Evaluation of the Diagnostic Value of Abdominal Sonographic Measurement of Lower Uterine Segment Thickness in Uterine Rupture during Caesarean Section and Determine its Associated Factors

The measurement of the lower uterine segment (LUS) thickness before labor predicts hazardous complications of vaginal birth after cesarean section (VBAC). Vaginal birth after cesarean is one of the most effective methods used to reduce the incidence of cesarean section. Therefore, this study was carried out to evaluate the diagnostic value of sonographic measurement of lower uterine segment (LUS) thickness in uterine rupture during cesarean section and its associated factors in women with and without previous cesarean section.
This prospective cohort study was conducted among 168 pregnant women in two groups of with and without the history of cesarean section (84 individuals per group) referred to Ardabil Alavi Hospital, Ardabil, Iran, in 2016. The thickness of the LUS was determined through transabdominal ultrasonography between the gestational ages of 36 to 40 weeks. At the time of cesarean section, the thickness of the women’s LUS and newborns’ weight and Apgar score were measured and recorded. Additionally, uterine rupture was recorded in patients with the past history of cesarean section. Moreover, the relationship between the LUS thickness and maternal age, gestational age, the indication for previous cesarean section, interdelivery interval, embryo weight, and abnormalities of erythrocyte were determined. Data analysis was performed using descriptive statistics and t-test in SPSS software, version 16.
According to the pre-operative assessments, the LUS thickness in the women with and without the history of cesarean section were 4.26±1.99 mm and 6.11±1.6 mm, respectively (P˂0.001). According to the findings obtained from sonography before and during the operation, there was a significant difference between the groups in terms of LUS thickness (P0.05). Based on the results, the LUS thickness of 1.8 mm was considered as the critical cutoff value for predicting uterine rupture.
The measurement ofLUS thickness is a non-invasive technique to predict the uterine rupture, which leads to increased rate of VBAC.