MRI Helps Detect Life-Threatening Pregnancy Complication

The women participating in the study were referred for MRI based on a suspicious prenatal ultrasound, clinical examination, or significant risk factors for the condition (including placenta previa, uterine scarring, prior cesarean births, and pregnancies after the age of 35). The researchers were able to compare the MRI images with surgical and/or pathology results in 71 of the 108 cases; when correlated with surgical and pathology findings, MRI was found to have a 90.1% accuracy rate in detecting the presence of accreta. The study was presented at the annual meeting of the Radiological Society of North America (RSNA), held during November-December 2009 in Chicago (IL, USA).

"MRI is a useful and accurate adjunct to ultrasound for diagnosis of placenta accreta,” said study presenter and coauthor Michele Browne, M.D. "Women at high risk for placenta accreta, such as those who've had multiple cesarean sections, should undergo ultrasound. And if ultrasound is inconclusive, MRI should be considered.”

"Having placenta accreta is not necessarily a bad prognostic indicator for the pregnancy,” said lead researcher radiologist Reena Malhotra, M.D. "It is not knowing about the condition that is potentially life threatening. Accreta needs to be diagnosed ahead of time so that delivery can be planned.”

Placenta accreta is a severe obstetric complication involving an abnormally deep attachment of the placenta, through the endometrium and into the myometrium; there are three forms of placenta accreta, distinguishable by the depth of penetration. The placenta usually detaches from the uterine wall relatively easily, but women who encounter placenta accreta during childbirth are at great risk of hemorrhage during its removal. Severe cases, particularly when undiagnosed, may lead to massive hemorrhage requiring blood transfusion, hysterectomy, or death of the mother.

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