Morbidly adherent placenta: evaluation of ultrasound diagnostic criteria in a Sub-Saharan setting

Abstract

Background: Morbidly adherence placenta has become increasingly a major obstetric hemorrhage. There  is inadequate literature regarding the diagnostic accuracy of ultrasound in low income settings such as the Sub-Saharan Africa. This study aimed to determine the diagnostic accuracy of 2-D gray-scale ultrasound and color Doppler ultrasound for morbidly adherent placenta among placenta previa cases in an Ethiopian setting.

Methods: Forty-nine cases of placenta previa cases that received maternity care at St.Paul’s Hospital Millennium Medical College in Addis Ababa (Ethiopia) from June 2018 - October 2020 were retrospectively reviewed. A structured questionnaire was used to extract data from maternal charts. Data were analyzed using SPSS version 23. Simple descriptive statistics and sensitivity an specificity tests were performed as appropriate. We used proportions and 95% CI to present the results.

Results: Morbidly adherent placenta was detected at the time of CS in 8 patients. Eight of them had complete placenta previa, 7 had anterior placenta while 1 had posterior placenta. MRI was not done to confirm the diagnosis in all of the cases. The evaluated sonographic criteria showed good diagnostic performance; in MAP patients at least four out of five criteria were detected, with none of the criteria present in the cases without MAP. Thin myometrium was found to be best predictor for the diagnosis of MAP, with high specificity and no false positive rate. Retro placental hypoechoic space, bladder line: thinning/interruption, placental lacunae, and hypervascularity of uterine serosa–bladder wall interface were detected in majority of patients with MAP but there was high false positive rate.

Conclusions: In this study, the diagnostic performance of 2D and color Doppler ultrasound criteria for MAP was high. Presence of thin myometrium was found to be the single best predictor for the diagnosis of MAP. Gray scale ultrasound and color flow Doppler mapping should be used as first-line techniques for the identification of morbidly adherent placenta.