[Transperineal ultrasound to measure cervical length of pregnant women in general and in particular with cervical insufficiency - a comparison of transabdominal and transperineal ultrasound as alternatives to transvaginal ultrasound].

PURPOSE: To investigate the feasibility of measuring cervical length by transabdominal and transperineal ultrasound as alternatives to transvaginal ultrasound.

MATERIALS AND

METHODS

33 pregnant women with and 28 without cervical insufficiency at 16 to 35 weeks of gestation were examined by an experienced examiner (DEGUM II) and the cervical length was measured twice at an interval of 6 months. Comparability, reliability and comfort of the patients during the examinations were taken for statistical analysis.

RESULTS

There is poor agreement between transabdominal and transvaginal ultrasound (Lin's rho = 0.578), whereas transperineal ultrasound shows high correlation (Lin's rho = 0.922) to the measurements obtained transvaginally, a preference referring to the comfort scale and good reliability (ICC = 0.949). When regarding sub-groups (pregnant women with and without cervical insufficiency), transperineal ultrasound shows better results than transabdominal ultrasound. However, small cohort sizes affect the statistical validity.

CONCLUSION

Transabdominal ultrasound cannot be recommended to measure cervical length. Besides providing exact measurements, transperineal ultrasound avoids contact between the cervix and the probe, is better accepted by patients and offers a simplified examination. This method is a good alternative to transvaginal ultrasound. Due to minor inaccuracies of the method, we recommend this technique only for patients with a cervix longer than 2.5 cm. For further analysis concerning patients with cervical insufficiency, large-scale studies should be performed.