Cervical length varies considering different populations and gestational outcomes: Results from a systematic review and meta-analysis.

BACKGROUND: The uterine cervical length is an important risk factor for preterm birth. The aim of this study was to assess cervical length distribution in women with singleton pregnancies, measured by transvaginal ultrasound between 16 and 24 weeks, and its association with population characteristics. MATERIALS AND METHODS: We searched electronic databases and other sources for studies published from April 1, 1990 to July 21, 2020. Of the 2019 retrieved publications, full-text versions of 137 articles were considered. We included 77 original articles that reported cervical length measurements of 363,431 women. The main aim of this study was to identify the pattern of cervical length in different populations. We collected demographic and clinical data concerning the population, in addition to information regarding the ultrasound examination and cervical length measurement. Regarding study bias, 56 were at low risk of bias and 21 were at medium risk of bias. RESULTS: The meta-analysis included 57 articles with data from 158,346 women. The mean cervical length was 37.96. mm (95% CI [36.68, 39.24]). Cervical length was shorter in women from Africa and Asia, in those from low-income countries, with a lower body weight, and in those who delivered before 37 gestational weeks. We found that the cervical length from pooled studies is longer than that usually discussed in the literature. Regarding limitations, we had difficulty assessing our main variable because there was no consistent pattern in the way authors reported cervical length measurement. Another limitation was the great heterogeneity between studies. CONCLUSIONS: The use of a single cutoff value to define a short cervix diagnosis, an important risk factor for preterm birth, may not be correct and cervical length must be considered according to maternal population characteristics. Future studies should identify different specific curves and cutoff values for cervical length in different populations. This meta-analysis was registered in the PROSPERO database under CRD42017070246 at https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=70246.

Interruption of a study of cervical ripening with isosorbide mononitrate due to adverse effects.

PURPOSE OF INVESTIGATION: The objective of this study was to evaluate cervix length and the presence of cervical gland area (CGA) in ultrasounds performed before and after the administration of vaginal isosorbide mononitrate (IMN) for cervical ripening. METHODS: We performed an observational, descriptive, and longitudinal study of pregnant patients indicated for labor induction and with a Modified Bishop Score (MBS) lower than six. For cervical ripening, 40 mg of vaginal IMN was administered at 0, 16, and 24 hours after the initiation of cervix preparation. RESULTS: After enrolling 11 patients, the study had to be discontinued due to adverse effects. Three patients requested that they be withdrawn. Headaches were reported by all patients. Nausea, dizziness, dyspnea, and vomiting were also reported. The average cervical lengths at 0, 16, 24 and 36 hours were 27.6, 27.7, 25.9, and 23.0 mm, respectively. CGA disappeared in one of seven patients. CONCLUSIONS: The use of IMN appears to increase the MBS, slightly reducing cervical length without altering the appearance of CGA. Considering the importance of maternal wellbeing during labor, the routine use of IMN cannot be recommended for cervical ripening in the third trimester due to the frequency and intensity of side-effects.