SUPPLIES :  The supplies to collect anal cytology (sometimes called the anal Pap) are available in most clinical settings. A polyester swab with a plastic shaft is the preferred swab. It is important that only swabs with synthetic fibers be used, such as polyester or Dacron® (picture).  Cells will cling to cotton fiber and cannot be utilized. Avoid using a wooden stick, because these often break. Although a Cytobrush can be used it is considerably less comfortable for the patient. Flocked swabs may also be used.                       

For liquid cytology collection, a liquid-based preservative vial is used. Many centers are still using conventional cytology. The swab is smeared directly onto a glass slide and placed into a jar with cytology fixative solution.  Do not use cytology fixative spray as this can interfere with reading the cells. 

Liquid cytology is the preferred method for preservation. This eliminates artifact with drying and reduces the amount of fecal material and bacteria that can obscure cellular detail. However, conventional slides and a jar of fixative solution may be used if liquid cytology is not available.  

Liquid-based

Glass slide

METHODS:  Patients are asked to refrain from douching, using an enema, sex or inserting anything into their anus for 24 hours prior to an anal cytology exam.

Lubricants should not be used prior to obtaining a cytology sample because the lubricant may interfere with the collection, processing and interpretation of the sample. The digital anorectal examination (DARE) with lubricant should be done only after the cytology collection or any other swab collections including HPV or STI tests. 

The sample is obtained by the provider, usually with the patient lying on their left side, but other positions are acceptable.

The anal swab is moistened in tap water which facilitates swab insertion and cell collection. The buttocks are retracted to visualize the anal opening. The swab is then inserted into the anus approximately 2 to 3 inches (5-6 cm). Pass the swab past the internal sphincter to reach the distal rectum ensuring that cells are collected at the junction of the anus and rectum, where most of the HPV-related lesions are found. Once positioned, agitate the swab with rapid forwards/backwards motions before withdrawing. The swab is continually rotated 360 degrees in a circular fashion maintaining firm lateral pressure to the end of the swab, such that the plastic stick will bow slightly as it is slowly withdrawn over a period of 15 to 30 seconds from the anus. The continued lateral pressure ensures that cells are collected from the entire anal canal, beginning in the distal rectum and ending at the perianus. 

For liquid cytology collection, the swab is then placed in a preservative vial and vigorously agitated for approximately 30 seconds to disperse the cells for liquid-based cytology. Alternatively, the swab can be smeared directly onto a glass slide for a conventional smear by placing it into a jar with alcohol. Regardless of method used, the sample must be fixed quickly within 15 seconds to avoid air-drying artifacts, which occurs easily and makes interpretation difficult. The swab is then discarded unless the cytology collection system requires the swab to be broken off into the preservative vial.

The cytology slides are stained using the Papanicolaou stain, hence the term Pap smear, and then are examined by the cytopathologist.

HPV sampling is similar. Some systems allow the same swab to be used for both cytology and HPV. 

Self-collected anal swabs can be an alternative to clinician-collected swabs to overcome certain barriers to anal cytology collection; however the anal cytology self-collection technique is not the same as an anal swab collection for STD screening; specific instructions should be given to the patient (e.g. Hillman et all- Self- versus clinician-collected swabs in anal cancer screening: A clinical trial | PLOS One) to ensure adequate sampling for the cytology test and only liquid media is used in this alternative.