Gallstones & Biliary Disease
- Gallstones are crystallized bile pebbles; most just sit quietly in the gallbladder and never cause trouble.
- Ultrasound is the workhorse: stones cast a bright echo with a clean dark shadow behind them.
- The disease isn't the stone — it's where the stone gets stuck. Cystic duct = cholecystitis; common bile duct = obstruction and possible cholangitis.
- An inflamed (cholecystitis) gallbladder has a thick wall, surrounding fluid, and hurts right where the probe presses.
- Air in the wall or lumen, or a non-enhancing wall, means the gallbladder is dying — that's the emergency.
Picture your gallbladder as a small, polite storage pouch hanging off the underside of the liver. Its only job is to hold a few tablespoons of bile and squirt it into the gut when a cheeseburger shows up. Bile is a chemistry experiment waiting to happen, and when the recipe drifts out of balance, little pebbles precipitate out. Those pebbles are gallstones, and the entire drama of biliary disease comes down to one question: is a stone blocking a pipe, and which pipe?
The plumbing, in one breath
Bile drains from the liver down a tree of ducts that merge into the common bile duct (CBD), which empties into the duodenum. The gallbladder branches off this highway through a narrow side-road called the cystic duct. Stones live in the gallbladder, but they cause symptoms when they wander into a doorway and wedge there.
Where the stone parks tells you the whole story:
| Stone location | What happens | The name |
|---|---|---|
| Bouncing around the gallbladder | Usually nothing | Cholelithiasis (just stones) |
| Briefly jammed in the cystic duct | Cramping pain after meals, then relief | Biliary colic |
| Stuck in the cystic duct | Gallbladder inflames | Acute cholecystitis |
| Stuck in the common bile duct | Backed-up bile, jaundice | Choledocholithiasis |
| Stuck in the CBD plus infection | Bile turns into a bacterial soup | Ascending cholangitis |
Finding the stones: ultrasound is king
For gallstones, ultrasound is the first and usually only test you need. A stone is dense, so sound bounces off its front surface as a bright white arc, and almost no sound makes it through — leaving a clean black stripe behind it called posterior acoustic shadowing. That bright dot with a dark shadow is the money shot. Roll the patient and the stone tumbles to the dependent wall like a marble in a jar; that mobility helps tell it apart from a polyp glued to the wall.
When the gallbladder gets angry: cholecystitis
If a stone lodges in the cystic duct and stays, bile can't drain, pressure builds, the wall inflames, and you've got acute cholecystitis. On ultrasound, the supporting cast is consistent: a thickened gallbladder wall, fluid tracking around the gallbladder (pericholecystic fluid), and a stone wedged at the neck that won't budge when you reposition the patient.
The best part is a finding you can only get with a live patient: the sonographic Murphy sign. You press the probe right over the gallbladder, and if that's the exact spot that makes them wince, the test is positive. It's one of the few times the imaging and the physical exam happen in the same motion.
When ultrasound is equivocal but you still suspect cholecystitis, a nuclear HIDA scan settles it. If the tracer fills the gut but never fills the gallbladder, the cystic duct is blocked — the gallbladder is "excluded."
When the blockage is downstream
A stone that escapes the gallbladder and lodges in the common bile duct (choledocholithiasis) backs bile up the whole tree. The patient turns yellow, and on imaging the ducts dilate — think of a kinked garden hose ballooning upstream of the kink. Ultrasound shows a fat CBD; MRCP (an MRI sequence that makes fluid-filled ducts glow bright white) gives you a gorgeous roadmap of exactly where the stone sits without any contrast or radiation.
If bacteria climb up that stagnant, blocked bile, you get ascending cholangitis — fever, jaundice, and pain together. This is a drain-it-now emergency, not a watch-and-wait.
Don't-miss disasters
Two findings mean the gallbladder is gangrenous and the situation just got dangerous:
- Gas in the wall or lumen (emphysematous cholecystitis) — gas-forming bacteria, often in diabetics. On CT it's unmistakable: black air where it has no business being.
- A wall that doesn't enhance with IV contrast on CT, with an irregular, sloughing inner lining. No blood flow means dying tissue.
Both can perforate. Don't anchor on "routine cholecystitis."
A couple of mimics worth knowing: a gallbladder packed with tiny stones can throw a confusing shadow that looks like bowel gas, and a porcelain gallbladder (a calcified wall) is a hard, bright, shadowing curve that can be mistaken for a single giant stone.
The stone itself is rarely the problem. Always ask which pipe is blocked — cystic duct points you to the gallbladder, common bile duct points you to jaundice and possible infection. That single question routes the entire workup.
A quick honorable mention: not every right-upper-quadrant pain is biliary. Liver lesions and cirrhosis can hijack the neighborhood, and a stone tumbling past the bile duct can irritate the pancreas next door into pancreatitis. But when someone has fatty-meal pain and a yellow tinge, gallstones are where you start looking — and usually where you finish.