Investigation of Transvaginal and Transabdominal Ultrasound and Bladder Fullness in the Evaluation of Cervical Length in Low-risk Pregnant Women

Background and objectives: Assessment of cervical length is required at all trimesters of pregnancy to predict cervical incompetence and preterm labour. The aim of this study was to compare transabdominal and transvaginal cervical lengths in three trimesters and to investigate the effect of bladder fullness on transabdominal measurements. Methods: A prospective cross-sectional study implemented in Outpatients department of Maternity Teaching Hospital in Erbil City-Kurdistan region/Iraq in duration of one year from 1st of January to 31st of December, 2023 on sample of 300 low-risk pregnant women. The ultrasound was done for every woman first by transabdominal ultrasound with full bladder, then cervical length was measured by transvaginal and transabdominal ultrasound after bladder emptying. Results: The mean of cervical length assessed by transvaginal ultrasound (35.9±4.4mm) with empty bladder was significantly different from means of cervical length assessed by transabdominal ultrasound (32.3±3.8mm) with empty bladder and transabdominal ultrasound (35±4.3mm) with full bladder at all trimesters of pregnancy (p<0.001). However, there was a very strong positive correlation between transvaginal ultrasound with empty bladder cervical length and each of transabdominal ultrasound with empty bladder and transabdominal ultrasound with full bladder (p<0.001). Conclusions: The transabdominal ultrasound cervical length measurements are positively correlated to the measurements of transvaginal ultrasound with empty bladder in low-risk pregnant women.