In a child with sickle cell disease who presents with chest pain during crisis, the pain is most likely due to occlusion of which vascular bed?

• A. Pancreatic ducts occluded.
• B. Pulmonary microcirculation is occluded.
• C. Capillaries in the limbs are occluded.
• D. Coronary arteries occluded.

Answer: (B)

In sickle cell crisis, pain stems from blockage of small vessels by sickled red blood cells. When a child with SCD experiences chest pain during a crisis, the most likely cause is occlusion of the lungs’ microcirculation, leading to acute chest syndrome. The pulmonary microvasculature is particularly susceptible to sickling because of the low-oxygen environment in the lungs and the high flow of blood through this bed, so microvascular occlusion there produces chest pain, hypoxemia, and fever.

Occlusion of other vascular beds would present differently: blocking pancreatic ducts would cause abdominal/pancreatic pain, occluding capillaries in the limbs would cause limb pain and swelling, and coronary artery occlusion would imply myocardial ischemia (less common in children with SCD during a crisis). The chest pain in this context most strongly points to pulmonary microvascular occlusion.