Acute splenic sequestration is characterized by a rapid fall in hemoglobin, a rise in reticulocyte count, a fall in platelet count, acute pain and tenderness in the left upper quadrant with sudden increase in the size of the spleen, and signs and symptoms of hypovolemia.⁷ Splenic sequestration varies in severity from mild to life threatening.

Gallbladder Disease

Cholelithiasis is a relatively common occurrence in HbSS SCD patients because of repeated episodes of hemolysis with resultant bilirubin gallstone formation. The onset of cholelithiasis begins by age 4, and prevalence increases with age. Gallstones develop in approximately 30% of patients with SCD by age 18.⁷ Cholecystitis should be considered in SCD patients with abdominal pain; choledocholithiasis should be considered in patients with signs and symptoms of cholangitis or pancreatitis.

Intrahepatic cholestasis describes the reduction or complete prevention of bile excretion from the liver. In the SCD patient, this can result from erythrocyte sickling within the liver sinusoids, which leads to hepatic ischemia.⁸ Two types of intrahepatic cholestasis can be seen in patients with SCD. Most common is benign cholestasis (benign hyperbilirubinemia), in which the patient’s only symptoms are jaundice and possibly pruritus. It is a self-limited process that resolves without any particular therapy. Progressive cholestasis, on the other hand, although quite rare, has an extremely high mortality rate. These patients will present with right upper quadrant abdominal pain, fever, nausea, vomiting, and jaundice. They can develop a bleeding diathesis, encephalopathy, and renal failure. Abdominal examination reveals hepatomegaly with a tender right upper quadrant. Patients can become coagulopathic because of reduced synthesis of coagulation factors with resulting elevation of prothrombin and partial thromboplastin times. In progressive cholestasis, hepatic ischemia affects all aspects of liver function, which helps to explain its extremely high mortality rate and many symptoms.

Priapism

Priapism is a prolonged (4 hours or longer), painful erection caused by failure of timely penile detumescence. The mean age at which it occurs is 12 years, and it has been estimated that up to 90% of male patients with SCD will experience at least one episode by age 20.⁷ Untreated priapism can lead to cellular damage, fibrosis, and impotence.⁹

Critical Decision

Is it pneumonia, pulmonary infarction, or acute chest syndrome?

Acute chest syndrome is the most common cause of death, the leading cause of admission to an ICU, and the second most common cause (after VOC) of hospitalization in children with SCD.^10,11 The classic findings in acute chest syndrome are chest pain, hypoxia, fever, and a chest radiograph with new pulmonary infiltrates. Other findings include cough, dyspnea, and wheezing. Acute chest syndrome can be easily confused with pneumonia, pulmonary infarction, and pulmonary embolism. With severe presentations, it can even be confused with acute respiratory distress syndrome (ARDS). Acute chest syndrome tends to present two to three days after an episode of VOC; however, it can also present simultaneously with an acute infection. It can be difficult, if not impossible, for emergency physicians to distinguish among pneumonia, pulmonary infarction, and acute chest syndrome. The etiology of acute chest syndrome is multifactorial and includes both infectious and noninfectious causes, and it has been postulated that pneumonia and lung infarction are precipitants of acute chest syndrome.¹² Infectious agents include Streptococcus pneumoniae, H. influenzae, and Klebsiella pneumoniae. Noninfectious causes include pulmonary microvascular sludging, in situ pulmonary vascular thrombus formation, pulmonary parenchymal infarction, and bone marrow fat embolization.

Summary

Understanding SCD is crucial for any emergency physician who treats patients of African or Mediterranean descent. Children with SCD represent a unique challenge, given the potential for life-threatening pulmonary, central nervous system, gastrointestinal, and infectious complications associated with the unique anatomic and physiologic characteristics of children. The additional challenge posed by the difficulties in obtaining an accurate history and physical examination makes it important that emergency physicians understand the complexities of SCD in children.