An anal Pap smear is the anal counterpart of the cervical Pap smear

Pap smear

The Papanicolaou test is a screening test used in to detect pre-cancerous and cancerous processes in the endocervical canal of the female reproductive system. Changes can be treated, thus preventing cervical cancer...

. It is used for the early detection of anal cancer

Anal cancer

Anal cancer is a type of cancer which arises from the anus, the distal orifice of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer. The etiology, risk factors, clinical progression, staging, and treatment are all different. Anal cancer is typically a...

. The Human papilloma virus (HPV), the cause of anogenital wart

Genital wart

Genital warts is a highly contagious sexually transmitted disease caused by some sub-types of human papillomavirus . It is spread through direct skin-to-skin contact during oral, genital, or anal sex with an infected partner...

s, can cause anal carcinomas to form. Individuals with a history of anal warts are at risk of getting anal cancer.

Procedure

Typically, a small brush or cotton-tipped rod is inserted into the anus

Anus

The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...

. The cells collected by the brush or rod are smeared onto a glass slide, air-dried, and sealed with an adhesive. Many medical offices prefer to suspend the collected cells in a liquid medium; the suspension is then plated on a glass slide. The suspended cells can also be used for HPV typing. The specimen is sent to a pathologist, indicating the source of the smear (anal canal).

The procedure is easily performed in a doctor's office, using the same kit as for cervical cancer detection. It can be performed quickly, as a vaginal speculum or anoscope is not required.

Indications

There is no consensus on who should get an anal Pap smear. Some individuals recommend that all men and women who have anal sex should have an anal Pap smear performed regularly. Some recommend it for all men who have had sex with men, for all individuals with HIV and anal warts, or for all individuals with a history of anal warts. Cost-effectiveness modeling shows that anal Pap smears are cost-effective if performed in HIV-positive men with history of anal warts every year, and in HIV-negative men with history of anal warts every three years.

An informal survey of local infectious-disease doctors in southeast Michigan suggested that few know where to send patients for an anal Pap smear. The procedure is very simple, and can be easily performed in any doctor's office with a little training.

Treatment

A person might be referred to a colorectal surgeon, an infectious disease doctor, or a physician trained in colposcopy, examination, or biopsy of this region. At a minimum, a digital rectal exam is performed. A proctoscopic exam might follow. Ultimately, a biopsy might be performed, with or without the aid of a colposcope, a dermatoscope, or a high resolution anoscopy.