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. Vaginal progesterone (typically 200 mg daily) has been shown to reduce the risk of preterm birth in women with short cervix by helping to maintain cervical integrity and reducing uterine contractility 1.

Key Considerations

• The patient's cervical length of 22 mm is below the threshold of 25 mm, which is used to diagnose a short cervix in individuals with a singleton gestation and no previous history of spontaneous preterm birth 1.
• The Society for Maternal-Fetal Medicine recommends using vaginal progesterone to reduce the risk of preterm birth in asymptomatic individuals with a singleton gestation and a transvaginal cervical length of 20 mm diagnosed before 24 weeks of gestation 1.
• While cervical cerclage might be considered in some cases, progesterone is generally preferred as first-line therapy for women with short cervix without active cervical dilation 1.
• A vaginal pessary would not address the underlying issue, and fetal fibronectin testing is more useful in symptomatic women 1.

Management Plan

• Initiate vaginal progesterone supplementation (200 mg daily) to reduce the risk of preterm birth.
• Counsel the patient about signs of preterm labor and schedule regular follow-up to monitor cervical length.
• Consider shared decision-making for treatment with vaginal progesterone at a cervical length of 21-25 mm 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.