Monday, January 23, 2017
7 factors you must consider to avoid a missed diagnosis of colon cancer or polyps during your first colonoscop
1. Adequate bowel preparation is key The ability of the endoscopist (the physician performing your colonoscopy) to see is directly related to and dependent on you having colon clear of residual stool. This requires you to fast from solids for a full day before your exam and only drink clear fluids. You then must take one of several bowel preparations as directed by your provider. It has been proven that split dosing achieves the highest success rate in adequate clearing of the colon. All of the bowel preps must be supplemented with plenty of oral fluids, preferable clear liquids with sugar and electrolytes rather than plain water. At least 10-12 eight ounce glasses of fluid should be drank. The ability to find early cancers or pre-cancer polyps is clearly linked to the quality of the bowel preparation. Despite being given very detailed bowel preparation instructions some individuals fail to follow these instructions especially drinking plenty of fluids. Patients commonly present with less than ideal bowel preps. The degree of insistence on and documentation of adequate bowel prep is directly linked to the risk of interval cancers in someone with a prior “negative” colonoscopy. The patients in whom inadequate bowel prep is noted must be rescheduled for a repeat exam. You don’t want to go through the bowel preparation half-heartedly only to have to have to be canceled or have an incomplete or inadequate colonoscopy that requires a repeat exam. 2. Non-gastroenterologist preforming exam Multiple studies have confirmed that the risk of missed polyps and colon cancers is much higher when a gastroenterologist does not perform the colonoscopy exam. The risk of missed polyps has been reported as high as 50% when colonoscopy is performed by a non-gastroenterologist. You should if possible insist on a gastroenterologist performing your colonoscopy or a colorectal surgeon who does many exams a year. Most gastroenterologists perform over a 1000 colonoscopies a year. 3. Incomplete exam during your first colonoscopy Failure to reach the end of the colon is known risk for missed colon polyps and colon cancer. Inexperienced endoscopists and non-gastroenterologists may fail to reach the cecum but not be aware. Photo documentation of the anatomical landmarks of the cecum are increasingly used by endoscopists to document the extent of the exam was complete. If it is not clear from your report that exam was complete you should ask. 4. Inadequate removal of polyp Failure to completely remove a colon polyp and/or destroy residual pre-cancer polyp tissue is a well-recognized risk for interval colon cancers. The technique of the endoscopist as well as the experience of the technician and the equipment used is paramount to adequate removal of colon polyps. Many younger gastroenterologists are using a cold snare technique to remove colon polyps in order to reduce risk of post polypectomy bleeding or perforation, both well-known complications. The former is not uncommon but usually easily addressed with repeat examination and treatment of the bleeding site. The latter is less common but usually requires surgery. The aversion of younger and less experienced endoscopists to complications may actually be leading to less aggressive removal techniques that may increase risk of interval colon cancers in prior polyp removal sites. If your endoscopist asks you to have an interval repeat exam in sooner that expected time frame to ensure any polyp or polyps were completely removed you should follow that recommendation. 5. Women and older age Several studies have shown that the female gender and older age are independent risk factors for missed polyps and interval colon cancers. If you are a woman or an older individual you should be aware of these risks and not be dissuaded from insisting that you had adequate bowel prep, complete and careful withdrawal examination. Some women have more difficult examinations technically than men and older patients may also have significant diverticular disease making the examination more difficult so an experienced endoscopist is important. Also older patients commonly have multiple other medical problems that may influence the endoscopist to try to complete the exam quickly to avoid intra-procedure complications including sedation issues. 6. Colon cancer located in proximal colon Cancers are more commonly found in the proximal colon deeper into the large intestine than in past, especially in women and African Americans. This factor is related to several others in this list including the need for good bowel preparation and technique, insisting on reaching the end of the colon on every exam feasible, and if not able to reach the end then following up with additional testing such as imaging with barium enema. 7. Poor technique of the endoscopist Poor endoscopy technique is related to training of the endoscopist as well as number of procedures performed in the past. As the number of procedures increase the skill of the endoscopist almost always improved unless of course training in proper technique was not emphasized and mandated by the endoscopist’s trainer. More experienced endoscopists miss less lesions than trainees and less experienced endoscopists even when time of withdrawal is equal. The accepted standard for withdrawal time is now six minutes or more. Almost all exams report withdrawal time and many endoscopists have know withdrawal time averages correlated with their polyp detection rate. Subpar withdrawal times and polyp detection rates would be an indicator that an endoscopist’s technique is below that generally accepted within peers. References Am. J. Gastroenterol. 2010 Mar; 105(3):663-73; quiz 674. Am. J. Gastroenterol. 2015 Dec; 110(12):1657-64; quiz 1665. Biosci Trends 2009 Aug; 3(4):158-60. BMC Gastroenterol 2013.:78. Curr Gastroenterol Rep 2014 Mar; 16(3):375. Dig. Dis. Sci. 2015 Oct; 60(10):2937-45 Digestion 2012; 86(2):148-54. World J. Gastroenterol. 2015 Dec 7; 21(45):12735-41.