Tag Archives: peri-anal swabs

“Choosing wisely bacteriology II: Swabs from the peri-anal area”

There is so much scope for “choosing wisely” in general bacteriology, it is difficult to know where to start…

Peri-anal swabs are rarely of value in changing patient management. That is primarily because you are swabbing an incredibly “dirty” area in the first place. You can be sure that your peri-anal area will almost inevitably grow mixed enteric flora on culture. That is completely normal. It is no reflection on your personal hygiene!

So as a result the following swabs have very dubious microbiology value:

  • Swabs from peri-anal abscesses:- The very fact that you can swab a peri-anal abscess means that it is either self-discharging or has been intentionally incised. Either way the patient should be well on the way to recovery. And you will probably grow mixed enteric flora. On occasion, antibiotics may be indicated if there are systemic symptoms such as a fever, or there is extensive erythema surrounding the abscess. If an antibiotic is used, then it should be necessarily relatively broad spectrum, covering staphylococci, streptococci, anaerobes, and enterobacteraciae. The swab result rarely impacts on the choice of antibiotic.
  • Swabs from sacral ulcers:- This condition has the double whammy of not only being chronic, but is also in the peri-anal region. Rarely, if ever, does a superficial swab from a sacral ulcer change management. A well taken punch biopsy might…

We still accept such swabs at my laboratory, although sometimes I wonder if we are just encouraging poor practice.

Maybe we are just too nice…

We do however put a comment on all such swabs stating the following: “Superficial swabs from the peri-anal area are generally contraindicated. These swabs often grow a mixture of enteric flora, and are unhelpful in making clinical management decisions.”

I like report comments. Unlike one off educational material,  report comments offer continuous feedback to the lab user and can hopefully induce a change in culture over the long term.


“Should peri-anal swabs be accepted by the microbiology laboratory?”

Superficial swabs in general have limited value, but few are as useless as the peri-anal swab.

Given the area that one is attempting to swab from, it is not surprising that a good proportion of these grow mixed enteric flora.

And if there is something to swab (either because the abscess has been incised or is discharging naturally), then most of the time the patient is well on the way to recovery.

I would love to survey 100 patients who had a peri-anal swab performed, to see what proportion it changed the management in. It will be low, very low..

In today’s microbiology lab, where we are trying our best to focus our efforts where we can make a difference, there is no place for peri-anal swabs.


My apologies for this website being out of action for the past few weeks. The new baby (Albie) arrived, just a couple of days late, but he then had to spend a few days in the Special Care Unit with an infection. All is well now, but it has taken a few weeks to get back to normal life..

Simultaneously to the above, the website went down with technical problems and it has taken until now to get round to fixing it.  With 5 young children, I have to grab an hour here and there to do this, usually in the middle of the night when everyone else is sleeping!