# Diverticular Disease: Elective and Emergent Management

## Overview

Colonic diverticulosis is extremely common in Western populations, affecting more than 60% of individuals by the age of 60. Most colonic diverticula are "false" or pseudodiverticula, meaning that the mucosa and submucosa herniate through the muscular wall at weak points where the vasa recta penetrate the circular muscle layer. In Western patients, diverticula predominantly involve the left colon, while right-sided diverticulosis is more common in Asian populations. Despite the high prevalence of diverticulosis, only 10-25% of affected patients ever develop symptomatic diverticulitis.

## Pathophysiology

Diverticula form at the anatomically weak points where the vasa recta penetrate the circular muscle layer. When the neck of a diverticulum becomes obstructed by a fecalith, microperforation, inflammation, and infection follow. Known risk factors include a low-fiber diet, obesity, smoking, NSAID use, and immunosuppression. Genetics also play a meaningful role, with twin studies demonstrating approximately 40% heritability for the condition.

## Classification

### Hinchey Classification (Modified)

The modified Hinchey classification is the standard system for grading complicated diverticulitis:

| Hinchey Stage | Description | Management |
|--------------|-------------|------------|
| Ia | Phlegmon (confined pericolic inflammation) | Antibiotics |
| Ib | Pericolic or mesocolic abscess | Antibiotics ± percutaneous drainage |
| II | Pelvic, distant, or retroperitoneal abscess | Percutaneous drainage + antibiotics |
| III | Purulent peritonitis | Emergent surgery (resection + anastomosis/ileostomy or Hartmann) |
| IV | Feculent peritonitis | Emergent surgery (Hartmann procedure) |

Stage Ia describes a phlegmon with confined pericolic inflammation. Stage Ib involves a pericolic or mesocolic abscess. Stage II indicates a pelvic, distant, or retroperitoneal abscess. Stage III denotes purulent peritonitis from a perforated diverticulum with purulent contamination of the peritoneal cavity. Stage IV, the most severe, involves feculent peritonitis with free perforation and fecal contamination.

<image>Hinchey classification diagram showing stages I through IV of complicated diverticulitis with corresponding CT and intraoperative appearances</image>

## Uncomplicated Diverticulitis

### Diagnosis

The typical presentation includes left lower quadrant pain, fever, and leukocytosis. CT of the abdomen and pelvis with intravenous contrast is the imaging modality of choice. Characteristic findings include pericolonic fat stranding, bowel wall thickening, and inflamed diverticula. CT also serves to rule out complications such as abscess, perforation, and obstruction.

### Management

Patients with mild symptoms who are tolerating oral intake and have no significant comorbidities can generally be managed as outpatients. Oral antibiotics have historically been standard, but recent evidence from the AVOD and DIABOLO trials questions their necessity for uncomplicated diverticulitis in immunocompetent patients. Diet is advanced from clear liquids to a regular diet as tolerated.

Patients who are unable to tolerate oral intake, have significant comorbidities, have failed outpatient management, or are immunosuppressed should be admitted. Inpatient management includes intravenous antibiotics (broad-spectrum coverage such as piperacillin-tazobactam or ceftriaxone plus metronidazole), bowel rest or clear liquids, intravenous fluids, and serial abdominal examinations.

### Follow-Up Colonoscopy

A follow-up colonoscopy is recommended 6-8 weeks after resolution of acute diverticulitis to rule out an underlying malignancy. Colorectal cancer is found in 1-3% of patients presenting with diverticulitis. This evaluation is particularly important after a first episode, after complicated disease, or when the presentation is atypical.

## Complicated Diverticulitis

### Diverticular Abscess (Hinchey Ib/II)

Small abscesses measuring less than 3-4 cm can often be treated successfully with antibiotics alone. Larger abscesses exceeding 3-4 cm typically require CT-guided percutaneous drainage in addition to antibiotics, with a drainage success rate of approximately 70-80%. After resolution, an interval sigmoid colectomy is typically recommended on an elective basis, usually 6-8 weeks later.

### Perforation with Peritonitis (Hinchey III/IV)

Perforation with peritonitis requires emergent surgical intervention. For Hinchey III (purulent peritonitis), the Hartmann procedure -- sigmoid resection with end colostomy -- has historically been the standard approach. However, primary anastomosis with a diverting loop ileostomy is increasingly favored, supported by data from the LADIES/DIVERTI and SCANDIV trials showing similar outcomes with higher stoma reversal rates. Laparoscopic lavage was initially promising but has been largely abandoned after the LOLA, SCANDIV, and LADIES trials demonstrated higher reoperation rates and failure to control sepsis.

For Hinchey IV (feculent peritonitis), the Hartmann procedure remains the standard in most centers. In hemodynamically unstable patients, damage control surgery with an abbreviated laparotomy and temporary abdominal closure may be necessary.

### Hartmann Procedure

The Hartmann procedure involves sigmoid resection with an end descending colostomy and an oversewn rectal stump (the Hartmann pouch). Its advantage is that it removes the diseased segment and avoids performing an anastomosis in a contaminated field. The major disadvantage is that Hartmann reversal carries significant morbidity (15-30%), and up to 40-50% of patients never undergo reversal. When reversal is pursued, it is typically performed at 3-6 months.

### Primary Anastomosis with Diverting Ileostomy

This approach is increasingly preferred for Hinchey III disease. It offers a higher rate of eventual stoma reversal than the Hartmann procedure, and ileostomy reversal is a less morbid procedure than Hartmann reversal. Appropriate patient selection is important: candidates should be hemodynamically stable with adequate nutrition and minimal comorbidities.

<image>Intraoperative photograph showing purulent peritonitis from perforated sigmoid diverticulitis with inflamed sigmoid colon and surrounding contamination</image>

## Fistula

Diverticular fistulae are a complication of chronic or recurrent disease. The most common type is a colovesical fistula, which presents with pneumaturia, fecaluria, and recurrent urinary tract infections. Colovaginal fistulae, which are more common in women who have had a prior hysterectomy, present with feculent vaginal discharge. Coloenteric and colocutaneous fistulae are less common. Diagnosis involves CT with oral and rectal contrast, cystoscopy, and colonoscopy. Definitive treatment is sigmoid colectomy with fistula takedown and primary anastomosis, usually performed as a single-stage procedure.

## Stricture and Obstruction

Chronic or recurrent diverticulitis can cause fibrotic stricture with partial or complete bowel obstruction. It is essential to differentiate this from malignancy through colonoscopy with biopsy. Treatment is elective sigmoid colectomy with primary anastomosis. When complete obstruction is present, proximal decompression with a diverting colostomy or stent may be necessary before resection.

## Diverticular Hemorrhage

Diverticular hemorrhage is arterial bleeding from the vasa recta at the neck or dome of a diverticulum and is the most common cause of massive lower gastrointestinal bleeding. Fortunately, 70-80% of episodes stop spontaneously. CT angiography can localize active bleeding, and colonoscopy after bowel preparation can provide both diagnosis and treatment. Angiographic embolization is appropriate for ongoing bleeding that has been localized on CTA. Surgical resection (segmental colectomy) is reserved for recurrent or uncontrolled hemorrhage. A subtotal colectomy is performed when the bleeding source cannot be localized.

## Elective Sigmoid Colectomy

### Indications

Elective sigmoid colectomy is indicated after recovery from complicated diverticulitis, including episodes requiring abscess drainage, fistula, and stricture or obstruction. Immunosuppressed patients warrant a lower threshold for surgery given their higher perforation risk. For recurrent uncomplicated diverticulitis, the decision is now individualized. Current AGA and ASCRS guidelines no longer recommend surgery after a fixed number of episodes. Instead, the decision is based on symptom burden, impact on quality of life, and patient preference, including patients with smoldering or chronic symptoms despite medical management.

### Operative Principles

The standard approach is a laparoscopic sigmoid colectomy. The entire sigmoid colon should be resected, with the distal margin placed on the upper rectum at the point where the taeniae coli coalesce. The proximal margin should be in the descending colon where the bowel is soft, compliant, and not thickened, though it is not necessary to resect all diverticula-bearing colon. Splenic flexure mobilization is often needed to achieve a tension-free anastomosis. The anastomosis is a primary colorectal anastomosis, performed with either a stapled or hand-sewn technique.

<image>Laparoscopic view of sigmoid colectomy for diverticular disease showing mobilization of the sigmoid colon with identification of the left ureter and gonadal vessels</image>

### Outcomes of Elective Surgery

Morbidity is in the range of 10-15%, with anastomotic leak occurring in 3-5% of cases along with wound infection and ileus. Mortality is less than 1% in the elective setting. Recurrent diverticulitis after surgery occurs in 5-10% of patients and is more likely when the distal margin is not on the rectum.

## Special Populations

### Immunosuppressed Patients

Immunosuppressed patients face a higher risk of perforation and mortality with diverticulitis. A lower threshold for surgical intervention is appropriate, and elective resection should be considered after a first episode of complicated diverticulitis. This population includes organ transplant recipients, patients on chronic steroid therapy, and those receiving chemotherapy.

### Young Patients (<50 years)

Young patients with diverticulitis were previously thought to have more aggressive disease requiring earlier surgery. Current evidence does not support a more aggressive surgical approach based solely on age, and the same individualized approach used for older patients is recommended.

### Right-Sided Diverticulitis

Right-sided diverticulitis is more common in Asian populations and is often confused with appendicitis on presentation. CT is essential for differentiation. Right-sided diverticulitis is usually treated non-operatively, and surgery is rarely needed.

## Clinical Pearls

Always obtain a follow-up colonoscopy 6-8 weeks after acute diverticulitis to rule out malignancy, as colorectal cancer can mimic diverticulitis. The decision for elective surgery is no longer based on the number of episodes but rather on the impact on quality of life and the nature of complications. In emergent surgery for Hinchey III disease, primary anastomosis with a diverting ileostomy is increasingly preferred over the Hartmann procedure because of higher stoma reversal rates and equivalent outcomes. The distal margin must be placed on the upper rectum, not the distal sigmoid -- this is the most important technical point for preventing recurrence. Immunosuppressed patients deserve a lower threshold for both operative intervention and earlier elective resection. Laparoscopic lavage for Hinchey III has been largely abandoned based on trial data showing high failure rates.

## References
- Hinchey EJ, et al. Treatment of perforated diverticular disease of the colon. Adv Surg. 1978;12:85-109.
- Chabok A, et al. Randomized clinical trial of antibiotics in acute uncomplicated diverticulitis (AVOD). Br J Surg. 2012;99(4):532-539.
- Lambrichts DPV, et al. Hartmann's procedure versus sigmoidectomy with primary anastomosis for perforated diverticulitis with purulent or faecal peritonitis (LADIES). Lancet Gastroenterol Hepatol. 2019;4(8):599-610.
- Hall J, et al. The American Society of Colon and Rectal Surgeons clinical practice guidelines for the treatment of left-sided colonic diverticulitis. Dis Colon Rectum. 2020;63(6):728-747.
- Schultz JK, et al. Laparoscopic lavage vs primary resection for acute perforated diverticulitis (SCANDIV). JAMA. 2015;314(13):1364-1375.