SAVED
File name .JPG
File alt. text
Image should be px wide x px tall.
Select Image
home - Small Bowel - Miscellaneous - Radiation Written by Dr Sebastian Zeki
Knowledge


Defines the pathophysiology of fluid and nutrient malabsorption,
including causes, e.g. anatomical and functional short bowel
syndrome, high output stomas, enterocutaneous fistulae and
pancreatic insufficiency

Knows how to investigate patients with malabsorption
Describes the clinical consequences of malabsorption, including
malnutrition, fluid and electrolyte disturbance and micronutrient
deficiency and anaemia and how to manage these

Describes all other causes of anaemia, including bone marrow
disorders and haemolysis

Describes the metabolism, absorption and bioavailability of iron, B12
and folate and clinical conditions and diets associated with their
deficiency

Skills
Identifies and appropriately investigates clinical features suggestive of
malabsorption

Manages fluid, electrolyte and micronutrient disturbances associated
with short bowel syndrome or high output stomas

Uses the appropriate investigations for the different types of anaemia
Behaviours
Takes a careful clinical approach to managing patients with
malabsorption and anaemia. Explains plan of management clearly to
patients and their relatives.

Radiation

Chronic- Clnical Presentation RT planning techniques that minimize the amount of small bowel within the treatment fields are used to decrease toxicity.Treating patients in the prone position with a 'false tabletop' and/or bladder distension may decrease side effects by Radiation Enteritis Histology-Damage is seen within hours of irradiation.Radiation is followed by an infiltration of leukocytes with crypt abscess formation within 2-4 weeks; ulceration may also occur.After leucocyte infiltration, subsequent changes include a progressive occlusive vasculitis with foam cell invasion of the intima.Hyaline thickening of the arteriolar walls can occur.Collagen deposition and fibrosis in the submucosal layer can occur. The small bowel becomes thickened. Arterioles are obliterated, causing ischemia. Lymphatic damage worsening oedema The mucosa is atrophied, with atypical hyperplastic glands and intestinal wall fibrosis. Telangiectasias is present and can cause bleeding. Mucosal ulcerations are present and can progress to perforation, fistulae, or abscess formation. Healing ulcers cause fibrosis and stricturing. Even if the intestine appears normal, patients are at risk of spontaneous perforation. Diarrhea at 3rd week of treatment (frequency of 50 %). Resolves 2-6 weeks after the completion of RT. Occurs with doses of 18Gy up Diarrhea, abdominal pain, nausea and vomiting, anorexia, and malaise. May be at risk for chronic effects Clinical manifestations Acute- Clinical Presentation Risk factors For Chronicity:Schedule of RT- The faction size, treatment duration, and volume of intestine within the RT field all influence the likelihood of enterotoxicity.Dose of RT- 50Gy is the dose at which 5% will get complications at 5 years.Surgery- toxicity is more frequent in patients who have had abdominal surgery.Chemotherapy- combining chemotherapy with RT increases the risk.Decreased bowel motility may increase the focal radiation.Preexisting vascular disease exacerbates radiation induced vasculitis obliterans and ischaemia.Collagen vascular disease (eg, rheumatoid arthritis, systemic lupus erythematosus, polymyositis).Inflammatory bowel disease especially if active. Start 8 to 12m after RT, and sometimes much later Manifests as malabsorption (esp due to bacterial overgrowth and subsequent lactose intol- gut becomes dysmotile encouraging this) and diarrhoea (bile salts not reabsorbed)Bleeding from ulceration and pain and bloating from strictures, as well as fevers from abscess formation, is present. Patients with severe disease may develop intermittent, partial or complete small bowel obstruction. Limiting the volume of small bowel receiving >15 Gy may decrease toxicity.New chemotherapy agents such as oxaliplatin, irinotecan, and EGFR inhibitors with RT may increase risk. Prevention Written by Dr Sebastian Zeki