DEFINITION : An Ano-Rectal Abscess is a pus-filled cavity that develops in the Anal Canal, the lower part of the Rectum and the surrounding soft tissues when a pus forming bacteria enters and infects amucus secreting Anal Gland which is situated in an Anal Crypt.There are six to eight crypts in the Anal Canal.
SYMPTOMS AND SIGNS : Ano-Rectal Abscesses are most common in patients between twenty and fifty years old, but may occur at any age however rarely in childhood. It is more common in males. The patient complains of a rapid onset of pain which could be unbearable, in the Anus, Rectum and the surrounding soft tissues, of a few hours up to several days duration.
HISTORY AND MECHANISM of FORMATION OF ANO-RECTAL ABSCESSES : The pus which is formed in an Anal Gland and Crypt increases and tracks either medially to form 1) a Sub-Mucosal Abscess or downwards to form 2) a Peri-Anal Abscess or laterally to form 3) an Ischio-Rectal Abscess.
1. THE SUB-MUCOSAL ABSCESS is inside the rectum beneath the mucosa lining. The patient complains of a rapid onset of a few to several hours duration of severe and unbearable deep seated and constant Ano-Rectal pain. No visible outside swelling.
Examination of the patient in the left lateral Sim’s position with a good lighting and good assistance reveals a normal Anal Verge and no abnormal external signs. But very gentle and careful digital rectal examination will reveal extreme tenderness, three to five centimetres proximal (above) to the anal verge. Rectal temperature in my experience ranges from 37.5 to 38.5°C.
The diagnosis is clinical and MRI, if available, maybe useful to confirm the diagnosis.
Treatment is surgical incision and evacuation of the pus.Intravenous antibiotics are given in conjunction with but are not a substitute for surgery. Recovery isfast and there shall be no subsequent fistula. There is no place for suppositories or local applications.
2. PERI-ANAL ABSCESS is the most common of all Ano-Rectal Abscesses. There is arapid onset of an exquisitely painful, visible and tender swelling close to the Anal Verge of one to three days duration.Examination of the patient in the left lateral Sim’s position with good lighting and good assistance reveals a visible, red, hot and exquisitely tender abscess near the Anal Verge.
The diagnosis is clinical.
Treatment is surgical incision and evacuation of the pus.The natural history after the surgical drainage of a Peri-Anal Abscess is the formation of an Inter-Sphincteric Fistula which is the most common type of Ano-Rectal Fistulae.
3. ISCHIO-RECTAL ABSCESS The patient complains of a deep seated para-rectal pain over a period ofone to a few days and worsens after two to three days and becomes extremely painful and unbearable. Sitting is painful and defaecation is difficult.The patient is likely to be systemically unwell with general symptoms of a serious and large abscess i.e. malaise, loss of appetite, sweating, rapid pulse and increasing temperature.
Examination of the patient in the left lateral Sim’s position with good lighting and good assistance reveals a normal Anal Verge and Peri-Anal area. There is a mildly visible swelling of several centimetres laterally and away from the Anal Verge. The overlying skin is hot. There may or may not be a mildand visible light-coloured redness. There is exquisite tenderness.
The diagnosis is clinical.
Treatment is an emergency surgical operation and vigorous intravenous broad spectrum antibiotics including Metronidazole. If the operation is not carried out, the pulse rate will be rapid (110 to 130 beats per minute) which is an important sign. The temperature rises further and the patient looks very ill with severe pain and rigors, indicating bacteraemia which means bacteria are circulating in the bloodstream but are not multiplying. This chain of events is followed by imminent septicaemia, septic shock which could be irreversible and leads to death. Septicaemia, also known as “blood poisoning”, is a potentially fatal condition in which bacteria are multiplying rapidly in the blood stream.
All Ischio-Rectal Abscesses, after drainage, will be followed by Trans-Sphincteric Ano-Rectal Fistula which must be dealt-with surgically after a few weeks, otherwise recurrence of the abscess is certain.
It is common for bacteria to enter the blood stream in small numbers through a breach in the skin or through the gums when the teeth are brushed. The bacteria are usually destroyed by the immune system and do not cause symptoms. However, if virulent bacteria enter the blood stream in large numbers from a major source of infection, blood poisoning can result. Septicaemia can develop as a complication of almost all types of serious pyogenic infectious disease (bacteria producing pus). Diabetic patients, people with HIV/AIDS, patients having chemotherapy or immunosuppressant drugs, young children, elderly people, and intravenous drug users are more susceptible to septicaemia.