MRI provides accurate detection of life-threatening ob/gyn condition

December 2, 2009

Findings of a study by California researchers suggest MR imaging could be a highly accurate tool in the detection of placenta accreta, the leading cause of death in women directly before or after childbirth

Findings of a study by California researchers suggest MR imaging could be a highly accurate tool in the detection of placenta accreta, the leading cause of death in women directly before or after childbirth.

Placenta accreta is an increasingly common condition that occurs when the placenta attaches too deeply into a woman’s uterus. When left undetected, the delivery of the baby also rips part of the uterine wall causing hemorrhaging in the mother or damage to the baby.

In severe cases, placenta accreta requires blood transfusion or hysterectomy, and may also be life-threatening for about one in every 10 women, said study coauthor Dr. Michele A. Brown, an associate professor of clinical radiology at the University of California, San Diego. Brown presented the study Tuesday at the 2009 RSNA meeting.

Ultrasound has been the main imaging modality used to detect the condition until now, with success rates varying widely, from 33% up to 100%. Lead investigator of the study Dr. Reena Malhotra, a radiologist at UCSD, evaluated the accuracy of detection with MRI.

Malhotra and colleagues assessed 108 women referred to MRI after receiving suspicious ultrasound exams between 1992 and 2009. Of these, researchers were able to compare results from 71 cases to their respective surgical or pathological findings.

MRI provided a 90.1% accuracy rate in diagnosing the condition. Once detected, specialists were able to monitor prenatal care and plan delivery to avoid birth complications.

“We haven’t lost any mother or fetus when [the condition is] detected prenatally,” Brown said.

Incidence of placenta accreta has increased significantly over the past 20 years. A 2005 study published in the American Journal of Obstetrics and Gynecology analyzed nearly 65,000 births from 1982 to 2002 and reported placenta accreta occurring once in every 533 deliveries.

According to Brown, the increase in placenta accreta can be attributed mainly to an increase in cesarean section births. Women with prior C-sections face the highest risk and are three times more likely to develop the condition than are women who deliver vaginally. Risks increase exponentially with each succeeding cesarean. Other risk factors for developing the condition include pregnancy after the age of 35, uterine scarring, and placenta previa.

Based on these encouraging results, women at high risk should undergo MR scanning if ultrasound findings are inconclusive, researchers said.