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Rectal discharge (also called anal discharge, anal drainage, or anal leakage) is intermittent or continuous expression of liquid from the anus (per rectum). This is closely related to types of fecal incontinence (e.g. fecal leakage) but the term rectal discharge does not necessarily imply degrees of incontinence. Types of fecal incontinence that produce a liquid leakage could be thought of as a type of rectal discharge.
Different types of discharge are described. Generally rectal discharge refers to either a mucous or purulent discharge, but, depending upon what definition of rectal discharge is used, the following could be included:
Purulent rectal discharge
Mucous rectal discharge
Watery rectal discharge
Steatorrhoea("fatty diarrhea" caused by excess fat in stools, or an oily anal leakage)
keriorrhea(orange oily anal leakage caused by high levels of escolar and oilfish in the diet)
Pus usually indicates infection. Frequently medical sources do not differentiate between the two types of discharge, instead using the general term mucopurulent discharge, which strictly speaking should be used to refer to a discharge that contains both mucus and pus. Purulent discharges may be blood streaked.
Mucus coats the walls of the colon in health, functioning as a protective barrier and also to aid peristalsis by lubrication of stool. Mucous discharges can be thought of in 2 broad categories; viz:
Inappropriately expressed physiologically produced mucus (e.g. in the presence of sphincter defects, or lesions preventing normal sphincter closure, allowing seepage or soiling)
Mucus that is produced in pathological quantities (e.g. from a lesion, or generalized coloproctitis or as a result of bacterial overgrowth)
A mucous rectal discharge may be blood streaked. With some conditions, the blood can be homogenously mixed with the mucus, creating a pink goo. An example of this could be the so-called "red currant jelly" stools in intussusception. This appearance refers to the mixture of sloughed mucosa, mucus and blood.
Note: "mucus" is a noun, used to name the substance itself, and "mucous" is an adjective, used to apply a description to a discharge. "Mucoid" is also an adjective and means mucus-like. "Mucinous" strictly speaking refers to something having a mucin-like attribute, but it often is used interchangeably with the word mucous (as mucus usually contains a high percentage of mucin).
Differential diagnosis[edit source | edit]
The differential of rectal discharge is an extensive, but the general etiological themes are infection and inflammation. Some lesions can cause a discharge by mechanically interfering with, or preventing the complete closure of the anal canal. This type of lesion may not cause discharge intrinsically, but instead allow transit of liquid stool components and mucus.
While several pathologies can present with perianal discharge, this is not strictly speaking rectal discharge, however given the anatomical proximity this may be misinterpreted as such.
Fistulae draining into the perianal region, and pilonidal diseases are the main entities that fall within this category. Perianal tumours may also discharge when they fungate, or become cystic/necrotic.
Proctitis is inflammation of the anal canal and the distal 6 inches of the rectum.
There are many causes of proctitis, some due to infections and others not. Proctitis does not necessarily imply rectal discharge, however some of the types known to be associated with rectal discharge are discussed briefly.
Rectal gonorrhea is caused by Neisseria gonorrhoeae (also Neisseria meninigitidis). The condition is usually asymptomatic, but symptoms can include rectal discharge (which can be creamy, purulent or bloody), pruritus ani, tenesmus, and possibly constipation. When symptomatic, these usually appear 5–7 days post exposure. Discharge is the most common symptom, and it is usually a brownish mucopurulent consistency.
Anorectal syphilis is caused by Treponema pallidum and is contracted through anoreceptive intercourse. Symptoms are usually minimal, but mucous discharge, bleeding, and tenesmus may be present.
Anorectal abscess[edit source | edit]
Anorectal fistulae[edit source | edit]
Ileocolic actinomycosis[edit source | edit]
Non infectious inflammation[edit source | edit]
Ulcerative colitis[edit source | edit]
Diversion colitis[edit source | edit]
When the fecal stream is diverted as part of a colostomy, a condition called diversion colitis may develop in the section of bowel that no longer is in contact with stool. The mucosal lining is nourished by short chain fatty acids, which are produced as a result of bacterial fermentation in the gut. Long term lack of exposure to this nutrients can cause inflammation of the colon (colitis). Symptoms include rectal bleeding, mucous discharge, tenesmus and abdominal pain.
Anal carcinoma is much less common than colorectal cancer. The most common form is squamous cell carcinoma, followed by adenocarcinoma and melanoma. SCC usually occurs in the anal canal, and more rarely on the anal margin. Anal margin SCC presents as a lesion with rolled, everted edges and central ulceration. Symptoms include a painful lump, bleeding, pruritus ani, tenesmus, discharge or possibly fecal incontinence. SSC in the anal canal most commonly causes bleeding, but may also cause anal pain, a lump, pruritus ani, discharge, tenesmus, change in bowel habits and fecal incontinence. Because these symptoms are so unspecific, and because symptoms of anal carcinoma may not always be typical, this can lead to delays in diagnosis.
Rare neoplasms at this site that can give rise to discharge include Paget's disease (which is possibly a type of adenocarcinoma) and verrucous carcinoma.
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^Yamamoto, LG; Morita, SY; Boychuk, RB; Inaba, AS; Rosen, LM; Yee, LL; Young, LL (1997 May). "Stool appearance in intussusception: assessing the value of the term "currant jelly".". The American journal of emergency medicine15 (3): 293–8. PMID9148991.
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