Research Methods · Measurement and Statistics

Pitfalls in ultrasonic cervical length measurement for predicting preterm birth

Yost NP, Bloom SL, Twickler DM, Leveno KJ

Published April 24, 1999 Obstetrics and Gynecology, 93(4), 510-516
DOI 10.1016/s0029-7844(98)00438-4 PMID 10214824

Abstract

Objective

To describe the anatomic and technical difficulties encountered with transvaginal ultrasound imaging of the cervix in a consecutive series of women at risk for preterm delivery.

Methods

Three groups of women had cervical ultrasound examinations: those with histories of preterm birth, those with incompetent cervices, and those admitted for preterm labor that did not progress. Standardized ultrasound examinations of the cervix involved measuring the length of the endocervical canal, funneling length, and internal os dilation with and without fundal pressure.

Results

Sixty consecutive women had transvaginal ultrasound examinations for assessment of the cervix. Forty-six had histories of preterm birth, five had incompetent cervices, and nine had arrested preterm labor. Six types of problems arose, which can be divided into anatomic or technical considerations, with an overall frequency of 27% (95% confidence interval 16%, 40%). Anatomic pitfalls that hampered identification of the internal os included an undeveloped lower uterine segment (n = 5), a focal myometrial contraction (n = 1), rapid and spontaneous cervical change (n = 1), and an endocervical polyp (n = 1). Technical pitfalls included incorrect interpretation of internal os dilation because of vaginal probe orientation (n = 7) and artificial lengthening of the endocervical canal because of distortion of the cervix by the transducer (n = 1).

Conclusion

We caution those who perform cervical length examinations to be wary of falsely reassuring findings due to potential anatomic and technical pitfalls.

Topics

By this author

Related research

Research Methods › Measurement and Statistics › Research Tooling and Reproducibility · Diagnostics › Ultrasound › Transvaginal Ultrasound · Pregnancy › Preterm Birth › Prediction
Kenneth J Leveno
Ken Leveno, K Leveno
PMID 10214824 10214824 DOI 10.1016/s0029-7844(98)00438-4 10.1016/s0029-7844(98)00438-4 Yost et al. 1999, Yost 1999

Cite this article

Yost, N. P., Bloom, S. L., Twickler, D. M., & Leveno, K. J. (1999). Pitfalls in ultrasonic cervical length measurement for predicting preterm birth. Obstetrics and gynecology, 93(4), 510-516. https://doi.org/10.1016/s0029-7844(98)00438-4