Magnetic resonance imaging-guided laparoscopic-assisted anorectoplasty for imperforate anus.

PURPOSE

Magnetic resonance imaging (MRI) has been well described as a modality for evaluation of a failed anorectal pull-through procedure for imperforate anus. To the authors' knowledge, intraoperative MRI has not been previously used to guide a laparoscopic-assisted anorectoplasty (LAARP). We propose that such a procedure would assure anatomically correct placement of the pulled-through rectum.

METHODS

Three male patients with imperforate anus and a prostatic urethral fistula underwent an MRI-guided LAARP in an operative MRI suite. The patients' ages ranged from 5 to 6 months at the time of their pull-through procedure. Preoperative MRIs with mineral oil within the distal colostomy were performed on all patients to document the anatomy of the rectourethral fistula and its relationship to the parasagittal and vertical muscle complex. The perineum was pierced with an MRI compatible needle at the central portion of the parasagittal muscle complex as determined by a direct muscle stimulator. Further incremental advancement of the needle within the muscle complex was guided by serial MRIs in axial, coronal, and sagittal planes until the levator floor was penetrated, and the peritoneal cavity was entered. LAARP was then completed.

RESULTS

Completion MRI demonstrated placement of the pulled-through segment in a central location through the length of the muscle complex. Serial MRIs performed intraoperatively during advancement of the localization needle demonstrated a curved path of the vertical fibers. Attempts to nonincrementally advance the needle in a straight plane resulted in a breach of the vertical muscle complex or eccentric placement of the needle.

CONCLUSIONS

Magnetic resonance imaging-guided LAARP results in anatomically correct placement of the rectum within the vertical muscle complex. Straight needle advancement techniques in LAARP could result in a deviation of the pulled-through rectum from the central muscular path. Further follow-up will be required to demonstrate functional advantage.