Abdominal xray
Demonstrate position, shape, and number of<unk>  bodies
Demonstrates possible presence of free air (perforation of rectum or colon)
Perforation of rectum below peritoneal reflection shows extraperitoneal air along psoas
Perforation above peritoneal reflection reveals intraperitoneal free air under diaphragm
CT
Useful when<unk> <unk>  is radiolucent and for detection of small amounts of free air
Demonstrate position, shape, and number of<unk>  bodies
Demonstrates possible presence of free air (perforation of rectum or colon)
Perforation of rectum below peritoneal reflection shows extraperitoneal air along psoas
Perforation above peritoneal reflection reveals intraperitoneal free air under diaphragm
Perforation of rectum below peritoneal reflection shows extraperitoneal air along psoas
Perforation above peritoneal reflection reveals intraperitoneal free air under diaphragm
Useful when<unk> <unk>  is radiolucent and for detection of small amounts of free air
Rectal foreign body
Anal fissure
Anal fistula
Anal malignancy
Volvulus 
Anal tags
Volvulus
Anorectal abscess