What are Pregnancy Test Evaporation Lines?
Testing for Pregnancy >> What are Pregnancy Test Evaporation Lines?
Evaporation lines are caused by evaporation of the urine in
the result window of a pregnancy test. These are lines that shows in the result
window of the test. An evaporation line develops when the urine on the test
area begins to dry, leaving a faint, colorless line. Evaporation lines appear
as a result of the composition of the particular urine specimen - and they may
appear on any test regardless of brand.
Evaporation lines can confound results if tests are not interpreted
within the clinically recommended time frame. The complete reaction time of
our pregnancy tests is 5 minutes. With most home pregnancy testing products,
the "reaction time" of the test is a minimum five minute interval
to verify a negative result for pregnancy. Generally, at three to five minutes,
you can interpret the test results. To be accurate, the test results should
be read within the reaction time of the test, which is usually at 5 or so. Manufacturers
also recommend that you should not read tests after a designated time period,
as most test brands have the possibility of developing evaporation lines.
Once the reaction time of the home pregnancy test is complete,
color bands will either appear or not appear in the test region of the strip
or midstream unit. All tests have a "control" color band or color
line that indicates whether the test is working or not. The "test"
color band indicates a positive or negative result.
Assuming that the home pregnancy testing procedure has been followed properly and the results have been interpreted
within the time frame indicated by the manufacturer, a faint line in the test
region of the result window may be read as a positive result, though it's a
good idea to verify the result in a day or two using a first morning urine sample.
Now, an evaporation line
will not be confused with a faint test line (valid positive)
if the test is read within the five minute reaction time interval. Other explanations
for faint test lines include:
Too Early in Your Cycle: If you test too early, earlier than
seven to ten days past ovulation, the hCG may not be at a sufficient level to
produce more than a very faint line. If you do see a faint positive test result,
then we always recommend a follow up test in a day or two using that first morning
Test Sensitivity: Different tests have different sensitivity
levels. Check the sensitivity level of your test and try to purchase higher
sensitivity pregnancy tests so you can have accurate results sooner.
Urine Sample: Urine samples may experience "dilution"
due to frequent urination or consumption of liquids. This is whey first morning
urine is recommended for pregnancy testing as it contains the most concentrated
amount of the hormone, hCG.
pregnancy: A chemical pregnancy is indicated when implantation
of a fertilized egg takes place and hCG is produced. A chemical pregnancy is,
by definition, very shortly followed by miscarriage before any other pregnancy
signs can be detected. Hence, a faint positive line on a pregnancy test may
be detected, but there is a a miscarriage very quickly following implantation.
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