Magnetic resonance imaging is an effective means of diagnosing acute abdominal and pelvic pain in pregnant patients, and it avoids fetal exposure to the radiation of a computerized axial tomography exam, Katherine Birchard, M.D., and her colleagues have reported.
Although there have been no documented cases of MRI causing adverse effects to the fetus, MRI scans should be used in pregnant patients only when the benefits clearly outweigh the risks, the researchers said. “However, we should stress that the single greatest factor in morbidity and mortality of the pregnant patient is delay in diagnosis,” reported Dr. Birchard of the University of North Carolina, and associates (AJR Am. J. Roentgenol. 2005;184:452-8).
The researchers retrospectively analyzed all MRI studies of 29 pregnant patients referred to their facility from 2002 to 2004 for evaluation of acute abdominal or pelvic pain. The patients' mean age was 25 years (18-35 years), and mean gestational age was 23 weeks (10-36 weeks). Most of the patients (22) did not have gadolinium administered.
Every patient underwent fetal sonography before any other imaging. Six also underwent complete abdominal sonographic examination before the MRI, which was the imaging exam used in 23 patients.
MRI identified appendiceal abscess (1 case), appendicitis (2 cases), intraabdominal and rectus muscle abscess (1), pancreatitis (1), and ulcerative colitis (1). MRI also showed Crohn's disease with diffuse peritoneal inflammation (1), intussusception (1), bilateral adrenal hemorrhage (1), pyelonephritis (2), hydronephrosis (1), uterine fibroid degeneration (2), degeneration and torsion of a subserosal uterine fibroid (1), simple ovarian cysts (1), and ovarian torsion (1). The other 12 examinations were normal.
The MRI results were congruent with follow-up medical records in 28 of the 29 patients and accurately described the disease process in all except one patient. This patient was at 18 weeks' gestation and complained of acute right lower quadrant pain. The MRI identified multiple ovarian cysts, but a laparoscopy 1 month later showed a torsed right ovary with multiple cysts. When examined retrospectively, the MRI did not shown this finding.
“We believe this is due to the fact that the ovary was largely cystic, and therefore, edematous tissue was not seen,” the researchers said.