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Department of Reproductive Health and Research (RHR), World Health Organization

Sexually transmitted and other reproductive tract infections

A guide to essential practice



Annex 3. Laboratory tests for RTI


Rapid Plasma Reagin (RPR) laboratory tests

Perform RPR test and respond to results:

Seek consent.

Explain procedure.

Use a sterile needle and syringe. Draw up 5 ml of blood from a vein. Put in a plain test tube.

Let test tube sit 20 minutes to allow serum to separate. (Or centrifuge 3–5 minutes at 2000–3000 rpm). In the separated sample, serum will be on top.

Use sampling pipette to withdraw some of the serum. Take care not to include any red blood cells from the lower part of the separated sample.

Hold the pipette vertically over a test card circle. Squeeze teat to allow one drop (50 µl) of serum to fall onto a circle. Spread the drop to fill the circle using a toothpick or other clean spreader.

Important: Several samples may be done on one test card. Be careful not to contaminate the remaining test circles. Use a clean spreader for every sample. Carefully label each sample with a patient name or number

Attach dispensing needle to a syringe. Shake antigen.* Draw up enough antigen for the number of tests done (one drop per test).

Holding the syringe vertically, allow exactly one drop of antigen to fall onto each test sample. Do not stir.

Rotate the test card smoothly on the palm of the hand for 8 minutes.** (Or rotate on a mechanical rotator.)

Interpreting results

After 8 minutes rotation, inspect the card in good light. Turn or tilt the card to see whether there is clumping (reactive result). Most test cards include negative and positive control circles for comparison.

test card

1. Non-reactive (no clumping or only slight roughness)—Negative for syphilis

2. Reactive (highly visible clumping)—Positive for syphilis

3. Weakly reactive (minimal clumping)—Positive for syphilis

NOTE: Weakly reactive can also be more finely granulated and difficult to see than this illustration

* Make sure antigen was refrigerated (not frozen) and has not expired.

** Room temperature should be 22.8oC–29.3oC

If RPR positive:

  • Determine if the woman and her partner have received adequate treatment.
  • If not, treat woman and partner for syphilis with benzathine penicillin.
  • Treat newborn with benzathine penicillin.
  • Follow-up newborn in 2 weeks.
  • Counsel on safer sex.


Interpreting syphilis test results

Syphilis tests detect antibodies, which are evidence of current or past infection. Syphilis tests are not needed to diagnose patients with genital ulcers (who should be managed using Flowchart 3 on page 117).

Non-treponemal tests (such as RPR and VDRL) are the preferred tests for screening. These tests detect almost all cases of early syphilis, but false positives are possible. RPR can be performed without a microscope.

Treponemal tests, such as Treponema pallidum haemagglutination test (TPHA), fluorescent Treponema antibody absorption test (FTA-Abs), microhaemagglutination assay for antibodies to Treponema pallidum (MHA-TP), if available, can be used to confirm non-treponemal test results.

Quantitative RPR titres can help evaluate the response to treatment.

The following table can be used to interpret syphilis test results.

Note: where additional tests are not available, all patients with reactive RPR or VDRL should be treated.


Interpreting serological test results


RPR titre


Active infection




Latent syphilis


Often <1:4


False positive


Usually <1:4


Successful treatment

+ or -

2 titres decrease
(e.g. from 1:16 to 1:4)



Clinical criteria for bacterial vaginosis (BV)

BV can be diagnosed using simple clinical criteria with or without the aid of a microscope.

Collect specimen

Note colour and consistency of discharge. Take a sample of discharge from the side walls or deep in the vagina where discharge pools (or use discharge remaining on speculum). Touch pH paper to discharge on swab or speculum and note pH.

Prepare slide

Place specimen on a glass slide. Add a drop of 10% potassium hydroxide and note any odour.

What to look for

The diagnosis of BV is based on the presence of at least 3 of the 4 following characteristics

  • Homogeneous white-grey discharge that sticks to the vaginal walls

  • Vaginal fluid pH >4.5

  • Release of fishy amine odour from the vaginal fluid when mixed with 10% potassium hydroxide (positive whiff test)

  • "Clue cells" visible on microscopy


Look for evidence of other vaginal or cervical infections—multiple infections are common.


Wet mount microscopy

Direct microscopic examination of vaginal discharge can aid in diagnosis of yeast infection (Candida albicans), bacterial vaginosis and trichomoniasis.

Collect specimen

Take a sample of discharge with a swab from the side walls or deep in the vagina where discharge accumulates.

Prepare slide

Mix specimen with 1 or 2 drops of saline on a glass slide and cover with a coverslip.

What to look for

Examine at 100X magnification and look for typical jerky movement of motile trichomonads.

Examine at 400X magnification to look for yeast cells and trichomonads.

To make identification of yeast cells easier in wet mount slides, mix the vaginal swab in another drop of saline and add a drop of 10% potassium hydroxide to dissolve other cells.


Look for evidence of other vaginal or cervical infections—multiple infections are common.


Gram stain microscopy of vaginal smears

Collect specimen

A Gram stain slide can be prepared at the same time as the wet mount by rolling the swab on a separate slide.

Prepare slide

1. Heat fix.

2. Stain with crystal violet (60 seconds) and rinse.

3. Stain with iodine (60 seconds) and rinse.

4. Decolorize with acetone-ethanol for few seconds (until the liquid runs clear).

5. Stain with safranin (60 seconds) and rinse.

6. Gently blot dry and examine under oil immersion (1000X).

What to look for

1. Lactobacilli only—normal

2. Mixed flora, mainly lactobacilli with a few short rods (coccobacilli)—considered normal

3. Presence of clue cells; mixed flora, mainly Gardnerella-like and anaerobic bacteria with a few lactobacilli—treat for BV

4. Presence of clue cells; mixed flora of Gram-positive, Gram-negative and Gram-variable rods; no lactobacilli—treat for BV


Look for evidence of other vaginal or cervical infections—multiple infections are common.


Use of Gram stain for diagnosis of cervical infection

1. The Gram stain method is not recommended for the diagnosis of cervical infection. Its usefulness in detecting Neisseria gonorrhoeae or suggesting Chlamydia trachomatis in women is limited even where well-trained technicians are available.

2. The costs associated with the method, including the cost of maintaining microscopes, outweigh the benefits in terms of improved quality of care.


html files


Infections of the male and female reproductive tract and their consequences:

What are RTIs?

Why STI/RTIs are important?

What can be done about RTIs?

The role of clinical services in reducing the burden of STI/RTI

Preventing STIs/RTIs and their complications

How to prevent STI

How to prevent iatrogenic infections

How to prevent endogenous infections

Detecting STI/RTI

Detecting STI/RTI


Vaginal infections

Cervical infections

Pelvic inflammatory disease

HIV counselling and testing

STI/RTI education and counselling

Key points

Privacy and confidentiality

General skills for STI/RTI education and counselling

Health education


Promoting prevention of STI/RTI and use of services

Key points

Reducing barriers to use of services

Raising awareness and promoting services

Reaching groups that do not typically use reproductive health services

STI/RTI Assessment during Routine Family Planning Visits

Key points

Integrating STI/RTI assessment into routine FP services

Family planning methods and STIs/RTIs

STI/RTI Assessment in pregnancy, childbirth and the postpartum period

Key points

Management of symptomatic STIs/RTIs

Syndromic management of STI/RTI

Management of common syndromes

STI case management and prevention of new infections

STI/RTI complications related to pregnancy, miscarriage, induced abortion, and the postpartum period

Key points

Infection in early pregnancy

Infection in lated pregnancy

Infection following childbirth

Vaginal discharge in pregnancy and the postpartum period

Sexual violence

Key points

Medical and other care for survivors of sexual assault

Annex 1. Clinical skills needed for STI/RTI


Common STI/RTI symptoms

Examining patients

Annex 2. Disinfection and universal precautions

Preventing infection in clinical settings

High-level disinfection: three steps

Universal precautions

Annex 3. Laboratory tests for RTI

Interpreting syphilis test results

Clinical criteria for bacterial vaginosis (BV)

Wet mount microscopy

Gram stain microscopy of vaginal smears

Use of Gram stain for diagnosis of cervical infection

Annex 4. Medications

Medications in pregnancy

Antibiotic treatments for gonorrhoa

Annex 5.

STI/RTI reference table


Additionnal resources


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