Diagnosis
Where chronic radiation proctopathy or RAVE is suspected, a thorough evaluation of symptoms is essential. Evaluation should include an assessment of risk factors for alternate causes of proctitis, such as C. difficile colitis, NSAID use, and travel history. Symptoms such as diarrhea and painful defecation need to be systematically investigated and the underlying causes each carefully treated. Testing for parasitic infections (amebiasis, giardiasis) and sexually transmitted infections (Neisseria gonorrhoeae and herpes simplex virus) should be considered. The location of radiation treatment is important, as radiation directed at regions of the body other than the pelvis (eg brain, chest, etc) should not prompt consideration of radiation proctopathy.Endoscopy is the mainstay of diagnosis for radiation damage to the rectum, with either colonoscopy or flexible sigmoidoscopy. RAVE is usually recognized by the macroscopic appearances on endoscopy characterized by vascular ectasias. Mucosal biopsy may aid in ruling out alternate causes of proctitis, but is not routinely necessary and may increase the risk of fistulae development. Telangiectasias are characteristic and prone to bleeding. Additional endoscopic findings may include pallor (pale appearance), edema, and friability of the mucosa. Classification
Radiation proctitis can occur a few weeks after treatment, or after several months or years:

Acute radiation proctitis — symptoms occur in the first 3 months after therapy. These symptoms include diarrhea and the urgent need to defecate. Radiation associated vascular ectasias (RAVE) and Chronic radiation proctopathy — previously known as "chronic radiation proctitis" occur 3-6 months after the initial exposure. RAVE is characterized by rectal bleeding, chronic blood loss and anemia.
The mechanism is believed to be the release into the bloodstream of muscle breakdown products—notably myoglobin, potassium and phosphorus—that are the products of rhabdomyolysis (the breakdown of skeletal muscle damaged by ischemic conditions). The specific action on the kidneys is not understood completely, but may be due partly to nephrotoxic metabolites of myoglobin. The most devastating systemic effects can occur when the crushing pressure is suddenly released, without proper preparation of the patient, causing reperfusion syndrome. In addition to tissue directly suffering the crush mechanism, tissue is then subjected to sudden reoxygenation in the limbs and extremities. Without proper preparation, the patient, with pain control, may be cheerful before recovery, but die shortly thereafter. This sudden failure is called the "smiling death".These systemic effects are caused by a traumatic rhabdomyolysis. As muscle cells die, they absorb sodium, water and calcium; the rhabdomyolysis releases potassium, myoglobin, phosphate, thromboplastin, creatine and creatine kinase.Crush syndrome can directly come from compartment syndrome, if the injury is left untreated. Symptoms include the 5 Ps: pain, pallor, paresthesias (pins and needles), paralysis, and pulselessness. Treatment
There is no distinct treatment option that can undo the effects and damage from rhabdomyolysis because it is a necrosis. However, the rate of the pathology that can lead to more complications can be decreased by acting early and consistently. Overall treatment depends on preventing kidney failure (renal failure) which is done by rehydrating the patient. It also depends on making urine have a more basic pH (alkalinization of urine).