Getting rid of public service ads

AdSense generally does a very good job of targetting ads based on the content of my medical website.
Sometimes, hoever, it keeps running a public service ad and I can't figure out why. I have a rather large entry for a spinal cord condition known as autonominc dysreflexia and no matter where I put the ad it won't display anything else besides a PSA. Can anyone help me out here? The entry is located at xxxhttp://www.medfriendly.com/autonomicdysreflexia.html
Thanks

Could just be they have nothing relevant in that size/shape... Have you experimented with other shapes?

Try digitalpoint's adsense sandbox... there are no ads for this keyword. Suggest that you compose your own ad for an affiliate marketing page and load it as an alternative ad that google will automatically use whenever there are no adsense items for one of your pages.

http://www.digitalpoint.com/tools/adsense-sandbox/

I looked at the Sandbox tool but don't think the explanation is that there are no ads for the keyword "autonomic dysreflexia." Although this may be true, Google scans the content of the page to come up with ads and there is plenty of info on that page for them to come up with ads. On pages with much less information than that on my site, I have ads for spinal cord injury that show up. Certainly, spinal cord injury ads would be appropriate for this page and the term spinal cord injury is written throughout the site. I have experimented with different shapes but still no luck. Any other ideas?