Evaluation of anorectal malformations using magnetic resonance imaging.

Demonstration of the anatomy of the anal sphincter muscles in patients with anorectal malformations is important. The information can help us in preoperative planning for surgical repair and in predicting a patient's prognosis. For patients with postoperative incontinence, the anatomic imaging is especially useful. Magnetic resonance imaging (MRI) is a relatively new diagnostic tool that generates images of sections of the body taken in any plane. From Oct. 1989 to Dec. 1990, twelve patients received MRI examination, imaging the pelvis and lumbosacral spine in the sagittal, transverse, and coronal planes. Normal anorectum in 2 cases was recorded for comparison. The other ten cases included three of postoperative incontinence, three of cloacal anomaly, and four of questionable level of anorectal anomaly before MRI evaluation. Our experience proved that MRI is a useful examination in selected patients with anorectal malformation. To be cost-effective, we suggest that MRI is performed only in patients with postoperative incontinence and some questionable cases.