagnosis
Transvaginal ultrasound showing cervical length <25 mm before 24 weeks.
Treatment
Cervical cerclage placed at 12-14 weeks; do not perform if active labor or infection.
Prognosis
High risk of preterm birth; requires serial monitoring of cervical length.
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Epidemiology & Etiology
Commonly associated with prior cervical surgery such as LEEP or cold knife conization. Patients may also have a history of in utero DES exposure or congenital uterine anomalies. It is a leading cause of recurrent second-trimester pregnancy loss.
Pertinent Anatomy
The cervix acts as a mechanical barrier; structural weakness at the internal os leads to premature opening. The cervicovaginal junction is the critical site for structural integrity during pregnancy.
Pathophysiology
Structural collagen defects or mechanical trauma lead to premature cervical shortening and dilation. This process is typically painless, distinguishing it from preterm labor. The loss of the mucus plug and subsequent exposure of fetal membranes leads to rupture and delivery.
Clinical Manifestations
Patients present with painless cervical dilation and vaginal pressure. Physical exam reveals bulging membranes at the external os. Red flags include vaginal bleeding, uterine contractions, or signs of chorioamnionitis, which necessitate immediate delivery.
Diagnosis
The transvaginal ultrasound is the gold standard for assessment. A cervical length <25 mm before 24 weeks is diagnostic. Serial screening is indicated for patients with a history of prior preterm birth.
Treatment
The cervical cerclage (e.g., McDonald or Shirodkar procedure) is the first-line surgical intervention. Contraindications include active preterm labor, clinical chorioamnionitis, or fetal demise. Progesterone supplementation is often used as an adjunct to prevent further shortening.
Prognosis
Significant risk of preterm birth and neonatal morbidity. Patients require serial ultrasound monitoring if a cerclage is not placed or if they are at high risk for recurrent insufficiency.
Differential Diagnosis
Preterm labor: associated with painful, regular uterine contractions
Abruptio placentae: associated with painful vaginal bleeding and rigid uterus
Chorioamnionitis: associated with maternal fever and fetal tachycardia
Placenta previa: associated with painless vaginal bleeding, not cervical dilation
Vasa previa: associated with fetal heart rate abnormalities upon membrane rupture