Diverticular disease is one of those Step questions that looks straightforward… until the stem mixes bleeding, LLQ pain, fever, and constipation in the same paragraph. Here’s a quick, shareable way to lock in diverticulosis vs diverticulitis—with a mnemonic you can recall in 2 seconds.
The 2-Second Acronym Trick
“-OSIS = Oozes” (painless bleeding)
DiverticulOSIS → Oozes blood
- Think: “Oooh—blood in the bowl, but I feel fine.”
“-ITIS = Irritated/Infected” (pain + fever)
DiverticulITIS → Inflamed/Infected
- Think: “It is painful.”
Visual/Mnemonic Device (sticky in your brain)
DO vs DI
| Condition | Mnemonic | What you feel | What you see |
|---|---|---|---|
| Diverticulosis | D.O. = “Doesn’t hurt, Oozes” | Painless | Painless hematochezia (often brisk) |
| Diverticulitis | D.I. = “Discomfort + Infection” | LLQ pain, fever | ± constipation/diarrhea, nausea; no major bleed typically |
One-liner to memorize:
- Diverticulosis: painless bleeding.
- Diverticulitis: LLQ pain + fever = infected diverticulum.
High-Yield USMLE Facts You’ll Actually Use
Diverticulosis (the “bleeder”)
- Path: Outpouchings of mucosa/submucosa through muscularis (classically “false” diverticula).
- Presentation: Painless hematochezia (bright red/maroon).
- Bleeding can be significant because it involves vasa recta adjacent to diverticula.
- Risk factors: Age, low-fiber diet, constipation (↑ intraluminal pressure).
- Complications: Bleeding is the classic one tested; can also progress to diverticulitis.
Step-style clue: older patient + sudden painless large-volume hematochezia + stable abdominal exam → think diverticulosis (or angiodysplasia; diverticulosis is very common).
Diverticulitis (the “infected LLQ pain”)
- Path: Microperforation of a diverticulum → localized inflammation/infection.
- Presentation:
- LLQ abdominal pain (sigmoid most common)
- Fever, leukocytosis
- ± constipation or diarrhea
- Key complications (high yield):
- Abscess
- Fistula (classically colovesical → recurrent UTIs, pneumaturia)
- Perforation → peritonitis
- Stricture/obstruction
Step-style clue: LLQ pain + fever + ↑ WBC, especially with localized tenderness → diverticulitis.
Imaging + Management (the board-relevant version)
Imaging
- Best test for suspected diverticulitis: CT abdomen/pelvis with IV contrast
- Looks for inflammation, abscess, perforation.
- Avoid colonoscopy during acute diverticulitis (risk of perforation).
- Colonoscopy is typically done later to rule out malignancy if indicated.
Treatment (very testable)
- Uncomplicated (mild): bowel rest, fluids, pain control; antibiotics depending on severity/risk.
- Complicated (abscess, perforation, sepsis, obstruction): IV antibiotics, drainage for abscess, possible surgery.
Micro “Rapid-Fire” Differentiators (exam speed)
- Painless bleeding? → Diverticulosis
- Pain + fever + leukocytosis? → Diverticulitis
- Pneumaturia/recurrent UTIs? → diverticulitis complication (colovesical fistula)
- CT is the move for diverticulitis; no colonoscopy during the acute episode
Final One-Liner (shareable)
DiverticulOSIS oozes (painless hematochezia). DiverticulITIS is infected (LLQ pain + fever).