Treating sexually transmissible infections (STIs)

Women: To perform an internal examination, the doctor or nurse gently insert a hinged metal or plastic speculum into the vagina to view the cervix. A high vaginal swab (HVS) and cervical swab are taken and sent to a lab to identify any infectious bacteria. First, however, the HVS and cervical swab are smeared onto two glass slides and stained with dyes for examination under the microscope. This will show the presence of any bacterial imbalance (bacterial vaginosis), Candida yeasts or the bacteria responsible for gonorrhoea. The HVS will also be dipped onto a glass slide containing a drop of water to look for the presence of a single-celled organism (protozoon) called Trichomonas.

A second cervical swab is also taken and sent for immunological testing to detect the presence of chlamydia. Most women also have a urethral swab taken to check for chlamydia.

Men: Urethral discharge in males is investigated by obtaining swabs from the end of the penis. These are cultured and smeared onto a glass plate, stained and examined under the microscope to look for gonorrhoea bacteria. A swab will also be sent for immunological analysis to detect the presence of chlamydia.

Routine blood tests: syphilis, HIV and Hepatitis B
A routine blood test to check for syphilis is usually offered to everyone attending a GUM clinic. You may also be offered routine blood tests to check for Hepatitis B and - after counselling - for human immunodeficiency virus (HIV).

Urine tests
Urine samples may be tested for the presence of a variety of substances by simply dipping in a reagent stick. This contains a series of small pads, each impregnated with a different chemical that changes colour in the presence of certain substances such as glucose, protein, white blood cells and haemoglobin.

Urine testing is a useful screening test for diagnosing urinary tract infections. Urine may also be examined under a microscope to look for cells (for example, white blood cells which suggest an infection). Immune testing of urine is now available to help detect chlamydia, even when no obvious discharge is present.

Visual inspection of urine is also important. Cloudiness that does not clear (when certain chemicals are added to dissolve any suspended crystals) suggests infection is present. The presence of threads (clumps of cells) suggests there is an inflammation of the urethra, which can occur in NSU (non-specific urethritis), especially if chlamydia infection is present.