Explanation

Herpes simplex virus type 1 PCR (urine): what is measured?

Herpes simplex virus type 1 (HSV-1) mainly causes cold sores, but through oral sex it increasingly also causes genital herpes. The PCR looks for genetic material of the virus in the first portion of urine. After a first infection, the virus stays in the body for life and is shed from time to time, with or without blisters; the test only measures whether there is virus in the urine at the moment of sample collection. Urine is less sensitive than a swab of a blister or sore; with such a spot, a swab of it says more.

What can it detect?

Shedding of HSV-1 in the urethra or genitals at the moment of sample collection, with or without symptoms

Result

What does the result mean?

Positive result

A positive result means that HSV-1 has been found in the urine. This fits virus shedding in the urethra or genitals and confirms that you carry the virus. The result cannot show when you were infected, whether it is a first infection or exactly where the virus comes from. According to the LCI guideline (RIVM), genital herpes caused by HSV-1 comes back less often than herpes caused by HSV-2 (on average about 1 time per year after a first outbreak), and shedding without symptoms decreases sharply in the first year. The virus stays present for life; treatment is only needed with symptoms.

Negative result

A negative result says little. Urine is less sensitive than a swab of a blister, and without blisters the virus is only shed from time to time. So a negative result does not rule out that you carry HSV-1 or can pass it on. If you have a blister or sore, a swab of that spot is the better test.

After an abnormal result

With a positive result without symptoms, no treatment or monitoring is needed; the GP can explain the risk of transmission, condom use and informing a steady partner. With blisters or sores, a swab of the spot can confirm the diagnosis. Herpes is not notifiable.

Reliability

How reliable is the test?

According to the LCI guideline (RIVM) and the Multidisciplinary Guideline on STIs, PCR (NAAT) is the first choice for showing herpes on a swab of a blister or sore, of the cervix or of the urethra. Urine as a sample material for genital herpes in adults has been studied less well and is less sensitive than a swab of a blister or sore. A positive result is meaningful; a negative result does not rule out herpes.

What can affect the result?

Urine is less sensitive than a swab of a blister or sore.
Without a blister or sore, the virus is only shed from time to time; a negative result does not rule out carriership or being contagious.
The result does not say whether it is a first infection or a recurring outbreak, nor when you were infected.
If you urinated less than 1 hour before sample collection, or collect more than the first part of the stream, the sample is diluted and the test can miss an infection.

Preparation

Collect the urine when you have not passed urine for at least 1 hour.
Collect only the first part of the stream, not the middle part.

Who it is for

Who is the test useful for?

Useful for

A positive result shows that you carry the virus. A negative result says little, also without symptoms, because the virus is only shed from time to time. With a blister or sore, a swab of that spot says more. Pregnant women with a blister or sore should go straight to their midwife, GP or gynecologist.

How common is it?

In 2023, GPs made the diagnosis of genital herpes about 28,600 times, more often in women than in men; the sexual health centers, which do not test for herpes as standard, did so in 616 people in 2024. In a national population study (Pienter-2, 2006 to 2007), about 43 in 100 inhabitants had antibodies against HSV-1, usually from a cold sore. An increasing share of genital herpes is caused by HSV-1, especially in young women.

RIVM (GPs 2023, sexual health centers 2024); LCI guideline on herpes simplex virus infections (Pienter-2)

Drawbacks and risks

A negative result can give false reassurance about carriership or being contagious.
A positive result without symptoms can cause worry and tension in a relationship, without any treatment being needed.

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