Placenta accreta scoring system (PASS)—assessment of a simplified clinico-radiological scoring system for antenatal diagnosis of placenta accreta

Abstract

Background Placenta accreta spectrum (PAS) of disorders is an important cause of post-partum hemorrhage and resultant maternal morbidity and mortality. Imaging plays an indispensable role in antenatal diagnosis of PAS. However, diagnosis of PAS on both ultrasonography and magnetic resonance imaging (MRI) is reliant on recognition of multiple imaging signs each of which have a wide range of sensitivity and specificity. There is no single pathognomonic diagnostic feature. This results in interobserver variability. In our study, we aim to assess the accuracy of a combined clinico-radiological scoring system in predicting placenta accreta. Results This retrospective study included 60 MRI examinations done for suspected placenta accreta (PA). MRI findings were assessed by two radiologists in consensus. Clinical details of the patients were obtained from the hospital information system. Two clinical and six imaging criteria were assessed and a total score was calculated for each patient. Patients were stratified into three groups—low, moderate or high probability for placenta accreta based on the total score. The presence of any statistically significant difference in prevalence of PA among these groups was assessed. Intra-operative findings/histopathology were considered the gold standard. The prevalence of PA was 3% (1/33), 28.5% (2/7) and 90% (18/20) in the low-, moderate- and high-risk groups respectively. There was a statistically significant difference in the prevalence between the three groups (chi-square statistic = 41.54, p value < 0.0001). A score of greater than or equal to 6 provided sensitivity, specificity and accuracy of 85.71, 94.87 and 92.5% respectively in diagnosing placenta accreta. Conclusion PASS provides a simple, objective and accurate way to stratify patients into low, intermediate and high probability categories for PA.

Placenta Accreta Spectrum Diagnosis Challenges and Controversies in Current Obstetrics: A Review

“…Nevertheless, in some clinics, it is done consistently in all cases with doubted PAS. 10 , 20 , 42 Hence, the diagnosis of PAS requires the availability of multidisciplinary team care with well-experienced radiologists in ultrasound and MRI, histopathologists, obstetricians, nursing staff experts, blood bank, and laboratory specialists to establish the accurate diagnosis and management of PAS. 5 , 24…”

“…However, in some clinics, it is required for all patients with doubted PAS. 42 MRI is also used to assist the ultrasound in the evaluation of the placental deepness invasion, the lateral outspreading degree of myometrial and parametrial invasion in doubted features found on ultrasound. 20 MRI has the advantages of sensitivity to blood flow, large imaging range, high soft tissue separation rate, and is not affected by maternal obesity, less amniotic fluid, posterior placenta, and so on.…”

“…After a meta-analysis of 20 studies, Familiar et al 86 concluded that the diagnostic sensitivity of MRI for placental adhesion, implantation and penetration were 94.4%, 100%, and 86.5%, respectively, this indicates that MRI has high accuracy in the diagnosis of PAS, and has certain significance in the differentiation of PAS degree. Mahalingam et al 42 retrospectively analyzed the MRI and histopathological tests of 60 pregnant women with probable PAS. It was concluded that the sensitivity, specificity, and accuracy of MRI in the diagnosis of PAS were 85.71%, 94.87%, and 92.5%, respectively.…”

“…Common MRI signs of PAS: 42 Direct signs: on T2WI (T2-weighted images), the placenta invaded the myometrium or other surrounding organs forming dark intra-placental bands (Figure 4A and B), and the uterine layer becomes thinner and interrupted, the junction zone between the uterus and placenta becomes thinner or disappears. The low signal of uterine serosa also disappears, and the bladder wall is not smooth due to the uterus bulging inside (Figure 4C).…”

“…After a meta-analysis of 20 studies, Familiar et al 86 concluded that the diagnostic sensitivity of MRI for placental adhesion, implantation and penetration were 94.4%, 100%, and 86.5%, respectively, this indicates that MRI has high accuracy in the diagnosis of PAS, and has certain significance in the differentiation of PAS degree. Mahalingam et al 42…”