What is the next step in assessing an elderly female patient with maroon colored stool, tachypnea, pallor, hypotension, and tachycardia?

Immediate Assessment of Acute Lower GI Bleeding with Hemodynamic Instability

The next step is to place a nasogastric (NG) tube to exclude an upper GI source, as this is critical before proceeding with further diagnostic or therapeutic interventions in a patient presenting with maroon stools and hemodynamic compromise. 1

Rationale for NG Tube Placement

• Maroon-colored stool can originate from either upper or lower GI sources, and distinguishing between these is essential for appropriate management, as up to 10-15% of patients presenting with apparent lower GI bleeding actually have a briskly bleeding upper GI source 1, 2

• An NG tube aspirate helps differentiate upper from lower GI bleeding before committing to colonoscopy or other lower GI interventions 1

• The presence of blood or coffee-ground material in the NG aspirate indicates an upper GI source, which would necessitate urgent esophagogastroduodenoscopy (EGD) rather than colonoscopy 1, 3

• A clear NG aspirate does not completely exclude upper GI bleeding (particularly from duodenal sources distal to the pylorus), but makes a lower GI source more likely 1

Why Other Options Are Inappropriate at This Stage

Colonoscopy (Option B)

• Colonoscopy should not be performed until an upper GI source is excluded, as proceeding directly to colonoscopy without ruling out upper GI bleeding can delay appropriate treatment and worsen outcomes 1, 2

• Early colonoscopy may be appropriate after initial resuscitation and exclusion of upper GI bleeding, but timing should be after hemodynamic stabilization 2

Angiography (Option A)

• Angiography is reserved for patients with ongoing active bleeding who have failed endoscopic management or when the bleeding source cannot be identified endoscopically 1, 4

• Angiography requires a bleeding rate of at least 0.5-1.0 mL/min to detect extravasation, making it inappropriate as an initial diagnostic step 1

Barium Studies (Option D)

• Barium studies are absolutely contraindicated in acute GI bleeding because they interfere with subsequent endoscopic visualization and angiographic procedures 1

Concurrent Initial Management

While placing the NG tube, the following should occur simultaneously:

• Rapid IV fluid resuscitation with crystalloids (normal saline or lactated Ringer's) to correct hypovolemia and maintain blood pressure, given the patient's hypotension (BP 100/60) and tachycardia (HR 90) 1, 4

• Obtain laboratory studies including complete blood count, basic metabolic panel, coagulation studies, type and crossmatch for potential blood transfusion 1, 4

• Blood transfusion should be initiated when hemoglobin falls below 7 g/dL in hemodynamically unstable patients 4

• Initiate high-dose proton pump inhibitor (PPI) therapy immediately upon presentation, as this is indicated regardless of whether the source is upper or lower GI 4, 5

Clinical Pitfalls to Avoid

• Do not assume maroon stools always indicate lower GI bleeding—brisk upper GI bleeding can present with maroon or even bright red blood per rectum 1, 2

• Do not delay resuscitation to obtain diagnostic studies—fluid resuscitation should begin immediately when hemodynamic instability is identified 1

• Do not proceed directly to colonoscopy without excluding upper GI bleeding, as this represents a critical diagnostic error that can delay life-saving intervention 1