Splenic Infarction
The most likely diagnosis is splenic infarction (option e), which occurs when a hemoglobin S carrier experiences hypoxia at high altitude during mountain climbing, triggering red blood cell sickling and vascular occlusion in the spleen. 1, 2, 3
Pathophysiologic Mechanism in Sickle Cell Trait
- Hypoxia at high altitude is the fundamental trigger that causes hemoglobin S polymerization and red blood cell sickling, even in carriers who have only one abnormal gene 2
- The reduced ambient oxygen availability during mountain climbing creates the exact physiologic conditions (hypoxemia, dehydration, acidosis) that promote sickling 1, 2
- Sickled red blood cells cause vascular occlusion in the splenic microvasculature, leading to ischemic infarction 1, 3
Clinical Presentation
- Left upper quadrant or left shoulder pain is the classic presentation of splenic infarction, with the shoulder pain representing referred pain from diaphragmatic irritation 4, 3
- The 3-day timeline after mountain climbing fits perfectly with the delayed presentation of altitude-induced splenic infarction 3
- This specific scenario—a hemoglobin S carrier with left shoulder pain after high-altitude exposure—is a well-documented clinical entity 3
Why Other Options Are Incorrect
- Pneumonia (a): Would present with respiratory symptoms (cough, dyspnea, fever) and would not be specifically linked to sickle cell trait or altitude exposure 3
- Shoulder dislocation (b): Would require direct trauma and would show obvious physical examination findings of joint deformity 5
- Brachial vein thrombosis (c): Not associated with sickle cell trait or altitude exposure, and would present with arm swelling rather than shoulder pain 5
- Cholecystitis (d): Presents with right upper quadrant pain, not left-sided pain 4
Diagnostic Confirmation
- Enhanced CT scan is the gold standard for confirming splenic infarction, showing wedge-shaped areas of non-enhancement 4, 3
- Hemoglobin electrophoresis should be performed to confirm sickle cell trait (typically showing 40% hemoglobin S) 3, 6
- The peripheral blood smear may appear normal in carriers, unlike in sickle cell disease 3
Critical Clinical Pitfall
Emergency physicians must recognize that sickle cell trait carriers are NOT immune to complications—they can develop serious vascular occlusive events under specific high-risk conditions like high altitude, intense exercise, dehydration, or hyperthermia 1, 2. The combination of being a hemoglobin S carrier + recent high-altitude exposure + left shoulder pain is pathognomonic for splenic infarction 3.