Fecal Soiling

   Definition and Clinical Features of Soiling

Soiling or leakage is a bothersome condition. In contrast to fecal incontinence Opens in new window, which is loss of control over (solid) stools, soiling is characterized by liquid discharge from the anus or perianal area.

There is much confusion in the literature about the use of the word soiling. Many authors use soiling to indicate minor fecal incontinence. It is preferable to use the term soiling for the liquid discharge, since although the causes of soiling may differ, the diagnostic procedures and work-up are generally less complex.

Depending on the cause of soiling the aspect of the discharge may be mucous, fecal, hemorrhagic, purulent, or a combination. Patients complain about stains in their underwear. The discharge causes inflammation of the perianal skin with itching, burning sensations, and pain. Patients often wear tissues, pats, or sanitary napkins in their underclothing and some develop meticulous cleaning procedures.

The frequency of soiling in the general population is unknown. In a large survey (n = 1128) of students and hospital personnel; fecal soiling was found in 2.7% of the people without, and in 10% with, bowel dysfunction Opens in new window. However, cases of fecal incontinence Opens in new window may have been included. In children, chronic constipation Opens in new window can lead to fecal soiling. In the population referred to us for investigation of anorectal function, 10% complained of soiling.

The causes of soiling may vary. Hemorrhoids Opens in new window, mucosal prolapsed, fistula Opens in new window, and rectal prolapse Opens in new window are often the cause. Surgical procedures, necessary to treat these anal diseases, can lead to scarring. The anal canal is then not able to close completely, therefore losing its seal function, with subsequent development of mucous or fecal soiling. This has been observed after hemorrhoidectomy, anal stretch for hemorrhoids, and sphincterotomy for fissures.

Fistulotomy through the internal and especially the external anal sphincter is notorious, not only causing fecal soiling but also fecal incontinence. Anal manometry measuring the anal sphincter pressures could reduce postoperative soiling by avoiding internal sphincterotomy and opening the fistula with division of the striated muscles in favor of the seton procedure. Also surgical procedures where the rectum is removed and pouches or anastomoses are constructed, causing stretch damage to the internal anal sphincter, can contribute to fecal soiling.

In children, anal surgery for Hirschsprung’s disease and for imperforate anus can be a cause of fecal soiling. Rectal intussusception can lead occasionally to fecal soiling.

The fecal microbacterial flora is not different in patients with soiling and pruritus ani Opens in new window. The aspect of the discharge may give a clue as to the diagnosis. Mucus is almost invariably found. Hemorrhagic discharge is often seen with hemorrhoids Opens in new window and may also occur from damaged anorectal mucosa due to rectal prolapsed or proctitis. Fistula Opens in new window may produce purulent material.

Fecal soiling is mostly seen in combination with constipation Opens in new window or with sphincter damage. The cause of soiling can almost always be correctly diagnosed with good inspection and additional proctoscopy. It is important to ask the patient to strain, since a prolapse of hemorrhoids, mucosa, or rectal wall can become obvious. In case of fecal soiling without a visible cause it may be necessary to perform a defecography to demonstrate an intussusception of the rectal wall. Anorectal function tests like anal monometry, rectal compliance measurements, and fluid challenge with the saline infusion test do not contribute to establish a diagnosis.

Overall, patients with soiling do not differ from controls in their anorectal function. However, patients with fecal soiling and rectal prolapsed or extensive (peri)anal scarring were found to have lower basal anal pressures. This demonstrates the difference between fecal soiling and fecal incontinence, since the anal squeeze pressures are generally normal in patients with fecal soiling, while they are almost always low in patients with fecal incontinence.

Anal endosonography can be of assistance in patients with soiling. Fistula Opens in new window and abscesses Opens in new window can be visualized with anal endosonography, although digital palpation under anesthesia is more accurate. In patients with extensive perianal scarring it can be helpful to differentiate between the original disease (fistula, fissure) and sphincter defects.

The treatment and prognosis of soiling varies and depends upon the underlying cause. Internal hemorrhoids are treated primarily by rubber band ligation; surgery is reserved for unsuccessful cases or when large external hemorrhoids are also present. Fissures and fistulas are surgically treated.

Extensive (peri)anal scarring can be treated surgically by removing scar tissue and by a sphincter repair. Rectal intussception in patients with soiling forms an indication to perform a rectopexy. In children with fecal impaction conservative measures will generally improve most patients; additional biofeedback does not lead to further improvement. In our own series of 45 patients with different causes of soiling the resulting of medical or surgical therapy were reasonably favorable; 44% were cured and 29% improved.

In conclusion, soiling is characterized by liquid discharge of the anus or perianal area, caused by conditions easily diagnosed by simple means of inspection and proctoscopy. Anorectal function tests do not show important abnormalities, except in patients with rectal prolapsed or extensive (peri)anal scarring, and do not contribute to establishin a diagnosis. Defecography and endosonography are indicated when no initial diagnosis can be made. In most cases appropriate treatment is available.