Scoping review of the evaluation of lower uterine segment thickness and trial of labour after caesarean section

The fact that the integrity of the lower uterine segment (LUS) has not been routinely evaluated sonographically before deciding on the mode of delivery after caesarean section has deemed it fit that the lower uterine segment thickness (LUST) should be assessed. The authors carried out a scoping review in October 2023. Four databases were searched for peer reviewed articles that discussed evaluation of LUST and TOLAC. The year of publication, primary author抯 country of origin, sample size, study design, gestational age at ultrasonographic assessment, scanning route and key findings were extracted from the included articles. The articles identified were 625 while 250 were screened after removing duplicates and finally 30 articles were included in the review. The first authors of the included articles originated from 10 different countries and 30% of them were Indians. The most frequently used study designs in the articles were prospective cohort studies (63.3%). Majority of the key findings were as follow: Ultrasonography is the best modality for LUS assessment, LUST measurement is more reliable through vaginal scan; maternal age, body mass index and pregnancy related factors affect LUST and LUST of ?3.5 mm at term is safe for TOLAC. Maternal socio-demographic characteristics and past obstetric history affect the LUST and success of TOLAC. Ultrasonographic evaluation of the LUST at term is safe, needed before TOLAC and more reliable when conducted through vaginal route. The LUST influences the pregnancy outcome during TOLAC and a LUST cut-off value of ?3.5 mm is safe for TOLAC.