Can ultrasound scan done late be wrong

[Knowledge22]

How accurate is an ultrasound done at 32 weeks? My friend was unaware she was pregnant till 32 weeks and had her scan at 32 weeks. Can it be wrong by 2 weeks?
Thanx

[AnnieBrooke]

OK, well, since it was only in her 32nd week that she finally got the date estimate, yes, it's certainly possible she could have gotten pregnant from sex around April 27 but it's also possible that the earlier sex produced the baby, especially given that she had the baby so much earlier than her estimated due date. (Unless the baby was noticeably premature.) She should get a DNA test done to be sure.

[Knowledge22]

Thank you so much

[AnnieBrooke]

Hi, I suppose so. Can you give some dates or name the issue? Doctors will say it can be off by +/- 7 days at 12 weeks GA, and off by up to 3 weeks by 40 weeks GA.

[Knowledge22]

She had sex on the 27th April 2017 n the condom slipped off bt they only noticed after the round was over that it had slipped off and again on the 28th protected this time with no mistakes. In november on the 29th dr told her she is 32 weeks n 4days. She gave birth on the 3rd January. She was in many sexual relationships b4 this encounter but all before the 15th of April. Her due date was 20th January. So now we would like to know if i could be wrong coz it was done so late even she had sex around that time

[AnnieBrooke]

Yes indeed.

[Knowledge22]

How wrong? A week? 2 weeks?