Type your tag names separated by a space and hit enter

Anemia, Sickle Cell

Anemia, Sickle Cell is a topic covered in the 5-Minute Clinical Consult.

To view the entire topic, please or purchase a subscription.

Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:

Medicine Central

-- The first section of this topic is shown below --



  • Hereditary, hemoglobinopathy marked by chronic hemolytic anemia, acute episodes of painful “crises,” and increased susceptibility to infections
  • The heterozygous condition (Hb AS), sickle cell trait, is usually asymptomatic without anemia.
  • Synonym(s): sickle cell disease (SCD); Hb SS disease
Pediatric Considerations
  • Sequestration crises and hand–foot syndrome seen typically in infants/young children
  • Strokes occur mainly in childhood.
  • Adolescence/young adulthood
    • Frequency of complications and organ/tissue damage increases with age.
    • Psychological complications: body image, interrupted schooling, restriction of activities; stigma of disease; low self-esteem
Pregnancy Considerations
  • Complicated, especially during 3rd trimester and delivery
    • Fetal mortality 35–40%. Fetal survival is >90% if the fetus reaches the 3rd trimester.
    • High prevalence of small for gestational age (SGA) babies
  • Increased risk of thrombosis, preterm delivery, pain, toxemia, infection, pulmonary infarction, and phlebitis
  • Partial exchange transfusion in 3rd trimester may reduce maternal morbidity and fetal mortality but is controversial.
  • Chronic transfusions have been effective in diminishing pain episodes in pregnant women. However, this method should be used with caution due to risk of alloimmunization.


  • ~90,000 Americans have sickle cell anemia (SCA), and 3.5 million people in the United States have sickle cell trait.
  • The condition affects mainly people of African descent. Hispanic, Middle Eastern, and Asian Indian ancestry may also be affected.

Etiology and Pathophysiology

  • Hemoglobin S (HbS) results from the substitution of the amino acid valine for glutamic acid at the sixth position of the β-globin chain.
  • HbS polymerizes in the RBC in the deoxygenated state, resulting in RBC sickling.
  • Sickle RBCs are inflexible, causes increased blood viscosity, stasis, obstruction of small arterioles and capillaries, and ischemia.
  • Chronic anemia; crises
    • Vaso-occlusive crisis: tissue ischemia and necrosis; progressive organ failure/tissue damage from repeated episodes
    • Hand–foot syndrome: Vessel occlusion/ischemia affects small blood vessels in hands or feet.
    • Aplastic crisis: suppression of RBC production by severe infection (e.g., parvoviral and other viral infections)
    • Suppression of RBC production
    • Hyperhemolytic crisis: accelerated hemolysis with reticulocytosis; increased RBC fragility/shortened lifespan
    • Sequestration crisis: splenic sequestration of blood (only in young children as spleen is later lost to autoinfarction)
  • Susceptibility to infection: impaired/absent splenic function leading to decreased ability to clear infection; defect in alternate pathway of complement activation
  • Increased RBC destruction causes decreased hemoglobin levels and results in anemia and fatigue.
  • Sickle cells exhibit increased adhesion and decreased ability to maneuver through small vessels, leading to vaso-occlusion.

  • Autosomal recessive. Homozygous condition, Hb SS; heterozygous condition, Hb AS
  • The heterozygote condition can also be combined with other hemoglobinopathies: Sickle cell hemoglobin C (HbSC) disease and Sβ + thalassemia are clinically similar to the heterozygous condition, whereas Sβ thalassemia is clinically similar to the homozygous condition.

Risk Factors

  • Vaso-occlusive crisis (“painful crisis”): hypoxia, dehydration, fever, infection, acidosis, cold, anesthesia, strenuous physical exercise, smoking
  • Aplastic crisis (suppression of RBC production): severe infections, human parvovirus B19 infection, folic acid deficiency
  • Hyperhemolytic crisis (accelerated hemolysis with reticulocytosis): acute bacterial infections, exposure to oxidant

General Prevention

  • Prevention of crises
    • Avoid hypoxia, dehydration, cold, infection, fever, acidosis, and anesthesia.
    • Prompt management of fever, infections, pain
    • Hydration
    • Avoid alcohol and smoking.
    • Avoid high-altitude areas.
  • Minimizing trauma: Aseptic technique is imperative.

-- To view the remaining sections of this topic, please or purchase a subscription --


Stephens, Mark B., et al., editors. "Anemia, Sickle Cell." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116027/all/Anemia_Sickle_Cell.
Anemia, Sickle Cell. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116027/all/Anemia_Sickle_Cell. Accessed August 21, 2019.
Anemia, Sickle Cell. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116027/all/Anemia_Sickle_Cell
Anemia, Sickle Cell [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 August 21]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116027/all/Anemia_Sickle_Cell.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Anemia, Sickle Cell ID - 116027 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116027/all/Anemia_Sickle_Cell PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -