Which test is utilized to determine if priapism is ischemic or nonischemic?

The determination of whether priapism is ischemic or nonischemic is most accurately made through the analysis of blood gas levels in the penis, specifically through a blood gas analysis (ABG). In cases of ischemic priapism, the blood in the corpus cavernosum becomes deoxygenated due to impaired venous outflow, leading to hypoxia and acidosis, which can be detected during the blood gas analysis. This will show low oxygen levels and potentially elevated levels of carbon dioxide and decreased pH.

In contrast, nonischemic priapism typically results from an arterial blood flow issue, usually due to trauma, and the blood remains oxygenated, so a blood gas analysis would reflect normal or near-normal levels of oxygen and pH. Thus, by looking at these gas levels, clinicians can distinguish between the two types of priapism effectively.

Other imaging methods like CT scans, X-rays, and MRIs are not routinely used for this specific purpose as they do not provide the necessary metabolic and gas exchange information needed to differentiate between ischemic and nonischemic states.