A 20-year-old female with melena, five-day fever, and left periumbilical tenderness—what are the differential diagnoses and how should I work her up?

Differential Diagnoses and Workup for 20-Year-Old Female with Melena, Fever, and Left Periumbilical Tenderness

Most Likely Diagnosis

This presentation most strongly suggests splenic abscess or infarction complicating infective endocarditis, which requires immediate blood cultures, echocardiography, and abdominal CT imaging. 1

Critical Differential Diagnoses

High-Priority Life-Threatening Conditions

Infective Endocarditis with Splenic Complications

• Splenic abscess develops in approximately 5% of patients with splenic infarction from endocarditis, and splenic infarction itself occurs in 40% of left-sided endocarditis cases 1
• Left upper quadrant/periumbilical pain with fever and melena (from GI bleeding secondary to septic emboli or DIC) is the classic triad 1
• Viridans streptococci and S. aureus each account for 40% of splenic abscess cases in endocarditis 1

Pelvic Inflammatory Disease with Complications

• Lower abdominal tenderness, adnexal tenderness, and fever are minimum criteria for PID diagnosis 1
• Can present with GI symptoms including melena from associated inflammatory bowel involvement 1
• Oral temperature >38.3°C supports this diagnosis 1

Peptic Ulcer Disease with Perforation or Penetration

• Melena indicates upper GI bleeding, most commonly from peptic ulcer disease 2, 3
• Left periumbilical tenderness could represent posterior gastric ulcer penetration into pancreas or lesser sac 2
• Five-day fever suggests complicated ulcer with abscess formation 2

Small Bowel Pathology

• Meckel's diverticulum with bleeding and diverticulitis (can cause left-sided pain and melena) 3
• Small bowel tumor (important in patients <50 years) with bleeding and obstruction 3
• Angiectasia causing obscure bleeding (accounts for up to 80% of small bowel bleeding sources) 3

Immediate Clinical Assessment

Hemodynamic Evaluation (First Priority)

• Calculate shock index immediately (heart rate ÷ systolic blood pressure): value >1 indicates hemodynamic instability requiring ICU admission 2, 4, 3
• Check orthostatic vital signs: drop in BP >20 mmHg or HR increase >20 bpm indicates significant blood loss 2, 4
• Perform digital rectal examination to confirm melena (black, tarry, sticky stool with distinctive odor) 2, 3

Risk Stratification

• Calculate Oakland score (age, gender, previous GI bleeding, rectal findings, heart rate, systolic BP, hemoglobin): score >8 requires hospital admission 2, 4, 3
• High-risk features: age >65 years, shock, poor health status, low hemoglobin, fresh red blood on rectal exam 2, 3

Diagnostic Workup Algorithm

If Hemodynamically Unstable (Shock Index >1)

Immediate Actions:

1. Initiate IV fluid resuscitation with crystalloids to normalize blood pressure and heart rate 2, 4
2. Obtain blood cultures before antibiotics (critical for endocarditis diagnosis) 1
3. Perform CT angiography immediately to localize active bleeding 2, 4, 3
4. Transfuse if hemoglobin <7 g/dL (or <8-9 g/dL if cardiovascular disease present) 2, 4
5. Correct coagulopathy: FFP if INR >1.5, platelets if <50,000/µL 2, 4

If Hemodynamically Stable

Step 1: Laboratory Studies

• Complete blood count with differential (looking for leukopenia, thrombocytopenia, anemia) 1
• Comprehensive metabolic panel (elevated transaminases suggest systemic infection or hepatic involvement) 1
• Coagulation studies (PT/PTT, INR) 1
• Blood cultures × 3 sets from different sites 1
• Erythrocyte sedimentation rate and C-reactive protein (elevated in PID and endocarditis) 1
• Cervical cultures for N. gonorrhoeae and C. trachomatis 1

Step 2: Imaging Studies

• Abdominal CT with IV contrast (first-line imaging): evaluates for splenic abscess/infarction (90-95% sensitivity and specificity), appendicitis, tubo-ovarian abscess, and other intra-abdominal pathology 1
• Transthoracic echocardiography (if endocarditis suspected): look for vegetations, valve dysfunction 1
• Pelvic ultrasound (if PID suspected): identifies tubo-ovarian abscess 1

Step 3: Endoscopic Evaluation

• Upper endoscopy (EGD) within 24 hours: melena indicates upper GI source in 95% of cases; EGD has both diagnostic and therapeutic capabilities 2, 4, 3
• If EGD negative, proceed to colonoscopy after bowel preparation 3
• If both negative, consider capsule endoscopy for small bowel evaluation (13% of melena cases are small bowel sources) 3

Specific Physical Examination Findings to Elicit

Cardiovascular Examination

• New or changing heart murmur (present in endocarditis) 1
• Peripheral stigmata of endocarditis: Osler nodes, Janeway lesions, splinter hemorrhages 1
• Signs of heart failure from valvular dysfunction 1

Abdominal Examination

• Splenomegaly (present in 30% of endocarditis cases, though not reliable for splenic abscess) 1
• Rebound tenderness or guarding (suggests peritonitis from perforation) 1
• Location and character of tenderness (left periumbilical suggests splenic, pancreatic, or posterior gastric pathology) 1

Gynecologic Examination

• Cervical motion tenderness (minimum criterion for PID) 1
• Adnexal tenderness and masses (minimum criterion for PID) 1
• Abnormal cervical or vaginal discharge 1

Skin Examination

• Petechiae or purpura (suggests septic emboli or DIC from endocarditis) 1
• Tick bites or rash (though tickborne illness less likely with melena) 1

Critical Pitfalls to Avoid

Do not delay endoscopy to obtain stool studies—melena is a clinical diagnosis based on visual inspection and digital rectal examination that warrants immediate evaluation 2, 3

Do not assume lower GI source based on left-sided pain—melena indicates upper GI bleeding until proven otherwise, and upper endoscopy must be performed first 2, 4, 3

Do not miss endocarditis with splenic complications—persistent fever with melena and left upper quadrant pain is splenic abscess until proven otherwise; this requires blood cultures before antibiotics and immediate imaging 1

Do not overlook PID in young women—maintain low threshold for diagnosis as atypical presentations are common and long-term reproductive consequences are severe 1

Do not treat splenic abscess with antibiotics alone—definitive treatment requires splenectomy or percutaneous drainage in addition to antibiotics 1

Mortality in GI bleeding relates more to comorbidities than exsanguination—aggressive management of underlying conditions (sepsis, endocarditis) is essential 2

Empiric Treatment Considerations

If Endocarditis/Splenic Abscess Suspected:

• Obtain blood cultures, then start broad-spectrum antibiotics covering streptococci and staphylococci 1
• Surgical consultation for potential splenectomy (should be performed before valve replacement if both needed) 1

If PID Suspected:

• Hospitalize for IV antibiotics (recommended for all PID patients by many experts) 1
• Cover N. gonorrhoeae, C. trachomatis, Gram-negative bacteria, anaerobes, and streptococci 1

If Peptic Ulcer Disease:

• Proton pump inhibitor therapy 2
• Avoid NSAIDs and anticoagulants 3