Are you having a hard time telling if your test result is a faint positive or evaporation line? Here’s how to figure it out. 

 
By OBGYN Dr. Kenosha Gleaton

Peeing on a stick (affectionately known as POAS) can bring a lot of emotions and sometimes confusion. Home pregnancy tests might be convenient, but they may also leave you with questions: Is it a false positive or negative? Why do I see faint lines?  If you get a faint line, how do you know if that's a positive result or an evaporation line? This guide will walk through how to tell the difference and how to avoid getting evaporation lines.

What is an evaporation line on a pregnancy test?

An evaporation line on a pregnancy test is a faint line (or rather, mark) caused by a test reaction that occurs when the urine evaporates, or when the test gets wet. Sometimes this line appears in the test window, making it look like a faint positive result. 

Evaporation lines are colorless streaks, not actual lines. They typically appear if a person waits for longer than the suggested time to read the test result. An evaporation line can also appear if the test gets wet.

What color are evaporation lines on pregnancy tests? What does an evaporation line look like? 

Evaporation lines are actually streaks and not faint lines. They are called "squinters," meaning you have to look closely to see them. Often, these lines will not go entirely across the test. Depending on the type of test, the evaporation line may look more gray than pink. Yet, a faint positive line can be mistaken for an evaporation line on a home test. If an evaporation line appears, it is best to take another test for an accurate result.

What can cause a faint positive line?

Before discussing the difference between a faint positive line and an evaporation line on a pregnancy test result, it helps to know what can cause a faint positive. A faint positive line can simply mean that the levels of hCG hormone, often referred to as the pregnancy hormone because it is one of the first signs of pregnancy, are low. So, if you see a faint line on your home pregnancy test, this simply means that the hCG hormone level in your urine is low, and you want to try again in the morning when it's more concentrated or levels have risen.

How can I tell the difference between a positive result and an evaporation line?

So, you're trying to read a pregnancy test result and there's a faint line, how can you distinguish between the two? There are two ways to tell the difference between a positive result and an evaporation line:

  1. Is it a pink line? If the result shows a pink test line that looks similar to the pink control line, then it’s likely a positive result. A positive result will run from the top of the test window to the bottom with the same thickness as the control line (even if it’s more faint). Is it a greyish white squinter that doesn’t look like the control line? Then it’s probably an evaporation line.
  2. When did the line show up? If a pink line showed up quickly, then it is likely a positive, pregnant result. If the line only showed up much later (say ten minutes or more) than the control line, it may be an evaporation line.

The best way to know for sure is to take another test. We suggest waiting a day, since the level of hCG (the pregnancy hormone) in your urine typically doubles in a matter of days. If the line on your test tomorrow becomes darker and more clear, then you can be confident it's a positive pregnancy test and not an evaporation line.

How to prevent evaporation lines

Usually evaporation lines appear if you haven’t followed the instructions on the test’s packaging. But if you continue to get evaporation lines, we suggest:

  • Try peeing in a cup and dipping the test in the cup (instead of peeing directly on the test). This prevents splashing of urine that can make a test invalid.
  • Try testing first thing in the morning (when your urine has a higher concentration of hCG hormone).
  • Only use tests before the expiration date on the wrapper.
  • Don’t open the wrapper until you’re ready to start testing, and don’t use it if the wrapper is damaged or torn.
  • Store your pregnancy tests between 36-86°F (2-30°C).
  • Wait five minutes to look at your results—and make sure to read the results within 15 minutes.

What pregnancy tests are best for avoiding evaporation lines?

Make sure to find a pregnancy test that uses pink dye. That's because blue dye tests are notorious for leaving evaporation lines. The Natalist Pregnancy Test is easy to use, with pink dye that makes the answer as clear as possible. 

Takeaways

  • Evaporation lines do occasionally happen when the urine evaporates.
  • The best way to tell is by reading the results within the timeframe explained in the instructions.
  • A positive result will have a test line that runs from the top of the test window to the bottom with the same thickness and color as the control line.
  • An evaporation line will be a grayish white mark that appears after ten minutes.
  • The best way to know if you are pregnant is to test again tomorrow.

We’re believing in a positive test and outcome for you!

 

Featured Image by Edgar Hernandez