The Use of Trans-abdominal Ultrasound in Assessment of The Lower Uterine Segment Thickness in Patients with Previous Cesarean Section: Meta-Analysis

Background: The rising global Cesarean section (CS) rate has increased interest in vaginal birth after Cesarean (VBAC) due to its benefits over elective repeated CS.
Aim: This study aimed to evaluate the use of trans-abdominal ultrasound (TAUS) in assessing lower uterine segment (LUS) thickness in females with previous CS, highlighting its predictive value and potential clinical decision-making role.
Methods: We conducted a thorough search on Google Scholar, PubMed, Embase, & Cochrane Library. The investigation utilized both textual terms and medical subject titles, such as TAUS, CS, LUS and trial of labour (TOL) across Medline, Embase, ClinicalTrials.gov and Cochrane Library.  In addition, we conducted a thorough search on ClinicalTrials.gov and examined the references cited in selected publications and reviews to discover more relevant observational research.
Results: Regarding elective repeat CS, TAUS measurements correlated with delivery outcomes and LUS thickness, with cut-off values varying from 1.5 to 4.05 millimeters. The pooled analysis exhibited a relative risk (RR) of 0.7 (95% confidence interval: 0.4, 0.9), with high heterogeneity (Chi-p <0.001, I² = 100%). Concerning uterine dehiscence & rupture, an association was found between thin LUS and uterine dehiscence (7 studies) and uterine rupture (1 study). An RR of 0.09 (95% confidence interval: 0.04, 0.15) for dehiscence and 0.003 (95% confidence interval: -0.001, 0.006) for rupture. Major heterogeneity for dehiscence (Chi-p <0.001, I² = 100%) and homogeneity for rupture (Chi-p <0.9, I² = 0%).
Conclusion: TAUS is a valuable non-invasive tool for assessing LUS thickness in females with previous CS, thereby influencing clinical decisions.