[Vaginal ultrasound studies of cervix closure with special reference to parity].

In this study, the cervical length, thickness, the width of the internal os, the cervical canal and the external os of 62 primipara and 77 multipara were measured vaginosonographically. Only patients with normal pelvic scores were examined. The measurements were carried out approx. every fortnight between the 16th and 34th gestational week. In the primipara group, the average cervical length was 36.8 mm +/- 12.0 mm, the thickness 27.8 mm +/- 4.4, the width of the internal os 6.3 +/- 2.1 mm, the cervical canal 4.2 +/- 2.0 mm and the external os 5.4 +/- 2.2 mm. In the multipara group, an average cervical length of 40.1 mm +/- 7.4 mm, a thickness of 29.3 +/- 3.9 mm, an internal os of 5.1 +/- 2.6 mm, a cervical canal of 4.3 +/- 1.3 mm and an external os of 5.8 +/- 1.8 mm were found. Contrary to our expectations, there was no statistically significant difference between the two groups. Furthermore we did not find any correlation between the internal and the external os.