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Ano rectal syndrome (ARS)

Ano rectal syndrome is defined as soreness, burning, itching or other irritation of the rectum together with redness in the area of anus. Sometimes it is accompanied by diarrhea and it may occur as a toxic side effect of oral administration of certain broad spectrum antibiotics.


Ano-rectal syndrome may include a number of presentation. The most common include proctitis and rectal discharge.The most common sexually transmitted pathogens which cause ARS are Neisseria gonorrhoeae, Chlamydia trachomatis, Treponema pallidum and Herpes simplex. 

Proctitis is an inflammation of the rectal wall and is the most common reaction to an ano-rectal STI (due to gonorrhoea, syphilis, chlamydia or herpes). Anyone whose immune system is impaired is at increased risk of developing proctitis, particularly from infections caused by the herpes simplex virus or cytomegalovirus, or from reactivation of an earlier infection.

Proctitis may be caused by Salmonella spp., Shigella spp., or Entamoeba histolytica as a part of gastroenteritis, which may manifest as diarrhoea with fever, anorexia, and abdominal cramps. Antibiotics that destroy normal intestinal bacteria and allow other bacteria to grow in their place may also cause proctitis. 

Herpes proctitis may be mistaken for the rectal manifestation of ulcerative colitis or Crohn’s disease. Proctitis typically causes painless bleeding or the passage of mucus (sometimes mistaken for diarrhoea) from the rectum.


There may also be ineffectual straining to defecate (“tenesmus”), sometimes mistakenly described as “constipation” by patients.


The anus and rectum may be intensely painful, with external and internal ulceration, when the cause is gonorrhoea, herpes, or cytomegalovirus infection.


A proctoscopic examination (which should be done, if feasible) will reveal rectal pus, bleeding or ulceration. 

All cases of proctitis in MSM should be treated for gonorrhoea and chlamydia infections. Symptoms of diarrhoea, bloody stools, abdominal cramping, nausea, and/or bloating may indicate giardia infection or amoebic dysentery. 

Rectal discharge is a condition associated with intermittent or continuous expression of any discharge that is not stool or blood from the anus. 

Generally "rectal discharge" refers to either a mucous or purulent discharge. The discharge can occur for many reasons, including anal fissure, anal fistula (an abnormal connection between two organs) or abscess, other infections including sexually transmitted diseases, or chronic inflammatory diseases. 

When the definition of rectal discharge is related to STI, the following could be observed:

  • Purulent rectal discharge

  • Mucous rectal discharge

  • Watery rectal discharge 


Other non-STI causes of ARS include:  

Anal fissure, Fecal impaction, Food intolerance, Gastroenteritis (bacterial and viral), Inflammatory bowel disease (includes Crohn’s disease and ulcerative colitis), Neurological damage, and Perirectal or perianal abscess. 

Other symptoms might occur with rectal discharge includes gastrointestinal symptoms which vary depending on the underlying disease, disorder or condition.


These may include: 

  • Abdominal pain or cramping, abdominal swelling, distention or bloating; bloody stool (blood may be red, black, or tarry in texture), burning feeling, change in bowel habits, constipation, diarrhea; fecal incontinence (inability to control stools), flatulence; pain, which may be severe, in the abdomen, pelvis, or lower back, urgent need to pass stool and watery diarrhea including multiple episodes. 

Updated on, 4.11.2020


1. STG

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