Routine MRI evaluation of low imperforate anus reveals unexpected high incidence of tethered spinal cord.

BACKGROUND/PURPOSE: Previous clinical practice has included evaluation for the presence of tethered cord in those children who have imperforate anus with a high lesion. To define the incidence in children with low lesions, the authors reviewed their experience with a protocol employing routine magnetic resonance imaging (MRI), regardless of the level of the lesion, to determine the presence of a tethered cord in all children with imperforate anus.

METHODS: A retrospective review of children with imperforate anus was conducted over the last 13 years at our institution. Lesions were categorized as high versus low based on the supralevator or infralevator position of the fistula.

RESULTS: Sixty-three patients completed evaluation for a tethered cord. Twenty-two (34.9%) of these 63 patients had a tethered cord: 11 of 41 (26.8%) patients with high lesions and 11 of 22 (50.0%) of those with low lesions. Of those children with a low lesion, 83% of the boys had a tethered cord, whereas 38% of the girls had a tethered cord. Forty-five percent of the patients with low lesions and a tethered cord did not have any other lumbosacral anomalies. All 22 children with a tethered cord underwent surgical release.

CONCLUSIONS: The incidence of tethered cord in children with low lesions of imperforate anus is not lower than those with high lesions. The authors advocate early evaluation of all children with imperforate anus for a tethered cord.