The Large Intestine - Diverticular Disease

Question 1

What is a diverticulum?

Answer 1

A pouch or pocket of colonic mucosa ithrough the muscular proprietor that has come to lie in the subserosal (pericolic) fat outside the bowel wall, usually ranging in size from 0.5-1cm.

Question 2

What is diverticulosis?

Answer 2

The presence of diverticula, without inflammation or infection. (Wear-and-tear of the bowel.)

Question 3

What is diverticular disease?

Answer 3

The state when patients with diverticulosis experience symptoms.

Question 4

What is diverticulitis?

Answer 4

Inflammation and infection of the diverticula - faecal matter impacts and obstructs the neck of a diverticulum; trauma to the mucosa by the faecolith causes mucosal injury and and acute inflammatory response.

Question 5

Pathophysiology of diverticulosis (4).

Answer 5

1. Large Intestine wall contains a layer of circular muscle.
2. Circular muscle is penetrated by blood vessels - areas of weakness.
3. Increased intraluminal pressure (insufficient dietary fibre) overtime - gap forms in these areas of weakness.
4. Mucosa herniates through the muscle layer and pouches to form diverticula.

Question 6

Why do diverticula not form in the rectum?

Answer 6

The rectum has an outer longitudinal muscle layer that completely surrounds the diameter of the rectum, to add extra support.

Question 7

What are the teniae coli?

Answer 7

3 longitudinal muscles that run along the colon to form strips/ribbons. These ribbons are the teniae coli.

Question 8

What is the relevance of teniae coli in diverticulosis?

Answer 8

The teniae coli do not surround the entire diameter of the colon - the areas not covered by the teniae coli are vulnerable to the development of diverticula.

Question 9

Which part of the GI tract is most commonly affected by diverticulosis?

Answer 9

Sigmoid Colon - smallest diameter of any portion of the large bowel - intraluminal pressure is the highest here.

Question 10

Risk Factors of Diverticulosis (4).

Answer 10

1. Increased Age (50+).
2. Low Fibre Diet (Western).
3. Obesity + Sedentary Lifestyle.
4. Use of NSAIDs - Risk of Diverticular Haemorrhage.

Question 11

Clinical Features of Diverticulosis (5).

Answer 11

1. Asymptomatic.
2. Left Abdominal Pain.
3. Constipation.
4. Rectal Bleeding.
5. Bloating.

Question 12

Investigation of Diverticulosis (2).

Answer 12

1. No need to investigate unless symptomatic.

2. Incidental - Colonoscopy/CT scans.

Question 13

Management of Diverticulosis (5).

Answer 13

1. No need to treat unless symptomatic.
2. Lifestyle Measures : High Fibre Diet and Weight Loss.
3. Bulk-Forming Laxatives e.g. Ispaghula Husk.
4. AVOID Stimulant laxatives e.g. Senna.
5. Surgery - if significantly symptomatic.

Question 14

Clinical Features of Acute Diverticulitis (7).

Answer 14

1. Colicky Pain/Tenderness in LIF.
2. Fever.
3. Altered Bowel Habit - Constipation > Diarrhoea.
4. Nausea & Vomiting (due to ileus/complicated diverticulitis with colonic obstruction).
5. Painless + Spontaneous Rectal Bleeding.
6. Palpable Abdominal Mass (if Abscess).
7. Urinary Symptoms (Irritation of Bladder by Inflamed Bowel).

Question 15

Management of Uncomplicated Diverticulitis in Primary Care (4).

Answer 15

1. Oral Co-Amoxiclav (5 days).
2. Analgesia - not NSAIDs or Opiates.
3. Clear Liquid Foods (Not Solids) until symptoms improve (2-3 days).
4. Follow-up within 2 days to review symptoms.

Question 16

Management of Acute Complicated Diverticulitis or Lasting More than 72 Hours (4).

Answer 16

1. NBM/Clear Fluids.
2. IV Antibiotics - Cephalosporin + Metronidazole.
3. IV Fluids.
4. Analgesia.

Question 17

Complications of Acute Diverticulitis (6).

Answer 17

1. Perforation (since diverticular wall is supported only by a thin layer of subserosal tissue).
2. Peritonitis (Perforation of Pericolic Abscess).
3. Peridiverticular Abscess (Acute Inflammatory Process may extend beyond the diverticulum into the surrounding subserosal tissue).
4. Large Haemorrhage - require blood transfusions.
5. Fistula e.g. colon and bladder/vagina (vaginal passage of faeces/flatus = colovaginal fistula).
6. Stricture - Smooth Muscle Hypertrophy + Fibrosis around Diverticula) = presenting as ileum / bowel obstruction.

Question 18

Investigations of Diverticular Disease.

Answer 18

1. Diverticular Disease : Colonoscopy, CT Cologram, Barium Enema.
2. Erect CXR : Perforation.
3. Abdominal CT : Oral/IV Contrast - Acute Acute Inflammation + Local Complications e.g. Abscess.

Question 19

Hinchey Classification of Diverticular Disease (4).

Answer 19

1. I - Paracolonic Abscess - Drained Surgically/Radiologically.
2. II - Pelvic Abscess.
3. III - Purulent Peritonitis.
4. IV - Faecal Peritonitis - Resection + Stoma.

Question 20

What are Colovesical Fistulae associated with?

How are they diagnosed?

Answer 20

Pneumaturia, Faecaluria, Recurrent UTIs.

Diagnosis : Cystoscopy and Cystography.

Question 21

Indication for Elective Colectomy.

Answer 21

Recurrent Severe Episodes of Diverticulitis.

Question 22

Why is fibre so important to prevent diverticula formation? (2)

Answer 22

1. Fibre binds salt and water in the colon to result in bulky moist faeces that are easily propelled through the colon.
2. Movement of faeces from a low-fibre diet along the colon requires increased muscular effect - muscular hypertrophy and increased intraluminal pressure.