Hirschsprung disease is characterized by delayed meconium passage in newborns, abdominal distention, vomiting, occasional fever, and foul-smelling stools. This condition is caused by failure of ganglion cells to migrate into the distal bowel, resulting in spasm and functional obstruction of the aganglionic segment. Only about 6% of infants with Hirschsprung disease pass meconium in the first 24 hours of life, compared with 95% of normal infants. Most affected babies rapidly become ill with symptoms of enterocolitis or obstruction. Affected older children do not pass large-caliber stools because of rectal spasm, and they do not have encopresis. Other causes of constipation include spinal cord abnormalities, hypothyroidism, drugs, cystic fibrosis, and anorectal malformations (see Table 126-10). A variety of systemic disorders affecting metabolism or muscle function can result in constipation. Children with developmental disabilities have a great propensity for constipation because of diminished capacity to cooperate with toileting, reduced effort or control of pelvic floor muscles during defecation, and diminished perception of the need to pass stool.
Table 126-10 includes typical characteristics of the common causes of constipation. Congenital malformations usually cause
Table 126-10 Common Causes of Constipation and Characteristic Features CAUSES OF CONSTIPATION CLINICAL FEATURES Hirschsprung disease History: Failure to pass stool in first 24 h, abdominal distention, vomiting, symptoms of enterocolitis (fever, foul-smelling diarrhea, megacolon). Not associated with large-caliber stools or encopresis Examination: Snug anal sphincter, empty, contracted rectum. May have explosive release of stool as examiner’s finger is withdrawn Laboratory: Absence of ganglion cells on rectal suction biopsy specimen, absent relaxation of the internal sphincter, “transition zone” from narrow distal bowel to dilated proximal bowel on barium enema
Functional constipation History: No history of significant neonatal constipation, onset at potty training, large-caliber stools, retentive posturing, may have encopresis Examination: Normal or reduced sphincter tone, dilated rectal vault, fecal impaction, soiled underwear, palpable fecal mass in left lower quadrant Laboratory: No abnormalities, barium enema would show dilated distal bowel
Anorectal and colonic History: Constipation from birth due to abnormal anatomy malformations Examination: Anorectal abnormalities are shown easily on physical examination Anal stenosis Anteriorly displaced anus is found chiefly in females, with a normal-appearing anus located close to the Anteriorly displaced anus posterior fourchette of the vagina Imperforate anus Laboratory: Barium enema shows the anomaly Colonic stricture
Multisystem disease Muscular dystrophy Cystic fibrosis Diabetes mellitus Developmental delay Celiac disease History: Presence of other symptoms or prior diagnosis Examination: Specific abnormalities may be present that directly relate to the underlying diagnosis Laboratory: Tests directed at suspected disorder confirm the diagnosis
Spinal cord abnormalities History: History of swelling or exposed neural tissue in the lower back, history of urinary incontinence Meningomyelocele Examination: Lax sphincter tone due to impaired innervation, visible or palpable abnormality of lower back Tethered cord usually (but not always) present Sacral teratoma or lipoma Laboratory: Bony abnormalities often present on plain x-ray. Magnetic resonance imaging (MRI) of spinal