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Clinical Characteristics

The underlying problems for patients with sickle cell disease are (1) the hemolytic anemia, and (2) the sickle shape of the red cell, which makes the blood more viscous. There is clumping of the cells leading to blocking of the capillaries. Such vaso-occlusion can occur anywhere and will present clinically as ischemia or infarction. Because the infarcts can affect any part of the body, the clinical findings are protean, and sickle cell disease is as great an imitator of other conditions as are syphilis and tuberculosis. In the sickle cell trait, there is an increased frequency of hemoglobinuria, but no other clinical symptoms.

Sickle cell anemia is primarily a pediatric disease that becomes clinically apparent from about 4 months of age onwards. Until that time, the fetal hemoglobin persists in sufficient amounts to prevent sickling. Some patients survive to become adults but throughout most of the tropics, particularly where medical facilities are limited, it is children who are affected.

The appearance of children with sickle cell disease is often characteristic; there is bossing of the frontal and parietal bones and the maxilla is prominent. Because there is some flattening of the vertebrae, the arms and legs appear longer than normal. As a result of previous infarction, there may be altered and delayed development in some of the digits. (The cause of these findings is discussed under the "Imaging Diagnosis" section.)

A common presentation in children is swelling and pain in the hands or feet; parents may notice that the child is limping. Diffuse pain may also occur in the joints, but seldom causes limitation of function. The limb swelling may be symmetrical and is usually related anatomically to the pain. In the tropics bone infarction may be complicated by a low grade osteomyelitis, which can occur in multiple sites simultaneously. If there is sufficient vascular stasis, there may be peripheral gangrene. Other complaints will be weakness, abdominal pain, jaundice, and loss of appetite. In older children and adults it is often the symptoms of anemia that bring the patient to the physician. Less commonly, subarachnoid hemorrhage may occur. In poorer tropical countries, protein malnutrition, dysentery, parasites, and other infections add to the mortality. Systemic typhoid can occur.

Clinical examination will show enlargement of the liver in many patients. In early childhood the spleen is usually enlarged and subject to painful attacks of infarction. The resulting fibrosis renders the spleen nonpalpable by the age of 10 years. However, where malaria is endemic, splenomegaly may persist. If the infarction is severe and there is secondary infection, a splenic abscess may occur. Pain, vomiting, and abdominal distension can also result from mesenteric occlusion, which is self-limiting in most patients and resolves in 2 to 3 days. The clinical and radiological findings cannot easily be distinguished from other types of peritonitis, but surgery is contraindicated. This is a major diagnostic problem requiring skillful clinical judgment.

Damage to the kidney impairs ability to concentrate urine (isosthenuria) and increases the risk of pyelonephritis. Renal infarction causes hematuria and may lead to papillary necrosis; albuminuria and the nephrotic syndrome also occur. Priapism can occur and is occasionally the presenting symptom. Priapism results from sequestration of sickled cells within the corpora cavernosa and obstruction of venous outflow from the penis. This may eventually lead to impotence. In North American and West Indian black people, there is an increased incidence of gallstones and chronic leg ulceration, though neither is common anywhere else in the tropics. The gallstones are pigment stones and result from hyperbilirubinemia. This increased incidence may be related to diet and an increased incidence of vascular diseases in many Western Hemisphere blacks.

Patients with sickle cell disease go through "crises". These were previously known as "hemolytic crises," but there is usually no evidence of excessive hemolysis; rather, there is stasis and sequestration of blood cells causing tissue anoxia and leading to infarction. Sickle cell crises are commonly precipitated by infection and are most frequent at times when malarial transmission is at its highest, such as during the rainy season. Late in the disease the heart may become enlarged and, because of pulmonary infarction, cor pulmonale develops.

During pregnancy the crises increase in frequency; placental infarction is common, and there is a high abortion and stillbirth rate. There is an increase in premature delivery, and damage to the uterus may cause it to rupture during labor. The anemia adds to the risk of cardiac failure during pregnancy; there is also an increase in maternal mortality resulting from pulmonary embolization by bone marrow during pregnancy and the puerperium.

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Copyright: Palmer and Reeder