Non-syndromic anorectal malformation

Non-syndromic anorectal malformation (ARM), also known as non-syndromic imperforate anus, refers to a spectrum of congenital defects affecting the anus and rectum that occur in isolation, without the additional anomalies that characterize syndromic forms (such as VACTERL association or Currarino syndrome). In these malformations, the anorectal canal fails to develop normally during embryogenesis, resulting in abnormal positioning, narrowing, or complete absence of the anal opening. The rectum may end as a blind pouch or may form abnormal connections (fistulae) to adjacent structures such as the urinary tract, vagina, or perineal skin. The condition is typically identified at birth or shortly thereafter during routine neonatal examination when the absence or abnormal appearance of the anal opening is noted. The clinical spectrum ranges from mild forms, such as anterior ectopic anus or anal stenosis, to more severe forms including high anorectal atresia with rectovesical or rectourethral fistulae. The gastrointestinal system is primarily affected, but associated genitourinary complications may arise depending on the type and location of any fistulae. Symptoms in the newborn include failure to pass meconium, abdominal distension, and signs of intestinal obstruction. Treatment is surgical and depends on the specific type of malformation. Low-type malformations may be corrected with a single-stage perineal procedure (anoplasty), while high-type malformations typically require a staged approach involving initial colostomy, followed by definitive posterior sagittal anorectoplasty (PSARP, also known as the Peña procedure), and subsequent colostomy closure. Long-term outcomes vary, and many patients require ongoing management for issues such as fecal incontinence, constipation, or urinary problems. Bowel management programs, including dietary modifications, enemas, and biofeedback therapy, play an important role in optimizing quality of life.

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