Variation in Cervical Length over Time during a Single Transvaginal Ultrasound Examination

Abstract

Objective To quantify the degree of change in cervical length (CL) over a 3-minute transvaginal ultrasound.

Study Design We conducted a prospective observational study of nulliparous patients who underwent routine transvaginal CL screening at the time of their second-trimester ultrasound. We recorded CL at four time points (0, 1, 2, 3 minutes) and compared these values to determine the minute-to-minute change within a single patient.

Results A total of 771 patients were included. The mean gestational age was 20.8 weeks (±0.84). We used a linear mixed effect model to assess if each minute during the ultrasound is associated with a change in CL. The intraclass correlation coefficient between minute 0 to minute 3 was 0.82 (95% confidence interval: 0.80, 0.84). This indicates that there is a relatively high within-patient correlation in CL during their ultrasound. Additionally, we stratified patients based on their starting CL; the intraclass correlation coefficient remained high for all groups. We additionally compared CL at each minute. Although there is a statistically significant difference between several time points, the actual difference is small and not clinically meaningful.

Conclusion The variation in CL over a 3-minute transvaginal ultrasound examination is not clinically significant. It may be reasonable to conduct this examination over a shorter period.

Keywords

cervical length - preterm delivery - screening

Note

This work was presented in an oral session at the 38th Society for Maternal-Fetal Medicine Annual Pregnancy Meeting on February 3, 2018, Dallas, TV (Abstract# 091).

• References

• 1 Berghella V. What's new in preterm birth prediction and prevention?. J Perinat Med 2017; 45 (01) 1-4
• 2 Berghella V, Roman A, Daskalakis C, Ness A, Baxter JK. Gestational age at cervical length measurement and incidence of preterm birth. Obstet Gynecol 2007; 110 (2 Pt 1): 311-317
• 3 Mari G, Norton ME, Stone J. , et al; Society for Maternal-Fetal Medicine (SMFM). Electronic address: [e-mail]. Society for Maternal-Fetal Medicine (SMFM) Clinical Guideline #8: the fetus at risk for anemia--diagnosis and management. Am J Obstet Gynecol 2015; 212 (06) 697-710
• 4 Committee on Practice Bulletins—Obstetrics, The American College of Obstetricians and Gynecologists. Practice bulletin no. 130: prediction and prevention of preterm birth. Obstet Gynecol 2012; 120 (04) 964-973
• 5 Romero R, Nicolaides KH, Conde-Agudelo A. , et al. Vaginal progesterone decreases preterm birth ≤ 34 weeks of gestation in women with a singleton pregnancy and a short cervix: an updated meta-analysis including data from the OPPTIMUM study. Ultrasound Obstet Gynecol 2016; 48 (03) 308-317
• 6 Berghella V. Universal cervical length screening for prediction and prevention of preterm birth. Obstet Gynecol Surv 2012; 67 (10) 653-658
• 7 Foundation PQ. Cervical Length Education and Review. 2017 [cited November 1, 2017]. Available at: https://clear.perinatalquality.org/ . Accessed November 30, 2018
• 8 Clement S, Candy B, Heath V, To M, Nicolaides KH. Transvaginal ultrasound in pregnancy: its acceptability to women and maternal psychological morbidity. Ultrasound Obstet Gynecol 2003; 22 (05) 508-514
• 9 Bennett CC, Richards DS. Patient acceptance of endovaginal ultrasound. Ultrasound Obstet Gynecol 2000; 15 (01) 52-55
• 10 Braithwaite JM, Armstrong MA, Economides DL. Assessment of fetal anatomy at 12 to 13 weeks of gestation by transabdominal and transvaginal sonography. Br J Obstet Gynaecol 1996; 103 (01) 82-85
• 11 Fonseca EB, Celik E, Parra M, Singh M, Nicolaides KH. ; Fetal Medicine Foundation Second Trimester Screening Group. Progesterone and the risk of preterm birth among women with a short cervix. N Engl J Med 2007; 357 (05) 462-469