Wednesday, September 30, 2009

Hic Sunt Dracones

The New York Public Library houses a cool historical curiosity, the Hunt-Lenox Globe, which according to Wikipedia is the second or third oldest terrestrial globe still in existence. And, popular myth aside, it is also the only historical map that contains the phrase "Hic Sunt Dracones," or "here be dragons" (the Carta Marina to the left, while it contains dragons, doesn't identify them in the same way) That's a phrase I am drawn to frequently when delving into hostile abdominal territory --- patients who have an abdominal catastrophe, huge pancreatic phlegmons, or a dense thicket of adhesions from prior surgery. These are cases where we tread carefully, and quietly, trying to avoid awakening a slumbering beast.

Surgical dragons, however, aren't always found in dangerous or unfriendly regions. The "routine" operation is populated with enough fire breathing demons to make St. George wince. It is the surgeon's job to perform the "routine" operation with the same care and wariness as he would the more complicated one, or he risks falling into the dragon's lair and dragging his patient with him. Such is the case with laparoscopic cholecystectomy, which is bedeviled with a small but definable risk of bile duct injury, estimated at somewhere between 0.2 t0 0.5% (about one in 200 patients to one in 400), compared to a risk of about 0.1-0.2% for open cholecystectomy. Because cholecystectomy is such a common operation, while the risk for this complication are quite small, it is seen not infrequently. Hence quite a bit of research has gone into trying to figure out why it occurs and what we can do to minimize the incidence of common bile duct injury with laparoscopic cholecystectomy. The amount of ink poured out discussing this problem could easily fill a large reservoir.

The most recent interesting article I have read about this subject comes from the Surgical Outcomes Research Center at the University of Washington, published in the Journal of the American College of Surgeons -- "Risk Tolerance and Bile Duct Injury: Surgeon Characteristics, Risk-Taking Preference, and Common Bile Duct Injuries." The article reports on a survey sent to a random selection of 4,100 general surgeons in the ACS database. The authors received about 1,400 valid responses; in addition to what would be considered typical questions (Have you had a common bile duct injury in your practice? What do you think was the cause? How was it repaired? etc.), an interesting additional set of questions were asked:

  • I enjoy taking risks
  • I try to avoid situations with uncertain outcomes.
  • Taking risks does not bother me if the gains involved are high.
  • I consider security an important element in every aspect of my life.
  • People have told me that I seem to enjoy taking chances.
  • I rarely take risks when there is another alternative.
This method of assessing one's level of risk taking (or aversion) has been used in several studies; for example, one study demonstrated that the degree of an ED's risk-taking or risk-aversion correlated with admission rates for patients presenting with chest pain. So, the question is, does this study show a trend towards a higher rate of common bile duct injury with laparoscopic cholecystectomy depending on a surgeon's risk tolerance?

Er, well, not exactly. The authors concluded that "we did not find any substantial differences based on low-, moderate-, and high-risk categories." But, to justify the title of the article, they did feel that there was a trend in this direction...."Compared with surgeons in the lowest three deciles of risk score, relative risk for CBDI among surgeons in the upper three deciles was 17% greater (p = 0.07)."

Sorry. I'm not buying this or the Brooklyn Bridge. I think that this study is yet another example of authors trying to prop up an idea without solid data that proves their point. I have a few nits to pick with this one, such as:
  1. When you mail out 4,100 surveys, and get back only 1,412 that are usable for your study, I'd say that you may have a bit of a selection bias.
  2. Who is more likely to respond to this kind of survey? The surgeon who has had a CBD injury? Or the surgeon who has not? (I really don't know).
  3. Who is more likely to respond to this kind of survey, the very busy surgeon who may have a boatload of experience but not a whole lotta time or patience for filling out surveys, or the less busy surgeon? (This one I know the answer to. You may guess if you like.)
  4. Risk taking behavior may vary rather considerably from one's clinical practice to one's private life. I know more than a few unbelievably careful and conservative neurosurgeons who ride motorcycles. Without helmets. Fast.
Maybe I'm just not into that whole touchy-feely, psychobabble part of medicine. Blame it on a bad experience in college psychology (waste of time extraordinaire) and a worse experience in medical school psychiatry (AKA, my time in Purgatory). I prefer cold, hard facts and think that solutions to thorny medical problems lies in dealing with those facts directly. In the case of common bile duct injury with laparoscopic cholecystectomy the facts are that
  • It happens, once again somewhere between 0.2-0.7% of the time
  • The incidence has not dropped in the past decade, as many had predicted
  • There are a few techniques that when utilized routinely can help to minimize (N.B, not eliminate) this risk
  • The average general surgeon in this country will have this complication once in his or her career
When I was doing a little reading and thinking for this post, I thought it would be interesting to do a Google search on the incidence of CBD injury in laparoscopic cholecystectomy. Unlike the last time I performed this search, there were more medical journal articles than lawyer sites. That's a good thing, IMHO, and may reflect a gradual maturation in the way that this known, rare complication is seen --- not as always reflecting malpractice, but as something that can and will happen with a certain, small degree of frequency. Indeed, one legal site even describes the routine steps we use to minimize the risk of CBD injury. Now that we have had a two decade experience with laparoscopic cholecystectomy in this country, I agree with a recent editorial by Dr. Josef Fischer from Harvard -- injury to the common duct during laparoscopic cholecystectomy is not a result of practice below the standard, but an inherent risk of the operation. This injury needs to be emphasized by the surgical community as an inherent risk of the operation, and patients should be fully informed of this potential complication.

Hic sunt dracones --- here, I like to say when doing a cholecystectomy, be dragons. This part of the body is expensive real estate, the seat of the soul, a slippery precipice. But even the best sailors have been lost at sea, even Donald Trump has had a real estate venture go south, even Rob Hall fell to his death on Everest. And at some point, the dragon known as a common bile duct injury may breathe fire on even the best surgeon around.