What laboratory studies should be ordered for a sickle cell disease patient presenting with four days of right lower quadrant abdominal pain?

Laboratory Studies for Sickle Cell Disease Patient with Right Lower Quadrant Pain

Order a complete blood count with differential, reticulocyte count, comprehensive metabolic panel, and C-reactive protein immediately, followed by CT abdomen and pelvis with IV contrast to identify the underlying cause of abdominal pain. 1, 2

Essential Initial Laboratory Tests

Hematologic Assessment

• Complete blood count (CBC) with differential is mandatory to assess for acute anemia from splenic sequestration, aplastic crisis, or hyperhemolysis 1
• Reticulocyte count must be obtained to differentiate between hemolytic crisis (elevated reticulocytes) and aplastic crisis (low reticulocytes from parvovirus B19 infection) 1
• Baseline hemoglobin comparison is critical—acute drops in hemoglobin with pallor suggest life-threatening splenic sequestration or aplastic crisis requiring urgent intervention 1

Metabolic and Inflammatory Markers

• Comprehensive metabolic panel should be ordered to assess renal function, electrolytes, and liver function, as sickle cell patients are at risk for chronic organ dysfunction 1
• C-reactive protein and white blood cell count help assess for inflammatory processes, though normal values do not exclude serious pathology 2
• Leukocytosis with fever increases likelihood of acute cholecystitis or appendicitis, but is present in only ~50% of classic presentations 2

Specific Considerations for Right Lower Quadrant Pain in SCD

• Beta-hCG in all women of reproductive age must be obtained before imaging to exclude pregnancy and guide imaging choices 2
• Blood type and crossmatch should be sent given the potential need for transfusion if acute anemia or surgical intervention is identified 1

Critical Differential Diagnosis in SCD Patients

Gallbladder Disease

• Evaluation for gallstones is specifically indicated for sickle cell patients with right upper quadrant pain, frequent vomiting, and/or worsening jaundice due to chronic hemolysis 1
• However, right lower quadrant pain for 4 days makes cholecystitis less likely unless pain has migrated

Appendicitis and Alternative Diagnoses

• CT identifies alternative diagnoses in approximately 50% of cases presenting with right lower quadrant pain, including appendicitis, bowel obstruction, inflammatory bowel disease, and gynecologic conditions 2
• Ureteral stones represent roughly 19% of right-sided inflammatory presentations in post-surgical cohorts and should be considered 2

Imaging Strategy After Laboratory Assessment

Primary Imaging Recommendation

• CT abdomen and pelvis with IV contrast is the definitive imaging study, achieving 95% sensitivity and 94% specificity for appendicitis while identifying alternative diagnoses 2, 3
• Do not delay CT for oral contrast—IV contrast alone provides equivalent diagnostic accuracy without treatment delays 2
• Whole abdomen/pelvis imaging is mandatory, as limiting CT to pelvis only misses 7% of surgical pathology 2

Alternative Imaging Considerations

• Ultrasound has limited utility as initial study for general right lower quadrant pain, with sensitivity of only 71.4-87.1% 2
• MRI achieves 96% sensitivity and specificity for inflammatory conditions when CT is inconclusive or contraindicated 2

Common Pitfalls to Avoid

• Do not assume vaso-occlusive crisis is the only diagnosis—maintain broad differential given the 50% alternative diagnosis rate in right lower quadrant pain 2
• Do not overlook acute anemia—check reticulocyte count to identify aplastic crisis, which requires isolation from other sickle cell patients due to parvovirus B19 contagion 1
• Do not delay imaging if laboratory studies suggest inflammation or if pain persists beyond typical vaso-occlusive crisis duration (usually resolves within 5-7 days) 4, 5
• Do not rely on absence of fever to exclude surgical pathology—fever is absent in approximately 50% of appendicitis cases 2, 6

Management Algorithm Based on Laboratory Results

If Acute Anemia with Low Reticulocytes

• Suspect aplastic crisis from parvovirus B19 infection 1
• Isolate patient from pregnant healthcare workers and other sickle cell patients 1
• Check hemoglobin and reticulocyte count on siblings with SCD 1

If Acute Anemia with High Reticulocytes

• Suspect acute hemolysis or splenic sequestration 1
• Urgent hematology consultation for potential transfusion 1

If Inflammatory Markers Elevated with Persistent RLQ Pain

• Proceed immediately to CT abdomen/pelvis with IV contrast 2, 3
• Surgical consultation if appendicitis, cholecystitis, or other surgical pathology identified 2, 6