How Can I’ve False Positive or False Negative STD Evaluation Results?

March 15, 2018

Another day I got a telephone call from a really confused woman. She told me that she did not know whether or not she had chlamydia. As she explained, her urine test was positive, however her vaginal culture was negative. She and her doctors had made a decision to take a course of antibiotics as though she had been infected. However, she did not understand the way both tests could disagree.

The simple explanation – no diagnostic test is ideal. False STD evaluation results can and do occur.

The Way STD Tests Are Made

Most modern STD tests are very good. However, no evaluation is going to be 100% accurate 100% of the time. The measure of how good a test is has to do with its sensitivity and specificity. Sensitivity is how good a test is in finding people who have a disorder. By comparison, specificity is how good a test is at figuring out that does NOT have the disease. Both of these factors are important in determining how well an STD evaluation works in any circumstances.

The significance of sensitivity is evident to most people. Apparently, you would like the evaluation to be able to find as many cases of the disease as you can. But many wonder why should it matter how good a test is at detecting people who do not have a disease. The answer is straightforward. Without having the ability to correctly detect a person’s negative condition, the test results will be inundated with false positives.

False Positive vs. False Bad STD Tests

A false positive outcome is when a test claims that a individual has a disorder when they do not. Conversely, a false bad result is every time a test states a person does not have a disease when they really are infected. Because STD tests aren’t perfect, people who design them often have to select whether it is far better to have more false positive or more false negative evaluations.

Which is better depends upon the intensity of this illness, and physicians’ ability to take care of it.

For instance, envision a non-contagious disorder where treatment delay doesn’t have some long-term consequences but the treatment itself is grueling. In this case, false positives are much worse than false negatives. The disease isn’t likely to cause big problems if a situation is overlooked. However, the treatment may be expensive or make people feel very ill. Therefore, it’s far better to under-treat compared to over-treat.  On the other hand, if early treatment is important for good outcomes, the choice differs.  False negatives can cause more significant issues. Doctors don’t need to miss an chance to deal with a condition premature. That is true even when they unintentionally treat some people who do not have the disease. 

What Cases a False Positive STD Exam Result?

How frequently a test gives a false positive or false negative effect doesn’t only rely on the sensitivity and specificity of the test. It also depends upon how common the disorder is. The math to prove it could be seen in this piece . It is possible to think about it like this. Imagine you have a population where a disease is very rare. It affects just one in every thousand people.

When a test is quite good at discovering the disease, it can always find that person. However, if it is not ideal at discovering people who do not have the disease, then several people will test positive who don’t have it. As there’s only one genuinely infected individual, there are far more false positives than true positives! On the flip side, if half of those people have the disease, the situation differs. The disorder will be discovered in all them. It will also be detected in a small number of people who aren’t infected. However, in that circumstance, the amount of false positives is a lot smaller than the number of true positives.

In other words, how many people have the disorder produces a massive difference in how tests work. That’s why there isn’t any simple answer to how accurate a test outcome is. The fact that precision is dependent upon disease prevalence is why testing businesses and physicians can not simply give you a simple answer about how likely your result is to be right. It depends not just on the test but on the population it is used in.

Dealing with Inconsistent STD Test Results

What do you do if you get two different results from two different diagnostic tests? It is dependent on the disease. Imagine that the disease is simple enough to treat, and the treatment does not have any severe side effects. Then you’ll want to just go with the flow and take the drugs prescribed for you. If not, then take yet another test. Based on the sort of evaluations involved, it normally becomes less and less likely that you’d continue to possess false results with every succeeding test you take.

This is actually the principal behind many HIV testing protocols. False negatives are not that prevalent on HIV tests. (They do happen. This often occurs when someone is newly infected.)   However, false positives can be a real problem. An HIV diagnosis is indeed scary and stigmatizing that you don’t wish to tell someone they have the illness when they don’t. That’s why many labs do a second test for anybody who originally turns out to be HIV positive. If both tests are positive, the individual in question is almost certainly infected.

Rapid tests are an exception to this principle about HIV testing protocols. Their results have been based on a single evaluation. That is the reason why they are primarily available in high prevalence settings. In areas where HIV is relatively common, they’re very useful. The quick test does a relatively good job of correctly diagnosing positive people rather than vastly over assessing unwanted individuals.That’s less true in areas where HIV is more thicker. 

A Word from Verywell

If you wind up with inconsistent STD evaluation results, stop and have a breath. Then speak to your physician about what makes the most sense in how you want to move. If treatment is simple, you may just wish to get treated for the STD — even if you’re unsure you have it. When treatment is much more complicated, more testing might be required.

One of the most difficult things about dealing with inconsistent STD evaluation results is knowing how to speak to a sexual partner. My recommendation would be to be open and honest. Inform them that you’d results suggesting you may get an STD, but the outcomes were not clear. If you decided on treatment, inform them. After that, suggest they might want to get tested themselves. It is the simplest way for them to understand how to proceed with the information that you provided them. What’s more, if they are positive, it might also help you realize your results a bit more clearly.