Diverticular disease

 One meaning of diverticulum is a wayside house of ill-fame; certainly these ‘wayside houses’ live up to their evil reputation. Diverticula can occur from the stomach to the recto sigmoid. There are two varieties:

 1. Congenital. All three coats of the bowel are present in the wall of the diverticulum, e.g. Meckel’s.

2. Acquired. The wall of the diverticulum lacks a proper muscular coat. Most alimentary diverticula are thought to be acquired.

 Small intestine

Most of these diverticula arise from the mesenteric side of the bowel probably as the result of mucosal herniation through the point of entry of blood vessels.

Duodenal diverticulum

 There are two types:

 1. Primary. Mostly in older patients on the inner wall of the second and third parts, these diverticula are found incidentally on barium meal and usually do not cause symp­toms. They can cause problems locating the ampulla during endoscopic retrograde cholangiopancreatography (ERCP) (Fig. 57.10).

2. Secondary. Diverticula of the duodenal cap resulting from long-standing duodenal ulceration (Fig. 57.11).

 Jejunal diverticula

 These are usually of variable size and multiple (Fig. 57.12). Clinically they may (1) be symptomless, (2) give rise to abdominal pain, flatulence and borborygmi, (3) produce a malabsorption syndrome, or (4) present as an acute abdomen with acute inflammation and occasionally rupture. They are more common in patients with connective tissue disorders. In patients with major malabsorption problems giving rise to anaemia, steatorrhoea, hypoproteinaemia or vitamin B1, deficiency; resection of the affected segment with end-to-end anastomosis can be effective.

 Meckel’s diverticulum

 Meckel’s diverticulum is present in 2 per cent of the population; it is situated on the antimesenteric border of the small intestine, commonly 60 cm from the ileocaecal valve, and is usually 3—5 cm long. Many variations occur (2 per cent — 2 feet — 2 inches is a useful aidenldmoire) (Figs 57.13 and 57.14).

A Meckel’s diverticulum possesses all three coats of the intestinal wall and has its own blood supply. It is therefore vulnerable to infection and obstruction in the same way as the appendix. In 20 per cent of cases the mucosa contains heterotopic epithelium, namely, gastric, colonic or sometimes pancreatic tissue. When present, the abnormal mucosa lines the greater part of the proximal end of the pouch and extends sometimes for a short distance into the nearby ileum.

Although Meckel’s diverticulum occurs with equal frequency in both sexes, symptoms usually resulting from the epithelium contained in the diverticulum predominantly occur in males. In order of frequency,

 these symptoms are as follows.

1.  Severe haemorrhage, caused by peptic ulceration. The blood is passed per rectum, and is maroon in colour. Although the patient may vomit, the vomit does not contain blood. There is rarely any pain and sometimes the bleeding precedes perforation. An operation is required for serious progressive gastrointestinal bleeding. When no lesion in the stomach or duodenum can be found the terminal 150 cm of ileum should be carefully inspected.

2. Intussusception. In most cases, the apex of the intussusception is the swollen, inflamed, heterotopic epithelium at the mouth of the divertictilum.

3.  Meckel’s diverticulitis, with or without perforation, may result from obstruction by food residue. The symptoms are those of acute appendicitis and, unless the appendix has already been removed, the diagnosis is impossible before operation. When a diverticulum perforates the symptoms may simulate those of a perforated duodenal ulcer. Whether or not the diverticulum is perforated urgent surgery is required. In nonperforated cases an inflamed diverticulum should be sought as soon as it has been demonstrated that the appendix and Fallopian tubes are not at fault.

4. Chronic peptic ulceration. As the diverticulum is part of the midgut, the pain, although related to meals, is felt around the umbilicus.

5. Intestinal obstruction. The presence of a hand between the apex of the diverticulum and the umbilicus may cause obstruction either by the band itself or by a volvulus around it.

Radiology

Meckel’s diverticulum can he very difficult to demonstrate by contrast radiology; small bowel enema would he the most accurate investigation. Technetium-99m scanning

In cases of repeated gastrointestinal haemorrhage of unknown cause where a Meckel’s diverticulum is suspected the abdomen is imaged with gamma camera after the injection of 30—100 mic Ci (111—370 x 1010 Bq) of 99”Tc-labelled pertechnetate intravenously. This may localise heterotopic gastric mucosa revealing the site of a Meckel’s diverticulum in 90 per cent of cases.

‘Silent’ Meckel’s diverticulum

An aphorism attributed to Dr Charles Mayo is: ‘a Meckel’s diverticulum is frequently suspected, often sought for and seldom found’. A Meckel’s diverticulum usually remains symptomless throughout life and is found only at necropsy. When a silent Meckel’s diverticulum is encountered in the course of an abdominal operation, provided it is wide-mouthed and the wall of the diverticulum does not feel thickened, it can he left. Where there is doubt and it can he removed without appreciable additional risk it should he resected.

Exceptionally a Meckel’s diverticulum is found in an inguinal or a femoral hernia sac — Littre’s hernia.

Meckel’s diverticulectomy

A Meckel’s diverticulum which is broad based should not he amputated at its base and invaginated in the same way as a vermiform appendix, because of the risk of stricture. Furthermore this does not remove heterotopic epithelium where it is present. The steps of diverticulectomy are shown in Fig. 57.15. Alternatively, a linear stapler device maybe used. Where there is induration of the base of the diverticulum extending into the adjacent ileum, it is advisable to resect a short segment of ileum containing the diverticulum, restoring continuity with an end-to-end anastomosis.

Colon

Diverticula of the colon are acquired herniations of colonic mucosa, protruding through the circular muscle at the points where the blood vessels penetrate the colonic wall. They tend to occur in rows between the strips of longitudinal muscle, sometimes partly covered by appendices epiploicae. The con­dition is most commonly found in the sigmoid colon but the caecum can also be involved and on occasion the entire large bowel can be affected. The rectum with its complete muscle layers is not affected. In 90 per cent of cases the sigmoid colon is involved and is almost always the site of inflam­mation, i.e. diverticulitis. Some 5 per cent of patients have associated gallstones and hiatus hernia (Saint’s triad).

Diverticular disease is rare in Africans and Asians who eat a diet that contains natural fibre. In Western countries, where the roughage has been removed from flour and refined sugar forms a large part of the diet, diverticula are found in 25 per cent of barium enemas of patients over the age of 40 and the incidence increases with age.

Diverticulosis

It is important to distinguish between diverticulosis and the presence of diverticula which may be asymptomatic, and clinical diverticular disease where the diverticula are causing symptoms. Diverticula probably arise as a result of muscular inco ordination and spasm, resulting in increased segmenta­tion and intraluminal pressures. Excessive segmentation in response to food, prostigmine and morphine is found in colonic motility studies, and this exaggerated response is more apparent in symptomatic than in asymptomatic individ­uals. On histological investigation the diverticulum consists of a protrusion of mucous membranes covered with peritoneum. There is thickening of the circular muscle fibres of the taeniae and the intestine develops a concertina or saw­tooth appearance on barium enema (Fig. 57.16). The diver­ticula occur between the muscle clefts making the mucosal surface appear trabeculated. The elastin content of the taenia coli is increased compared with controls.

Diverticulitis

Diverticulitis is the result of inflammation of one or more diverticula, usually with some pericolitis. Episodes of diverticulitis may be followed by years free of symptoms, but the condition is essentially progressive — the longer the duration the worse the symptoms and the greater the risk of compli­cations. Diverticulitis is not a precancerous condition, but cancer may coexist.

The complications are the following:

1. recurrent periodic inflammation and pain — in some

    patients these episodes may be clinically silent;
2.    perforation leading to general peritonitis or local
    (pericolic) abscess formation;
3. intestinal obstruction:

(a)  in the sigmoid as a result of progressive fibrosis causing stenosis,

(b) in the small intestine caused by adherent loops of small

      intestine on the pericolitis;
4.    haemorrhage: diverticulitis may present with profuse
    colonic haemorrhage in 17 per cent of cases, often
    requiring blood transfusions;
5. fistula formation (vesicocolic, vaginocolic, enterocolic,
    colocutaneous) occurs in 5 per cent of cases, vesicolic
    being the most common.

 Clinical features

 Diverticulosis may be asymptomatic, but the disordered colonic function may cause symptoms of distension, flatu­lence and a sensation of heaviness in the lower abdomen, all of which may be indistinguishable from the symptoms of irritable bowel syndrome. Excessive colonic segmentation can cause severe pain in the left iliac fossa, but this must be distinguished from episodes of often subclinical inflammation in the sigmoid colon as a result of diverticulitis.

Diverticulitis. Persistent lower abdominal pain, usually in the left iliac fossa with or without peritonitis in patients of either sex over the age of 40, could be caused by diverticuli­tis. Fever, malaise and leucocytosis can differentiate diver­ticulitis from painful diverticulosis. The patient may pass loose stools or may be constipated; the lower abdomen is tender especially on the left but occasionally also in the right iliac fossa if the sigmoid loop lies across the midline. The sigmoid colon is often palpable, tender and thickened. Rectal examination may but does not usually reveal a tender mass. The condition has been likened to left-sided appendicitis. Any urinary symptoms may herald the formation of a vesicocolic fistula which leads to pneumaturia (flatus in the urine) and even faeces in the urine.

Diagnosis

 Radiology. Diverticulosis, as for the ‘irritable bowel’ syn­drome, is a diagnosis of exclusion and symptoms should not be attributed to diverticulosis unless other diseases have been excluded by barium enema, sigmoidoscopy or colonoscopy. Although the diagnosis of acute diverticulitis is made on clinical grounds it can be confirmed during the acute phase by computerised tomography (CT). This will demonstrate not only the diverticula but also any associated pericolic abscess (Fig. 57.17). Barium enemas and sigmoidoscopy are usually reserved for patients who have recovered from an attack of acute diverticulitis for fear of causing perforation or peritonitis. Water-soluble contrast enemas may, however, be helpful in sorting out patients with large bowel obstruction. Barium radiology is carried out to exclude a carcinoma and to assess the extent of the disease. Where the sigmoid colon is thickened and narrowed, a ‘saw-tooth’ appearance may be seen. Some strictures can be very difficult to distinguish by radiology alone and in those circumstances colonoscopy will be necessary to rule out a carcinoma.

Sigmoidoscopy. The mucosa may be normal and in acute attacks the sigmoidoscopy will be painful and the mucosa inflamed. Colonoscopy or flexible sigmoidoscopy is more helpful (Fig. 57.18). The necks of diverticula can be seen and the narrowed area of diverticulitis can be entered, but on occasion not passed because of the severity of disease. The differential diagnosis from a carcinoma can be impossible if a tight stenosis prevents endoscopy.

 Management

Diverticulosis should be treated with a high-residue diet containing roughage in the form of wholemeal bread, flour, fruit and vegetables. Bulk formers such as bran, Celevac, Isogel and Fybogel may be given until the stools are soft. Painful diverticular disease may require bed rest and antispasmodics.

Acute diverticulitis is treated by bed rest and intravenous antibiotics (usually cefuroxime and metronidazole). After the acute attack has subsided and if the diagnosis has not already been confirmed by CT, a barium enema should be carried out.

Operative procedures for diverticular disease. Some 10 per cent of patients require an operation either for recurrent attacks which make life a misery or for the complications of diverticulitis.

 1. The ideal operation carried out as an interval procedure after careful preparation of the gut is a one-stage resec­tion. This involves removal of the affected segment and restoration of continuity by end-to-end anastomosis. At this operation the sigmoid loop is often found adherent in the pouch of Douglas. Careful dissection will allow even­tual mobilisation of the recto sigmoid out of the pelvis exposing the normal rectum, and greater mobility will allow an easier anastomosis.

2. If there is obstruction, inflammatory oedema and adhesions or the bowel is loaded with faeces, a Hartmann’s operation is the procedure of choice. The involved area is resected. The rectum is closed at the penitoneal reflection, and the left colon brought out as a left iliac fossa colosto­my. The once popular staged procedures using a preliminary transverse colostomy are now rarely used except by inexperienced surgeons because of the high mortality associated with them. In selected obstructed cases the bowel can be cleaned by on-table lavage, placing a urinary catheter through the appendix stump and washing the colon with physiological saline or water for irrigation. This makes subsequent restoration and bowel continuity with an anastomosis much safer (Fig. 57.19a, h).

3. In acute perforation, peritonitis soon becomes general and may be purulent, which has a mortality rate of about 15 per cent. Gross faecal peritonitis carries more than a 50 per cent mortality rate and pneumoperitoneum is usually present; the diagnosis may not be confirmed until emer­gency laparotomy. There is a choice of procedures:

(a)   primary resection and Hartmann’s procedure (see above);

(b)   primary resection and anastomosis after on-table lavage in selected cases;

(c)   exteriorisation of the affected bowel which is then opened as a colostomy, now rarely used;

(d)  suture of the perforation with drainage with or without proximal defunction. In selected cases with a small leak and minimal soiling.

4.  Fistulae can only be cured by resection of the diseased bowel and closure of the fistula. In the case of a colovesical fistula it is usually possible to ‘pinch off’ the affected bowel from the bladder, close it and then resect the sigmoid. In very difficult cases a staged procedure with a preliminary defunctioning stoma may be necessary on occasion.

5.  Haemorrhage from diverticulitis must be distinguished from angiodysplasia. It usually responds to conservative management and occasionally requires resection. On-table lavage and colonoscopy may be necessary to localise the bleeding site.

Diverticular disease and carcinoma coexist in 12 per cent of cases. Exploration may be necessary but, even then, differ­entiation may be difficult until histological investigations are available (Table 57.1). Weight loss, falling haemoglobin and persistently positive occult blood are sinister features.

Solitary diverticulum of the caecum and ascending colon is rare and is congenital, and may present with symptoms and signs identical to those of acute appendicitis.

Extensive diverticular disease can sometimes affect the right colon. This, however, is rare in the West hut more common in Eastern countries. In Japan, China, Malaysia and Korea, right-sided disease is twice as common as left-sided disease.