Journal of Ultrasound in Medicine, Vol 20, Issue 10 1071-1078, Copyright © 2001 by American Institute of Ultrasound in Medicine
Ultrasonographic evaluation of the cervix: transperineal versus endovaginal imaging
B. S. Hertzberg, E. Livingston, D. M. DeLong, P. J. McNally, C. K. Fazekas and M. A. Kliewer
Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
OBJECTIVE: This study compares transperineal and endovaginal
ultrasonography of the gravid cervix to evaluate image quality and assess
for a systematic difference in cervical lengths measured by the 2
techniques. METHODS: Transperineal and endovaginal ultrasonography of the
cervix was performed on 64 pregnant women. Two physicians reviewed the
images and rated the relative diagnostic value of the techniques for
assessing the cervix and for evaluating for placenta previa. Cervical
length was measured prospectively in both techniques. Data were analyzed to
determine if there is a systematic difference in length using the 2
approaches and if length differences are dependent on gestational age.
RESULTS: There was a strong reviewer preference for endovaginal
ultrasonographic images over transperineal images for both assessing the
cervix (P< .001) and evaluating for placenta previa (P< .001).
Despite this, transperineal and endovaginal ultrasonographic images were
frequently rated as similar in diagnostic quality by both reviewers for
depicting the cervix (35.9% of patients) and evaluating for placenta previa
(57.8% of patients). The mean length of the cervix was slightly shorter at
transperineal ultrasonography (28.4 mm) than at endovaginal ultrasonography
(30.1 mm). When cervical lengths were subdivided by gestational age,
however, a significant length discrepancy was found only in the 14- to
20-week gestational age range. In this age range, mean cervical length at
transperineal ultrasonography (28.6 mm) averaged 5.5 mm less than at
endovaginal ultrasonography (34.1 mm). CONCLUSIONS: Both transperineal and
endovaginal ultrasonography can provide satisfactory images of the cervix,
but endovaginal images are frequently superior to transperineal images.
Endovaginal ultrasonography should be considered the optimal method for
imaging the cervix in most situations. Transabdominal or transperineal
ultrasonography can also be used, but if the cervix is not adequately
depicted from these perspectives, endovaginal ultrasonography is indicated.
Transperineal measurements of cervical length can be significantly shorter
than endovaginal measurements, particularly before 20 weeks; therefore,
short cervical lengths documented at transperineal ultrasonography before
20 weeks should be confirmed by endovaginal ultrasonography.
