Objective Gynecologic oncologist involvement in the surgical team of patients with placenta percreta has shown improved patient outcomes. Yet, stratification of cases is dependent on identification of placenta percreta by ultrasonography which has a poor detection rate. To allow patients to receive optimal team management by pre-operative stratification our objective was to identify the pre-operative characteristics of patients with previously underdiagnosed placenta percreta.

Methods A retrospective single institution case-control study was performed from January 2010 to December 2022 of singleton, non-anomalous pregnancies with suspicion for placenta accreta spectrum (PAS). Ultrasonography was used as the primary method of detection. Final inclusion was dependent on histology confirmation of PAS and degree of invasion. We explored the role of concurrent antenatal magnetic resonance imaging (MRI) on patients with previously unrecognized placenta percreta.

Results During the 13 year study period, 140 cases of histologically confirmed PAS were managed by our team and met inclusion criteria. A total of 72 (51.4%) cases were for placenta percreta and 27 (37.5%) of these were diagnosed pre-operatively while 45 (62.5%) were only diagnosed post-operatively. Comparison between these two groups revealed patient body mass index (BMI) >30 kg/m² was independently associated with unrecognized placenta percreta (p=0.006). No findings by MRI were associated with mischaracterization of placenta percreta. Yet, concurrent MRI assessment of patients with BMI >30 kg/m² (n=18), increased placenta percreta detection by 11 cases (61%).

Conclusion The ability to determine pre-operatively which patients are more likely to have placenta percreta allows for gynecologic oncologists to be involved in the most complex cases in a planned manner. This study shows that women at risk for placenta accreta spectrum, who are obese (BMI >30 kg/m²), may benefit from further assessment with pre-operative MRI to facilitate appropriate staffing and team availability for cases of placenta percreta.