Micturation syncope is a relatively rare phenomenon (2.4 to 8.4% of fainting episodes) which most commonly affects males, and can often be diagnosed by simply taking a thorough history.
Straining to urinate triggers the vagus nerve which results in hypotension and bradycardia; in turn, cardiac output and brain perfusion is decreased, often resulting in diaphoresis, pallor, and weakness, followed by syncope or fainting.
This process is transient and vital signs as well as consciousness typically return to normal rapidly.
When evaluating a patient for syncope, pay close attention for the presence of the following factors in order to make the diagnosis:
-- occurs during or immediately following urination, often when bladder is full.
-- occurs at night or after standing from the recumbent position of a deep sleep to urinate.
