Transvaginal as an adjunct to transabdominal ultrasound improved placenta accreta spectrum disorder diagnostic accuracy in a low-experienced operator.

BACKGROUND: Recently, transvaginal ultrasound (TVS) has been proposed as an adjunct to transabdominal ultrasound (TAS) to help guide the management of PAS. However, the diagnostic accuracy of either technique, or both in combination, is dependent on the experience of the operator. This study aimed to evaluate the diagnostic accuracy of combined TAS and TVS techniques for PAS in differently-experienced operators. METHODS: This study evaluated singleton pregnant women with placenta previa and suspected PAS from gestational age 28 weeks until delivery who had ultrasounds at a PAS tertiary referral center between January 2020 and November 2023. PAS was diagnosed following the International Federation of Gynecology and Obstetrics (FIGO) classification system and confirmed histopathologically. Retrospective evaluations were performed by two operators with different levels of experience, who were blinded to the clinical data and final diagnosis. Using stored images and video clips, they assessed the sonographic features selected from a Modified Delphi study of ultrasound signs associated with PAS. Inter-observer reliability was assessed using the kappa statistic. The predicted probability of PAS diagnosis was evaluated using a diagnostic accuracy test. RESULTS: The images and related information of 70 pregnant women were used for the study. Fifty-five (78.57%) had PAS and 15 (21.43%) had placenta previa only. TAS with adjunctive TVS showed excellent interobserver agreement for all ultrasound features. Interobserver agreement in diagnosing PAS significantly improved with the adjunct method, achieving excellent agreement (0.92, p < 0.01). The diagnostic accuracy of the lower-experienced operator increased from 81.40% to 94.30% and the higher-experienced operator from 94.30% to 97.10%. CONCLUSIONS: Prenatal diagnosis of PAS using TAS with adjunct TVS improved the PAS diagnostic accuracy, especially in the lower-experienced operator. These findings confirm the value of using TAS with TVS in the prenatal evaluation of high-risk pregnancies with suspected PAS.