How do you diagnose a sickle cell crisis?

How to Diagnose Sickle Cell Crisis

The diagnosis of a sickle cell crisis is made entirely on clinical grounds based on the patient's self-report of pain, without requiring any specific laboratory abnormalities. 1

Clinical Diagnostic Criteria

Trust the patient's report. Patients with sickle cell disease and their caregivers know their disease best, and their description of typical pain symptoms should be trusted and acted upon promptly. 1 The diagnosis does not depend on laboratory confirmation—it is a clinical diagnosis based on pain presentation. 1

Pain Distribution Patterns

• In infants: Pain typically affects the fingers (dactylitis). 1
• In older children and adults: Pain commonly involves long bones, sternum, ribs, or back. 1

Essential Clinical Exclusions

Before confirming an uncomplicated vaso-occlusive crisis, you must actively exclude life-threatening complications:

Acute Chest Syndrome

• Exclude this immediately in any patient with chest pain. This is characterized by new infiltrate on chest radiograph with respiratory symptoms. 1
• Emergency transfer to an acute care setting is recommended for all patients reporting acute chest pain to ensure rapid evaluation. 1
• Obtain chest radiograph and assess for fever, cough, shortness of breath, sputum production, and abnormal pulmonary examination. 2

Splenic Sequestration Crisis

• This presents with a drop in hemoglobin >2 g/dL from baseline, which distinguishes it from typical vaso-occlusive pain. 1

Infection

• Fever >102°F is an absolute indication for admission and workup. 3
• White blood cell count >20,000 warrants further investigation. 3

Stroke

• Review previous transcranial Doppler results, especially in children with suspected neurological symptoms. 4

Laboratory Testing Approach

Laboratory tests do not diagnose the crisis itself but help assess severity and exclude complications. 1, 4

Baseline Assessment

• Complete blood count: Assess hemoglobin level against the patient's known baseline (typically 6-9 g/dL in HbSS). 4, 5
• Reticulocyte count: Evaluates bone marrow response; a decreased count suggests transient aplastic crisis rather than typical vaso-occlusive crisis. 1, 4

Markers of Hemolysis and Organ Function

• Bilirubin (total and direct): Increased due to red cell breakdown. 4
• Lactate dehydrogenase (LDH): Elevated with hemolysis. 4, 5
• Aspartate aminotransferase (AST) and alanine aminotransferase (ALT): May be elevated with liver involvement. 4
• Blood urea nitrogen (BUN) and creatinine: Assess for acute kidney injury from vaso-occlusion. 4
• Electrolytes: Monitor for imbalances from renal dysfunction or dehydration. 4

Additional Tests Based on Clinical Presentation

• Urinalysis: Check for hematuria, proteinuria, or urinary tract infection. 4
• Arterial blood gas: If acute chest syndrome is suspected to evaluate oxygenation and acid-base status. 4
• Blood cultures: If infection is suspected as a trigger. 4
• Chest radiograph: Obtain if patient has fever, cough, shortness of breath, chest pain, or abnormal pulmonary examination. 2

Critical Pitfalls to Avoid

• Do not wait for laboratory abnormalities to diagnose or treat pain. Sickle cells are chronically present on peripheral smears and do not distinguish acute episodes from baseline. 1
• Do not dismiss the patient's pain report. The diagnosis is clinical, and delays in treatment worsen outcomes. 1
• Do not rely solely on hemoglobin levels for transfusion decisions. Consider the patient's baseline hemoglobin and overall clinical status. 4
• Do not assume absence of fever excludes infection. An inciting cause is identified in only 35% of painful events. 3
• Do not perform extensive workup for uncomplicated pain crisis. A complete history, physical examination, and CBC are sufficient for triage in straightforward cases. 3

Absolute Indications for Hospital Admission

• Sepsis or suspected infection 3
• Fever >102°F 3
• White blood cell count >20,000 3
• Worsening anemia from baseline 3
• Hypoxemia 3
• Acute chest syndrome 3
• New central nervous system events 3