[Length of the cervix in the 2d and 3d trimester: vaginal study versus measurement by perineal scan--an improved indication guide for cerclage?].

In a study made at the Department of Gynaecology of the University of Heidelberg, the cervical length, as measured by vaginal examination, was compared in 100 impatients between the 16th and 40th week of pregnancy with a special ultrasonic examination method termed "perineal scan". Examination results can be considerably simplified, corrected and, above all, increased in objectivity through the use of perineal scan. As a result, in 53 patients in which, clinically, a definite shortening of the cervix was apparent (portio-length 0.5-1 cm), 12 cases (23%) were found by sonography to exhibit a normal finding with a cervical length greater than or equal to 3 cm. Conversely, from 47 patients with either clinically normal findings or clinically minimal cervical shortening (portio-length 1.5-2 cm), 25 cases (53%) were established as pathological by ultrasonic methods (cervical length less than 3 cm). The superior objectivity of the results obtained by perineal scan when compared to vaginal examination could be statistically established, primarily through the number of premature births occurring during the further course of pregnancy. The incidence of premature births was not significantly increased in clinically established cervical shortening of less than 1.5 cm, whereas a significant result was obtained if sonography revealed cervical shortening below 2.5 cm (p less than 0.01). Perineal scan is however also recommended for controlling therapeutic success of tocolytic treatment and for confirming and/or detecting premature rupture of the foetal membranes, as well as in cases of suspected cervical insufficiency or incompetent cervix.(ABSTRACT TRUNCATED AT 250 WORDS)