Micturition syncope
Encyclopedia
Micturition syncope or post-micturition syncope is the name given to the human phenomenon of fainting shortly after or during urination
.
People often become pale, nauseated, sweaty and weak before they lose consciousness. Sometimes even defecating, cough
ing or severe vomiting
may cause fainting in a similar way.
s, it most commonly occurs in male
s. The events often occur at night or after awaking (this means that it occurs while standing immediately after being recumbent for some time).
(usually more pronounced in elderly men with large prostates
). The vagus nerve stimulus causes slowing down of the heart (bradycardia
) and severe drop
in blood pressure
. The heart cannot perform as a pump effectively because insufficient blood comes to it.
Urination
Urination, also known as micturition, voiding, peeing, weeing, pissing, and more rarely, emiction, is the ejection of urine from the urinary bladder through the urethra to the outside of the body. In healthy humans the process of urination is under voluntary control...
.
People often become pale, nauseated, sweaty and weak before they lose consciousness. Sometimes even defecating, cough
Cough
A cough is a sudden and often repetitively occurring reflex which helps to clear the large breathing passages from secretions, irritants, foreign particles and microbes...
ing or severe vomiting
Vomiting
Vomiting is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose...
may cause fainting in a similar way.
Epidemiology
Responsible for 2.4 to 8.4 percent of all cases of fainting in adultAdult
An adult is a human being or living organism that is of relatively mature age, typically associated with sexual maturity and the attainment of reproductive age....
s, it most commonly occurs in male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s. The events often occur at night or after awaking (this means that it occurs while standing immediately after being recumbent for some time).
Causes
When one strains to increase the flow of urine it stimulates the vagus nerveVagus nerve
The vagus nerve , also called pneumogastric nerve or cranial nerve X, is the tenth of twelve paired cranial nerves...
(usually more pronounced in elderly men with large prostates
Benign prostatic hyperplasia
Benign prostatic hyperplasia also known as benign prostatic hypertrophy , benign enlargement of the prostate , and adenofibromyomatous hyperplasia, refers to the increase in size of the prostate....
). The vagus nerve stimulus causes slowing down of the heart (bradycardia
Bradycardia
Bradycardia , in the context of adult medicine, is the resting heart rate of under 60 beats per minute, though it is seldom symptomatic until the rate drops below 50 beat/min. It may cause cardiac arrest in some patients, because those with bradycardia may not be pumping enough oxygen to their heart...
) and severe drop
Hypotension
In physiology and medicine, hypotension is abnormally low blood pressure, especially in the arteries of the systemic circulation. It is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the...
in blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...
. The heart cannot perform as a pump effectively because insufficient blood comes to it.