Anorectal Malformations

Paige E. Finkelstein

One does not have to be a doctor to make the diagnosis of anorectal malformation (ARM), and thus it has been known throughout history for centuries—as early as 650 BC.¹
Aristotle described humans born with ARM in the third century BC, and reports of treatment via membrane incision and dilation began to appear in the second century CE.²
With primitive surgery, children with low malformations tended to have greater survival than those with high malformations.³
Dr Douglas Stephens in 1953 was the first pediatric surgeon who studied the pelvic anatomy in patients who died from ARM; posterior sagittal anorectoplasty (PSARP) by Dr Alberto Peña was published in 1982, which became a preferred technique for surgical management of these conditions.⁴,⁵

RELEVANT ANATOMY

The anal passage may be narrow or misplaced in front of where it should be located.
A membrane may be present over the anal opening.
The rectum may not connect to the anus.
The rectum may connect to part of the urinary tract or the reproductive system through a passage called a fistula, and an anal opening is not present.

EPIDEMIOLOGY AND ETIOLOGY

Incidence: It is approximately 1 to 2 in 5000 live births.⁶,⁷
Most common ARM in females is rectovestibular fistula, and the most frequent ARM in males is rectourethral fistula.⁸
Etiology: It is unknown, but genetic factors are believed to play an important role, as evidenced by increased risk in first-degree relatives of probands, association with
chromosomal abnormalities, and reproducibility using knockout animal models.⁶,⁸
Up to 50% is estimated to be unrelated to any known syndrome.⁷
Chromosomal abnormalities are present in 4.5% to 11% of patients.⁶
Maternal exposure during pregnancy has been associated with increased risk of anorectal atresia, including lorazepam, and lack of folic acid, vitamin A, as well as obesity, asthma, epilepsy, and thyroid disease.⁶,⁹

CLINICAL PRESENTATION

Classic presentation of ARMs can range in phenotypes from perfectly healthy infant with minor abnormalities who can be easily treated to complex with poor functional prognosis.⁶,⁸
Diagnosis is made by newborn physical examination (Figure 31.1).
50% of ARMs are associated with genitourinary, cardiovascular, skeletal, or gastrointestinal (GI) defects.⁶,⁸
This nonrandom coexistence of anomalies is often part of the VACTERL association, which includes spinal and/or vertebral defects (V), ARM (A), congenital cardiac anomalies (C), esophageal atresia/tracheoesophageal fistula (TE), renal and urinary abnormalities (R), and limb lesions (L).¹⁰
Persistent cloaca represents the most severe malformation, where the rectum, vagina, and urinary tract converge into a single channel.¹¹

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Tags: Handbook of Pediatric Surgery

May 5, 2019 | Posted by drzezo in PEDIATRICS | Comments Off

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