Special Surgery 19. Colon Diverticulosis, Diverticulitis: Symptoms, Diagnosis, Conservative Treatment, Surgical Indications

I. Colon Diverticulosis

Definitions

• Diverticulum = outpouching of gut wall
• Diverticulosis = presence of multiple diverticula
• Diverticular disease = symptomatic diverticulosis with symptoms or complications
• Colonic diverticula are usually false diverticula

Classification

1. According to Histology

• True diverticulum:

• All layers of bowel wall protrude
• Usually congenital
• Example: Meckel diverticulum, not typical colonic diverticulosis

• False diverticulum:

• Mucosa and submucosa herniate through muscular wall
• Usually acquired
• Typical colonic diverticulum

2. According to Pathomechanism

• Pulsion diverticulum:

• Increased intraluminal pressure + focal weakness of colonic wall
• Usually false diverticulum
• Forms where vasa recta penetrate muscularis propria

• Traction diverticulum:

• External inflammatory/fibrotic traction pulls bowel wall outward
• Usually true diverticulum
• Not typical for common sigmoid diverticulosis

Localization and Epidemiology

• Western countries: sigmoid colon most common
• Japan/China/East Asia: right-sided diverticula are more frequent
• Prevalence increases with age
• Most patients remain asymptomatic

Etiology and Risk Factors

• Age-related connective tissue and muscular wall changes
• Low-fiber Western diet and constipation in classical teaching
• Obesity
• Smoking
• Low physical activity
• Regular NSAID use increases complication risk
• Connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome
• Genetic factors contribute significantly

Clinical Features

• Asymptomatic: most common
• Symptomatic uncomplicated diverticular disease:

• Left lower quadrant discomfort/cramps
• Pain relieved by defecation
• Bloating
• Altered bowel habit: constipation/diarrhea
• No fever, no leukocytosis, no CT inflammation

• Diverticular bleeding:

• Painless hematochezia
• Can be massive
• Often right-sided bleeding source despite sigmoid diverticulosis being common

Diagnosis of Diverticulosis

• Often incidental finding
• Colonoscopy:

• Detects diverticula and excludes cancer/polyps
• Avoid during acute diverticulitis

• CT colonography or barium enema can show diverticula but are less central today
• CT abdomen can show diverticulosis and complications

Treatment of Diverticulosis

• Asymptomatic diverticulosis:

• No specific medical treatment
• Education about bleeding/diverticulitis symptoms

• Lifestyle:

• High-fiber / high-quality diet rich in fruit, vegetables, whole grains and legumes
• Weight reduction if obese
• Regular physical activity
• Smoking cessation
• Avoid regular non-aspirin NSAID use if possible

• Routine avoidance of seeds, nuts, corn or popcorn is not required
• Mesalamine, rifaximin and probiotics are not routine recurrence-prevention treatment

II. Acute Diverticulitis: Symptoms and Diagnosis

Definition and Pathogenesis

• Diverticulitis = inflammation of one or more diverticula
• Often caused by obstruction of diverticular neck by fecalith → microperforation → inflammation/infection
• Can be uncomplicated or complicated

Clinical Features

• Classical triad:

• Left lower quadrant pain
• Fever
• Leukocytosis

• Other symptoms:

• Localized tenderness
• Altered bowel habit: constipation or diarrhea
• Nausea, vomiting
• Palpable tender mass if phlegmon/abscess
• Urinary symptoms if inflammation near bladder

• Right-sided diverticulitis can mimic appendicitis
• Generalized peritonitis suggests free perforation

Complications

• Abscess → sepsis
• Perforation:

• Contained microperforation
• Free perforation → purulent/fecal peritonitis

• Fistula:

• Colovesical: pneumaturia, fecaluria, recurrent UTI
• Colovaginal
• Coloenteric or colocutaneous

• Stricture / obstruction
• Diverticular bleeding can coexist but bleeding is usually from diverticulosis rather than active diverticulitis

Hinchey Classification

Diagnosis

Laboratory

• Increased WBC / leukocytosis
• Increased CRP
• Renal function and electrolytes before contrast CT and surgery
• Urinalysis if urinary symptoms, because colovesical fistula or adjacent inflammation can mimic UTI

Imaging

• Contrast-enhanced CT abdomen/pelvis = gold standard in suspected acute diverticulitis
• CT findings:

• Colonic wall thickening
• Pericolic fat stranding
• Inflamed diverticula
• Abscess
• Extraluminal air / perforation
• Fistula or obstruction

• CT is especially important in first episode, severe presentation, immunocompromised patient, failure to improve, or before elective surgery planning
• Ultrasound can be useful in expert hands but is less complete than CT for complications

Colonoscopy

• Avoid colonoscopy during acute diverticulitis because of perforation risk and pain
• Delayed colonoscopy after recovery:

• Usually after 6-8 weeks or complete symptom resolution
• Recommended after complicated diverticulitis
• Recommended after first uncomplicated episode if no recent high-quality colonoscopy or if alarm symptoms/CRC screening not current
• Purpose: exclude colorectal cancer or other colitis mimics

III. Conservative Treatment

Uncomplicated Diverticulitis

• Uncomplicated = localized inflammation without abscess, free perforation, fistula, obstruction or sepsis
• Outpatient treatment possible if:

• Mild symptoms
• Immunocompetent
• No severe comorbidities/frailty
• Tolerates oral intake
• Reliable follow-up

• Diet:

• Clear liquids or light diet during acute phase if needed
• Advance diet as symptoms improve

• Pain control:

• Paracetamol/acetaminophen preferred
• Avoid regular NSAIDs if possible because complication/bleeding risk

• Antibiotics:

• Can be used selectively, not routinely, in low-risk immunocompetent mild uncomplicated diverticulitis
• Give antibiotics if frail, comorbid, immunocompromised, refractory symptoms, vomiting, high CRP/WBC, fluid collection or longer inflamed segment on CT
• Examples: amoxicillin-clavulanate, or ciprofloxacin + metronidazole depending on local resistance/allergy

When to Hospitalize

• Elderly/frail or significant comorbidity
• Immunocompromised
• Severe pain, high fever, sepsis concern
• Unable to tolerate oral intake or oral antibiotics
• Failed outpatient treatment
• Complicated disease on CT
• Uncertain diagnosis or need for urgent surgical evaluation

Inpatient Conservative Treatment

• Nil by mouth or clear liquids initially if severe symptoms/vomiting
• IV fluids and electrolyte correction
• IV antibiotics covering Gram-negative and anaerobic bacteria
• Analgesia and antiemetics
• Serial abdominal exams and labs
• DVT prophylaxis if admitted
• Escalate if no improvement after 48-72 h or clinical worsening

Abscess Management

• Small pericolic abscess: antibiotics and observation may be enough
• Larger abscess, usually >=3-4 cm or distant/pelvic abscess:

• CT-guided / percutaneous drainage if accessible
• Antibiotics
• Culture-guided therapy

• Emergency surgery if drainage impossible and sepsis persists or perforation/peritonitis develops

Prevention After Recovery

• High-quality high-fiber diet
• Weight control
• Regular physical activity
• Smoking cessation
• Avoid regular non-aspirin NSAIDs if possible
• No routine avoidance of nuts/seeds/popcorn
• No routine mesalamine, probiotics or rifaximin for recurrence prevention

IV. Surgical Indications and Procedures

Emergency Surgical Indications

• Diffuse peritonitis: Hinchey III-IV
• Free perforation with sepsis
• Failure of conservative treatment
• Abscess not suitable for percutaneous drainage with persistent sepsis
• Obstruction with acute deterioration
• Uncontrolled bleeding requiring colectomy after localization, rare

Elective Surgical Indications

• Decision is individualized, not based only on number of attacks
• Consider elective sigmoid colectomy after:

• Complicated diverticulitis treated nonoperatively, especially abscess
• Fistula: colovesical, colovaginal, colocutaneous
• Stricture or recurrent obstruction
• Recurrent attacks with significant quality-of-life impairment
• Immunocompromised patient after recovery, individualized risk discussion
• Suspicion of underlying malignancy not excluded

Operative Options in Acute Complicated Diverticulitis

Hartmann Procedure

• Sigmoid/proctosigmoid colectomy
• End colostomy
• Closure of rectal stump
• Used especially in unstable patients, severe sepsis, fecal peritonitis, high operative risk or unsafe anastomosis
• Stoma reversal may be considered later, often months after recovery; reversal is not guaranteed

Primary Resection with Anastomosis

• Colectomy with colorectal anastomosis
• May include diverting loop ileostomy
• Consider in stable patients with acceptable tissue quality and lower risk
• Can avoid permanent end colostomy in selected patients

Laparoscopic Lavage

• Previously considered for selected Hinchey III purulent peritonitis
• Role is limited/controversial because of recurrence/abscess/reoperation risk
• Not used for fecal peritonitis

Elective Sigmoidectomy

• Usually laparoscopic if feasible after inflammation resolves
• Resect diseased sigmoid segment
• Proximal margin: soft, compliant, non-inflamed colon
• Distal margin: upper rectum, below diseased sigmoid to reduce recurrence
• Restore continuity with colorectal anastomosis
• Temporary diverting stoma only if anastomotic risk is high

Special Situations

• Colovesical fistula:

• Symptoms: pneumaturia, fecaluria, recurrent UTI
• Treatment: elective sigmoid resection and fistula management after inflammation control

• Diverticular bleeding:

• Resuscitation, colonoscopy/CTA depending on severity
• Angioembolization if active bleeding localized
• Segmental colectomy only if bleeding site localized and uncontrolled

• Obstruction/stricture:

• Rule out cancer
• Elective or urgent resection depending on severity