الفهرس 
ANATOMY OF ABDOMINAL VASCULATUREOnly 14 pages are availabe for public view
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Abstract
The diagnosis of gastrointestinal bleeding is not always an easy task for the physician or the surgeon thus our aim of work is to review and assess the recent literature about the diagnosis and management of obscure gastrointestinal bleeding. The common causes of obscure gastrointestinal bleeding such as; angiodysplasia, small bowel vascular lesions or tumors, inflammatory bowel disease and diverticulosis are usually diagnosed by endoscopy, sometimes these lesions are overlooked by the unexperienced endoscopist especially if they are difficult to locate or if at the time of endoscopy no bleeding is present. Those with recurrent gastrointestinal bleeding that is difficult to diagnose should undergo a sequence of investigations from panendoscopy through small and large bowel, radiological contrast studies, radio-isotope scan and selective visceral angiography to preoperative endoscopy.
By definition, an obscure source of hemorrhage has not been discovered by routine, standard investigations. The first rule in such patient; however, is that one must not hesitate to repeat previously normal investigations.
Endoscopy:
It should be repeated in particular, several times if necessary for many reasons:
First, some lesions are only seen intermittently as arteriovenous malformation in the stomach.
Second, blood and clot may obscure a lesion which may become clear when the stomach clears. Conversely, some causes as Dieulafoy lesion or haemobilia may only be visible when bleeding is active.
Third, endoscopy is somewhat operator dependent.
Enteroscopy:
It is a more sophisticated form of endoscopy which has not come into very general use. There are 5 types of enteroscopy:
1. Sonde enteroscopy.
2. Push enteroscopy.
3. Double Balloon enteroscopy.
4. Vedio capsule endoscopy.
5. Intra-operative enteroscopy.
Enteroscopy has been particularly useful in defining small vascular lesions.
Capsule Endoscopy:
The advantages of which are the following:
1. No pain.
2. No need to push the device.
3. Artifact induction doesn’t occur as in push enteroscopy.
4. No need for air insufflation and the rate of propulsion is determined by peristalsis.
5. Absence of sedation, and its resultant change in the physiological state.
6. Examination of the intestine under physiological parameters.
Barium study: Barium studies have a little value in the presence of acute hemorrhage and indeed, should be avoided as they preclude useful angiography.
Ultrasound:
Ultrasound studies have become an important part of clinical life, but in the field of obscure bleeding, they are of limited value. Doppler ultrasound is of course valuable in assessing liver diseases and varices, as a part of an overall assessment.
CT Scanning:
It has particular value in three areas which may be of relevance to obscure gut hemorrhage. These are: The assessment of liver diseases, particularly of the pancreas, and of the major vessels.
Radionuclear Scanning:
It can be performed in two ways:
- 99mTc-labelled sulphucolloid injected intravenously.
- 99mTc-labelled and re-injection of autologous red cells .
It is valuable in localizing sites of bleeding in upper or lower small bowel, or particularly in right or left colon.
Visceral Angiography:
It has become a vitally important tool in the management of obscure bleeding. In the case of active bleeding, extravasation of contrast may be seen into the bowel lumen. This requires bleeding rate of at least 0.5 ml/min, but gives precise localization of the source.
Laparotomy:
Laparotomy may be necessary for diagnosis, and is often required for the treatment of lesions. Small bowel lesions are particularly likely to remain undiagnosed before laparotomy, and abdominal pain associated with obscure bleeding should be an indication for surgery.
Operative Treatment:
In the majority of cases, a clear diagnosis at laparotomy defines treatments; localized lesions such as a Meckel’s diverticulum or a small bowel tumour are resected appropriately. Small multiple AVMs which are identified may be excised through small ’wedge’ incision.