Ischemic priapism (venocclusive, low-flow priapism) results from failure of blood to drain from the erectile bodies due to prolonged blockage of the draining veins. Ischemic priapism may result from prolonged relaxation of the erectile smooth muscle (generally due to drugs or toxins) or from sludging of blood (due to blood disorders) with subsequent prevention of venous drainage.
The potential causes of ischemic priapism include: penile injection therapy (used by men for erectile dysfunction), medications (including drugs for depression, psychiatric conditions, certain blood pressure medications, cocaine), toxins (spider venom, rabies), intravenous nutrition (called TPN), and blood disorders (including sickle cell disease, thallasemia, leukemia, and multiple myeloma). Erectogenic medications are the most common cause of ischemic priapism in the adult United States population. Sickle cell disease is the commonest cause of priapism in the pediatric and adolescent populations. 40% of all men with Sickle cell disease experience at least one episode of ischemic priapism in their lifetime. There are a group of men with ischemic priapism who have no obvious causes and by definition have idiopathic priapism. This latter condition is often a recurrent problem. Stuttering priapism refers to males who have recurrent episodes of ischemic priapism.