Evaporation Lines A true positive will appear within two to 10 minutes, while urine won't dry and form streaks until some time later.
In reality, it's likely what's called an evaporation line, a faint line that can occur when the test sits too long. The faint line appears after the test has dried, but most tests are meant to be read while they're still damp, says DuMontier.
But even a faint positive line has color, and this distinguishes it from an evaporation line, which is colorless. Any coloration in a positive line indicates pregnancy. A mark on a pregnancy test may be an evaporation line if: More than 10 minutes have passed since taking the test.
If a person reads the pregnancy test after the recommended time has elapsed, it may result in what looks like a positive test result. However, in most cases, this is not a positive pregnancy test but an evaporation line left by the urine after the recommended time for reading the test.
The easiest way to differentiate between a positive test result and evaporation line is to check your test within the allotted time. A true positive will appear within two to 10 minutes, while urine won't dry and form streaks until some time later.
Many at-home pregnancy tests suggest reading the results within two, five, or up to 10 minutes after urinating on the stick. Checking results after that window means your urine has dried up, potentially causing that streaky evap line.
Read the test result after 15 to 30 minutes. Results may be incorrect after 30 minutes. In a positive result, a coloured line will also appear in the lower section of the result window. This is the test line (T).
Evaporation lines are relatively common, and they might appear on a pregnancy test as the urine dries. They typically show up after the timeframe where you're instructed to read the results—which is generally from two to five minutes after you pee on the stick.
If you had a true evaporation line, future tests will show a negative result. On the other hand, if your test showed a faint line, you should continue to see the line darkening with each day that progresses. (See image below.) An evaporation line will not do this.
A test will only show a false positive if you have hCG in your system for another reason such as you were recently pregnant, are taking fertility medications containing hCG, or if you have a medical condition, like some rare ovarian cysts.
Many women save the test once they see a negative result and check it again an hour later. If another line appears hours later, it is an evaporation line and not a pregnancy indicator. While it depends on the type of test you are using, the reaction time is usually 5 minutes for most tests.
It's common to see evaporation lines appear during a pregnancy test, but they don't always. Make sure you check your results within the reaction time if you're using a home pregnancy test. Depending on the brand, this is the window of opportunity to get an accurate result.
The levels of hCG are very low at first and then they rise quickly, usually doubling every three days in early pregnancy. That's why you might have a faintly positive result at first and one that's crystal clear a few days later.
The instructions that come with the test will tell you how long to wait before checking the results. If the faint line appeared a few minutes after this time, it's possible that it's just an evaporation line. If you get a faint positive, you could try again using a digital pregnancy test.
Sometimes the line on a pregnancy test might be so faint as to be almost invisible. But often, it's definitely a faint positive test result, just like these below.
Unlike a faint positive result, which will result in a light pink or blue line, an evaporation line does not activate the dye in the pregnancy test. This means that it may show up as a colorless or translucent line.
Evaporation lines generally don't vanish over time once they've formed on a test strip. Once the liquid element of the sample evaporates, it can leave behind residue or a faint mark. These marks can be on the test face, performing in the appearance of an evaporation line.
The result will be ready in 15 minutes. Note: DO NOT interpret your test result until after your 15-min timer has completed, as the T line may take as long as 15 minutes to appear. Result shown at 2x. Repeat testing is needed to improve test accuracy.
If you are taking a pregnancy test before the day of your expected period, and are indeed pregnant, the line will start as a faint line (a “squinter”) and get darker as time progresses.
A faint, slow-to-appear line could still represent high levels of virus, meaning that if you can see any line at all, you are still highly likely to be infectious.
Some very sensitive pregnancy test kits can detect pregnancy as early as 6 days before your missed period (5 days before you expect your period), however the levels of hCG this early are so low that you can expect any line to be faint.
Can Too Much Pee on a Pregnancy Test Make It Negative? Urinating too much on a urine pregnancy test should not cause a false negative result. But diluted urine, or urine with a higher water content, can impact a pregnancy test by skewing results.
Buying Options. Clearblue is best known for its blue-dye plus-sign tests, but the pink-dye Clearblue Early Detection test is more sensitive and, in our experience, easier to read. This test's sensitivity is similar to that of the First Response Early Result.