Role of Transabdominal Ultrasound in the Evaluation of Threatened Abortion During the First Trimester of Pregnancy

Abstract

Background: Threatened abortion is one of the most common complications of early pregnancy, presenting with vaginal bleeding with or without lower abdominal pain in the presence of a closed cervical os. Early differentiation of viable from non-viable pregnancies is essential to reduce maternal morbidity and to guide timely management, particularly in rural settings where transabdominal ultrasound (TAS) is often the only accessible and culturally acceptable imaging modality. To assess the diagnostic role of transabdominal ultrasound in the evaluation of threatened abortion during the first trimester and to identify sonographic markers associated with pregnancy outcome. Methods: This cross-sectional descriptive study was conducted at Hassan Doppler Ultrasound, Bhakkar. One hundred pregnant women with gestational age ≤12 weeks presenting with symptoms of threatened abortion were enrolled using non-probability convenient sampling. Transabdominal ultrasound was performed with a 3.5–5 MHz convex probe, assessing gestational sac, yolk sac, fetal pole, cardiac activity, subchorionic hematoma and, where available, Doppler indices. Data were analyzed descriptively using frequencies, percentages, tables and figures. Results: Most participants were aged 25–30 years (42%) and resided in rural areas (73%). Vaginal bleeding with lower abdominal pain was the most common presentation (43%). Ultrasound confirmed a viable intrauterine pregnancy in 52% and pregnancy failure in 38% of cases. The principal sonographic predictors of poor outcome were subchorionic hematoma (30%), irregular gestational sac (28%), absent fetal cardiac activity (28%), abnormal yolk sac morphology (24%), and embryonic bradycardia (20%). A definitive diagnosis was reached at the first scan in 85% of participants. Transabdominal ultrasound showed sensitivity of 92%, specificity of 96%, positive predictive value of 94%, negative predictive value of 95%, and overall diagnostic accuracy of 94%. Conclusion: Transabdominal ultrasound is a reliable, safe, affordable and culturally acceptable first-line imaging modality for evaluating threatened abortion in rural settings. It effectively differentiates viable from non-viable pregnancies, identifies prognostic sonographic markers, and reduces unnecessary interventions; its routine use should be encouraged in women presenting with first-trimester bleeding and pain.

Keywords: Threatened abortion; transabdominal ultrasound; first trimester pregnancy; miscarriage; sonographic markers; pregnancy viability