(Last week, I began a two-part discussion of some of the inaccuracies that can reduce the effectiveness of colonoscopy as a screening method for colorectal cancer. I conclude that discussion, with references, this week.)

Ideally, performing all colonoscopies in the morning might reduce the number of patients needing a repeat procedure. However, this is not feasible given the huge number of patients undergoing the procedure. (The last time I had a colonoscopy, patients were lined up on their gurneys like airplanes waiting to leave O'Hare airport.) The study's authors suggested that one way to counteract the increased afternoon failure rate would be to ensure that any patients who are known to be at higher risk for colon cancer were tested in the morning rather than the afternoon.)

Slow Down - You Move Too Fast

A third study found that even among experienced colonoscopists, the rate of discovering tumors varies greatly. The time devoted to examining the mucous lining of the colon - which is performed during the withdrawal of the instrument - appears to be crucial to the successful detection of abnormalities.

Researchers monitored outcomes among 12 board-certified gastroenterologists. Data from a total of over 2,000 colonoscopies were evaluated. Gastroenterologists varied in how long they took to remove the instrument. Some took as little as 3.1 minutes, while others took as much as 16.8 minutes - more than five times longer.

The authors saw what they called a "striking, seemingly linear relationship" between withdrawal time and the rates of polyps and cancers that were detected. The overall rate of detection of polyps among operators who had relatively slow withdrawal times was nearly four times as great as the rate among those who had relatively fast withdrawal times. Slow workers were about three times more likely to find an abnormality than fast workers.

The author of this study (which was published in the New England Journal of Medicine) concluded that "a minimum adequate amount of time for colonoscopic withdrawal can be equated with quality of colonoscopy" (Barclay 2006).

Recommendations

Here's a reminder that readers who are over 50 (or 40, if you have exceptional risk factors) should not neglect having regular colonoscopies. They are at present the most reliable and safest way of determining the presence of polyps that can lead to colon cancer. But there are some uncertainties raised by these three studies. If you are at increased risk of colorectal cancer you might consider going on a three-year or even two-year schedule. If the procedure is done sloppily, five years might be too long to wait.

Also, choose your endoscopist carefully. As a general rule, pick only a board-certified gastroenterologist, not a family practitioner, internist or general surgeon. Make sure to have the procedure done in a hospital, not a doctor's office, and insist on having the procedure done in the morning, not in the afternoon.

As to getting your doctor to slow down and take his or her time in examining each patient, it is hard to know how laypeople can exert much influence in that direction. But the next time I go for a colonoscopy I intend to tell my gastroenterologist that I have read these three papers, particularly the New England Journal of Medicine article showing that slower procedures yield more accurate outcomes. I shall ask him politely to not rush things and to do the most thorough job possible, even if it takes more time. Hopefully Dr. David Lieberman's heartfelt call, in an accompanying New England Journal editorial, for endoscopists to take this message seriously, will have gotten through by then.

My gastroenterologist has an odd penchant for blaring the Rolling Stones into the operating room while doing these procedures. It's a bit unnerving to go under anesthesia to the refrains of Paint It Black. Next time, however, I think I will suggest Simon & Garfunkel's more appropriate 59th St. Bridge song:

"Slow down, you move too fast,
Gotta make the morning last..."

In fact, perhaps that groovy song might become the colonoscopists' professional anthem.

References:

Barclay RL, Vicari JJ, Doughty AS, Johnanson JF, Greenlaw RL. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy. N Engl J Med 2006;355:2533-2541,2588-2589.

Bressler B, Paszat LF, Chen Z, Rothwell DM, Vinden C, Rabeneck L. Rates of new or missed colorectal cancers after colonoscopy and their risk factors: a population-based analysis. Gastroenterology 2007;132:96-102.

Douglas D. Colon cancers missed more often in office setting. Reuters Health, February 23, 2007. Available at:
http://www.nlm.nih.gov/medlineplus/news/fullstory_45711.html

Lieberman D. A call to action - measuring the quality of colonoscopy. N Engl J Med. 2006 Dec 14;355(24):2588-2589.

Sanaka MR, Shah N, Mullen KD, Ferguson Dr, Thomas C, McCullough AJ. Afternoon colonoscopies have higher failure rates than morning colonoscopies. Am J Gastroenterol 2006;101:2726-2730.

Wazana A. Physicians and the pharmaceutical industry: is a gift ever just a gift? JAMA. 2000;283(3):373-80.