Can You Determine Weeks Gestation From a Pap Test?

Jane Foley's picture


Dear Ms Ultrasound,
I had unprotected sex with someone on April 21st. By May 11th she claimed that she was pregnant. Her last period was April 3rd. She went to the doctor May 14th and the doctor gave her an EDD of January 9th. She went the doctor for a follow up appointment and she the doctor gave her a pap smear and told her she was 7 weeks and 1 day. Is this possible? Can you determine who many weeks from a pap test?


I will try and clear up your confusion. From the sounds of it, you had unprotected sex right in the middle of your girl's cycle. This means that it is very possible that she conceived on April 21st. From an April 21st conception, her due date would be January 11th. Since the dating process is not an exact science, I would say this is pretty close to the January 9th her doctor gave her.

When she went in to see her doctor at 7 weeks, I think that there may be a communication problem. Sometimes doctors use words patients don't understand or the patient misinterprets what the doctor told them. The pap smear, if she had one was a test to check the tissue, not to date a pregnancy. In any case the doctor will be calculating the weeks from her last menstrual period.

The counting of weeks does not start from the day of conception. The weeks start on the first day of the last period. (Very confusing! I know!). So, at the moment of conception a woman is considered 2 weeks pregnant and the doctor counts forward from there.

When she found out on May 11th she was pregnant, she was considered to be 5 weeks along. Hope I haven't confused you more. If you have any more questions let me know.

-- Jane, RDMS