Sickle-cell disease may lead to various acute and chronic complications, several of which are potentially lethal.
Vaso-occlusive crisis
The vaso-occlusive crisis is caused by sickle-shaped red blood cells that obstruct capillaries and restrict blood flow to an organ, resulting in ischemia, pain, and often organ damage. The frequency, severity, and duration of these crises vary considerably. Painful crises are treated with hydration and analgesics; pain management requires opioid administration at regular intervals until the crisis has settled. For milder crises, a subgroup of patients manage on NSAIDs (such as diclofenac or naproxen). For more severe crises, most patients require inpatient management for intravenous opioids; patient-controlled analgesia (PCA) devices are commonly used in this setting. Diphenhydramine is sometimes effective for the itching associated with the opioid use. Incentive spirometry, a technique to encourage deep breathing to minimise the development of atelectasis, is recommended.
Because of its narrow vessels and function in clearing defective red blood cells, the spleen is frequently affected. It is usually infarcted before the end of childhood in individuals suffering from sickle-cell anaemia. This autosplenectomy increases the risk of infection from encapsulated organisms; preventive antibiotics and vaccinations are recommended for those with such asplenia.
One of the earliest clinical manifestations is dactylitis, presenting as early as six months of age, and may occur in children with sickle trait. The crisis can last up to a month. Another recognised type of sickle crisis is the acute chest syndrome, a condition characterised by fever, chest pain, difficulty breathing, and pulmonary infiltrate on a chest X-ray. Given that pneumonia and sickling in the lung can both produce these symptoms, the patient is treated for both conditions. It can be triggered by painful crisis, respiratory infection, bone-marrow embolisation, or possibly by atelectasis, opiate administration, or surgery.
Most episodes of sickle cell crises last between five and seven days.
Other sickle-cell crises
- ''Aplastic crises'' are acute worsenings of the patient's baseline anaemia, producing pallor, tachycardia, and fatigue. This crisis is triggered by parvovirus B19, which directly affects erythropoiesis (production of red blood cells). Parvovirus infection nearly completely prevents red blood cell production for two to three days. In normal individuals, this is of little consequence, but the shortened red cell life of sickle-cell patients results in an abrupt, life-threatening situation. Reticulocyte counts drop dramatically during the disease, and the rapid turnover of red cells leads to the drop in hemoglobin. Most patients can be managed supportively; some need blood transfusion.
- ''Splenic sequestration crises'' are acute, painful enlargements of the spleen. The abdomen becomes bloated and very hard. Management is supportive, sometimes with blood transfusion.
- ''Hemolytic crises'' are acute accelerated drops in hemoglobin level. The red blood cells break down at a faster rate. This is particularly common in patients with co-existent G6PD deficiency. Management is supportive, sometimes with blood transfusions.
Complications
Sickle-cell anaemia can lead to various complications, including:
- Overwhelming post-(auto)splenectomy infection (OPSI), which is due to functional asplenia, caused by encapsulated organisms such as ''Streptococcus pneumoniae'' and ''Haemophilus influenzae''. Daily penicillin prophylaxis is the most commonly used treatment during childhood, with some haematologists continuing treatment indefinitely. Patients benefit today from routine vaccination for ''H. influenzae'', ''S. pneumoniae'', and ''Neisseria meningitidis''.
- Stroke, which can result from a progressive vascular narrowing of blood vessels, preventing oxygen from reaching the brain. Cerebral infarction occurs in children, and cerebral hemorrhage in adults.
- Cholelithiasis (gallstones) and cholecystitis, which may result from excessive bilirubin production and precipitation due to prolonged haemolysis.
- Jaundice, yellowing of the skin, may occur due to the inability of the liver to effectively remove bilirubin from the filtering of damaged red blood cells out of the blood supply as well as blocks in the organ's blood supply.
- Avascular necrosis (aseptic bone necrosis) of the hip and other major joints, which may occur as a result of ischemia.
- Decreased immune reactions due to hyposplenism (malfunctioning of the spleen).
- Priapism and infarction of the penis.
- Osteomyelitis (bacterial bone infection), which is most frequently caused by ''Salmonella'' in individuals with sickle-cell disease, whereas ''Staphylococcus'' is the most common causative organism in the general population.
- Opioid tolerance, which can occur as a normal, physiologic response to the therapeutic use of opiates. Addiction to opiates occurs no more commonly among individuals with sickle-cell disease than among other individuals treated with opiates for other reasons.
- Acute papillary necrosis in the kidneys.
- Leg ulcers.
- In eyes, background retinopathy, proliferative retinopathy, vitreous haemorrhages and retinal detachments, resulting in blindness. Regular annual eye checks are recommended.
- During pregnancy, intrauterine growth retardation, spontaneous abortion, and pre-eclampsia.
- Chronic pain: Even in the absence of acute vaso-occlusive pain, many patients have chronic pain that is not reported.
- Pulmonary hypertension (increased pressure on the pulmonary artery), leading to strain on the right ventricle and a risk of heart failure; typical symptoms are shortness of breath, decreased exercise tolerance and episodes of syncope.
- Chronic renal failure—manifests itself with hypertension (high blood pressure), proteinuria (protein loss in the urine), hematuria (loss of red blood cells in urine) and worsened anaemia. If it progresses to end-stage renal failure, it carries a poor prognosis.
Heterozygotes
The heterozygous form (sickle cell trait) is almost always asymptomatic, and the only usual significant manifestation is the renal concentrating defect presenting with isosthenuria.
Further Reading
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