Two mechanisms are involved in the development of<unk> , either or both of which may be contributory to the condition: stenosis, or narrowing of the sphincter of<unk>  (also termed papillary stenosis), and dyskinesia, or alteration in the function of the sphincter of<unk>  (also termed biliary dyskinesia). Individuals with stenosis of the sphincter of<unk>  typically have an elevated baseline pressure of the sphincter of<unk> , due to an anatomical problem that leads to narrowing of the sphincter, such as recurrent passage of gallstones through the ampulla of Vater, trauma to the sphincter from procedures such as endoscopic retrograde cholangiopancreatography or biliary surgery, or infections of the common bile duct. In contrast, dyskinesia of the sphincter of<unk>  is a purely functional disorder, wherein there is intermittent obstruction of the bile duct due to inappropriate spasms. The reasons for dyskinesia of the sphincter of<unk>  are not completely understood, but believed to be due to alteration in local gut hormones and peptides, such as cholecystokinin, which act on the sphincter or to altered neuronal control of the sphincter.
Sphincter of Oddi dysfunction
Sphincter paralysis
Neurogenic bowel dysfunction
Retained antrum syndrome
Anorectal anomalies
Rectal foreign body
Functional constipation
Anal dysplasia