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
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.