[ RadSafe ] In utero dose

[North, David]

In the hypothetical case you describe, the principal risk which I am sure
the surgeon and any other physician caring for the patient would consider is
the risk of death or lasting injury to her and her unborn. Any risk from the
radiographs, or even CT scans, is insignificant by comparison. I work in a
hospital whose emergency unit is a Level I Trauma Center, and it is very
busy (fourth or fifth busiest in the USA, I believe). They see over 100,000
patients per year (more than 22,000 trauma cases), and the two dedicated CT
scanners each average an exam every 20 minutes, 24 hours a day, seven days a
week. Basically in that setting, the guideline for taking x-rays or doing a
CT scan is that if the exam is needed for the diagnosis or treatment course
of the pregnant patient, she gets it. I don't think I have ever been
consulted beforehand, and I don't very often get questions afterward. Any
exam involving ionizing radiation and a pregnant patient is reported to me
as standard procedure so that I can make an estimate of the dose to the
embryo/fetus, but I have never been asked before an exam whether or not I
think it should be done. I am not a physician, so I can not assess the
medical risks or benefits from omitting it or performing it.

Generally, we begin to get a little concerned if the total radiation dose
approaches ten rads. I have only seen that happen once, and the lady didn't
even know she was pregnant at the time. She had about three small bowel
exams with fluoroscopy in the period of a couple weeks for an intestinal
obstruction. That was over six years ago, and I have heard nothing about her
case since then. If the dose had been near twenty rads, we probably would
have proceeded to genetic counseling as the next step.

As far as "routine" x-rays are concerned, I think the physician's judgement
is that if the pregnant patient really needs the exam, then it is done. I
get lots of reports from "routine" chest x-rays, back and neck exams,
extremity films, etc. The radiation doses are very low, especially if the
abdomen is not directly exposed. Even a CT of the abdomen/pelvis gives only
about 1.5 rads or so.

David L. North, Sc.M., DABR
Associate Physicist
Medical Physics
Main Bldg. Rm 317
Rhode Island Hospital
593 Eddy St.
Providence, RI 02903
(401)444-5961
fax: (401)444-4446
dnorth at lifespan.org




> ----------
> From: 	radsafe-bounces at radlab.nl on behalf of Keith Welch
> Sent: 	Tuesday, April 18, 2006 9:48
> To: 	radsafe at radlab.nl
> Subject: 	[ RadSafe ] In utero dose
> 
> I have some questions for you medical experts.  I'm curious what 
> guidelines are used when there is a case requiring x-rays of a pregnant 
> female.  Let me give you a hypothetical case.  Let's say a woman is 
> injured in an auto accident, has some internal injuries and broken 
> bones.  She's 12 weeks pregnant.  To treat her injuries, she needs 
> surgery and a series of radiographs.  Are there generally accepted and 
> well known standards that physicians refer to in order to advise 
> patients and determine a course of treatment?  Are there risk-based 
> guidelines in place and widely known to general surgeons and 
> practicioners?  How common is it for a surgeon to seek the advice of an 
> HP or MP to assess the risks of such procedures?   My impression of the 
> handling of "routine" x-rays is that if a woman is pregnant, x-rays are 
> always postponed, just to be conservative.  But in a case where there is 
> a pressing need to preserve health, how is the decision to conduct the 
> x-rays arrived at?  How are these risks weighed?  What is the typical 
> "standard of care"?  Is there an agreed dose at which the patient is 
> advised to terminate the pregnancy?
> 
> Thanks.
> Keith Welch