Snapshot A 40-year-old man presents to the emergency room soon after arriving back from a vacation on a cruise ship. He reports feeling unwell and losing his appetite in the past few days. He has had several episodes of nausea and vomiting, but today had an episode of bloody diarrhea. He is otherwise healthy and is concerned about the amount of blood. He has also had subjective fevers. (Infectious colitis) Introduction Overview lower gastrointestinal bleed results from bleeding from the colon or rectum Epidemiology Elderly patients with comorbidities Incidence very common Risk factors diverticulosis angiodysplasia ischemic colitis neoplasm inflammatory bowel disease infection Salmonella Shigella hemorrhoids anal fissure etiology Pathogenesis mechanism depends on the etiology Presentation Symptoms common symptoms rectal bleeding hematochezia bright red (originating from left side of colon) maroon blood (originating from right side of colon) has the potential to be fatal and cause massive hemorrhagic shock fecal occult blood test is positive a fever may indicate infectious etiology painless bleeding may indicate angiodysplasia or diverticular bleeding abdominal pain may indicate ischemic colitis Physical exam inspection dehydration Imaging Radionuclide scan indications often performed before angiography as it is not invasive and a negative result negates a need for further invasive procedures high sensitivity Angiography indications hemodynamically unstable patients if colonoscopy does not reveal a bleeding site in hemodynamically stable patients can also be therapeutic Studies Serum labs complete blood count serum electrolytes coagulation studies Invasive studies colonoscopy/anoscopy/sigmoidoscopy indication first-line for patients who are hemodynamically stable patients require bowel preparation can also be used therapeutically for hemostasis in patients > 50 years of age, must rule out malignancy with colonoscopy Differential Upper gastrointestinal bleed key distinguishing factor source of bleeding from stomach or small intestine may also present as bright red blood if there is rapid hemorrhage Treatment Medical resuscitation modalities large-bore intravenous access crystalloid fluid replacement blood transfusions if needed Surgical colonoscopy/anoscopy/sigmoidoscopy indication both diagnostic and therapeutic colonoscopy specifically for all patients over 40 to rule out malignancy modalities hemostasis via coagulation i.e., electrocoagulation clip placement angiography indication both diagnostic and therapeutic used when colonoscopy is unrevealing or contraindicated hemodynamically unstable patients modalities embolization vasopressin drip surgical exploration indication hemodynamically unstable patients refractory to resuscitation persistent or recurrent bleeding Complications Death Shock Prognosis Can be inconsequential or life-threatening