Think there's any truth to this?

Found this on wikipedia:
Obstetric ultrasonography, either transvaginally or transabdominally, can check for the sagittal sign as a marker of fetal sex. It can be performed between 65 and 69 days from fertilization (week 12 of gestational age), where it gives a result in 90% of cases - a result that is correct in approximately ¾ of cases, according to a study from 2001.^[1] Accuracy for males is approximately 50% and for females almost 100%. When performed later, after 70 days from fertilization (at week 13 of gestational age), it gives an accurate result in almost 100% of cases.

I am not currently PG, but plan to be sometime this year, and I DISLIKE the wait to find out ;-)...so I am interested in this...what do you need to ask you Dr when you go? 

Here are the links:

http://en.wikipedia.org/wiki/Prenatal_development

http://en.wikipedia.org/wiki/Sex_prediction

 This is nub theory, guys.  The sagittal sign in the caudal or cranial notch:

Hey Al, could you please take a look at my nub again and tell me what you think?  Thanks!

 I think GIRL.  ;)

Sorry to bug you Al, but could you tell me why you think girl?  Just wondering what I'm looking at and the reasoning behind the girl guess.  I think I might want to be an u/s tech after my kids are in school...LOL

 I think girl becuse the nub isn't at an angle in relation to the spine.  Looks like a girl nub.

Ok, so you're saying the nub is flat or parallel to the spine.  Does the fork or shape of the nub mean anything or is it primarily the angle?

TTC#3- The link you found is the same as the nub theory...it's definatly not a guarentee as there are PLENTY of nub guesses on the u/s forum that we have professional u/s techs look at and they have been wrong. However...looking at your nub it's very flat...although the picture isn't clear on the computer it appears to be less than 20 degrees to the spine which is typical for a girly nub....all fetuses before a certain stage look the same "down there" the elongated part we see will turn penis for a boy and gradually sink in for a girl, it's the clitoris, and the outer fold will turn labia for girl and scrotum for boy. SOMETIMES boys can look very flat and still be boy and vise versa...but I think a lot of the time it's right as well. I hope that your nub is correct as it looks girly to me! The boy nubs tend to point up or are forked. Go to the u/s gender prediction forum and take a look at a few! Good luck!

Thanks for your response babybleu.  You said that boy nubs tend to look "forked".  Does mine look "forked"?  I wasn't sure if it did or not.  I have been looking at the ultrasound prediction forum...rather obsessively :)

 All nubs are forked especially in the 12th week - it is the urethra being imaged on ultrasound:

Thanks for the clarification Al!