Figure 7-31 Mistake-Proofing the Design of Health Care Processes - Figure 7.31. Sponges containing radio-opaque substances that are more easily found after surgery Return to Document Current as of May 2007 Internet Citation: Figure 7-31: Mistake-Proofing the Design of Health Care Processes -. May 2007. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/professionals/quality-patient-safety/patient-safety-resources/resources/mistakeproof/mistakefig7-31.html