Everyone knows the relief that comes with a negative test result, and those same people can imagine the fear and anxiety that comes with a positive test result.
But some people get a result that doesn’t inspire fear or relief – they just scratch their head.
Inconclusive results are rare, but do occur. Read on to find out what they are, why they occur, and what to do if you get one.
It is important to know your sexual health status.
How do STI tests work?
To understand what inconclusive test results can mean, we need to understand how STI testing works.
Like many medical tests, STI testing uses samples – a representative portion of a problem area – to determine whether an infection is present. These samples are usually in the form blood, urineor swab.
- Blood samples are taken from your vein with a needle. This can be done in a clinic by a nurse or at home with a finger lance.
- Urine samples are collected in containers either at the clinic or at home. In both cases they are usually picked up by the patient themselves.
- Swab samples are collected by using a swab to remove some material from the affected area – usually the genitals, mouth or rectum.
These samples are then processed using various testing methods such as: Polymerase chain reaction (PCR), antibody Tests and antigen tests, depending on the infection being tested for.
- PCR Tests detect the DNA of certain pathogens in a sample.
- Antibody tests Recognize antibodies your body produces to fight certain infections. Antibody tests are usually done for viral infections HIV And Hepatitis B.
- Antigen tests Detecting antigens produced by viruses. Antigen tests can help detect certain infections at an early stage.
There are four possible results of a test: positive, Negative, inconclusiveAnd ambiguous. You probably know what positive and negative mean. But what about the other two?
What does an inconclusive test result mean?
“Inconclusive” means that the test in question was performed correctly – that is, there was no fault with the equipment – but the laboratory was unable to make a reliable determination as to whether it was positive or negative. In other words, the sample did not produce a definitive result one way or another.
What does an inconclusive test result mean?
An “ambiguous” test result is similar to an inconclusive test result. However, it means something a little more specific: that the results are in a borderline range – too low to be considered positive, but too high to be considered negative. This result is most common in antibody tests.
Why should you get these results?
An inconclusive or ambiguous test result can be caused by a few factors.
Example outputs
Sometimes a sample is not optimal. If the sample provided is not viable, the test cannot detect infection.
The most common sampling problems include:
- Insufficient sampling: The amount of blood or urine provided did not meet the required limit.
- Dismantling: Too much time has passed since the sample was taken. This is usually due to delayed transport.
- Contamination: Foreign substances have contaminated the sample and made it unusable for testing.
- Improper collection: Problems during collection may affect sample viability.
Incorrect sampling time or early stage of disease
For an infection to reach detectable levels in your body, samples must be taken at the right time.
For most STI testing, 14 days after the worrisome incident should be sufficient. However, a longer period (a few more days to several weeks) could provide a more robust and reliable sample.
For example, it often happens that HIV-infected people are tested too early. The urgency to gain clarity about their condition may result in some people being tested before the appropriate level of antigens or antibodies have developed. Anyone who gets tested too early may receive a negative test result but will still be infected.
If you are tested, follow clinical guidelines at the time of testing.
Biological variation
When tested for antibodies, some people naturally experience borderline or fluctuating levels of antibodies, and the immune response may vary from patient to patient. In other words, some people may produce more antibodies than others in response to the same infection. This can make determining critical concentrations of these antibodies somewhat difficult in certain circumstances.
Medicines and nutritional supplements
While most tests are not affected by medications or supplements, excessive intake of biotins (vitamin B7 or B8, vitamin H or coenzyme R) should be avoided in the days leading up to the test.
Other immunoassays for hormone testing can also be influenced by substances such as dopamine, fluorescein and prednisone.
Consult your doctor before getting tested if you are taking any medications or supplements.
Technical factors
These are laboratory and instrument-related factors that may affect accurate detection.
- Low level signal interference: Interference refers to substances or conditions that interfere with the test’s ability to accurately detect the pathogen signal. This can include sample contamination from powders or cleaning agents, but also matrix effects, in which the natural composition of a sample influences signal generation.
- Marginal Assay Performance: Tests are designed with defined thresholds. Marginal performance can occur when small fluctuations shift the results into a “gray area.”
- Instrument variability: Incorrectly calibrated equipment, unstable temperature control, or inconsistent reagent quality can cause a result to be unreliable.
- Procedural errors: Sometimes errors occur in sample handling and testing – pipetting errors, mislabeling, and protocol deviations can affect test performance.
Diet and lifestyle
Certain dietary and lifestyle factors can affect test results.
- Not fasting: Eating before a test that requires fasting can change your blood sugar and lipid levels.
- Physical activity: Strenuous exercise before a test can increase certain muscle enzymes.
- Time: The levels of some hormones such as cortisol fluctuate throughout the day depending on your circadian rhythm. The timing of the test can be crucial.
- Menstrual cycle: Getting tested during your cycle may produce uncertain results.
Other conditions
Cross-reactivity between antibodies and another, related virus (such as the common cold) can result in a dubious antibody test result.
Individual biological variability
Some people naturally have levels of certain biomarkers that are outside the “normal” range but are normal for them, which can be flagged as an indeterminate result.
What should you do when you get these results?
It can be confusing to get any of these results. Here is what we recommend to all of our patients who receive an inconclusive or ambiguous result.
Repeat the test
Getting tested again is the first step. This can provide clarity, especially if there were problems with the sample taken.
Follow clinical guidelines
If the result is inconclusive, subsequent tests must be carried out using the correct procedures and methods. Patients undergoing testing should follow clinical instructions, especially when taking samples after the corresponding incubation period.
Consider the clinical context
Symptoms, exposure history, or other relevant information can guide next steps beyond retesting.
Final thoughts
Receiving a test result other than negative can be very stressful. But it’s important not to panic. Remember that most sexually transmitted diseases are curable and most others can be treated with proper care and medication.
Book an STI test near you by clicking the button below. You can also speak to a member of our friendly patient services team. They can talk to you about your situation and even book a test for you.
Don’t leave your sexual health to chance.
