Micturition syncope or post-micturition syncope is the name given to the human phenomenon of
fainting shortly after or during
urination
Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
. The underlying cause is not fully understood, but it may be a result of
vasovagal response,
postural hypotension
Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure drops when standing up or sitting down. Primary orthostatic hypertension is also often referred to as neurogenic orthostatic hyp ...
, or a combination thereof.
People often become pale, lightheaded, nauseated, sweaty and weak before they lose consciousness. Sometimes
defecating
Defecation (or defaecation) follows digestion, and is a necessary process by which organisms eliminate a solid, semisolid, or liquid waste material known as feces from the digestive tract via the anus. The act has a variety of names ranging f ...
,
cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three ph ...
ing, or severe
vomiting
Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose.
Vomiting can be the result of ailments like food poisoning, gastroenter ...
may cause fainting in a similar way.
Causes
When one strains to increase the flow of urine, it stimulates the
vagus nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and righ ...
(usually more pronounced in elderly men with
large prostates). The vagus nerve stimulus causes slowing down of the heart (
bradycardia
Bradycardia (also sinus bradycardia) is a slow resting heart rate, commonly under 60 beats per minute (BPM) as determined by an electrocardiogram. It is considered to be a normal heart rate during sleep, in young and healthy or elderly adults, ...
) and a
drop in
blood pressure
Blood pressure (BP) is the pressure of circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term "blood pressure ...
. The heart cannot perform effectively as a pump because insufficient blood comes to it. It can be associated with a very rare tumour known as a paraprostatic
pheochromocytoma
Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred t ...
within the urinary bladder.
Treatment
There is no specific treatment for micturition syncope. General advice to men with micturition syncope includes:
* to sit while urinating
* to sit on the edge of the bed for a while before getting up and going to the toilet
* to avoid urinating while sleepy
* to urinate before sleep
* to stop urination, cross the legs, and flex them immediately upon feeling faintness
Epidemiology
Responsible for 2.4 to 8.4 percent of all cases of fainting in
adult
An adult is a human or other animal that has reached full growth. In human context, the term ''adult'' has meanings associated with social and legal concepts. In contrast to a " minor", a legal adult is a person who has attained the age of maj ...
s, it most commonly occurs in
male
Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization.
A male organism cannot reproduce sexually without access to ...
s. The events often occur at night or after awaking.
References
{{reflist
External links
Micturition Syncope - Patient Plus
Urological conditions