Diagnostic Utility of Sonography and Magnetic Resonance Imaging in Evaluating Placenta Previa and Its Variants Using Intraoperative Findings as the Gold Standard.

Abstract

Objective: To evaluate the diagnostic utility of ultrasonography and magnetic resonance imaging (MRI) for the diagnosis of placenta previa (PP) with accurate grading, keeping peroperative findings as the gold standard.

Study design: A cross-sectional study. Place and Duration of the Study: Department of Radiology, Combined Military Hospital, Gujranwala, Pakistan, from March 2023 to April 2024.

Methodology: Pregnant women aged 18-45 years in their third trimester with suspected PP were evaluated using transabdominal ultrasound and non-contrast MRI (1.5T). Perioperative findings during caesarean section served as the gold standard. Diagnostic accuracy was calculated for ultrasonography and MRI in diagnosing the accurate type of PP in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), keeping peroperative findings as the gold standard.

Results: In a total of 110 cases, the mean and gestational ages were 30.56 ± 3.46 years and 33.25 ± 2.95 weeks, respectively. The sensitivity of ultrasound was 83.3%, while MRI demonstrated sensitivity at 95.0%. Ultrasound and MRI showed equally high specificity at 98.0%. The PPV was 98.0% for ultrasound and 98.3% for MRI. The NPV was 83.1% for ultrasound and 94.2% for MRI. The diagnostic accuracy of ultrasound was 90.0%, while MRI achieved a diagnostic accuracy of 96.4%. The diagnostic performance of USG and MRI did not reveal significant differences (p = 0.065).

Conclusion: Ultrasonography can be a useful, cost effective, and safest initial assessment tool for diagnosis and grading of PP in the late pregnancy. It showed overall comparable results of USG and MRI.

Key words: Diagnostic accuracy, Gold standard, Transabdominal ultrasound, Placenta previa, Ultrasonography.