What is the suggested workup for an elderly female patient presenting with weight loss and melena (black stools)?

Workup for Elderly Female with Weight Loss and Black Stools

This patient requires immediate upper endoscopy (esophagogastroduodenoscopy) within 24 hours after hemodynamic stabilization, as melena with weight loss in an elderly patient strongly suggests upper gastrointestinal pathology—most critically peptic ulcer disease or malignancy—and EGD identifies the bleeding source in 95% of cases while enabling therapeutic intervention. 1

Immediate Assessment and Resuscitation

Hemodynamic evaluation must occur first:

• Calculate shock index (heart rate/systolic blood pressure)—a value >1 indicates hemodynamic instability requiring ICU admission 1
• Check for orthostatic hypotension (drop in systolic BP >20 mmHg or diastolic BP >10 mmHg upon standing), which indicates significant blood loss 1
• Perform digital rectal examination to confirm melena (black, tarry, sticky stool with distinctive odor) and exclude anorectal pathology 2, 1

Resuscitation priorities:

• Establish large-bore IV access and initiate fluid resuscitation concurrently with evaluation 2
• Transfuse packed red blood cells to maintain hemoglobin >7 g/dL (or >9 g/dL if massive bleeding, cardiovascular disease, or delayed intervention anticipated) 2
• Correct coagulopathy with fresh frozen plasma if INR >1.5 or platelets if <50,000/µL 2

Critical Laboratory Investigations

Obtain immediately:

• Complete blood count to assess anemia severity and guide transfusion 2, 3
• Serum albumin and ferritin to evaluate nutritional status and chronic blood loss 2, 3
• C-reactive protein to assess systemic inflammation 2, 3
• Liver enzymes, urea, and creatinine to assess comorbidities and establish baseline for monitoring 2
• Serum urea nitrogen:creatinine ratio—a value >30 increases likelihood of upper GI bleeding (LR 7.5) 4
• Coagulation studies (PT/INR, PTT) to identify bleeding risk 2

Mandatory stool testing:

• Clostridioides difficile toxin in all elderly patients with any diarrheal component, regardless of antibiotic history 2, 3, 5
• Fecal occult blood testing (though melena is already clinical confirmation of GI bleeding) 3

Differential Diagnosis Considerations in Elderly Patients

The combination of weight loss and melena in an elderly female raises specific concerns:

Upper GI sources (most likely):

• Peptic ulcer disease (35-50% of upper GI bleeding) 2
• Gastric or esophageal malignancy (critical given weight loss) 2
• Gastroduodenal erosions (8-15%) 2
• Esophagitis (5-15%) 2

Alternative diagnoses requiring exclusion:

• Colorectal cancer (elderly patients with melena have OR 2.87 for colorectal cancer) 1
• Small bowel tumors (particularly in patients <70 years with obscure bleeding) 1
• Angiodysplasia (up to 80% of small bowel bleeding sources) 1
• Inflammatory bowel disease (15% of new IBD diagnoses occur after age 60) 2
• Ischemic colitis 2, 5
• NSAID-induced pathology 2, 5

Endoscopic Evaluation Strategy

For hemodynamically unstable patients (shock index >1):

• Perform CT angiography immediately—this provides fastest localization of active bleeding 1
• Proceed to urgent angiography or surgery if bleeding rate >0.5 mL/min 2

For hemodynamically stable patients:

• Perform EGD within 24 hours (ideally within 12 hours, which increases bleeding source identification with OR 3.71) 1
• EGD has both diagnostic and therapeutic capabilities 2, 1
• Nasogastric lavage showing blood or coffee grounds increases likelihood of upper GI source (LR 9.6), though this should not delay endoscopy 4

If EGD is nondiagnostic:

• Proceed to colonoscopy as the next step, though it identifies bleeding source in only 4.8% of melena cases after negative EGD 1
• Colonoscopy remains valuable given the increased colorectal cancer risk in elderly patients with these symptoms 1, 5
• Obtain biopsies from both affected and normal-appearing areas to detect microscopic colitis and other histologic diagnoses 3, 5

If both EGD and colonoscopy are negative:

• Consider capsule endoscopy for small bowel evaluation, as up to 13% of melena cases originate from small intestine 1
• Melena predicts proximal small bowel bleeding (OR 1.97), so antegrade deep enteroscopy should be the initial approach if performed 6

Additional Diagnostic Testing Based on Clinical Context

Cross-sectional imaging:

• CT abdomen/pelvis is appropriate when abdominal pain is prominent or to exclude alternative diagnoses (ischemic colitis, diverticular disease, masses) 2

Inflammatory markers if IBD suspected:

• Fecal calprotectin (93-95% sensitivity, 91-96% specificity for IBD): values >200-250 μg/g strongly suggest IBD and mandate colonoscopy with biopsies 3, 5
• However, normal fecal calprotectin should NOT exclude serious pathology in elderly patients—colonoscopy is still required given cancer risk 5

Critical Pitfalls to Avoid

• Do not delay endoscopy to obtain stool studies—melena is a clinical diagnosis warranting immediate evaluation 1
• Do not assume lower GI source—melena typically indicates upper GI bleeding, and EGD should be performed first 2, 1
• Do not confuse simple black stools (from dietary iron, bismuth) with true melena—the latter has distinctive tar-like consistency and odor 1
• Do not rely on fecal calprotectin alone to exclude serious pathology in elderly patients with weight loss 5
• Do not miss colorectal cancer—approximately 40% of rectal carcinomas are palpable on digital rectal examination 2
• Be aware that 15-20% of patients with active inflammatory bowel disease have normal CRP, so normal inflammatory markers do not exclude IBD 3, 5
• Recognize that massive upper GI bleeding can present as hematochezia rather than melena if transit time is rapid 1, 7

Risk Stratification for Prognosis

Clinical predictors of poor outcome:

• Age >65 years 1
• Hemoglobin <8 g/dL (LR 4.5-6.2 for severe bleeding requiring intervention) 4
• Tachycardia (LR 4.9 for severe bleeding) 4
• Fresh red blood on nasogastric lavage (LR 3.1 for severe bleeding) 4
• Significant comorbidities (coronary artery disease, cirrhosis, COPD) 2

Blatchford score of 0 effectively excludes need for urgent intervention (LR 0.02) and can guide outpatient management in select cases 4