QuestionQUESTION: Hello just wondering if an ultrasound can tell the difference between 13 weeks and 15 weeks.. I had an ultrasound dating my 13 weeks 3 days.. I just want to know if it could be off by two weeks? Also the ultrasound gave me a lmp of 10/18/2011 due 7/24/2012 but my actual lmp 10/27/2011 gave me due date of 8/2/2012 which one would be more accurate because the first one means I concieved two days after my period and I heard your fertile 14 days AFTER your period!?!?? And to caculate conception you just remove two weeks correct?
ANSWER: Dear Stacy
1- yes Ultrasound dating have a margin of 2 weeks at full term, 40 weeks. At 13-14 weeks, the difference is few days. Definitely the experience of the operator and the model of the ultrasound machine play a role. The difference may exaggerate with poor quality machines and less experienced operator.
2-If you are sure of the date of your lmp, it should be more accurate than ultrasound dating.
3-The fertile period is 14 days before; not after, your menstruation.
I hope these info help.
Good Luck
---------- FOLLOW-UP ----------
QUESTION: Yes thank you just another question If you don't mind if the ultrasound is accurate than that would give me a conception day of 2 days after my lmp ended could that be possible also? And so The 13 weeks would defintaley not be off by two weeks if my ultrasound operator was experienced?
AnswerStacy
The answer for the first question is no. The fertile period never follows menstruation. If your cycle is 28 days then day 1 is the first day of bleeding. In this case your fertile period is between day 12 to day 16 (12, 13, 14, 15 and 16). In other words, you are not fertile from day 1 till day 12. Definitely variations occur depending on the length of your cycle but this would be within a margin of few days.
The answer for the second question is yes.
Good Luck
