Reference ranges for cervical length by transvaginal scan in singleton pregnancies.

Area of Science:

• Maternal-Fetal Medicine
• Diagnostic Ultrasound
• Obstetrics

Background:

• Cervical length (CxL) is a key indicator in assessing the risk of preterm birth.
• Standardized charts are essential for accurate interpretation of CxL measurements during pregnancy.
• Transvaginal ultrasound is the gold standard for CxL assessment.

Purpose of the Study:

• To develop a reference chart for cervical length (CxL) measured by transvaginal ultrasound.
• To provide normative data for CxL across different gestational ages (20-34 weeks).

Main Methods:

• Singleton pregnant women (n=1061) underwent transvaginal ultrasound for CxL measurement between 20 and 34 weeks.
• Exclusion criteria included multiple pregnancies, preterm rupture of membranes, cerclage, and vaginal progesterone use.
• Regression analysis was used to calculate the 5th, 50th, and 95th centiles of CxL.

Main Results:

• Cervical length (CxL) significantly decreased with advancing gestational age (r² = 0.0799).
• The study generated regression equations for the median, 5th, and 95th centiles of CxL.
• At 23 weeks, the 5th, 50th, and 95th centiles were 20 mm, 36 mm, and 47 mm, respectively.

Conclusions:

• The developed chart effectively illustrates the shortening of cervical length (CxL) throughout pregnancy.
• The chart provides valuable reference points (5th, 50th, 95th centiles) for CxL at various gestational ages.
• This tool can aid clinicians in identifying pregnancies at higher risk for preterm delivery.