Cervical cerclage is offered to pregnant women with prior history of preterm bih if cervical length is less than
**Core Concept**
Cervical cerclage is a surgical procedure performed to prevent preterm birth in pregnant women with a history of cervical insufficiency. The procedure involves stitching the cervix closed to prevent it from dilating too early in pregnancy. The American College of Obstetricians and Gynecologists (ACOG) recommends cerclage placement in women with a history of preterm birth and a short cervical length.
**Why the Correct Answer is Right**
The correct answer is based on the American College of Obstetricians and Gynecologists (ACOG) guidelines, which recommend cerclage placement in women with a history of preterm birth and a cervical length of less than 25 mm on transvaginal ultrasound between 16 and 24 weeks of gestation. This is because a short cervical length is a risk factor for preterm birth, and cerclage placement has been shown to reduce the risk of preterm birth in this population. The cervical length is measured using transvaginal ultrasound, and a measurement of less than 25 mm is considered abnormal.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is too low. A cervical length of less than 15 mm may be considered abnormal, but it is not the specific threshold recommended by ACOG for cerclage placement.
**Option B:** This option is incorrect because it is too high. A cervical length of 30 mm or greater is not a contraindication for cerclage placement, and many women with a history of preterm birth will have a normal cervical length.
**Option C:** This option is incorrect because it is not a specific measurement. While a cervical length of less than 25 mm is the recommended threshold for cerclage placement, a general statement of "less than" is not specific enough.
**Clinical Pearl / High-Yield Fact**
The American College of Obstetricians and Gynecologists (ACOG) recommends cerclage placement in women with a history of preterm birth and a cervical length of less than 25 mm on transvaginal ultrasound between 16 and 24 weeks of gestation. This is a high-yield fact for exam questions on cervical cerclage and preterm birth prevention.
**Correct Answer: B. 30 mm**