Magnetic resonance imaging evaluation after anorectal pull-through surgery for anorectal malformations: a comprehensive review

Anorectal malformations (ARM) include congenital anomalies of the distal anus and rectum with or without anomalies of the urogenital tract. Posterior sagittal anorectoplasty (PSARP) and minimally invasive laparoscopically assisted anorectal pull-through (LAARP) procedure are now mainly used to surgically treat ARMs. Magnetic resonance imaging (MRI) is the modality of choice for interval follow-up assessment of structural and functional outcome after these surgeries to assess future bowel continence. Well-developed pelvic musculature has been found to be a reflector of better anal continence after ARM surgery. Thus, MRI plays an important role in evaluating the external sphincter complex, puborectalis, and levator ani muscles. Other parameters that need to be noted include the position of the neoanus, rectal diameter, anorectal angle, presence or absence of megarectum, and other ancillary anomalies in the spine. Thus, MRI due to superior soft-tissue resolution is the modality of choice and indispensable for post-operative pelvic evaluation in children.