- Sickle cell disease (SCD) is a chronic hemolytic anemia that is most common among African Americans, of whom approximately 1 in 600 are affected with homozygous hemoglobin SS, the most severe of the sickle syndromes. Patients with a single abnormal gene for HbS have sickle cell trait and remain essentially asymptomatic.
- Acute vasoocclusive events, or painful “crisis,” are the most common complication of SCD and are the most frequent cause of emergency department visits.
- A complete blood count and reticulocyte count should be obtained every time a patient with SCD presents to the emergency department.
- Patients with SCD presenting with a new infiltrate on chest radiograph and chest pain, fever, and/or respiratory symptoms have acute chest syndrome (ACS). Therapy for ACS consists of antibiotics, pain control, respiratory support, and possibly transfusion. All children with ACS should be admitted to the hospital.
- A blood culture should be obtained and parenteral antibiotic given to every patient with SCD and fever due to the risk of sepsis from encapsulated bacteria, especially Streptococcus pneumoniae.
- Splenic sequestration crisis occurs when RBCs become entrapped in the spleen, resulting in a rapidly enlarging spleen and a sudden drop in Hgb. The mainstay of therapy is blood transfusion.
- Stroke occurs in 10% of patients with sickle cell anemia under 18 years of age. Patients with signs and symptoms concerning for stroke should have neuroimaging performed (preferably MRI and MRA) and consultation with a hematologist as soon as possible.
Hemoglobin S (Hgb S) is a variant resulting from a single nucleotide mutation in the sixth codon of the β-globin gene leading to the substitution of hydrophobic valine for the normal hydrophilic glutamic acid. Sickle cell disease (SCD) occurs when an individual is homozygous for Hgb S or is a compound heterozygote for Hgb S and another interacting β-globin variant. The most common combination of hemoglobins leading to SCD are Hgb SS (sickle cell anemia), Hgb SC (hemoglobin SC disease), and Hgb S-β thalassemia (either β0 or β+). Although there is wide variability in individual severity of illness, patients with double heterozygous states such as Hgb SC, Hgb Sβ+ thalassemia, and Hgb SD are typically less seriously affected than those with Hgb SS or Hgb Sβ0 (no hemoglobin A production). Approximately 8% of the African American population are sickle trait carriers, with 1 in 600 having sickle cell anemia.1 However, Hgb S also occurs in people of Mediterranean, Indian, Central and South American, and Middle Eastern descent.
Patients with a single abnormal gene for HbS have sickle cell trait. The concentration of HbS is typically 40%, and the large percentage of normal hemoglobin allows the patients to remain asymptomatic except under the most severe hypoxic stress. Sickle trait should be considered a benign condition. Patients with SCD experience a number of complications that are likely to bring them to the emergency department (ED).
Acute vasoocclusive events, or painful “crisis,” are the ...