What is the most appropriate next step in management for a 31-year-old primigravid woman at 20 weeks' gestation with a history of cervical intraepithelial neoplasia (CIN) and a cervical length of 22 mm on transvaginal ultrasonography?

From the Guidelines

The most appropriate next step in management for this patient is to initiate vaginal progesterone supplementation. This 31-year-old woman at 20 weeks' gestation has a short cervical length of 22 mm detected on transvaginal ultrasound, which is a significant risk factor for preterm birth. Her history of cervical intraepithelial neoplasia (CIN) may also increase this risk, although the primary concern here is the short cervical length. Vaginal progesterone (typically 200 mg daily) has been shown to reduce the risk of preterm birth in women with a short cervix (less than 25 mm) in the mid-trimester, as recommended by the Society for Maternal-Fetal Medicine 1. Progesterone helps maintain pregnancy by promoting uterine quiescence, inhibiting inflammatory processes that can trigger preterm labor, and potentially strengthening the cervical tissue. Unlike cervical cerclage, progesterone is less invasive and appropriate as a first-line intervention in this case where the patient is asymptomatic with no history of prior preterm births. The patient should continue this treatment until 36-37 weeks of gestation. Regular follow-up ultrasounds would be reasonable to monitor cervical length, but progesterone should be initiated immediately rather than waiting for repeat imaging, based on the guidelines provided by the Society for Maternal-Fetal Medicine 1.

Some key points to consider in the management of this patient include:

• The use of transvaginal ultrasound for cervical length measurement, as it is the most accurate method for assessing cervical length 1.
• The diagnosis of a short cervix is made when the cervical length is less than 25 mm in the mid-trimester, as defined by the Society for Maternal-Fetal Medicine 1.
• Vaginal progesterone is the recommended treatment for women with a short cervix and no history of prior preterm births, as it has been shown to reduce the risk of preterm birth 1.
• Cerclage placement is not recommended in the absence of cervical dilation, as it has not been shown to be effective in preventing preterm birth in women with a short cervix and no history of prior preterm births 1.
• Cervical pessary is also not recommended for the prevention of preterm birth in women with a singleton gestation and a short cervix, due to the lack of evidence supporting its effectiveness and potential safety concerns 1.

Overall, the initiation of vaginal progesterone supplementation is the most appropriate next step in the management of this patient, based on the current evidence and guidelines from the Society for Maternal-Fetal Medicine 1.

From the Research

Management of Cervical Intraepithelial Neoplasia (CIN) and Short Cervical Length

• The patient is a 31-year-old primigravid woman at 20 weeks' gestation with a history of CIN and a cervical length of 22 mm on transvaginal ultrasonography.
• The cervical length of 22 mm is considered short, and the patient is at risk for preterm birth 2.
• Studies have shown that vaginal progesterone, cervical cerclage, and Arabin cervical pessary are effective interventions for reducing preterm birth in women with a short cervical length 3, 4, 5.

Treatment Options

• Vaginal progesterone has been shown to prolong pregnancy and increase birth weight in women with a short cervical length 6, 3.
• Cervical cerclage has been shown to reduce the risk of preterm birth in women with a history of cervical incompetence 3, 4.
• Combined therapy with vaginal progesterone, cervical cerclage, and Arabin cervical pessary may be a promising management strategy for women with a short cervical length and a high background risk for preterm delivery 5.
• A study found that combined therapy with vaginal progesterone and cervical cerclage was associated with a lower risk of preterm birth and improved neonatal outcomes compared to single therapy 4.

Next Steps

• The patient should be closely monitored with regular transvaginal ultrasonography to assess cervical length and fetal well-being.
• Consideration should be given to administering vaginal progesterone to reduce the risk of preterm birth 6, 3, 4.
• Cervical cerclage may be considered if the patient has a history of cervical incompetence or if the cervical length shortens further 3, 4.
• The patient's history of CIN should be taken into account when making management decisions, and consultation with a specialist may be necessary to determine the best course of action.