Parcopresis can be described as "an inability to defecate when other people are perceived or likely to be around (e.g. in the same public toilet, house or building)". This inability restricts the sufferer's lifestyle by requiring that s/he defecate only in a limited number of 'safe' places, with less severe presentations also permitting defecation in places where the person is unknown and unlikely to become known in the future, such that any embarrassment is unlikely to have consequences lasting beyond the defecative episode itself (in effect a mundane application of the reasoning that the "game" in question is non-iterative). The level of restriction varies depending on the severity of each sufferer's condition but in extreme cases it can force people to give up their jobs, avoid holidays they would love to take, and generally dictate and limit most aspects of their lives.

It affects both men and women, of all ages and backgrounds. It is not clear how many people suffer with the condition, and level of severity is a key factor as some people may not find it affects their lives, while others find their lives are dictated by its demands.

One form of treatment is Cognitive behavioral therapy which promotes desensitization methods.

Several definitions have been offered:

- "Absence of normal relaxation of pelvic floor muscles during defecation, resulting in rectal outlet obstruction".

- "Malfunction (a focal dystonia) of the external anal sphincter and puborectalis muscle during defecation".

- "[...] failure of [the external anal sphincter and puborectalis] muscle[s] to relax, resulting in maintenance of the anorectal angle and the difficulty with initiating and completing bowel movements".

- "[...] failure of relaxation (or paradoxic contraction) of the puborectalis muscle sling during defaecation, attempted defaecation or straining."

Anismus is classified as a functional defecation disorder. It is also a type of rectal outlet obstruction (a functional outlet obstruction). Where anismus causes constipation, it is an example of functional constipation. Some authors describe an "obstructed defecation syndrome", of which anismus is a cause.

The Rome classification subdivides functional defecation disorders into 3 types, however the symptoms the patient experiences are identical.

- Type I: paradoxical contraction of the pelvic floor muscles during attempted defecation

- Type II: inadequate propulsive forces during attempted defecation (inadequate defecatory propulsion)

- Type III: impaired relaxation with adequate propulsion

It can be seen from the above classification that many of the terms that have been used interchangeably with anismus are inappropriately specific and neglect the concept of impaired propulsion. Similarly, some of the definitions that have been offered are also too restrictive.

It appears that paruresis involves a tightening of the sphincter and/or bladder neck due to a sympathetic nervous system response. The adrenaline rush that produces the involuntary nervous system response probably has peripheral and central nervous system involvement. The internal urethral sphincter (smooth muscle tissue) or the external urethral sphincter (striated muscle), levator ani (especially the pubococcygeus) muscle area, or some combination of the above, may be involved. It is possible that there is an inhibition of the detrusor command through a reflex pathway as well. The pontine micturition center (Barrington's nucleus) also may be involved, as its inhibition results in relaxation of the detrusor and prevents the relaxation of the internal sphincter.

Paruresis ( ) is a type of phobia in which the sufferer is unable to urinate in the real or imaginary presence of others, such as in a public restroom. The analogous condition that affects bowel movement is called parcopresis.