What is the appropriate initial evaluation and management for a 38‑year‑old male with fatigue, abdominal discomfort, intermittent hematochezia, and orthostatic light‑headedness?

Immediate Evaluation and Management for a 38-Year-Old Male with Fatigue, Abdominal Discomfort, Hematochezia, and Orthostatic Symptoms

This patient requires immediate hemodynamic assessment with vital signs (including orthostatic measurements), complete blood count, and urgent colonoscopy after stabilization, as the combination of hematochezia with orthostatic lightheadedness suggests significant blood loss requiring rapid diagnosis and intervention.

Initial Hemodynamic Assessment and Resuscitation

Check vital signs immediately, including orthostatic blood pressure and heart rate measurements, to quantify the degree of hypovolemia. 1 The orthostatic lightheadedness strongly suggests volume depletion from ongoing or recent blood loss.

• Establish two large-bore IV lines if any signs of hemodynamic instability are present (tachycardia, hypotension, or positive orthostatic vital signs) 1
• Begin crystalloid infusion targeting mean arterial pressure >65 mmHg if hemodynamically unstable 2
• Obtain complete blood count, coagulation parameters (PT/INR, PTT), blood urea nitrogen, creatinine, and serum electrolytes immediately 1
• Maintain hemoglobin >7 g/dL while avoiding fluid overload 2
• Correct any coagulopathy (INR >1.5) with fresh frozen plasma or thrombocytopenia (<50,000/µL) with platelets before invasive procedures 2

A critical pitfall is delaying resuscitation to perform diagnostic procedures—stabilization always takes priority. 3

Diagnostic Workup Based on Hemodynamic Status

If Hemodynamically Stable After Initial Resuscitation

Perform urgent colonoscopy within 24 hours after hemodynamic stabilization with thorough bowel preparation, as this provides the highest diagnostic yield (72-86%) for lower GI bleeding. 4, 1, 3

• Ensure adequate bowel preparation despite active bleeding to maximize diagnostic accuracy 1
• Consider upper endoscopy FIRST if severe hematochezia with hypovolemia is present, as 10-15% of apparent lower GI bleeding originates from an upper GI source 4, 3
• Nasogastric lavage is warranted if there is medium to low suspicion of an upper GI source, though it may be misleading if only clear fluid without bile or blood returns 4
• If blood, clots, or coffee grounds material is present in NG aspirate, upper endoscopy must be performed to exclude an upper GI source 4

If Hemodynamically Unstable or Requiring >5 Units Blood in 24 Hours

Proceed directly to CT angiography (CTA) as the first-line investigation, which detects bleeding rates as low as 0.3 mL/min and requires no bowel preparation. 4, 3

• CTA can identify sources in the upper GI tract, small bowel, or colon simultaneously 3
• If CTA shows active extravasation, proceed directly to transcatheter arteriography with embolization 4, 3
• Patients who are hemodynamically unstable with severe unremitting bleeding should forego nuclear scintigraphy and instead undergo resuscitation and angiography as soon as possible 4

Age-Specific Differential Diagnosis Considerations

At 38 years old, this patient's differential diagnosis should prioritize:

• Inflammatory bowel disease (Crohn's disease or ulcerative colitis) presenting with rectal bleeding, abdominal pain, and systemic symptoms like fatigue 2
• Infectious colitis (send stool culture for Salmonella, Shigella, Campylobacter, E. coli O157:H7, and Clostridium difficile toxin assay) 1
• Consider fecal calprotectin to evaluate for inflammatory bowel disease 1
• While diverticular disease and angiodysplasia are more common in patients over 70 years, they remain possible in younger patients 2
• Colorectal malignancy, though less common at age 38, must be excluded given chronic symptoms 2

If Initial Colonoscopy is Inconclusive

If colonoscopy is negative or inconclusive and bleeding continues, consider radionuclide scanning with 99mTc-labeled red blood cells, which can detect bleeding rates as low as 0.1 mL/min. 4, 3

• For hemodynamically stable patients with severe but intermittent bleeding, 99mTc red blood cell scanning is preferred over technetium sulfur colloid because labeled RBCs remain in the vascular space for 24 hours, allowing detection of intermittent bleeding 4
• Early bleeding scans (baseline and up to 1-4 hours later) are most helpful for localizing the bleeding site 4
• A positive red blood cell scan should necessitate urgent angiography within 1 hour of positive scintigraphy 4
• Even if the bleeding scan is positive, a confirmatory test such as colonoscopy, angiography, or push enteroscopy is recommended before emergency surgery is considered 4

Management Based on Findings

• If infectious colitis is identified, provide supportive care including IV fluids and electrolyte replacement 1
• If inflammatory bowel disease is suspected or confirmed, establish gastroenterology follow-up for long-term management 1
• If no source is identified on initial colonoscopy, consider repeat colonoscopy with thorough bowel preparation or CT angiography if hemodynamically unstable with suspected active bleeding 1

Follow-up and Monitoring

• Monitor hemoglobin weekly until stable, then monthly for 3 months 1
• Arrange gastroenterology follow-up for surveillance colonoscopy if IBD is diagnosed 1

A critical pitfall is inadequate bowel preparation leading to poor colonoscopic visualization and missed lesions—this must be avoided even in the setting of active bleeding. 3