[Ultrasonography of the uterine cervix in pregnancy. Curve of normality in a longitudinal and cross-sectional study].

BACKGROUND

The aim of the study was to establish a normality curve of cervical length variations during pregnancy in our pregnant women population, to be compared with pathological cases (risk of preterm labor and cervical incompetence).

DESIGN

A prospective longitudinal and cross-sectional study in women with single pregnancy and without risk factors for preterm labor was carried on.

SETTING

Obstetric and Gynecology Department, University of Brescia, Italy.

POPULATION OR SAMPLE

One hundred and thirty-four pregnant women with single pregnancy, 112 cross-sectionally and 22 longitudinally followed, with labor at term, were selected. Sixty-eight were nulliparous, 66 pluriparous. Multiple pregnancy, previous placental and vaginal bleeding were excluded.

METHODS

A transvaginal probe was used to assess uterine cervix and the patients were studied from the 12th to 41st gestational week. Statistical analysis was carried out by Student's "t"-test and Z-test.

MEASURES

Cervical longitudinal diameter, internal uterine os and funneling were assessed.

RESULTS

No statistically significant differences emerged in the curves with regard to nulliparous and pluriparous patients. The cut-off between normality and pathology, from the 24th to the 32nd gestational week (2ndSD), seems to correspond to a cervical length lower than 25 mm; a significant progressive decrement of the cervical longitudinal diameter begins from the 28th gestational week.

CONCLUSIONS

These results allows the gathering of reference data about normality to compare with pathology (cervical incompetence and preterm delivery), which could be useful both for prevention and follow-up of these cases.