Angiodysplasia is the most common vascular abnormality of the gastrointestinal tract, responsible for approximately 6% of lower GI bleeding cases and up to 8% of upper GI bleeds.
It is caused by the formation of arteriovenous malformations between previously healthy blood vessels, most commonly in the caecum and ascending colon and has a prevalence of between 1-2%.
Over the age of 60yrs, angiodysplasia is the second commonest cause of rectal bleeding, second only to diverticular disease, and it is the most common cause for bleeding in the small bowel.
In this article, we shall look at the risk factors, clinical features and management of a patient with angiodysplasia.
Angiodysplasia can be divided into acquired or congenital in cause:
- Acquired angiodysplasia – begins as reduced submucosal venous drainage of the colon, which gives rise to dilated and tortuous veins. This results in a loss of pre-capillary sphincter competency, and in turn causes the formation of small arterio-venous communications.
- Congenital angiodysplasia – such as hereditary haemorrhagic telangectasia (/Rendu-Osler-Weber syndrome) or Heyde’s syndrome.
The main feature of angiodysplasia is rectal bleeding. This typically presents in one of three ways:
- Asymptomatic – only diagnosed incidentally during colonoscopy (around 10% cases).
- Painless occult PR bleeding – this refers to bleeding that isn’t visible to the patient, but results in either a positive faecal occult blood test or iron deficiency anaemia.
- Acute haemorrhage (10-15% of cases).
As the AV lesions can occur throughout the GI tract, the degree of symptoms will depend upon the location and severity of the malformation. Like most cases of GI bleeding, upper GI lesions are more likely to present as haematemesis or melena, whereas lower GI lesions (more common in angiodysplasia) are more likely to present as haematochezia.
Elderly patients with chronic undiagnosed angiodysplasia are often anaemic, so can present with symptoms of fatigue, weakness, or dyspnoea.
Signs on examination are usually minimal. It is important to use the examination to exclude other causes of melena or haematochezia – this includes performing a PR examination for any rectal pathology.
The major differential diagnoses for painless GI bleeding include oesophageal varices (which may present with acute lower GI bleeding if large enough volume), GI malignancies, diverticular disease, or coagulopathies.
Blood tests will be usually ordered as routine work-up for any patient presenting with GI bleeding, particularly a full blood count (degree of anaemia) and clotting study (coagulopathies).
Depending on the clinical picture, a group and save or Crossmatch may be warranted if there is a potential need for transfusion.
Approximately 10% of patients with bleeding angiodysplasia have an iron deficiency anaemia, so assessment of haematinics is important (such as ferritin).
In patients presenting with symptoms of GI bleeding, it is essential to exclude any malignancy. Patients with occult angiodysplasia will likely receive an endoscopy (if medically fit), either an oesophago-gastro-duodenoscopy (OGD) or colonoscopy depending on the suspected site of bleeding. It is sometimes necessary to endoscopy both from the top and bottom of the GI tract when the cause of bleeding is uncertain.
Small bowel bleeds are trickier to get to, but recent technological advances enabled their visualisation via endoscopic methods. Wireless capsule endoscopy is the preferred method (although deep small bowel enteroscopy is an alternative), with any profuse bleeding identified and stemmed via administration of therapeutic agents at endoscopy.
In the setting of an overt angiodysplastic bleed, mesenteric angiography may be required to confirm the location of a lesion in order to plan for intervention as necessary. Angiography can involve either radionuclide scanning, CT scanning or MRI scanning to image the GI tract vascular supply after the injection of a radio-opaque contrast agent into the vessels.
10% of patients with angiodysplasia will present with a major GI bleed, for which patients should be managed accordingly.
Risk factors associated with poor outcome include advancing age, liver disease, patient presenting in hypovolaemic shock, and current inpatients (who have almost 4x the associated mortality compared to an outpatient at presentation).
Patients admitted with angiodysplasia can be treated conservatively, especially if there is only minimal limited bleeding in a haemodynamically stable patient. Bed-rest and IV fluid support will provide sufficient management due to the self-limiting nature of the condition.
In persistent or severe cases, when bleeding sites are identified, there are two main methods of treatment; endoscopic therapies and radiographic therapies (mesenteric angiography):
- Endoscopy – usually the first line of management, with most widely used technique being argon plasma coagulation. This involves subjecting the bleeding vessel to electrical current and argon, acting as a safe, cost-effective, successful treatment option. Other endoscopic techniques include monopolar electrocautery, laser photoablation, sclerotherapy, and band ligation.
- Mesenteric angiography – used for small bowel lesions that cannot be treated endoscopically. This procedure involves super-selective catheterisation and embolization of the vessel that has been demonstrated to be bleeding by extravasation of contrast dye into the bowel lumen from the identified angiodysplastic lesion.
Mesenteric angiography may also be indicated in GI bleeding from any other location when endoscopic therapy has failed (to treat or localise) or when endoscopy is not a suitable option (for example in patients who are not fit for endoscopy). The sensitivity of angiography ranges from 58-86% and increases depending on the bleeding rate of the lesion.
In a minority of cases, surgical intervention is the only option, whereby a resection and anastomosis of the affected segment of bowel is necessary to limit bleeding.
Indications for bowel resection in patients with angiodysplasia are:
- Continuation of severe bleeding despite angiographic and endoscopic management (or such therapies are unavailable)
- Severe acute life-threatening GI bleeding
- Multiple angiodysplastic lesions that cannot be treated medically
Bowel resection in patients with angiodysplasia is associated with a relatively high mortality, thus should only be considered if absolutely necessary.
The complications of angiodysplasia are mainly related to the treatment, as re-bleeding post-therapy is relatively common.
Endoscopic techniques have a very small risk of bowel perforation, whereas mesenteric angiography carries risks of haematoma formation, arterial dissection, thrombosis and bowel ischaemia.