Thursday, April 23, 2009

How Low Can You Go?

Dallas in the early 80s was nightclub heaven, a city where there was always a "hot new trendy" place to go. "Trendy" as in "spendy." "Trendy" was not a good way to describe yours truly, so the amount of time I spent in hot new clubs was similar to the amount of time Nanc Pelosi has spent educating herself about basic economics. You could not, however, be young in that city and not hear something about a string of restaurants & clubs operated by a guy named Shannon Wynne. He had a thing for the letter "o" for some reason, and all of his clubs and restaurants ended with "o" --

8.0
Rocco Oyster Bar
Nostromo
Mexico
Tang-o

Everything he opened turned to gold, at least initially, with great crowds and publicity. But it was the Tang-o nightclub that was the place for an all-too-brief period of time in the early 80s. It was festooned with a gaudy cluster of six dancing frogs that were sculpted by Bob "Daddy-o" Wade specifically for the roof of the building, making it an instant landmark for the young and cool.

I gotta admit, I never went in. The lines were too long, and I wasn't really part of that crowd. But I absolutely loved their ads, and think about them every time I'm doing a particular operation. You see, Tang-o was located at the very southern end of Greenville Avenue in Dallas, a long stretch of road that at the time contained a treasure trove of restaurants and clubs. There was really nothing that far down Greenville, so the ads intoned with a deep, gravelly voice:

How low can you go?
Tang-o, on lowest Greenville.

How low can you go? That, in fact, is a question a surgeon must ask himself when evaluating and operating on a patient with a low rectal cancer.

Basically, a lot of what I do is plumbing --- the GI tract is one long tube, with twists, turns, special functions, different anatomic characteristics, etc. Each part of that tube has specific blood supply and lymphatic drainage, and anatomic positions and attachments that influence the ease, or lack thereof, with which we can operate upon it. The esophagus, for example, lies within the neck, the chest, and the abdomen, and depending upon what needs to be done to a patient it may be approached through any (or all) of those areas.

The rectum poses a few thorny problems for us. It's function is simply as a reservoir, albeit a rather important one for obvious reasons. Almost always, removal of a portion of the rectum is done for malignancy (or polyps that cannot otherwise be removed), but the location of the tumor dictates what must be done surgically. A tumor that is "too low," or too close to the anus, cannot be removed without leaving the patient with a permanent colostomy. But how low is "too low?"

The best way to describe this anatomic issue is to think of two bowls nestled one within another, with the inner bowl being more pliable but pretty thick, and the outer bowl as firm as stone. A garden hose runs from inside the inner bowl, down through its thick wall, and then out the outer bowl. From a simplistic standpoint:
  • Removing a segment of the hose and putting the two ends together above the inner bowl is pretty straightforward. This is the situation for the colon and the uppermost part of the rectum, which lies within the free peritoneal cavity.
  • Removing a segment of the hose that abuts, or lies within the wall of the inner bowl and connecting the two ends is more challenging. This is in general the case for the mid portion of the rectum, straddling the intra- and extraperitoneal areas as the bowel passes out of the abdomen on its way to the anus.
  • Removing a segment of the hose near its final exit pretty much can't be done if the goal is to have two functional ends to connect together. This is the issue for distal rectal cancers, i.e., how low can one go without crossing the Rubicon and committing a patient to a permanent colostomy?

There is much more involved, obviously --- blood supply and lymphatic drainage, for example --- and we need to make sure that our surgical margins are quite clear of tumor (at least a 2cm margin distally is a minimum requirement) for the best outcome. We help no patient if we leave tumor behind, or leave their sphincter mechanisms no longer functional.

This is, however, the kind of operation where there is just as much artistry as there is science, as well as a whole lotta patient-specific factors in play. There are a few tricks in a surgeon's bag that help us get way, way down in the pelvis, and a few things that make it impossible to do so. This is a physically demanding operation as well, and there are portions of the procedure where there is as much "feeling" as "seeing"...... the surgeon must free the rectum from the tissues in front of the sacrum, from the bladder and uterus & vagina or prostate anteriorly, and from dense fibrous and vascular tissues (the lateral rectal stalks) on either side, and tactile feedback is very important. Freeing the rectum in the deep pelvis becomes a process of working in each of these regions circumferentially, not in any single organized fashion but rather "taking what's easy" in one area and then doing the same in another.

Gradually, we reach the muscular floor of the pelvis, the levators (levator ani). Actually getting this far is very dependent upon the patient's anatomy --- it is easier to work in a wider space, i.e., in a women's pelvis in comarison to a man's. An obese patient poses big challenges (pun intended), as does a patient who has had a lot of prior surgery.

Remember the movie with Catherine Zeta-Jones slinking under, over, and around the laser beams of an alarm system to steal a rare piece of art? It sure left an impression on me, and I'm sure it was absolutely crucial to the plot. Well, in some respects, when we are working on "stealing" a part of the rectum, we must work carefully to avoid a few danger zones of our own. Potential problems include big-time bleeding from a nest of snakes along the anterior aspect of the sacrum known as the presacral plexus, injury to the ureter (which drains urine from the kidney to the bladder), injury to the bladder, and injury to the prostate or vagina (especially with bulky tumors).

At some point, though, a point is reached where the surgeon must decide if a complete and safe resection with an anastomosis (putting the bowel back together in continuity) is possible. We try. We sweat it out. We really work at it to try to avoid a permanent colostomy. But each patient is different, so it is not always possible to be 100% sure before we are in the OR whether or not we will be able to put Humpty Dumpty back together again.

So, in the end, the question in each case remains the same --- how low can you go?