Sickle Cell Anemia Case Definition

A hereditary chronic form of anemia in which abnormal sickle or crescent-shaped erythrocytes are present. Due to the presence of abnormal type of hemoglobin, hemoglobin S, in the red blood cells. The frequency of the gene that causes this disease is high in Mediterranean and African populations.
Taber's Cyclopedic Medical Dictionary

Sickle Cell Crises:
The sickled cells interfere with oxygen transport, obstruct capillary blood flow, and cause fever and severe pain in joints and the abdomen. The abdominal pain may simulate that caused by appendicitis or other indications for surgical intervention. The crisis is precipitated by decreased ambient oxygen as can occur during flying at high altitude without use of supplemental oxygen.
Taber's Cyclopedic Medical Dictionary