HomeAnswersObstetrics and GynecologypregnancyMy LMP and ultrasound differ by two days. Why?

How to find the exact date of conception?

Share

The following is an actual conversation between an iCliniq user and a doctor that has been reviewed and published as a Premium Q&A.

Medically reviewed by

iCliniq medical review team

Published At January 28, 2017
Reviewed AtJanuary 29, 2024

Patient's Query

Hi doctor,

According to my LMP, I was 9 weeks and 5 days pregnant, and ultrasound showed I was 9 weeks and 3 days pregnant. There was a CRL measurement of 26.96 mm. I had sex on the last day of my periods and then again after 11 days. And, my LMP and ultrasound calculation show two days difference. So, can I tell that I pregnant on the second event? My periods are irregular. The previous month, I also had endometriosis surgery. I have heard that endometriosis surgery can cause high fertility and regular ovulation. Since my LMP and ultrasound are close enough, is it safe to say ovulation was normal at least for that month?

Hi,

Welcome to icliniq.com.

Your estimation is correct. There is the least possibility of conceiving on the last day of the period. You must have conceived around the second event. Now, LMP (last menstrual period) and ultrasound time cannot match exactly. Although in your case, it is almost the same. Do not confuse about two days difference. Ultrasound calculates the period of gestation according to some measurements as you have seen CRL (crown-rump length) at different periods and separate parameters for calculating the time of gestation. Now, LMP also cannot tell you exactly the day of ovulation until unless ovulation study was done and you have seen the size of the follicle and then its rupture to release the egg. Usually, early scan done at six weeks or so is the best predictor of your dates. But, now also, everything is fine, and you can monitor growth in further scans.

Same symptoms don't mean you have the same problem. Consult a doctor now!

Dr. Kamalpreet Kaur Nagpal
Dr. Kamalpreet Kaur Nagpal

Obstetrics and Gynecology

Community Banner Mobile
By subscribing, I agree to iCliniq's Terms & Privacy Policy.

Ask your health query to a doctor online

Obstetrics and Gynecology

*guaranteed answer within 4 hours

Disclaimer: No content published on this website is intended to be a substitute for professional medical diagnosis, advice or treatment by a trained physician. Seek advice from your physician or other qualified healthcare providers with questions you may have regarding your symptoms and medical condition for a complete medical diagnosis. Do not delay or disregard seeking professional medical advice because of something you have read on this website. Read our Editorial Process to know how we create content for health articles and queries.

This website uses cookies to ensure you get the best experience on our website. iCliniq privacy policy