reliability of ultrasounds in predicting sex

  Hi--
  I've just had my first ultrasound done (at 22 weeks), and the technician
  identified a penis and a scrotum between my baby's legs and stated with
  no doubt that my husband and I are having a little boy.  Still, I know that
  ultrasounds can be wrong.
  Just how reliable are ultrasounds in prediciting/determining a fetus's sex?
  Is it more likely for an ultrasound to mis-identify a girl, or vice versa?
  If a fetus's sex is misidentified, what's usually the reason?  In other
  words, if that's not a penis and a scrotum between my fetus's legs, what
  is it?
  Thanks very much for your help!
Dear Lauren:
Ultrasound is very reliable at 22 weeks' gestation to define normal anatomy: with 99% certainty, you and your husband are expecting a son.
There is more likely to be error identifying a daughter: one must see the male genitals to make the call. Failure to see genitals could be the result of the baby's position.
Misidentification can occur with developmental issues wherein the genetic sex does not match the phenotypic (appearance) sex. There are hormonal conditions that cause the phallus to enlarge in females, just as there are situations wherein the phallus never forms in a boy. These are all rare.
It is normal to worry about possible problems with unborn babies and healthy that you are asking the right questions. The overwhelming likelihood is that your baby is normal and you now only have to think of one-half as many names.
This material is provided for general information purposes only and should not be considered a formal medical evaluation. If your have specific questions, please contact your primary physician.
Keywords: pregnancy, sex of baby