Many reports on the treatment and diagnosis of incontinence have been published in recent years. Gas and faecal incontinence is a serious disability and, depending on its severity, it may lead to a varying degree of social exclusion. Due to the embarrassing nature of the disorder, all epidemiological estimates are imprecise and certainly largely underestimated. Incontinence is more common among women, which is related to both the sex differences in the anatomical structure of the sphincters, as well as to childbirth. Some epidemiological data indicate that up to about 9% of adult women experience episodes of faecal incontinence at least once a month. Women with obstetric sphincter injuries (forcep or vacuum delivery) are at particular risk (1).

According to some reports, gas and faecal incontinence affects from 2 to up to 21% of the adult population (2, 3). Incontinence is more common in the elderly, which may be associated with dementia, pelvic floor descent, sphincter fibrosis and lumbar pathologies. An interesting study in a group of adult patients who reported underwear soiling was presented by Bouchouch et al. (4). The aim of the study was to search for psychological and clinical correlates in patients experiencing soiling. The authors pointed out that both patients and physicians often confuse symptoms related to soiling with those of faecal incontinence. A total of 1,454 consecutive outpatients (71% women) were enrolled in the study. A Rome III questionnaire, psychological tools to assess depression and anxiety, as well as Likert scales for constipation, diarrhoea, flatulence and abdominal pain were used. Soiling was reported by 123 patients (8.5%). These patients had a higher incidence of irritable bowel symptoms such as diarrhoea, as well as functional constipation and levator ani syndrome. No relationship was found with psychological assessment. In the study group, the symptoms of soiling were mainly associated with irritable bowel syndrome (IBS) and functional diarrhoea.

In order to understand the causes of incontinence, it is necessary to become aware of the multifactorial mechanism underlying faecal continence.

The key factors contributing to continence include:

1. Sphincter muscle system – the puborectalis muscle, which “encloses” posteriorly the U-shaped rectum and acts dynamically during bowel movement, is the most essential muscle for continence. Damage to the arms of the puborectalis muscle leads to complete rectal immobility and involuntary faecal leak. The other two sphincter muscles are the striated (voluntary) external sphincter muscle, which divides into three parts: subcutaneous, superficial, and deep, and the thin, smooth (involuntary) internal sphincter muscle. The external sphincter is responsible for keeping solid stool, while the internal sphincter prevents the leakage of liquid stool and gas. It should be emphasised that even extensive sphincter damage can be compensated by the strong puborectalis muscle, whose function is irreplaceable. In practice, we observe patients several years after childbirth, during which external sphincter damage occurred, who develop symptoms of incontinence only after menopause, when the compensatory effect of the puborectalis muscle is significantly compromised.

2. Rectal compliance – this characteristic is directly related to the action of sensory receptors located in the rectal wall. Since the decrease in rectal compliance is age-related, this is a common cause of involuntary bowel movement in elderly people.

3. Sensory innervation, mainly parasympathetic (L2-L4) – the pudendal nerve provides sensory supply to the perineum, and motor supply to anal and urethral sphincters, and any damage to this nerve at any level of its course may result in faecal, gas, and urinary incontinence, without accompanying damage to muscle structures.

Most patients, as well as some doctors, identify the cause of faecal incontinence with an injury to the anal sphincters (fig. 1). As mentioned above, this is only one of the causes of the disorder.

Other causes include:

• vaginal delivery without sphincter injury, but with complete or partial damage to the pudendal nerve,

• diseases of the central and peripheral nervous system (cancer, spinal cord injuries, neurological disorders),

• inflammatory bowel diseases (Crohn’s disease, ulcerative colitis),

• chronic diarrhoea,

• complications after colorectal surgeries (low anterior resection of the rectum, rectopexy),

• systemic disorders, e.g. diabetes, hyperthyroidism, obesity,

• IBS,

• mental disorders, depression,

• old age, dementia.

The simplest and probably the most commonly used classification system distinguishes mechanical (sphincter damage), neurogenic (nerve damage) and mixed (both of the above factors) incontinence.

There have also been interesting attempts at other classification systems, taking into account the coexisting symptoms and the aetiological factor.

Cauley et al. (5) considered constipation in their classification and divided patients into those who reported isolated faecal incontinence (FI) and those with incontinence accompanied by constipation. They assessed a group of 946 FI patients. Concomitant constipation was found in 656 (69.3%) patients. Patients with FI and constipation were less likely to report a history of pregnancy (89.2 vs 91.4%) or a complicated delivery. Concomitant pelvic organ prolapse, urinary incontinence and higher manometry parameters were more common in patients with FI and constipation. Intussusception was a common defecography finding. Quality of life scores decreased with increasing severity of constipation. The authors of the study came to an interesting conclusion, believing that patients with FI and concomitant constipation represent a different disease phenotype, have different clinical and anorectal physiology test findings, and report a worse overall quality of life. The management of these patients requires careful evaluation and coordinated management of comorbidities.

Another classification system used by some authors, which is based on the clinical symptoms, distinguishes three types of incontinence (6):

1. type 1 – passive incontinence with involuntary passing of faeces most often indicative of a neurological disorder, impaired anorectal reflexes or dysfunction of the internal sphincter,

2. type 2 – urge incontinence with inability to control bowel movements despite active attempts to maintain sensation indicating dysfunction (damage) of the sphincter or the rectum,

3. type 3 – undesirable leakage of stool often after bowel movement (faecal seepage) despite normal continence mechanisms (intact sphincters, normal anorectal sensation).