If the EPT is positive before a missed period how accurate it?

An early pregnancy test (EPT) that shows a positive result before a missed period is highly accurate, with an accuracy rate of over 99%. However, it's important to note that a positive EPT result only indicates the presence of the pregnancy hormone hCG in the urine, and does not guarantee a viable pregnancy. Some factors that could affect the accuracy of an EPT result include:

1. Early Testing: Testing too early, before the hCG levels in the urine are high enough to be detected by the EPT, may result in a false negative result. It's recommended to wait until at least the day of the expected period or a few days after for the most accurate results.

2. Medication and Medical Conditions: Certain medications, such as fertility drugs containing hCG, and underlying medical conditions can interfere with EPT results, leading to false positive or false negative outcomes.

3. Evaporation Lines: Some EPTs may produce faint lines due to evaporation of the urine on the test strip. These evaporation lines can sometimes be mistaken for a positive result, but they are usually distinguishable from a true positive line by their faintness and lack of color.

4. Chemical Pregnancy: In some cases, a positive EPT result can be due to a chemical pregnancy, which occurs when a fertilized egg implants but fails to develop into a viable pregnancy. This can result in a brief rise in hCG levels, leading to a positive EPT, followed by a negative result as the hCG levels decline.

5. Ectopic Pregnancy: A positive EPT result does not rule out the possibility of an ectopic pregnancy, where the fertilized egg implants outside the uterus. This condition requires medical attention, and a healthcare provider should be consulted if there are concerns about an ectopic pregnancy.

It's always recommended to consult a healthcare professional if you have any questions or concerns about the accuracy of an EPT result or your pregnancy status. A blood test or a follow-up visit to your doctor can confirm the pregnancy and provide further information about its viability and progression.