Vascular anomalies (angiodysplasia)

Capillary or cavernous haemangiomas are a cause of haemorrhage from the colon at any age presenting with colonic bleeding. In the middle-aged or elderly patient it needs to be distinguished from other causes of sudden massive haemorrhage, such as diverticulitis, ulcerative colitis or ischaemic colitis.

Angiodysplasia is a vascular malformation associated with ageing. It has been recognised since the introduction of intestinal angiography and colonoscopy. Angiodysplasias occur particularly in the ascending colon and caecum of elderly patients over the age of 60 years and are not associated with cutaneous lesions. The malformations consist of dilated tortuous submucosal veins and in severe cases the mucosa is replaced by massive dilated deformed vessels. On histological investigation, they are made up of dilated, distorted, thin-walled vessels with only a scanty amount of muscle in their walls.

Inspection of the mucosa is often unremarkable. The lesions are only a few millimetres in size and appear as reddish raised areas at endoscopy. Bleeding is usually chronic and intermittent and can be severe. Many patients previously thought to have bled from diverticular disease have probably been bleeding from angiodysplasia in the caecum. There is an association with aortic stenosis.

Barium enema is usually unhelpful and should be avoided. Provided the bleeding is not too brisk colonoscopy may show the characteristic lesion in the caecum or ascending colon. Selective superior and inferior mesenteric angiography shows the site and extent of the lesion by a blush. If this fails a radioactive test using technetium-99m (9smTc)4abelled red cells may confirm and localise the source of haemorrhage.

Some angiodysplastic lesions can be treated by colonoscopic diathermy, but if bleeding is brisk and the patient seriously ill   emergency surgery will be necessary. Here a catheter is placed in the appendix stump and the colon irrigated progradely with saline or water. On-table colonoscopy is carried out and the site of the bleeding can then be confirmed. Angiodysplastic lesions are sometimes demonstrated by transillumination through the caecum (Fig. 57.8). If it is still not clear exactly which segment of colon is involved then a total abdominal colectomy with ileorectal anastomosis may be necessary.

Blind loop syndrome

It has been shown in dogs that, if a blind loop of the small intestine is made (Fig. 57.9), defects of absorption will appear. If this occurs in the upper intestine the defect is chiefly of fat absorption; if in the lower intestine there is vitamin B12 deficiency. This has been found to occur in humans and is referred to as the blind loop syndrome.

Essentially, the stasis produces an abnormal bacterial flora, which prevents proper breakdown of the food (especially fat) and mops up the vitamins that are present. Sometimes the only manifestation is anaemia, resulting from vitamin B12 deficiency, but if steatorrhoea appears, other serious malabsorption features follow. In general, high loops produce steatorrhoea, whereas low loops tend to produce anaemia.

Temporary improvement will follow the use of antibiotics to destroy the bacteria causing the trouble, but the main treatment is surgical extirpation of the cause of the stasis where applicable.