Vaginal swab for flora: what it shows and how to read the result

What the test is — and what it is not

A flora swab is a microscope examination of vaginal discharge. The sample is spread on a slide, stained, and examined for what lives there: how many lactobacilli there are, whether there is yeast, and whether there are signs of bacterial vaginosis or inflammation. In Polish it is wymaz z pochwy; on the report it appears as biocenoza pochwy or stopień czystości pochwy.

The main confusion is with three other tests taken in the same chair and also loosely called "a swab":

Test	What it looks for	When it is needed
Flora swab wymaz z pochwy, biocenoza	microbes and inflammation in the vagina	with symptoms: discharge, itching, odor
Cytology cytologia, Pap test	changes in cervical cells — precancer	screening every three years from 25, without symptoms
Culture posiew z antybiogramem	which bacterium grows and what it responds to	when treatment has already failed
PCR for infections PCR	chlamydia, gonorrhea, trichomonas, mycoplasma	after unprotected sex, or if an STI is suspected

These tests do not replace one another. A good flora swab says nothing about the cervix, and normal cytology says nothing about thrush. Chlamydia cannot be seen on a flora swab at all. Cytology is covered in detail in how to read a cytology result.

When a swab is needed, and when it is not

A swab makes sense when there is a question it answers:

unusual discharge, itching, burning, an unpleasant odor;
treatment did not help, or symptoms came back within a week or two;
before procedures where an instrument passes through the cervix: IUD insertion, hysteroscopy — inflammation has to be ruled out beforehand;
in pregnancy — when there are symptoms, not by the calendar.

How to prepare and how it is taken

Preparation decides whether the result can be read at all. The rules are simple:

not during your period — blood makes the slide unreadable;
for 2–3 days before — no vaginal pessaries, creams, gels or lubricants;
no douching and no antiseptic washes — water is enough;
for 24 hours before — no sex;
if you are on a course of treatment — finish it and come a week after.

Taking the sample takes a few seconds: during the speculum examination a sterile brush or swab is passed along the vaginal wall. It does not hurt. I take the sample at the same appointment, so there is no second trip. Sampling is included in the visit fee; the laboratory is paid separately, and the price depends on the lab and the scope of the test.

How to read the report

Labs word things differently, but they all look at the same things. The ranges below are a guide: every laboratory has its own reference values, printed next to the result.

On the report	Normal	What a deviation means
Lactobacilli, Döderlein bacilli pałeczki kwasu mlekowego	plentiful, predominant	few or none — the flora has shifted, most often vaginosis
Leukocytes leukocyty	occasional, usually up to 10–15 per field	many — a sign of inflammation, but not a diagnosis
Squamous epithelial cells komórki nabłonka	present, in moderate numbers	mean nothing on their own
Clue cells komórki jeżowe	none	a hallmark of bacterial vaginosis
Cocci, mixed flora ziarenkowce, flora mieszana	none or few	many, with few lactobacilli — imbalanced flora
Yeast cells, pseudohyphae grzyby drożdżopodobne	none	candidiasis — thrush
Trichomonas rzęsistek	none	trichomoniasis; both partners are treated

If the report says "no gonococci found", that is not a certificate of being free of gonorrhea. In women it is easy to miss under the microscope; it is reliably detected only by PCR.

The purity grade and the Nugent score

The result is often boiled down to a single number. Polish and Ukrainian labs use the vaginal purity grade; internationally it is the Nugent score, the reference laboratory method for diagnosing vaginosis.

Purity grade	What is seen	What it means
I	almost only lactobacilli, no leukocytes	normal
II	fewer lactobacilli, occasional leukocytes and other bacteria	a variant of normal
III	few lactobacilli, many leukocytes and other flora	inflammation or vaginosis — needs an examination
IV	no lactobacilli, many leukocytes and pathogenic flora	marked inflammation

On the Nugent score: 0–3 is normal, 4–6 intermediate flora, 7–10 bacterial vaginosis.

When numbers on the report are not a reason for treatment

The patient is treated, not the swab. These are the most common routes to an unnecessary course:

Leukocytes slightly above range with no symptoms. Their number varies with the cycle, after sex and with cervical ectropion. Without symptoms it is a reason to take a look, not to prescribe an antibiotic;
Gardnerella on a culture. It lives in the vagina of many healthy women. That is exactly why a culture for it is not recommended as a diagnostic test: vaginosis is diagnosed from the slide and the symptoms, not from finding the organism;
Ureaplasma and Mycoplasma hominis. Part of ordinary flora; they are not looked for routinely and are not treated without symptoms;
A few cocci alongside plenty of lactobacilli. That is normal.

The reverse also holds: symptoms with a good swab do not mean "nothing is there". Itching can come from dermatitis or an allergy to hygiene products, and a flora swab does not detect STIs.

If the swab comes back abnormal

The result is read together with the examination and the symptoms. Thrush is treated with antifungals, vaginosis with antibiotics, and mixing them up is the most common reason "nothing works". How to tell them apart from the symptoms is in the article on discharge.

If treatment has already been tried and failed, a culture with antibiotic sensitivity is added to the swab — usually 60–130 złoty — and treatment follows the result rather than guesswork. A follow-up swab is taken no sooner than a week after the course ends.

Appointments in Warsaw at ul. Głębocka 9, held in Polish, Russian and Ukrainian. No referral or NFZ insurance is needed and a PESEL number is not required.

Short answers

What does a vaginal flora swab show?

Which microorganisms live in the vagina and whether there is inflammation: how many lactobacilli there are, whether there is yeast, the clue cells of bacterial vaginosis, trichomonas, and how many leukocytes. It does not show the state of the cervix or infections such as chlamydia — those need cytology and PCR.

How is a flora swab different from cytology?

A flora swab looks for microbes and inflammation in the vagina and is needed when there are symptoms. Cytology looks for changes in cervical cells, that is precancer, and is a screening test every three years with no symptoms at all. One does not replace the other.

How is a flora swab different from a culture?

A swab is examined under the microscope and gives an overall picture within a day. A culture grows the bacteria and tests which drugs they respond to; it is done when treatment has already failed.

How many leukocytes on a swab are normal?

In the vagina, usually up to 10–15 per field, but every laboratory has its own range, printed on the report. A small excess without symptoms is not a reason for antibiotics: the count changes with the cycle and after sex.

How do I prepare for a flora swab?

Not during your period; for 2–3 days before, no vaginal pessaries, creams or lubricants and no douching; no sex for 24 hours. If you are on treatment, the swab is taken a week after it ends.

Sources

The primary sources this text rests on. Links open in a new tab.

Bacterial Vaginosis — STI Treatment GuidelinesCDC, USA — diagnostic criteria: pH, clue cells, the Nugent score; why a Gardnerella culture is not recommended
Sexually transmitted infections (STIs)World Health Organization — which infections need their own tests rather than a flora swab
Rekomendacje Polskiego Towarzystwa Ginekologów i PołożnikówPTGiP — the standard of care in Poland; my skills certificate is issued under the same rules

This text describes the general picture and does not replace a consultation. Timings and indications differ from woman to woman and are decided at the appointment, from your history and test results.