Gastrointestinal bleeding
Synonyms and keywords: Blood loss from GI tract; bloody stool; blood in feces; PR bleeding; gastrointestinal hemorrhage; gastrointestinal hemorrhage; GI bleeding; bright red blood per rectum; BRBPR.

# Overview
Gastrointestinal (GI) bleeding is defined as bleeding from any part of GI tract starting from mouth to anus. It can also be called as gastrointestinal hemorrhage. Based on the origin of bleeding it can be classified into upper gastrointestinal bleeding and lower gastrointestinal bleeding. Upper gastrointestinal bleeding (UGIB) is defined as bleeding from the gastrointestinal tract that originates proximal to the ligament of Treitz. Lower gastrointestinal bleeding is defined as blood loss originating distal to the ligament of Treitz. The most common causes of UGIB are peptic ulcer disease and esophageal varice while diverticulosis is the most commonly responsible for lower gastrointestinal bleeding. Clinical presentation includes overt bleeding from the gastrointestinal tract, rapid or slow, either manifested by hematemesis of fresh (blood-streaked to frankly bloody), old ('coffee ground') vomitus, melena and or as frank blood per rectum.
Common risk factors in the development of GI bleeding include advancing age, previous history of gastrointestinal bleed, chronic constipation, hematologic disorders, anticoagulants medications, non-steroidal anti-inflammatory drugs.  It is essential to distinguish between lower gastrointestinal bleeding and brisk upper gastrointestinal bleeding as they can present with similar symptoms. Patients with severe bleeding or hemodynamic disturbance require hospitalization and urgent investigation. Treatment depends on the cause and the severity of the bleeding.

# Types of bleeding
Bleeding from the gastrointestinal tract can be of the following types:
- Haematemesis: Vomiting fresh red blood.
- Coffee ground emesis: Vomiting of altered black blood.
- Melaena: Passage of black tarry stools.
- Haemochezia: Passage of red blood per rectum (usually due to bleeding from the lower gastrointestinal tract but occasionally can be due to massive upper gastrointestinal bleeding).
- Rebleeding: Defined as fresh haematemesis and/or melaena associated with the development of shock (pulse greater than 100 beats/min, systolic pressure less than 100 mm Hg), a fall in CVP greater than 5 mm Hg, or a reduction in haemoglobin concentration greater than 20 g/l over 24 hours. Rebleeding should always be confirmed by endoscopy.

# Causes

# Classification
The following flow chart elobarates the classification of gastrointestinal bleeding:

# Differentiating Gastrointestinal Bleeding from other Diseases
Abbreviations:
RUQ= Right upper quadrant of the abdomen, LUQ= Left upper quadrant, LLQ= Left lower quadrant, RLQ= Right lower quadrant, LFT= Liver function test, SIRS= Systemic inflammatory response syndrome, ERCP= Endoscopic retrograde cholangiopancreatography, IV= Intravenous, N= Normal, AMA= Anti mitochondrial antibodies, LDH= Lactate dehydrogenase, GI= Gastrointestinal, CXR= Chest X ray, IgA= Immunoglobulin A, IgG= Immunoglobulin G, IgM= Immunoglobulin M, CT= Computed tomography, PMN= Polymorphonuclear cells, ESR= Erythrocyte sedimentation rate, CRP= C-reactive protein, TS= Transferrin saturation, SF= Serum Ferritin, SMA= Superior mesenteric artery, SMV= Superior mesenteric vein, ECG= Electrocardiogram

# Symptomatic approach to the differential of Upper gastrointestinal bleeding

# Symptomatic approach to differential of lower gastrointestinal bleeding