Pain typically begins suddenly and is usually localized to the **left lower quadrant (LLQ)**

Inflamed diverticula cause focal peritoneal irritation.

Low-grade fever, chills, and malaise due to localized infection.

• Constipation (more common)

• Diarrhea (sometimes)

• Change in stool caliber

Occurs due to ileus or localized peritoneal irritation.

Due to ileus or inflammation-related bowel dysfunction.

Coughing, walking, or sudden motion worsens discomfort.

Suggests perforation, peritonitis, or abscess.

Irritative voiding symptoms due to bladder inflammation:

• Dysuria

• Frequency

• Urgency

If present, consider diverticular bleeding rather than diverticulitis.

• Pneumaturia

• Fecaluria

• Recurrent UTIs

(Colovesical fistula)

• Abscess formation

– Localized collection of pus around the inflamed diverticulum

– May require percutaneous drainage

• Perforation

– Free perforation → generalized peritonitis

– Surgical emergency

• Fistula formation

– Most commonly colovesical fistula

– Symptoms: pneumaturia, fecaluria, recurrent UTIs

– Colo-vaginal fistula in females (rare)

• Bowel obstruction

– Due to inflammation, edema or stricture formation

– May cause large bowel obstruction

• Stricture / fibrosis

– Chronic inflammation → scarring → narrowed lumen

– Can mimic malignancy

• Bleeding (diverticular hemorrhage)

– Painless lower GI bleeding

– Usually self-limiting but may be severe

• Sepsis

– Occurs with severe infection, perforation, abscess rupture

• Recurrent diverticulitis

– Multiple episodes over time

– Increases risk of chronic complications

Right lower quadrant pain but may mimic left-sided diverticulitis in a mobile cecum.

Recurrent abdominal pain without fever, leukocytosis, or imaging evidence of inflammation.

May present with changes in bowel habits, obstruction, anemia, or mass; must be excluded especially in recurrent or complicated cases.

Segmental involvement, fistulas, perianal disease; may resemble diverticulitis clinically.

Localized left lower quadrant pain; CT shows fat-density lesion adjacent to colon.

Pain + bloody diarrhea; CT shows segmental colonic wall thickening rather than focal inflammation.

Dysuria, urinary frequency; urinalysis positive.

Severe colicky flank-to-groin pain; hematuria common.

Ovarian torsion, ectopic pregnancy, pelvic inflammatory disease — pelvic exam and ultrasound help differentiate.

Severe pain out of proportion to exam; risk in elderly or arrhythmia patients.

It occurs when a diverticulum becomes obstructed by stool, undigested food, or inspissated mucus → bacterial overgrowth → inflammation.

• Diverticulosis → presence of diverticula

• Diverticulitis → inflammation/infection of diverticula

*Risk increases with age*, especially >50 years.

• Smoking

• NSAID use

( Diverticulitis occurs when a pre-existing colonic diverticulum becomes inflamed and/or infected.

Underlying requirement: presence of colonic diverticulosis

• Diverticulosis = multiple sac-like mucosal outpouchings through weak points in the colonic wall.

• Most commonly affects the sigmoid colon (high intraluminal pressure segment).

• These are acquired “pseudodiverticula” (mucosa and submucosa only, not full-thickness).

Why diverticula form (mechanical factors)

• Low-fibre, refined-carbohydrate diet → small, firm stools → higher segmental intraluminal pressure.

• Repetitive segmental contractions of the colon (especially sigmoid) → focal herniation where vasa recta penetrate the muscularis.

• Age-related weakening of connective tissue in the colonic wall.

Triggering events for diverticulitis

• Fecalith or inspissated stool obstructs the neck of a diverticulum.

• Stasis within the sac → bacterial overgrowth, localized mucosal injury.

• Local ischemia of the diverticular wall → micro-perforation and inflammation.

• Secondary infection by colonic flora leads to phlegmon, abscess, or perforation.

Key risk factors for diverticulitis

• Increasing age (especially >50 years).

• Low-fibre “Western” diet and constipation.

• Obesity and sedentary lifestyle.

• Smoking.

• Regular NSAID use, corticosteroids, or opioids (impair mucosal defence and healing).

• Immunosuppression (post-transplant, chemotherapy, uncontrolled diabetes).

Right-sided vs left-sided disease

• In Western populations, diverticula and diverticulitis are typically left-sided (sigmoid).

• In some Asian populations, right-sided diverticulitis (cecum/ascending colon) is more frequent, sometimes mimicking acute appendicitis.

Not all diverticulosis progresses to diverticulitis

• Majority of patients with diverticulosis remain asymptomatic.

• Only a minority develop acute inflammation; recurrent attacks can lead to chronic changes (stricture, fistula, segmental colitis).

Classified as:

• *Uncomplicated diverticulitis* — localized inflammation

• *Complicated diverticulitis* — abscess, fistula, obstruction, perforation, peritonitis

Most cases respond to conservative therapy; a minority progress to complications requiring imaging or intervention.)

• CBC – leukocytosis, neutrophilia

• CRP – elevated; correlates with severity

• ESR – may be raised

• Serum electrolytes – dehydration, vomiting-associated imbalance

• Renal function tests – baseline before contrast CT

• Urinalysis – rules out UTI mimicking left lower quadrant pain

• Pregnancy test (β-hCG) in women of childbearing age

• Shows diverticula

• Pericolic fat stranding

• Bowel wall thickening

• Local abscess

• Extraluminal air (microperforation)

• Fistula or obstruction if complicated

Ultrasound abdomen

• Useful when CT unavailable

• Good for abscess detection

• Operator-dependent

MRI abdomen

• Alternative if CT contraindicated (pregnancy, contrast issues)

Risk of perforation.

Colonoscopy (performed 6–8 weeks after recovery)

• Evaluate for malignancy

• Assess extent of diverticular disease

Stool occult blood test

• May be positive in complicated disease

Imaging differentiates painless diverticulosis from inflammatory diverticulitis.

Diverticulitis occurs when a colonic diverticulum becomes obstructed by stool, food particles, or inflammation, leading to localized infection.

Diverticula form where vasa recta penetrate the muscularis, creating weak points → mucosa herniates through muscular layer.

Obstruction of diverticulum → stagnation of colonic contents → bacterial proliferation.

Segmental colonic spasm and high-pressure zones (especially sigmoid colon) reduce blood flow → increased risk of micro-rupture.

Leakage of bacteria into pericolic fat → fat stranding, localized phlegmon, or abscess.

If perforation worsens → peritonitis, fistula formation (colovesical most common), obstruction, or bleeding.

Repeated attacks lead to fibrosis and thickening of colon wall → narrowing and recurrent symptoms.

Age-related weakening of colonic wall, low-fiber diet, obesity, NSAID use, smoking, and altered gut microbiome all enhance inflammation.

Most risk factors relate to lifestyle and bowel habits.

Regular fibre → softer stools → lower intraluminal pressure → reduced diverticulum formation.

Constipation increases colonic pressure → formation & inflammation of diverticula.

Adequate water improves stool bulk & transit.

Improves bowel motility and metabolic health.

Obesity increases diverticulitis risk and complications.

These increase inflammation and gut dysbiosis.

Smoking increases risk of perforated diverticulitis.

Chronic NSAIDs, steroids, opiates ↑ risk of perforation and recurrence.

• Encourage daily fruits & vegetables

• Encourage routine bowel habits

• Avoid straining during defecation

• Probiotics may help gut microbiome

Inflammation of diverticula without abscess, perforation, obstruction, or fistula.

Diverticulitis with one or more of:

  • Abscess

  • Microperforation

  • Perforation with peritonitis

  • Fistula formation

  • Obstruction / stricture

  • Sepsis

Repeated episodes after initial recovery; risk increases with low-fiber diet, constipation, obesity.

Persistent low-grade symptoms (LLQ pain, bloating) even between attacks.

More common in Asians; may mimic acute appendicitis.

• Left-sided diverticulitis

Most common type globally; usually affects sigmoid colon.

• Hinchey classification (severity staging)

• Hinchey I – Pericolic abscess or phlegmon

• Hinchey II – Pelvic/retroperitoneal abscess

• Hinchey III – Purulent peritonitis

• Hinchey IV – Feculent peritonitis

Most classic physical finding—corresponds to sigmoid colon involvement.

Suggests peritoneal irritation; may indicate phlegmon or early abscess.

Low-grade fever

Tachycardia (correlates with systemic inflammation/sepsis risk)

Reduced bowel sounds

LLQ palpable fullness or mass (suggests localized abscess/phlegmon)

Rectal exam: tenderness in left pelvis

Mild abdominal distension

Occasional right-sided tenderness (in Asian populations with right-sided diverticulitis)

Indicates perforation, peritonitis → surgical emergency.

Hypotension / toxic appearance (severe complicated diverticulitis)

Diverticulitis occurs when small pouch-like outpouchings in the colon wall (diverticula) become inflamed or infected.

Common in the sigmoid colon where increased intraluminal pressure pushes mucosa through the muscular layer.

More common after age 40 due to weakening of the bowel wall and long-term increased colonic pressures.

• Uncomplicated diverticulitis – localized inflammation

• Complicated diverticulitis – abscess, perforation, fistula, obstruction, peritonitis

Left-lower-quadrant abdominal pain, fever, and altered bowel habits (diarrhea or constipation).

Low-fiber diet, obesity, sedentary lifestyle, aging, connective tissue disorders.

Most cases involve the sigmoid colon (descending colon).

After an initial attack, risk of recurrence increases if lifestyle modifications are not made.

Term “diverticulitis” stems from the Latin “diverticulum” meaning a small side path or pocket; condition first widely described in early 20th century with rise of refined low-fiber diets in Western countries.

(Meckel's diverticulum is a congenital outpouching of the small intestine that is present from birth and is the most common congenital abnormality of the gastrointestinal tract. It is often harmless but can cause complications such as bleeding, intestinal obstruction, or inflammation, particularly if it contains abnormal tissue like gastric mucosa. Symptoms can include abdominal pain and blood in the stool, and the condition is typically diagnosed with a Meckel's scan)

Most patients present with sudden or gradually worsening pain in the LLQ (sigmoid colon involvement).

Systemic inflammatory response due to bacterial infection of a diverticulum.

May have constipation or diarrhea depending on degree of colonic irritation.

Inflammation + localized ileus contribute to reduced appetite and nausea.

Usually localized to LLQ; may progress to guarding if peritonitis develops.

Local inflammation can cause transient ileus.

Dysuria (inflammation near bladder may irritate urinary tract)

Urgency or urinary frequency (due to bladder irritation)

Rectal discomfort or tenesmus (inflammation near rectum)

Mild leukocytosis-related malaise and fatigue

Stable patients without peritonitis can be managed outpatient.

Clear liquids for 24–48 hours → advance diet as symptoms improve.

Paracetamol preferred; avoid NSAIDs due to perforation risk.

Not always required in mild cases.

Used when: fever, leukocytosis, significant comorbidity, immunosuppressed, or moderate/severe symptoms.

• Significant leukocytosis

• Immunocompromised

• Suspected complications

Urgent surgical consultation → Hartmann’s procedure or primary anastomosis based on patient stability.

Elective surgery recommended.

• High-fibre diet

• Weight reduction

• Stop smoking

• Regular physical activity

• Avoid routine antibiotics for prevention (no benefit)