OBSOLETE: High isolated anorectal malformation

High isolated anorectal malformation (Orphanet code 171201) is an obsolete clinical classification that was previously used to describe a specific subtype of anorectal malformation (ARM) in which the rectal pouch terminates at a relatively high level above the pelvic floor musculature, occurring without other associated congenital anomalies (i.e., in an isolated fashion). Anorectal malformations are a spectrum of congenital defects affecting the development of the anus and rectum, which are part of the gastrointestinal and genitourinary systems. In 'high' malformations, the rectum may end well above the levator ani muscle complex, often with a fistulous connection to the urinary tract (in males, rectoprostatic urethral or rectovesical fistula) or to the upper vagina (in females). This classification has been rendered obsolete as modern nomenclature, particularly the Krickenbeck classification, replaced the traditional high/intermediate/low categorization with more anatomically precise descriptions of fistula type. Clinically, affected neonates typically present at birth with an absent or abnormally positioned anal opening, abdominal distension, and failure to pass meconium. Diagnosis is usually made in the neonatal period through physical examination and imaging studies. Surgical correction is the mainstay of treatment, often requiring a staged approach: an initial colostomy in the newborn period, followed by a definitive pull-through procedure (most commonly a posterior sagittal anorectoplasty, or PSARP, as developed by Peña), and subsequent colostomy closure. Long-term outcomes depend on the level of the malformation and the quality of the surrounding pelvic musculature and nerve supply, with higher malformations historically associated with greater challenges in achieving fecal continence. Bowel management programs, including dietary modifications, enemas, and sometimes further surgical interventions, may be necessary for ongoing management of constipation or fecal incontinence.

Common questions about OBSOLETE: High isolated anorectal malformation