Answer to Question #3719 Submitted to "Ask the Experts"

Seven years ago I herniated a disc in my lower spine (L5-S1). I am 32. Since the accident, I have been given many x rays of the lower back, as I have changed jobs (and thus insurance plans and health care providers) multiple times. Each new doctor wants to get his or her own set of new x rays. I have had periodic incidents of aggravation of the injury over the years which have prompted these x rays. I estimate I have received at least 30 x rays of the area (and possibly more) since the original accident. Once, a technician couldn't get the x rays to come out right (they were blurry for the first two series) and repeated them three times. Now I have a new doctor and I pinched a nerve in my spine recently. I have been sent for a new set of x rays—five of the lower spine and two of the pelvis. Is this necessary? I brought a set of two-year-old x rays to this doctor but was told they were too old to be of use. I am concerned about repeated diagnostic x rays and the exposure to my gonads with respect to spermatogenesis and birth defects. My wife and I are planning to have children, and I'm worried not only about my past exposure, but about taking any additional x rays of the area. Also, is there a significantly increased risk of cancer due to this exposure? I am concerned because the gonads cannot be shielded due to the location of the injury.

I hope we can allay your concern about the genetic risks of diagnostic studies that you have had for your back problems. These exposures are low and will not measurably increase your reproductive genetic risks.

Actually, in your case the risks are very small because your sperm received a very low dose. Secondly, time has gone by and you have gone through many complete cycles of spermatogenesis after each study. That means that if any sperm were affected, the vast majority of damaged sperm will no longer be available at the time your wife becomes pregnant. Your risks for having a child with a genetic disease due to your radiological studies are far below the risk of inheriting a genetic disease already present in your genes or resulting from a spontaneous mutation that occurs in a low frequency in all of us. The studies of the survivors of the atomic bombings have not shown they had an increase of genetic disease in their offspring and they received much larger exposures than patients who received diagnostic radiological studies. If you and your wife are healthy, young, and have no reproductive problems or family history of reproductive problems, your family's risk for birth defects is 3 percent and for miscarriage, 15 percent. Neither you nor I can change that risk, which all families have when they begin a pregnancy. Good luck with your pregnancy.

Robert L. Brent, MD, PhD