A 24-year-old Indian man comes to the emergency department due to 3 days of left upper quadrant abdominal pain. The pain began after he flew back from India, where he was visiting family. He has had no fever, palpitations, nausea, vomiting, or diarrhea. He does not use tobacco or alcohol regularly, but on the flight back to the United States, he had some alcohol to help him sleep. He has no chronic medical conditions and takes no medications. Temperature is 37.3 C (99.1 F), blood pressure is 120/80 mm Hg, pulse is 96/min, and respirations are 16/min. Pulse oximetry is 97% on room air. Mucous membranes are moist, and there is no jugular venous distension or palpable lymphadenopathy. Cardiopulmonary auscultation is normal. Abdominal examination reveals left upper quadrant tenderness with no rigidity or rebound guarding. Bowel sounds are present, and there is no hepatosplenomegaly. There is no lower extremity edema or skin rashes. Laboratory results are as follows:
| Complete blood count | |
| Hemoglobin | 14.1 g/dL |
| Reticulocytes | 2.5% |
| Platelets | 220,000/mm3 |
| Leukocytes | 10,400/mm3 |
| Liver function studies | |
| Indirect bilirubin | 1.7 mg/dL |
Abdominal ultrasound shows normal liver size, but the spleen is slightly enlarged with a hypoechoic wedge consistent with an infarction. Which of the following would be most helpful in determining the underlying cause of his current condition?
This patient underwent a long plane flight and developed a splenic infarction, an uncommon condition that usually arises in the setting of acute splenic artery (or subbranch) occlusion; possible underlying etiologies include a hypercoagulable state, embolic disease, or hemoglobinopathy. In this patient, a mild hemoglobinopathy such as sickle cell trait is most likely given the mild intravascular hemolysis (eg, elevated reticulocyte count, indirect hyperbilirubinemia), normal hemoglobin level, and negative past medical history for pain crises (making sickle cell disease unlikely).
Sickle hemoglobin mutations are often linked to Sub-Saharan Africa but are also common in other regions that have a high burden of malaria, including Central/South America, the Caribbean, the Middle East, the Mediterranean, and India. Most patients with sickle cell trait (eg, one altered beta-hemoglobin chain) are asymptomatic and considered benign carriers; however, certain stressors, such as flying at high altitude or dehydration due to alcohol consumption, can sometimes lead to intravascular hemolysis, tissue ischemia (eg, splenic infarction), and/or vasoocclusive pain. Hemoglobin electrophoresis is diagnostic.
(Choice A) 24-hour ECG monitoring can diagnose atrial fibrillation, which can cause splenic infarction due to atrial thromboembolism. However, atrial fibrillation would be unusual in a 24-year-old and does not typically cause reticulocytosis or bilirubinemia.
(Choice B) Blood cultures can diagnose infective endocarditis, which can cause splenic infarction due to septic thromboembolism. However, most patients are ill (eg, fever, chills, anorexia, weight loss) and cardiac murmur is usually present on examination.
(Choice C) Bone marrow biopsy can diagnose hematopoietic malignancies such as myelofibrosis, which may cause splenic infarction due to venous occlusion from congestive splenomegaly. However, myelofibrosis typically presents in older adults and causes splenomegaly (a hallmark feature not seen in this patient).
(Choice D) Factor V Leiden mutation is a common cause of thrombosis in middle-aged adults and typically causes venous thromboembolism, which can occasionally lead to splenic infarction. However, signs of intravascular hemolysis are not typically present.
Educational objective:
Splenic infarction usually occurs in the setting of splenic artery (or subbranch) occlusion due to hypercoagulable states, embolic disease, or hemoglobinopathy (eg, sickle cell disease or trait). Although patients with sickle cell trait are generally asymptomatic, they occasionally develop splenic infarction and intravascular hemolysis in the setting of certain stressors such as air travel or dehydration. Diagnosis of most hemoglobinopathies is made by hemoglobin electrophoresis.