In vaso-occlusive crisis, what causes the vessels to become occluded?

In vaso-occlusive crisis, also commonly referred to as a sickle cell crisis, the primary issue arises from the presence of abnormal red blood cells (RBCs). These RBCs, due to their sickle shape, can become rigid and sticky, leading to blockages in small blood vessels. This is particularly relevant in individuals with sickle cell disease, where the abnormal hemoglobin causes the red blood cells to change shape under conditions of low oxygen, dehydration, or other stressors.

When these sickle-shaped cells aggregate or clump together, they obstruct blood flow, which can result in tissue ischemia and pain. The occlusion of blood vessels leads to a cascade of inflammatory responses and complications, emphasizing the critical role that these abnormal red blood cells have in initiating and perpetuating the crisis.