LOWER GIT BLEEDING

LOWER GIT BLEEDING

Severe acute lower gastrointestinal bleeding:  This is an unusual medical emergency. Patients present with profuse red or maroon diarrhoea and with shock.

1.    Diverticular disease is the most common cause. Acute bleeding is due to erosion of an artery within the mouth of a diverticulum and bleeding almost always stops spontaneously. If bleeding continues, the diseased segment of colon will need to be resected after confirmation of the site (by angiography or colonoscopy).

2.    Angiodysplasia is a disease of the elderly in which vascular malformations develop in the proximal colon. Bleeding can be acute and profuse; it usually stops spontaneously but commonly recurs. Diagnosis is often difficult. Colonoscopy reveals characteristic vascular spots which are reminiscent of spider naevi. In acute bleeding, visceral angiography shows bleeding into the intestinal lumen and an abnormal large, draining vein. In some patients diagnosis is only achieved by laparotomy with on-table  colonoscopy.. 

The treatment of choice is endoscopic thermal ablation, but resection of the affected bowel may be required if bleeding continues.

3.    Ischaemia is due to occlusion of the inferior mesenteric artery and presents with abdominal colic and rectal bleeding. It should be considered in patients (particularly the elderly) who have evidence of generalised atherosclerosis. Diagnosis is made at colonoscopy. Resection is required only in the presence of peritonitis.

4.    Meckel's diverticulum with ectopic gastric epithelium may ulcerate and erode into a major artery. The diagnosis should be considered in children or adolescents who present with profuse or recurrent lower gastrointestinal bleeding. A Meckel's 99mTc-pertechnate scan is sometimes positive but the diagnosis is commonly made only by laparotomy, at which time the diverticulum is excised.

Subacute or chronic lower gastrointestinal bleeding

This is extremely common at all ages and is usually due to haemorrhoids or anal fissure. Haemorrhoidal bleeding is bright red and occurs during or after defecation. Proctoscopy is used to make the diagnosis but in subjects who also have altered bowel habit and in all patients presenting at over 40 years of age, colonoscopy or barium enema is necessary to exclude coexisting colorectal cancer. Anal fissure should be suspected when fresh rectal bleeding and anal pain occur during defecation. chronic/subacute,  

Other causes: Inflammatory bowel disease, Carcinoma, Large polyps, Angiodysplasia

Radiation enteritis, Solitary rectal ulcer)

OBSCURE MAJOR GASTROINTESTINAL BLEEDING:

In some patients who present with major gastrointestinal bleeding, upper endosopy and colonoscopy fail to reveal a diagnosis. When bleeding continues, urgent mesenteric angiography is indicated. This will usually identify the site if the bleeding rate exceeds 1 ml/min and embolisation can sometimes be used to stop the bleeding. If angiography is negative, enteroscopy can be used to visualise the proximal small intestine and treat the bleeding source. Wireless capsule endoscopy is also used to define a source of bleeding and, unlike push enteroscopy, the jejunum and ileum are visualised. When all else fails, laparotomy with on-table endoscopy is indicated.

OCCULT GASTROINTESTINAL BLEEDING :

 'Occult' means that blood or its breakdown products are present in the stool but cannot be seen. Occult bleeding may reach 200 ml per day, cause iron deficiency anaemia and signify serious gastrointestinal disease. Any cause of gastrointestinal bleeding may be responsible but the most important is colorectal cancer, particularly carcinoma of the caecum which may have no gastrointestinal symptoms. In clinical practice, investigation of the gastrointestinal tract should be considered whenever a patient presents with unexplained iron deficiency anaemia. Testing the stool for the presence of blood is unnecessary and should not influence whether or not the gastrointestinal tract is imaged because bleeding from tumours is often intermittent and a negative faecal occult blood (FOB) test does not exclude important gastrointestinal disease. Many colorectal cancer patients are FOB-negative at presentation, and the only value of FOB testing is as a means of screening for colonic disease in asymptomatic populations .