CLINICAL PRESENTATION

If bleeding is overt, patients may present with melaena or haematochezia. Most patients do not have overt bleeding and are observed to have iron deficiency anaemia of varying severity. Some patients are profoundly anaemic, but others may have a more subtle persistent anaemia. Depending on the severity and the rapidity of onset of anaemia, some patients complain of significant lethargy. If the gastrointestinal bleeding is more acute, patients may present with signs and symptoms of hypovolaemia and shock.

AETIOLOGY

Most causes of occult gastrointestinal bleeding derive from the small intestine. In patients aged 40 years or younger, small intestine tumours, Meckel’s diverticulum, polyposis syndromes and Crohn’s disease are more common. In patients over 40 years of age, arteriovenous malformation (the most common cause overall), neoplasia and Dieulafoy’s malformation are more prevalent. Some of the specific causes of gastrointestinal bleeding are listed below.

neck of the hernia rub against adjacent mucosa. The mainstay of medical treatment is acid suppressive therapy. If blood loss is severe or persistent, or if the ulceration of hernia is complicated, surgical repair of the hernia should be considered.

Gastric antral vascular ectasia

Gastric antral vascular ectasia (GAVE), or watermelon stomach, results from ectatic mucosal and submucosal capillaries. Typically, patients present in their 70s (age range 50–90 y) with occult or slow gastrointestinal bleeding. Endoscopically, GAVE appears most commonly as raised, convoluted, red antral folds radiating in a spoke-like pattern towards the pylorus. This appearance of GAVE has been likened to the stripes on a watermelon rind. A more diffuse involvement of the stomach is also recognised in which many ectasias coalesce to form a large red lesion resembling honeycomb.

Endoscopic thermal ablation therapy using heater probes or Argon plasma coagulator is accepted first-line therapy for control of gastrointestinal bleeding due to GAVE. Treatment coagulates the lesion, with success rates of 90% achievable.

Portal hypertensive gastropathy

Portal hypertensive gastropathy (PHG) is a vascular disorder, which is recognised to be a complication of advanced liver disease. Although its pathogenesis is directly related to portal hypertension, the exact mechanisms involved in the development of this condition remain unclear. On endoscopy, the characteristic lesion is a mosaic pattern of small, raised erythematous areas outlined by a white or yellowish reticular pattern resembling that of snakeskin. PHG is more commonly localised to the proximal stomach.

Mild PHG is generally of no clinical significance and can be considered an incidental endoscopic finding in patients with portal hypertension. In contrast, severe PHG is associated with a high risk of gastrointestinal bleeding. Bleeding characteristically presents as chronic mucosal oozing with the development of iron deficiency anaemia, but may occasionally be acute.

The treatment of PHG consists of addressing the underlying portal hypertension. Unlike variceal bleeding, this condition cannot be treated with band ligation. Effective treatment requires a reduction in portal pressure. This can be accomplished with β-blockers, such as propranolol, portal decompression using radiological placement of a transjugular, portosystemic intrahepatic shunt, or surgical shunting. Somatostatin infusion is routine first-line treatment for actively bleeding cirrhotic patients with PHG.

Dieulafoy’s disease

Dieulafoy’s disease is characterised by a bleeding or clot-bearing artery protruding into the intestinal lumen, usually without ulceration. It occurs mostly in the stomach, usually on the lesser curvature and within 6 cm of the cardio-oesophageal junction. The disease is thought to be caused by an area of necrosis in an unusually large artery with a relatively superficial location in the gastric submucosa. The appearance is that of a tiny necrotic spot with or without a slightly protruding vessel stump, with minimal or no surrounding erosion. While bleeding is usually significant, producing haematemesis and/or melaena, the condition is nevertheless notoriously difficult to diagnose. Quite often, multiple endoscopies are necessary before the lesion is recognised. Treatment consists of endoscopic local injections of adrenaline 1:10,000 and coagulation using heat probes.

Small intestine neoplasms

Small intestine neoplasms are rare. Although the small intestine provides about 80% of the luminal surface area of the entire alimentary canal, only 2% of alimentary cancers involve this anatomical site. Nevertheless, small intestine tumours account for 5%–10% of all cases of small intestinal bleeding. Patients with small intestine tumours are generally younger. Small intestine tumours may present with chronic blood loss and, overall, are the second most common cause of occult small intestinal bleeding. Early use of endoscopy, capsule endoscopy and radiological evaluation is essential to make a preoperative diagnosis.

Benign small intestine tumours are more common than malignant tumours. Of these, the leiomyomas are most frequently associated with bleeding. Frequently, abdominal pain and nausea are associated presenting symptoms. Leiomyomas are diagnosed endoscopically and, in recent times, increasingly using capsule endoscopy. Arteriography demonstrates a well circumscribed tumour blush in most lesions. Treatment for all symptomatic leiomyomas is surgical resection, because they are macroscopically indistinguishable from malignant leiomyosarcomas. Adenomas are the most common mucosal tumour of the small intestine, typically occurring in the periampullary region. Bleeding may occur in large polypoid lesions. All adenomas should be removed, usually endoscopically, because of the risk that they may progress to carcinoma. Other small intestine tumours such as carcinoids, adenocarcinomas, lymphomas and metastatic disease can also present with chronic blood loss.

Malignant small intestinal tumours account for less than 2% of all gastrointestinal cancers. Adenocarcinomas are the most common type of malignant small intestine neoplasm and may present with occult gastrointestinal bleeding as well as abdominal pain and weight loss. Most adenocarcinomas are diagnostically accessible by gastroscopy, push enteroscopy or capsule endoscopy. Metastatic lesions in the small intestine (e.g. from malignant melanoma, carcinoma of the lung and renal carcinomas) can present with chronic blood loss.

Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is a dominantly inherited disorder characterised by mucocutaneous pigmentation and gastrointestinal hamartomas. It is important to consider this diagnosis in young patients with unexplained gastrointestinal bleeding. Polyps are generally small (<1 cm), but can grow larger and cause occult gastrointestinal bleeding. There is an increased risk of malignancy arising from the polyps. The polyps may be visualised endoscopically but, because they are usually multiple, endoscopic polypectomy is not possible and segmental surgical resection should be performed.

Aorto-enteric fistulas

Aorto-enteric fistulas are a rare source of chronic blood loss but frequently present with massive haemorrhage, usually in the form of haematemesis, melaena or haematochezia. Consequently, this condition is life-threatening. Think about this possibility in anyone who has had an aortic graft or a diagnosed aortic aneurysm. Most fistulas communicate with the third or fourth portion of the duodenum. Fistulas may be primary and associated with aneurysms, or secondary, following aortic reconstructive surgery. Characteristically, the bleeding is intermittent, often starting with a ‘herald bleed’ and subsequently (usually within 1–3 weeks) presenting with an exsanguinating haemorrhage. Ultimately the diagnosis is made at laparotomy, although endoscopic visualisation with upper endoscopy or push enteroscopy and aortography can make the diagnosis in up to 50% of cases.

Meckel’s diverticulum

Meckel’s diverticulum of the terminal ileum occurs in about 2% of the population and is located 100 cm from the ileocaecal valve. It is the cause of bleeding in two-thirds of men under the age of 30 years presenting with small intestine bleeding. The ectopic gastric epithelium within the diverticulum may lead to peptic ulceration of the diverticulum, with consequent haemorrhage. Bleeding is invariably brisk. The diverticulum is identified by means of a technetium-99m pertechnetate scan. Parietal cells in the ectopic gastric mucosa take up the radioisotope. A superior mesenteric arteriogram may help identify the anomaly.

Jejunal diverticula

Jejunal diverticula can cause small intestine bleeding. These are acquired pseudodiverticula that develop on the mesenteric border of the intestine at sites of perforating blood vessels. Although they may give rise to gastrointestinal bleeding, jejunal diverticula are mostly an incidental finding on a small bowel series. Nevertheless, when bleeding does occur it is usually massive and associated with a mortality rate as high as 20%.

Coeliac disease

Coeliac disease is the most common cause of malabsorption in the Western world and frequently presents with iron deficiency anaemia. This condition is discussed in more detail in the chapter on malabsorption syndromes.

Crohn’s disease

Gross bleeding is unusual in Crohn’s disease—occurring in 4%–10% of patients with ileitis. Transmural inflammation can erode submucosal vessels, causing massive bleeding at times. Usually the patients do not present with bleeding as the sole symptom.

Treatment-induced mucosal lesions

Non-steroidal antiinflammatory drugs may cause small intestinal inflammation, ulceration and web-like structures, which, if sufficiently severe, may result in blood loss presenting as haemoccult-positive stools and iron deficiency anaemia. Such medication-induced mucosal lesions are best diagnosed with capsule endoscopy.

Radiation injury to the small intestine can cause vasculitis and subsequent bleeding. Since the ileum is most frequently affected, this condition is often referred to as radiation ileitis.

Haemobilia

Haemobilia is a rare cause of obscure gastrointestinal tract bleeding. The term describes any bleeding originating in the liver, biliary tree or pancreas and passing through the ampulla of Vater. Haemobilia usually follows abdominal trauma, surgical treatment of biliary disease or liver biopsy. Gastroscopy may reveal obvious bleeding from the ampulla of Vater. Angiography can confirm haemobilia, since it permits visualisation of the hepatic artery and its branches. Vascular tumours and aneurysms may require surgical intervention or selective angiographic embolisation using Gelfoam coils.

Haemorrhage through the pancreatic duct, or haemosuccus pancreaticus, is an uncommon cause of gastrointestinal bleeding. Patients present with haematemesis or melaena in combination with epigastric pain and hyperamylasaemia. The source of bleeding is secondary to an aneurysmal bleed from a splenic artery aneurysm. The diagnosis is made angiographically.

INVESTIGATION OF UNIDENTIFIED GASTROINTESTINAL BLEEDING

The discussion is based on the premise that the patient has already had a gastroscopy and colonoscopy, which have not been able to identify the source of bleeding (see Table 23.2).

TABLE 23.2 Diagnostic tips

SUMMARY

Patients presenting with obscure gastrointestinal haemorrhage represent a difficult diagnostic and management problem. This patient group frequently requires sophisticated investigations in an effort to make a specific diagnosis. Patients with anaemia and faecal occult blood test-positive stools can be investigated as outpatients (Figure 23.1). However, patients who present with massive haemorrhage certainly require prompt hospital referral for resuscitation and further investigation (Figure 23.2). When gastroscopy and colonoscopy fail to identify a source of bleeding, it may be necessary to investigate the small intestine. While radiological techniques are still frequently utilised, the advances in technology such as capsule endoscopy and double-balloon enteroscopy are now incorporated into clinical practice.

FIGURE 23.1 Occult gastrointestinal bleeding.

FIGURE 23.2 Active gastrointestinal bleeding.

NSAIDs = non-steroidal antiinflammatory drugs.