Retentive
Functional constipation (95 percent)
Organic (5 percent)
Anal causes
	Fissures
	Stenosis/atresia with fistula
	Anterior displacement of anus
	Trauma
	Postsurgical repair
Neurogenic causes
	Hirschsprung's disease
	Chronic intestinal psuedo-obstruction
	Spinal cord disorders
	Cerebral palsy/hypotonia
	Pelvic mass
Neuromuscular disease
Endocrine/metabolic causes
	Hypothyroidism
	Hypercalcemia
	Lead intoxication
Drugs
	Codeine
	Antacids
	Others
Nonretentive
Nonorganic (99 percent)
Organic (1 percent)
Severe ulcerative colitis
Acquired spinal cord disease (i.e., sacral lipoma, spinal cord tumor)
Rectoperineal fistula with imperforate anus
Postsurgical damage to anal sphincter