Lower GI Disorders
IBD, diverticulitis, appendicitis, bowel obstruction and colorectal screening
Crohn's disease vs. ulcerative colitis
| Crohn's disease | Ulcerative colitis | |
|---|---|---|
| Where | Anywhere mouth to anus (often terminal ileum); skip lesions; full wall thickness | Colon and rectum only; continuous; inner lining |
| Stools | Diarrhea, often not bloody; fatty stools | Bloody diarrhea, many times a day; urgency |
| Complications | Fistulas, strictures, obstruction, malabsorption (B12, iron) | Toxic megacolon, perforation, hemorrhage, colon cancer |
| Surgery | Not curative: disease can recur elsewhere | Removing the colon and rectum is curative |
Treatment: aminosalicylates (mesalamine, mainly UC), steroids for flares only, immunomodulators, biologics (infliximab, adalimumab, vedolizumab, ustekinumab, risankizumab), JAK inhibitors. Screen for TB and hepatitis B before biologics. During flares: low-residue diet, small meals, fluids, avoid trigger foods; TPN if severe.
Diverticulitis
- LLQ pain, fever, change in bowel habits.
- Mild, uncomplicated cases may not need antibiotics; clear liquids → advance as tolerated.
- Prevention: high-fiber diet, fluids, activity. Updated No need to avoid nuts, seeds or popcorn.
- Perforation, abscess → surgery; possible colostomy.
Appendicitis
- Pain starts around the navel, moves to the RLQ (McBurney's point); rebound tenderness, low fever, nausea, loss of appetite.
- No heat to the abdomen and no laxatives or enemas (risk of rupture).
- Sudden relief of pain may mean rupture → peritonitis (rigid abdomen, fever, shock).
- Appendectomy; antibiotics.
Bowel obstruction
- Small bowel: early, frequent vomiting (may smell feculent), cramping, distension.
- Large bowel: marked distension, constipation, late vomiting.
- Bowel sounds high-pitched early, then absent.
- NPO, NG tube to suction, IV fluids, electrolytes; surgery if strangulated (fever, constant pain, tachycardia).
Colorectal cancer screening (USPSTF)
Average risk: ages 45–75. Options: colonoscopy every 10 years · FIT (stool) every year · stool DNA-FIT every 1–3 years · CT colonography or flexible sigmoidoscopy every 5 years. A positive stool test needs a follow-up colonoscopy. Earlier screening for family history or IBD.
Colonoscopy prep: clear liquids the day before; bowel prep until output is clear yellow; avoid red/purple liquids.