BACKGROUND AND PURPOSE:

• Jayakumaran et al. (AJOG, 2019) studied a transabdominal ultrasound program vs reflex transvaginal ultrasound program for the assessment of cervical length in a low risk population

METHODS:

• Cross-sectional study
• Participants
  • Singleton pregnancies
  • Between 16w0d and 23w6d
  • No risk factors for spontaneous preterm birth
• Study design
  • Preexposure period (June to December 2016)
    • Universal transabdominal cervical length (TACL) screening program was performed without a protocol for reflex transvaginal scanning
  • Postexposure period (June to December 2017)
    • Routine TACL was performed with reflex transvaginal cervical length (TVCL) ultrasound scans if (1) TACL cervical measurement <30 mm or (2) transabdominal views limited
• Primary outcome
  • The proportion of reflex TVCL ultrasound scans
• Secondary outcomes
  • The number of TACL studies <30 mm
  • Various obstetric outcomes
• Reproducibility studies (6 sonographers)

RESULTS:

• 616 patients in the preexposure group | 669 patients in the post exposure group
• Overall demographics were similar between groups except for a small difference in BMI between the groups (P<.001)
  • Preexposure median: 28.6 kg/m2
  • Postexposure median: 25.8 kg/m2
• 16 women in postexposure group had reflex transvaginal ultrasound
  • 9 scans were performed because of TACL <30 mm
  • 7 scans were due to poor visualization of TACL landmarks
• The percentage of cervical length <25cm was less than expected from the literature (0.3%)
• Secondary outcomes
  • There were no differences between groups
• Reproducibility
  • Intraclass correlation coefficients for TACL measurements: 0.15 (95% confidence interval, 0.04–0.45; <0.5 considered poor)
  • Within-subject variance for TACL measurements: 0.11 (95% confidence interval, 0.10–0.13)

CONCLUSION:

• TACL limited the number of women who received transvaginal scans
• Similar to previous studies, inter- and intrarater agreement was poor for TACL
• The authors state

…we urge providers to consider the possibility that the primary benefit of universal TACL screening is the avoidance of transvaginal scanning rather than the identification of high-risk patients.

Learn More – Primary Sources:

Transvaginal ultrasound is superior to transabdominal ultrasound in the identification of a short cervix

Related ObG Topics:

Cervical Cerclage – Professional Recommendations

Does Shortened Midtrimester Cervical Length Predict Preterm Birth?

Does Vaginal Progesterone Improve Birth Outcomes for Mothers with Short Cervix?

Does Cervical Length Actually Predict Preterm Birth?