What are evaporation lines?
Evaporation lines, as the name suggests are caused due to evaporation of the urine in then test area. These are lines that shows in the result window of the test, exactly where a positive sign would be. An evaporation line develops when the urine on the test area begins to dry, leaving a faint, usually colorless line. Evaporation lines appear to show up (or not show up) as a result of the composition of the particular urine specimen – and they may appear on any test regardless of brand.
How can you avoid formation of evaporation lines?
You should always read the literature that comes with the test and look for instructions on when to read your results. Usually home pregnancy tests have a reaction time of three to five minutes. While some tests are no longer accurate after a certain amount of time, others have been known to pick up Human Chorionic Gonadotropin (hCG) after a longer period of time than is recommended. You can only know for sure by testing again a few days or a week later. If you don’t see a positive result in the amount of time that the manufacturer states, you should not rely on that test result. Evaporation lines can cause confusion if the home pregnancy test is not interpreted within the clinically recommended time frame.