General appearance
Irritable
bowel
syndrome
Pain

Alleviated by defecation;
diffuse; no nighttime pain

Usually constant; occurs
particularly in the right lower
abdomen; may appear at
night

Healthy; no weight loss
Crohn
disease

Weight
loss; malnourishment
Ulcerative
colitis

Weight loss only in
severe cases


Weight loss

Colorectal
carcinoma
Stool habits

Diarrhea or constipation, possibly
alternating; no blood; no nighttime diarrhea

Non-bloody, watery diarrhea; increased
frequency; possible nighttime diarrhea
Mostly left lower abdomen;
may occur at night

Bloody diarrhea with mucus
Often no pain


Right-sided carcinomas: melena, diarrhea
Left-sided carcinomas: constipation