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an acute exacerbation may require steroids as part of their management; however, a taper beyond the standard 5-day course is necessary Stroke Initial Assessment The combined incidence of ischemic and hemorrhagic stroke is nearly 300-fold higher in patients with sickle cell disease compared with all children Eleven percent of all sickle cell anemia patients will suffer a stroke, with occurrence at a median age of 20 years Fatalities with ischemic strokes are less likely than with hemorrhagic stroke; however, neurologic sequelae are common with both Typical presenting symptoms and signs for ischemic stroke include focal weakness, dysarthria, aphasia, and seizure Hemorrhagic strokes present with evidence of increased intracranial pressure including severe headache, vomiting, impaired mental status, bradycardia, nuchal rigidity, coma, focal neurologic deficits, and seizure Risk factors include young age, low baseline hemoglobin concentration, and high leukocyte count Historical risk factors include previous stroke, moyamoya, cerebral aneurysms, acute chest syndrome, acute hypertension, hypertransfusion, and recent corticosteroid use Cerebral aneurysms occur with increased frequency in patients with sickle cell disease The origin of this complication, which is usually detected in teenagers or adults, remains obscure but may relate to local vessel damage The severe morbidity and high mortality associated with ruptured cerebral aneurysms require careful evaluation of patients with sickle cell disease and headaches or other neurologic findings (vertigo, syncope, nystagmus, ptosis, meningismus, or photophobia) Unfortunately, the aneurysm often escapes detection until after major, and often fatal, subarachnoid or intracerebral bleeding Management/Diagnostic Testing Use CT for initial evaluation of sickle cell patients with concern for stroke MRI can assist in early diagnosis in ischemic strokes (within to hours of symptoms) that may not be apparent on CT A 1.5 to times volume exchange transfusion should begin immediately for ischemic strokes This reduces the likelihood of further intravascular sickling and may prevent extension of cortical damage MRA should be performed in patients with identified intracranial hemorrhage to guide further diagnosis and management If an accessible aneurysm is identified and bleeding persists, surgical or interventional radiology intervention should follow radiologic confirmation Anemia Initial Assessment/H&P The baseline anemia of a patient with sickle cell disease may worsen acutely due to acute hemolysis triggered by a viral or bacterial infection or by an aplastic crisis usually in the setting of infection with parvovirus B19 halting RBC production for to days In both cases, patients will present with fatigue, pallor (or jaundice if hemolysis is present), and tachycardia Management/Diagnostic Testing Laboratory studies will demonstrate a fall in the hemoglobin from baseline Patients with a hemolytic crisis will typically have scleral icterus, jaundice, and a reticulocytosis Both hemolytic and aplastic crises are usually self-limited; once the infection clears, the patient recovers Patients with severe symptoms such as altered mental status, impaired oxygen delivery, and significant tachycardia should receive a transfusion of pRBCs Transfusion volume should be calculated to target the patient’s baseline hemoglobin level and not exceed 10 to 11 g/dL Splenic Sequestration Initial Assessment/H&P Splenic sequestration, a potentially life-threatening event, usually presents in children younger than years of age before the spleen has completely fibrosed The lifetime risk is 20% It may be the first presenting symptom of sickle cell disease in children less than years Patients with HbSC and sickle β-thalassemia have less splenic fibrosis and may experience splenic sequestration at any age During sequestration, the spleen becomes acutely engorged in some cases with a significant portion of the blood volume Patients will present with acute onset of left upper quadrant abdominal pain, progressive pallor, increasing tachycardia, and lethargy over several hours The spleen is palpable and may be tender A prominent reticulocytosis is usually present Hypotension and cardiovascular collapse can occur with a 10% to 15% mortality rate Management/Diagnostic Testing The mainstay of treatment is replenishment of the intravascular volume for patients in hypovolemic shock Resuscitation with crystalloid is used to stabilize perfusion emergently However, aggressive crystalloid use can compromise tissue oxygenation due to dilutional worsening of anemia Transfuse pRBCs for patients in shock (5 to 10 mL/kg; begin carefully with to mL/kg) Since RBCs will be released from the spleen as the sequestration reverses, not overcorrect the hemoglobin (return it to patient’s baseline) with initial transfusion to avoid complications of circulatory overload and erythrocytosis Reversal of shock and a rising hemoglobin level signal improvement of a sequestration crisis The spleen becomes less firm and smaller over the course of days For milder cases, admission for serial splenic examinations and establishing trend of hemoglobin is appropriate Papillary Necrosis Initial Assessment/H&P Papillary necrosis in the kidneys causes hematuria that is usually sudden and painless and often persistent A history of recent trauma, streptococcal infection, or recurrent urinary tract infection should alert the physician to other causes of hematuria Similarly, hypertension suggests the presence of nephritis rather than simple vasoocclusion Management/Diagnostic Testing Laboratory evaluation should include CBC, reticulocyte count, type and cross, electrolytes, BUN/Cr, and urinalysis In papillary necrosis, microscopic examination of the urine shows numerous RBCs but RBC casts are rarely seen Pyuria and proteinuria in excess of what might be attributed to the blood in the urine are not found in papillary necrosis and may indicate nephritis Renal ultrasound may be obtained to confirm the diagnosis or evaluate for alternative etiologies for the hematuria Admission to the hospital is often required for IV hydration In severe hematuria, significant anemia may necessitate RBC transfusion Simple or exchange transfusion may also shorten the course of ongoing hematuria The lifetime risk of renal failure is 11% Avascular Necrosis Sickle cell disease is the most common cause of pediatric femoral head avascular necrosis This complication is even more common in patients with HbSC disease The lifetime risk of avascular necrosis is 21% Risk factors include a high baseline hematocrit and a clinical history of frequent or severe painful crises Management/Diagnostic Testing Treatment options are limited Bed rest and core decompression are the initial approaches Total hip replacement may become necessary Transfusions Patients with sickle cell disease may receive many transfusions throughout their lives and are at risk for developing alloantibodies Perform extended RBC antigen testing before their first transfusion; their primary hematologist usually performs this during routine outpatient monitoring Alloantibodies make future cross-matching more challenging and increase the risk of a hemolytic transfusion reaction Ensure that local blood banks communicate with the blood bank at patient’s primary institution The volume of simple transfusion should be calculated to avoid raising the patient’s hemoglobin level above 10 to 11 g/dL Exchange transfusion may be needed in some clinical settings, as discussed in the complication sections above; this procedure requires adequate large-bore IV access, or central venous access, and often requires a plasmapheresis machine Infants may be exchange transfused with simple syringes in consultation with a hematologist If sophisticated blood banking services are not available, consider transferring the patient to an appropriate center Clinical Indications for Discharge or Admission For patients with vasoocclusive crises, admit for IV analgesics if their pain is inadequately managed with an oral pain regimen Additionally, admit patients who are unable to maintain adequate oral intake and are at risk of dehydration Ill-appearing patients or those with clinical concern for acute chest syndrome, sepsis, splenic sequestration, or stroke require hospitalization and potentially intensive care management Consider hospitalization for febrile patients who are well appearing but are younger than months, underimmunized, if there is a concern for the reliability of follow-up, and in those with more than 5% (absolute) drop in hematocrit below baseline, or a Hb