Monday, March 26, 2007
Rocks in a Bag: what I know about gallbladders
Finally I'm getting around to writing about the gallbladder. Don't know what took me so long, seeing as how, next to hernias it's the thing upon which I operated most (if you don't count breast biopsies). And I liked it. When a person came to see me with a clear-cut gallbladder problem -- which was the case at least 90% of the time -- I could be quite confident that I was going to make him or her happy and, most likely, have a little fun while doing it. But there's the rub: it's not always a Tenantoid "slam dunk," nor is it always fun. A mysterious little bugger is that bag of bile: perhaps more than any other organ it's able to elude or confound diagnosis despite such apparent simplicity. And more than any other category, I sent people home from my office without surgery despite being referred with the idea of separating them from their gallbladders. Rocks get in your head.
First, some basics.
Among the many functions your liver performs for you (in addition to feeling neat) is the manufacture of bile, which is a clarified-butter-yellow liquid of complex composition and which serves to help with the absorption of fatty substances into your bloodstream. (The ancients believed it had something to do with emotions: "melancholia" means, literally, "black bile.") About a quart of bile per day is produced and flows from the liver through a tube called the bile duct, entering the duodenum just below the stomach. Of that quart, a few tablespoons are sidetracked into a pouch that hangs under the liver, and is called the gallbladder. It doesn't make bile; it stores a bit of it, with the intention of squirting a dose into the intestine once in a while, particularly after eating a fatty meal. (The picture to the left, by the way, is not to scale. It makes the gallbladder look much huger than it usually is.) There's some complicated anatomy involved, particularly since the south end of the bile duct passes through the pancreas, where it's joined by a duct therefrom, carrying digestive enzymes made therein. We'll get around to the implications thereof, later.
Here's my theory: the gallbladder evolved before refrigerators, when people might starve for a day or two or three while they hunted their next meal. After a kill, they'd gorge on a big greasy meal, at which point a supplemental blast of bile was useful. (During starvation, the gallbladder can get impressively large and full of bile.) Compared to those days, we eat more or less constantly: two, three, four meals a day, a few snacks. Bile remains a necessary component of digestion, but storage isn't really called for. Our food sort of steadily drips into the intestine, so constantly dripping bile works fine. Which is why the vast majority of people who have their gallbladder removed never miss it at all.
Bile is composed of many chemicals which are supposed to remain dissolved in the liquid medium. In some people, for various reasons (genetic, diet, certain prior operations, certain blood diseases, etc) one or another of the components of bile are in too high a concentration to remain dissolved, and they precipitate out, forming crystals, which tend to grow larger and larger -- like sugar candy on a string. Stones. Trouble.
Well, not always. Some people have gallstones all their lives and never hear from them. It's muscular contraction of the gallbladder that sends the bile into the bile duct. If a stone happens to be near the opening of the gallbladder when it squeezes, it clamps down and cramps up on the stone, gets plugged up, and that hurts or causes other problems. If the stones are out of the way during the squeeze, there may be no symptoms at all. Which means not everyone with gallstones needs surgery, a decision made easier with the use of a crystal ball. I'll see if I can do justice to that, and other concepts, in the next few posts...
[UPDATE: many readers who find this post by a web-search may be unaware it's the first in a series. The others are here, here, here, and here. Answers to remaining questions might turn up within them. Please check them out.]