Introduction Maternal and fetal morbidity and mortality from placenta accreta are considerable and associated with high demands on health resources. Identifying women at risk antenatally can improve their management and reduce complications of this condition before delivery.

Aim To ascertain the usefulness of MRI scan in predicting the risk of placenta accreta.

Method An audit of maternity notes of women diagnosed with placenta praevia (PP) between Aug 09 and Aug 12. Women with PP and a previous caesarean were considered to be at greater risk of placenta accreta and were audited against the RCOG Greentop Guidelines for antenatal imaging with MRI.

Results Of the 72 cases identified, there were eight cases of anterior PP with a history of caesarean section. A further set of notes was of a woman with multiple caesarean sections and mainly posterior PP but the anterior edge of placenta overlying the anterior lower segment.

Of these nine ‘high risk’ women, 5 women had an MRI scan performed antenatally. In these cases there were 3 true negative MRI scans and 1 was a false negative, with evidence of placenta accreta at delivery. There was 1 reported false positive with no accreta at delivery.

Discussion The use of MRI scanning has not been used in all high risk cases. Where used, the predictive value has been 60%. Detailed analysis of features of abnormal placentation is required to improve the predictive value of MRI scans.