Based on radiographic features
Stage 1a- phlegmon
Stage 1b-<unk>  with pericolic or mesenteric abscess
Stage 2 -<unk>  with walled off pelvic abscess
Stage 3 -<unk>  with generalised purulent peritonitis
Stage 4 -<unk>  with generalised faecal peritonitis
Stage 1a- phlegmon
Stage 1b-<unk>  with pericolic or mesenteric abscess
Stage 2 -<unk>  with walled off pelvic abscess
Stage 3 -<unk>  with generalised purulent peritonitis
Stage 4 -<unk>  with generalised faecal peritonitis
0	Mild clinical<unk> 
Ia	Confined pericolic inflammation or phlegmon
Ib	Pericolic or mesocolic abscess
II	Pelvic, distant intraabdominal, or retroperitoneal abscess
III	Generalized purulent peritonitis
IV	Generalized fecal peritonitis
Hinchey classification for diverticulitis
Upper GI bleeding guidelines
Glasgow-Blatchford Bleeding Score
Ultrasound: Abdomen
Beers criteria
Denver screening criteria
Acute abdominal series
Anoscopy