Second-trimester evaluation of cervical length for prediction of spontaneous preterm birth
- Vincenzo Berghella, MD
Vincenzo Berghella, MD
- Director, Maternal-Fetal Medicine
- Professor, Obstetrics and Gynecology
- Thomas Jefferson University
- Section Editors
- Charles J Lockwood, MD, MHCM
Charles J Lockwood, MD, MHCM
- Section Editor — Obstetrics
- Senior Vice President, USF Health
- Dean, Morsani College of Medicine
- Professor, Obstetrics and Gynecology
- University of South Florida
- Deborah Levine, MD
Deborah Levine, MD
- Section Editor — Imaging
- Professor of Radiology
- Director of Ob/Gyn Ultrasound
- Department of Radiology
- Beth Israel Deaconess Medical Center
This topic will review key issues related to sonographic cervical length screening for prediction of spontaneous preterm birth. The cause of preterm cervical shortening is often unclear. It has been attributed to several sources, including occult uterine activity, uterine overdistention, congenital or acquired cervical insufficiency, decidual hemorrhage, infection, inflammation, and biological variation.
RATIONALE FOR MEASURING CERVICAL LENGTH
Cervical shortening (ie, effacement) is one of the first steps in the processes leading to labor and can precede labor by several weeks. A decrease in cervical length in the second trimester is predictive of spontaneous preterm birth, with the highest risk in women with early and substantial cervical shortening [1-6]. Because effacement begins at the internal cervical os and progresses caudally [1,5], it is often detected on ultrasound examination before it can be appreciated on physical examination.
DISTRIBUTION OF CERVICAL LENGTH
Normally, cervical length is stable between 14 and 28 weeks of gestation and is described by a bell-shaped curve [1,7]:
●15 mm – 2nd centile
●20 mm – 5th centile
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- RATIONALE FOR MEASURING CERVICAL LENGTH
- DISTRIBUTION OF CERVICAL LENGTH
- DIAGNOSIS OF SHORT CERVIX
- GUIDELINES FOR CERVICAL LENGTH SCREENING AND INTERVENTION
- Our approach
- - Singleton pregnancy, no prior preterm birth
- - Singleton pregnancy, prior preterm birth
- - Singleton pregnancy, no prior birth, but risk factors for preterm birth
- - Multiple gestation
- Guidelines from national organizations
- PROCEDURE FOR SONOGRAPHIC MEASUREMENT OF CERVICAL LENGTH
- Timing and frequency
- Use of transvaginal sonography
- Pitfalls in measuring cervical length
- Cervical findings other than length
- Online resources
- Quality assurance
- SUMMARY AND RECOMMENDATIONS