Diagnostic Accuracy of Placental Thickness in Lower Uterine Segment Measured by Ultrasound in Prediction of Placenta Accreta Spectrum in Patients with Placenta Previa. A Diagnostic Test Accuracy Study

Ahmed Mohammed Elmaraghy, Salah Taha Fayed, Mahmoud Abd ElHamid Ali, Monira Ali Hassanien, Ahmed Mohamed Mamdouh, Ahmed Mohammed Elmaraghy, Salah Taha Fayed, Mahmoud Abd ElHamid Ali, Monira Ali Hassanien, Ahmed Mohamed Mamdouh

Abstract

Objective: The aim of the study was to evaluate the association between placental thickness and placenta accreta spectrum (PAS) in patients with placenta previa.

Materials and methods: In this prospective study, 40 patients diagnosed with placenta previa were included. The maximum placental thickness in the lower uterine segment was obtained using a transabdominal scan. For the image to be deemed suitable, a midline sagittal section of the lower uterine segment (with the implanted placenta) and the cervical canal, with the intervening urinary bladder had been required. Intraoperative attendance was ensured for the detection of cases with spontaneous separation and cases with morbid adherence. All specimens removed were sent for histopathology to confirm PAS. The primary outcome of the study was to detect a threshold of placental thickness which can be used as a cut-off value in such screening test. The number of units of packed RBCs transfused during the operation and bladder injury were secondary measures of outcome.

Results: Forty patients were included in the study; 20 patients were ultimately diagnosed with PAS while 20 patients did not have PAS. Mean placental thickness was significantly higher in the PAS patients compared with those with no invasive placentation (61.00 mm Vs 43.00 mm, P value 0.000). Using receiver operating characteristic (ROC) curve, a threshold placental thickness of 58mm was associated with 55% sensitivity, 90% specificity, 84.6% positive predictive value, and 66.7% negative predictive value. Multivariate logistic regression showed that placental thickness more than 58mm and having past history of more than three cesarean sections were independent risk factors for PAS among patients with placenta previa.

Conclusion: Placental thickness in the lower uterine segment is increased in patients with placenta previa with PAS compared to those with no PAS. Such finding can be implemented into clinical practice by using placental thickness as a screening test for PAS in patients with placenta previa.

Clinicaltrialsgov id: NCT05500404.

Keywords: cesarean section; placenta accreta spectrum; placenta previa; placental thickness; ultrasound.

Conflict of interest statement

All authors declare that: In the past 3 years, they had not received any funding from any organization that may have a financial interest in the manuscript.They do not hold any stock holdings or options in an organization that may have a financial interest in the publication of this manuscript.The content of the manuscript is not related to any patents they hold or currently applied for.They have not received any funding or salary from organizations that hold or have applied for patents relating to the content of the manuscript.They do not have any other financial competing interests.They have not received any equipment from an entity that might benefit or be at an advantage financially or reputationally from the published findings.They do not hold a position on an industry board or private company that might benefit or be at an advantage financially or reputationally from the published findings.They do not have any personal, political, religious, ideological, academic and intellectual competing interests which are perceived to be relevant to the published content.

© 2023 Elmaraghy et al.

Figures

Figure 1
Figure 1
Incidence of placenta accrete spectrum among study participants.
Figure 2
Figure 2
Incidence of cesarean hysterectomy among PAS and no PAS patients.
Figure 3
Figure 3
ROC curve of placental thickness by ultrasound as a predictor of placenta accreta spectrum.

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