Prenatal sonography can predict degree of placental invasion

To evaluate whether the maximum degree of placental invasion (placenta accreta, increta or percreta) can be predicted with ultrasound imaging, using criteria developed in our department.

This was a retrospective study of all 232 patients at risk for placental invasion who were part of a routine screening program for placental invasion from January 2001 to January 2011. The whole placenta was scanned in a systematic manner using both gray-scale ultrasound and color-flow mapping. Sonographic findings were compared with the clinical outcome during and after delivery and the histomorphological examination of the placenta.

Placental invasion was suspected by ultrasound in 40 (17.2%) patients and was clinically/histopathologically confirmed in a total of 35 (15.1%) patients. The sensitivity, specificity and positive and negative predictive values of ultrasound for placental invasion were 91.4% (95% CI, 77.6-97.0%), 95.9% (95% CI, 92.2-97.9%), 80.0% (95% CI, 65.2-89.5%) and 98.4% (95% CI, 95.5-99.5%), respectively. No case of placenta increta (n = 7) or percreta (n = 17) was diagnosed as showing normal placentation or placenta accreta on ultrasound, giving an overall accuracy for the differentiation between normal placentation/placenta accreta and placenta increta/percreta of 100%.

Our data suggest that prediction of the degree of placental invasion is possible using prenatal ultrasound, with high overall accuracy.