Diagnostic Accuracy of Doppler Ultrasonography in the Antenatal Diagnosis of Abnormal Placental Invasion Secondary to Placenta Previa

Abstract

Objective: To determine the diagnostic accuracy of Doppler ultrasonography in the antenatal diagnosis of abnormal placental invasion secondary to placenta previa, taking operative findings at caesarean section as the gold standard.

Study Design: Cross-sectional diagnostic accuracy study.

Place and Duration of Study: Radiology department, RTEH Indus Hospital MUZAFFARGARH, Recep Tayyip Erdogan Hospital, Muzaffargarh, Pakistan, over a six-month study period after ethical approval.

Methodology: A total of 284 multigravida women aged 20-40 years with gestational age greater than 28 weeks, previous caesarean section and ultrasound-diagnosed placenta previa were included by non-probability consecutive sampling. Doppler ultrasonography was performed using predefined vascular criteria for abnormal placental invasion. Operative findings at caesarean section were used as the reference standard. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were calculated from a 2 x 2 diagnostic table.

Results: The mean age was 29.80 +/- 4.02 years and the mean gestational age was 34.39 +/- 2.29 weeks. Operative findings confirmed abnormal placental invasion in 49 women (17.25%). Doppler ultrasonography identified 57 positive cases (20.07%). The true-positive, false-negative, false-positive and true-negative counts were 42, 7, 15 and 220, respectively. Doppler ultrasonography showed sensitivity of 85.71%, specificity of 93.62%, positive predictive value of 73.68%, negative predictive value of 96.92% and overall diagnostic accuracy of 92.25%.

Conclusion: Doppler ultrasonography demonstrated high sensitivity, high specificity and particularly strong negative predictive value for antenatal detection of abnormal placental invasion in women with placenta previa. These findings support its use as a practical first-line diagnostic tool in high-risk obstetric patients, especially in resource-constrained settings where MRI is not routinely available.