Why did it take eighteen days for Aunt Flo to show up before I tested?

Patient's question:

No

Doctor's answer:

To detect pregnancy, it is generally necessary to wait 10 days after the next menstrual period to get a result. With a menstrual cycle of 28 days, the ovulation period occurs 14 days after the last menstrual period. Adding 10 days to this means you need to wait approximately 24 days after conception to detect pregnancy.