However, during times of systemic hypoperfusion, such as in disseminated intravascular coagulation or heart failure, these regions are particularly vulnerable to ischemia because they are supplied by the most distal branches of their arteries, and thus the least likely to receive sufficient blood.
Additionally, the sigmoid colon and rectum form a watershed zone with blood supply from inferior mesenteric, pudendal and iliac circulations.
Hypoperfusion in watershed areas can lead to mural and mucosal infarction in the case of ischemic bowel disease.
When watershed stroke occurs in the brain, it produces unique focal neurologic symptoms that aid clinicians in diagnosis and localization.
For example, a cerebral watershed area is situated in the dorsal prefrontal cortex; when it is affected on the left side, this can lead to transcortical motor aphasia.