My OB told me I had to wait 6 months after weaning before getting mine. Which reminds me, 7 months now <img alt="" class="inlineimg" src="http://www.mothering.com/discussions/images/smilies/greensad.gif" style="border:0px solid;" title="greensad"> I guess I'd better schedule...
They're not very accurate.. But in my case, I will be having one in a few weeks. As the op said, U/S are more accurate, and I think "theromgraphy" scans are better, if I spelled that right, but are hard to find a place that uses them.
In general, they don't find they can get useful images because the milk scatters the x-rays. For that reason, they prefer to do breast ultrasounds on nursing mothers. However, when my daughter was a year old and still nursing, I had a mammogram and image quality was fine. I brought my daughter (and husband to take daughter away from x-rays) and my pump. The plan was for my daughter to empty breasts efficiently. Daughter wasn't interested in eating and refused to nurse. Since she didn't do her job, they put me in a room and had me pump as best as I could to empty my breasts. From reading the radiologist's report, I could tell that the milk did not cause a problem.<br><br>
Everyone is different. For example, I've never had engorgement or leaking or oversupply. My issues tended to be with undersupply issues, so there wasn't usually much milk in my breasts anyway.<br><br>
I think that if I had been nursing a very young baby, instead of my older child who was nursing much less frequently, the mamogram image might not have turned out. But maybe it would have been fine. I mean, it's not like the milk is in storage in the breast tissue. It's made on demand. I'm not an expert on mammograhy and breasts by any stretch of the imagination, so I don't know how much milk would present a problem. However, I am a physicist, so I know something about x-rays, and I know something about the physics of scattering by milk, so my guess is that a little bit of milk is fine, but more milk is not.