Gastroenterology · Lower Gastrointestinal Hemorrhage
The facts most likely to be tested
Diverticulosis is the most common cause of painless, large-volume hematochezia in adults.
Angiodysplasia is the most common cause of lower GI bleeding in patients with end-stage renal disease or aortic stenosis (Heyde syndrome).
Colonoscopy is the diagnostic and therapeutic procedure of choice for stable patients with suspected lower GI bleeding.
Ischemic colitis typically presents with crampy abdominal pain and bloody diarrhea following an episode of hypotension or low-flow state.
Meckel's diverticulum is the most common cause of painless lower GI bleeding in children, often diagnosed via Technetium-99m pertechnetate scan.
Mesenteric angiography is the preferred diagnostic modality for patients with massive, ongoing hematochezia who are too hemodynamically unstable for colonoscopy.
Upper GI bleeding must be ruled out in patients with hemodynamic instability or nasogastric lavage positive for blood, even if the patient presents with hematochezia.
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A 72-year-old male with a history of hypertension and chronic kidney disease presents to the emergency department with a large-volume, painless, bright red blood per rectum. He is hemodynamically stable with a blood pressure of 128/82 mmHg and a heart rate of 88 bpm. Physical examination reveals a soft, non-tender abdomen and no signs of chronic liver disease. Laboratory studies show a hemoglobin of 9.8 g/dL and a normal coagulation profile. The patient has no history of abdominal surgeries.
What is the most appropriate next step in the management of this patient?
Colonoscopy
The patient is hemodynamically stable with painless hematochezia, making diverticulosis or angiodysplasia the most likely etiologies; therefore, colonoscopy is the diagnostic and therapeutic procedure of choice.
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Etiology / Epidemiology
Most common cause is diverticulosis in elderly patients; angiodysplasia is the second most common cause.
Clinical Manifestations
Presents as hematochezia; if massive, may present as hemodynamic instability with orthostatic hypotension.
Diagnosis
Colonoscopy is the gold standard for diagnosis and therapeutic intervention.
Treatment
Initial management is hemodynamic resuscitation with IV fluids; colonoscopy is the first-line diagnostic/therapeutic tool.
Prognosis
Most cases resolve spontaneously; rebleeding occurs in 20-25% of patients with diverticular disease.
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Epidemiology & Etiology
Lower GI bleeding (LGIB) is defined as bleeding distal to the ligament of Treitz. Diverticulosis accounts for the majority of cases, typically presenting as painless, large-volume bleeding. Angiodysplasia is more common in patients with chronic kidney disease or aortic stenosis (Heyde syndrome).
Pertinent Anatomy
The bleeding source is located in the colon or rectum. The ileocecal valve serves as the anatomical boundary between the small and large bowel. Right-sided lesions often present with maroon stools, while left-sided lesions present with bright red blood per rectum (BRBPR).
Pathophysiology
Diverticular bleeding results from the rupture of a vasa recta at the neck of a diverticulum. Angiodysplasia involves dilated, tortuous submucosal vessels prone to friability. Ischemic colitis occurs due to watershed area hypoperfusion, specifically at the splenic flexure (Griffith's point) and rectosigmoid junction (Sudeck's point).
Clinical Manifestations
Patients typically present with hematochezia. Hemodynamic instability, including tachycardia and orthostatic hypotension, suggests a massive bleed. Painless bleeding is classic for diverticulosis, whereas abdominal pain is more characteristic of ischemic colitis or infectious colitis.
Diagnosis
Colonoscopy is the gold standard for both diagnosis and treatment. If the patient is too unstable for colonoscopy, CT angiography is the preferred initial imaging modality to localize the bleed. Tagged RBC scintigraphy is highly sensitive for detecting slow, intermittent bleeding rates as low as 0.1-0.5 mL/min.
Treatment
Initial stabilization requires two large-bore IVs and isotonic crystalloid resuscitation. If the patient is unstable and colonoscopy is non-diagnostic, angiography with embolization is indicated. Avoid anticoagulants during the acute phase. Surgical intervention is reserved for patients with persistent, life-threatening hemorrhage despite endoscopic or angiographic control.
Prognosis
The majority of LGIB cases stop spontaneously. Rebleeding is the most common complication, particularly in patients with underlying vascular disease. Close monitoring of hemoglobin and vital signs is required to assess for ongoing blood loss.
Differential Diagnosis
Diverticulosis: painless, large-volume hematochezia
Angiodysplasia: painless, recurrent, small-volume bleeding
Ischemic colitis: crampy abdominal pain followed by bloody diarrhea
Hemorrhoids: bright red blood on toilet paper or stool surface
Colorectal cancer: occult blood or chronic iron deficiency anemia