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Techniques for specimen collection when testing for STIs

The following information provides guidance on specimen collection in males and females.

Males

Note: NAAT refers to Nucleic Acid Amplification Test, such as PCR

Urethral specimens

Patients should not pass urine for at least 2 hours prior to specimen collection.

Distal urethral swab

Performed when:

  • discharge present
  • urethritis symptoms
  • confirming a positive urine NAAT for gonorrhoea
  • testing a gonorrhoea contact
  • test of cure after treatment for gonorrhoea.

Method:

  1. Massage the urethra from proximal to distal to present any discharge
  2. using a cotton swab, discharge present at the meatus is smeared on a slide and air dried and then placed on an appropriate transport medium
  3. in the absence of a discharge a thin dacron tipped plastic or metal swab is moistened with normal saline and placed 2 to 3 cm inside the urethra and gently rotated once or twice and removed
  4. if no slide is made the lab with prepare one from the swab placed in the transport medium
  5. an air dried smear made at the time of specimen collection is of superior quality.

Gram stain - to assess for:

  • polymorphonuclear leucocyte cell count
  • presence of gram negative intracellular diplococci.

Culture for gonorrhoea.

Proximal urethral swab

Performed when chlamydia testing required and urine not taken for chlamydia NAAT.

Method:

  1. A thin dacron tipped plastic or metal swab is moistened with normal saline and placed 3 to 4 cm inside the urethra and gently rotated once or twice and removed and placed in an empty transport container.

Rectal specimens

Proctoscopy should be performed to inspect for lumps, ulcers, pus, bleeding and specimen collection.

Swabs are taken for:

  • gonorrhoea culture (plate or transport medium)
  • chlamydia NAAT and gonorrhoea NAAT (dry or moistened cotton tipped swab)
  • herpes simplex NAAT if indicated.

Pharyngeal specimens

Swabs are taken from each tonsillar fossa for:

  • gonorrhoea culture if suspected or NAAT positive
  • chlamydia and gonorrhoea NAAT for screening.

Ulcer specimens

  • Dry or moist cotton tipped swabs taken from the ulcer base can be tested for HSV NAAT
  • swabs are transported in an empty transport container or in viral culture medium
  • syphilis NAAT dry cotton tipped swab.

First catch urine

  • Should not pass urine for at least 2 hours before the sample collection
  • first 10 ml of urine is collected
  • voiding within 30 minutes prior to sample collection should be considered in interpreting results
  • tests for chlamydia NAAT, gonorrhoea NAAT, mycolplasma genitalium NAAT and trichomonas vagnilais NAAT as indicated.

Females

Note: NAAT refers to Nucleic Acid Amplification Test, such as NAAT

Samples are taken during speculum examination.

Endocervical specimens

A Pap smear is taken first if due or indicated.

Method

  1. A cotton tipped swab is inserted into the cervical canal only 0.5 cm and
    1. smeared on a slide and air dried for gram stain
    2. placed in a transport medium for gonorrhoea culture
  2. a second cotton tipped swab is inserted 0.5 to 1 cm into the cervical canal and kept in place for 10 to 15 seconds and rotated 1 to 2 times for chlamydia NAAT and gonorrhoea NAAT and mycoplasma genitalium NAAT testing
  3. place in a transport container provided by the lab.

Vaginal specimens

From the lateral vaginal wall with a cotton tipped swab:

  • smeared on a slide and air dried for gram stain for bacterial vaginosis and candida
  • placed in a transport medium for gonorrhoea culture and candida culture.

From the posterior fornix with a cotton tipped swab for:

  • pH performed on a pH strip at the time
  • wet preparation for trichomonas
    • smear on to a slide and place a drop of normal saline on slide - must be read immediately
      • trichomas vaginalis NAAT if indicated.

Self collected vaginal specimens

Sample for chlamydia and gonorrhoea NAAT in asymptomatic female using cotton tipped swab and transported in a container provided by the lab.

Rectal specimens

These are taken if clinically indicated.

Proctoscopy should be performed to inspect for lumps, ulcers, pus, bleeding and specimen collection.

Swabs are taken for:

  • gonorrhoea culture (plate or transport medium)
  • chlamydia NAAT and gonorrhoea NAAT (dry or moistened cotton tipped swab)
  • herpes simplex NAAT if indicated.

Pharyngeal specimens

These are taken routinely in sex workers and samples are collected.

Swabs are taken from each tonsillar fossa for:

  • gonorrhoea culture if suspected or NAAT positive
  • chlamydia and gonorrhoea NAAT for screening.

 

Ulcer specimens

  • Dry or moist cotton tipped swabs taken from the ulcer base can be tested for herpes simplex virus (HSV) NAAT
  • swabs are transported in an empty transport container or in viral culture medium
  • syphilis NAAT using cotton tipped dry swab if indicated.

First catch urine

Can be performed if no endocervical swabs are available and samples:

  • should not pass urine for at least 2 hours before the sample collection
  • first 10 ml of urine is collected
  • voiding within 30 minutes prior to sample collection should be considered in interpreting results
  • tests for chlamydia NAAT, gonorrhoea NAAT, mycolplasma genitalium NAAT and trichomonas vagnilais NAAT as indicated.

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