Epidemiology & Risk Factors

Age: Increased incidence w/ age (mostly > 60 yrs).
Diet: Low dietary fiber, high red meat intake.
Lifestyle: Obesity, physical inactivity, smoking, NSAID/aspirin use.
Anatomy: Sigmoid colon is the most common site (high pressure zone in Western populations).

Clinical Features

History:
- Constant LLQ pain (may be RLQ in Asian pts w/ cecal/ascending diverticulitis). c
- Fever, chills, nausea, vomiting, anorexia.
- Altered bowel habits (constipation > diarrhea).
Physical Examination (PE):
- LLQ tenderness, localized guarding, and rebound tenderness.
- Palpable tender mass (phlegmon or abscess).
- Diffuse peritonitis (rigidity, guarding, rebound) if free perforation occurs.

Initial & Confirmatory Imaging: CT abdomen & pelvis w/ IV contrast.
- Findings: Colonic wall thickening (> 4 mm), pericolonic fat stranding, presence of diverticula, or complications (abscess, free air).
Key Labs:
- CBC: Leukocytosis w/ left shift.
- CRP: Elevated (correlates w/ severity).
- Urinalysis: May show sterile pyuria due to bladder irritation from adjacent inflammation.
Contraindicated Studies: Avoid colonoscopy and barium enema during acute phase due to high risk of colonic perforation. Delay for 6-8 weeks post-resolution to rule out CRC.

Colorectal Cancer (CRC):
- Diff by: Presence of weight loss, iron deficiency anemia, palpable non-tender mass, obstructive symptoms. Rule out via delayed colonoscopy.
Irritable Bowel Syndrome (IBS):
- Diff by: Absence of fever, leukocytosis, or inflammatory markers; chronic, intermittent course associated w/ stress.
Inflammatory Bowel Disease (IBD):
- Diff by: Recurrent bloody diarrhea, extraintestinal manifestations (uveitis, arthritis), younger age of onset, and characteristic endoscopic/histological findings.
Acute Appendicitis:
- Diff by: RLQ pain localized to McBurney’s point, migration of pain from periumbilical area. (Note: Left-sided appendicitis in situs inversus can mimic diverticulitis).
Pelvic Inflammatory Disease (PID) / Ectopic Pregnancy:
- Diff by: Bilateral adnexal tenderness, cervical motion tenderness, vaginal discharge, and (+) beta-hCG.

Uncomplicated Diverticulitis (Hinchey Stage 0 - Ia):
- First-line (Mild/Stable): Outpatient management. Bowel rest (clear liquid diet) + oral Abx (e.g., Ciprofloxacin + Metronidazole OR Amoxicillin-Clavulanate) for 7-10 days.
  - Note: Selective observation without Abx can be considered in immunocompetent pts w/ very mild symptoms.
- Second-line (High-risk/Failed outpatient): Inpatient admission. IV fluids, NPO, and IV broad-spectrum Abx (e.g., Piperacillin-Tazobactam OR Ceftriaxone + Metronidazole).
Complicated Diverticulitis (Hinchey Stage Ib - IV):
- Abscess (< 3 cm): IV Abx alone.
- Abscess (≥ 3 cm): CT-guided percutaneous drainage + IV Abx. c
- Perforation/Peritonitis/Obstruction (Refractory/Unstable): Emergency surgery.
  - Hartmann procedure: Resection of diseased sigmoid colon w/ creation of temporary end colostomy and closure of distal rectal stump.
  - Primary anastomosis w/ diverting loop ileostomy (in hemodynamically stable pts w/ minimal contamination).

Abscess: Suspect if fever/leukocytosis persist despite 48-72 hours of appropriate IV Abx.
Fistula: Most common is colovesical fistula (presents w/ pneumaturia, fecaluria, and recurrent polymicrobial UTIs). Also colovaginal or coloperitoneal.
Bowel Obstruction: Due to acute inflammatory edema or chronic fibrotic strictures.
Free Perforation: Leads to purulent or fecal peritonitis; surgical emergency.

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