Effective patient counseling decreases the high number of patients who avoid this preventive screening procedure.
Dr. Zanni is a psychologist and health-systemsspecialist based inAlexandria, Virginia.
Colorectal cancer (CRC) is thesecond leading cause of cancerdeaths in the United States,resulting in an estimated 57,000 deathsannually.1,2 Although CRC is among themost preventable cancers, <43% ofAmericans aged 50 years and olderadhere to the recommended screeningguidelines.3 The 5-year survival rate is90% with early detection of this slow-growingcancer; however, 61% of CRCcases are identified after it has metastasized.4
Colonoscopy is the preferred CRC-screeningprocedure. Research demonstratesits improved accuracy in detectingadenomas (precancerous polyps),compared with other procedures. Forexample, fecal occult blood testing aloneis insufficient; patients with adenomasoften test negative.5
The American College of Gastroenterology(ACG) issued CRC-screeningguidelines (Table) in 2000 that varyaccording to the following risk categories5:
The ACG recommends physiciansmodify guidelines consistent with thestrength of known risk factors and medicalhistories.
Surveys reveal that patients find thepreparatory regimen the most objectionableaspect of colonoscopy.7 Somepatients fail to complete the preparationprocess because of adverse effectsexperienced with the prescribed purgatives.6 Colonoscopy's invasiveness isanother factor fueling nonadherence; 1survey found most patients wouldreadily accept noninvasive procedures(eg, computed tomography scans) butare less agreeable to invasive procedures.8 Finally, some patients refusescreening because of negative reportsreceived from their families and friends.
Bowel preparation formulations areeither glycol-electrolyte lavage solutionformulations (eg, Golytely, Colyte, TriLyte,HalfLytely with bisacodyl tablets, Movi-Prep) or sodium phosphate preparations,available in tablet and liquid formulations(eg, Fleet Phospho-soda, Fleet Accuprep,Visicol tablets, Osmoprep tablets).Dosages vary among products; patientsmust follow directions precisely.
Common side effects for both formulationcategories include nausea, vomiting,abdominal cramping, and bloating. Somestudies report fewer side effects withsodium phosphate tablets.6 Rare sideeffects include bleeding in the mucousmembrane that connects the esophagusto the stomach, esophageal perforation,toxic colitis, medication malabsorption,pulmonary aspiration, hypothermia, cardiacarrhythmias, pancreatitis, inappropriateantidiuretic hormone secretion,and renal failure. Some extremely rareadverse reactions resulted in patientfatalities.6
Proper hydration is required before,during, and after colonoscopy to avoidelectrolyte imbalances. Although dehydrationis a significant component underlyingsome of the most serious adverseeffects, clinicians often forget to counselpatients about volume repletion. It mayseem counterintuitive that dehydrationcan occur when consuming 4 L of fluid;however, large amounts of fluids arerequired to evacuate the colon. Thesefluids, along with fluids in undigestedfood, are eliminated.
The ACG notes that decreasing dietaryanimal fat, increasing vegetables anddietary fiber, and increasing calcium andfolic acid may help prevent colon cancer,but further study continues.2 A recentreview of >7000 studies concludes thatheavy consumption of red meat, especiallyprocessed meat (eg, sausage, ham,salami) increases CRC risk, as do poordiets, physical inactivity, and obesity. Thesame review recommends consuming<18 oz of red meat per week.10
Researchers are refining diagnosticalternatives, and the virtual colonoscopyholds promise for the future. Until then,health professionals must promote theimportance of colonoscopy. Somepatients find the topic difficult andembarrassing to discuss and feel morecomfortable with written information.The National Institute of Diabetes andDigestive and Kidney Diseases publishesan excellent, easy-to-understandbrochure on colonoscopy that can befound at digestive.niddk.nih.gov/ddiseases/pubs/colonoscopy. Many patientstake complimentary copies placedon the counter; therefore, this method isrecommended.