Editing Radiation bowel injury

== '''Classification of radiation enteritis''' ==

* Classify as acute (during     treatment) or chronic (>18 months post-treatment)

== '''Risk factors''' ==

* High-dose radiotherapy     (>5000cGy)
* Previous abdominal surgery     (adhesions - higher risk with laparotomy)
* Pre-existing vascular disease
* HTN
* Diabetes
* Adjuvant treatment with     certain chemotherapeutic agents (5-FU, doxorubicin, dactinomycin, MTX)
* Fixed locations are     highest-risk for injury: TI, caecum, rectum
* Development of acute symptoms     is a risk factor for development of chronic symptoms, but not necessary

== '''Pathophysiology''' ==

* Acute
** Free radicals causing direct      inflammation
** Effects seen within hours -      leucocyte infiltration, ulceration
* Subsequent effects
** Most important effect of      acute injury is to damage mucosal stem cells, which leads to a long-term      reduction in cellular reserves for intestinal villi. Mucosal denudation      occurs, with shortened villi and decreased absorptive area.
** Progressive obliterative      vasculitis, and collagen deposition and fibrosis in submucosa
** Small bowel becomes      thickened due to chronic inflammation and ischaemia
** Telangiectasias can be      present due to disordered revascularisation, causing bleeding
* Chronic outcomes on bowel     function
** End up with impaired normal      absorption and transit - particularly B12 and bile salts due to impact on      ileum, and subsequent bile salt diarrhoea
** Commonly leads to strictures      with obstructive symptoms, or small bowel fistulas
** Risk of malignancy as a late      consequence of radiation injury


= '''Acute radiation enteritis''' =

== Presentation ==

* Normally starts during third     week of treatment, and resolves 2-6 weeks after completion
* Diarrhoea
* Cramping pain
* Minor bleeding
* Nausea
* Faecal urgency

== Management ==

* ACE inhibitors and statins     may reduce acute GIT symptoms during radical pelvic radiotherapy
* Supportive treatment -     antimotility agents, antispasmodics and avoidance of dehydration
* Typically self-limiting,     resolving within a few weeks
* Loperamide usually works well


= '''Chronic radiation enteritis''' =

== '''Presentation''' ==

* Typically develops from 18     months 6 years after treatment, but can take up to 30 years
* Malabsorption
** Diarrhoea/steatorrhoea/weight      loss/nutritional
** Loss of bile salts -      cholestyramine may be helpful
* Disordered motility - from     fibrosis, or from true mechanical obstruction in areas of chronic     stricture
** CT or MR enterography useful      in identifying strictures
** Avoid pillcam due to high      risk of pill trapping

== '''Management''' ==

* Indications for surgery (very     uncommon):
** Obstruction - adhesional vs      strictures
** Perforation
** Fistulisation
** Severe bleeding
* Perioperative:
** Assess nutritional status
** Decompress with NGT
** Control sepsis
* Surgery:
** Avoid extensive adhesiolysis      - obstruction caused by rigid fixed loops in the pelvis is best bypassed
** Drain intra-abdo collections
** If resection and anastomosis      is required, use diverting stoma, and ensure at least one end of the      anastomosis is from outside the irradiated field
** Bypass may be easier than      resection and anastomosis


= Radiation proctitis =

* Common acutely, and generally     resolves shortly after completion of therapy
* Chronically - relates to     histologic changes of progressive fibrosis and disordered     revascularisation
** Diarrhoea/urgency/incontinence      from fibrosis
** Telangiectasias result in      bleeding
***
*** Evaluation:
**** Flexi sig - consider        recurrence cancer, especially if >3 years since treatment, but avoid        deep biopsies. Visual appearance of bowel is not a good indicator of        severity of disease.
*** Treatment
**** Optimise bowel function by        treating constipation or diarrhoea
**** Sucralfate enemas -        effective, likely to improve bleeding and tenesmus
***** See proctitis topic
**** Hyperbaric oxygen is a        POTENTIAL therapy
**** Severe bleeding -
**** For minor bleeding: not        recommended by UTD, but some sources suggest apply 4% or 10% formalin        solution via a long cotton-tipped applicator through rigid proctoscope.        4% formalin can be instilled directly into rectum in 50mL aliquots or        on formalin-soaked gauze, then removed after 2-3 minutes followed by        saline irrigation, ensuring protection of perianal skin, can be done        biweekly.
**** Endoscopic - bipolar for        individual vessels, APC for more diffuse. Repeat treatment may be        necessary.
**** APC and formalin have been        found to be equally efficacious in refractory bleeding from chronic        radiation proctitis, but formalin does carry risk of complications        including necrosis and fistulisation.
**** Surgery is rarely required        <1% - in severe uncontrollable haemorrhage, an APR or        inter-sphincteric proctectomy may be required.
** Fistulae
*** Management dependent on       location, timing, state of surrounding tissue, and overall condition.
*** Similar principles to       non-radiated patients with fistulae - but harder to dissect it out due       to poor tissue
*** Mid to upper rectal       fistulae - resection with anastomosis of healthy, nonradiated colon to       distal rectum or anal canal
*** Low rectal fistula to       vagina or prostatic urethra - various approaches - abdominal, perineal,       trans-sacral, trans-sphincteric. Need to divert before reconstruction.       Need to use a graft (omentum/rectus/gracilis/buccal mucosa/labial fat       pad). Diversion alone (colostomy + SPC) may be offered to some patient.       Need to exclude recurrent malignancy prior to repair.

[[Category:Colorectal]]