Cholecystitis (Acute/Complications)
- Acute cholecystitis is a gallbladder that got blocked, then angry: a stone wedged in the neck, a wall that's inflamed, and a patient who hurts right where you press.
- Ultrasound is the first stop. The combo to hunt for: gallstones plus a thickened wall, fluid around the gallbladder, and a sonographic Murphy's sign (pain exactly where the probe sits on the gallbladder).
- If the ultrasound is equivocal but suspicion stays high, a hepatobiliary (HIDA) nuclear scan settles it — a gallbladder that won't fill means the duct is blocked.
- The scary words all mean "it got worse": gangrenous (wall dying), emphysematous (gas in the wall), and perforated (wall gave way). Spot these and the conversation changes from "antibiotics" to "surgeon, now."
Here's the gallbladder's whole job: it's a little muscular pouch that stores bile and squirts it into the gut when a cheeseburger shows up. Picture a water balloon with a narrow neck. Now imagine a pebble rolls down and plugs that neck. The balloon can't empty, pressure climbs, the wall gets irritated and waterlogged, and the whole thing turns red, tense, and tender. That, in one mental image, is acute cholecystitis — an obstructed, inflamed gallbladder.
Most of the time the pebble is a gallstone. The stones themselves and the plumbing they live in get the full tour over on Gallstones & Biliary Disease; here we're focused on what happens once one of them picks the worst possible place to get stuck.
Why ultrasound goes first
Ultrasound is the opening move because it's fast, painless, radiation-free, and gallstones practically glow on it. If you want a refresher on how the probe turns sound into a picture, the ultrasound technique page covers the knobs. For our purposes, just know that stones are dense and reflective, so they show up as bright dots that throw a dark shadow behind them — like a thumb held in front of a flashlight.
The findings cluster into a recognizable look. No single one seals the deal, but together they tell the story:
| Finding | What it looks like | Why it's there |
|---|---|---|
| Gallstones | Bright echo with a dark shadow behind it | The actual culprit, usually lodged in the neck |
| Wall thickening | The rim measures thicker than it should (roughly over 3 mm) | The wall is inflamed and edematous |
| Pericholecystic fluid | A dark stripe hugging the gallbladder | Inflammation weeping fluid around it |
| Sonographic Murphy's sign | Maximal pain when the probe presses right on the gallbladder | You're literally poking the sore spot |
The sonographer's superpower here is the sonographic Murphy's sign — they can put the probe directly on the gallbladder and watch the patient wince. That's more specific than the bedside version, because you're pressing on the organ itself, not just the general neighborhood.
When ultrasound shrugs: the HIDA scan
Sometimes the ultrasound is a maybe — the wall can thicken for plenty of unrelated reasons, and a single shadowing stone doesn't prove the gallbladder is obstructed. That's where the hepatobiliary scan, the HIDA scan, earns its keep. You inject a tracer the liver grabs and dumps into bile; you then watch where the bile goes. If the gallbladder lights up, the duct is open and cholecystitis is essentially off the table. If everything else fills but the gallbladder stays a stubborn dark hole, the neck is blocked — the smoking gun for acute cholecystitis. The deeper walkthrough lives on the HIDA detail page.
CT isn't the first-line test, but a lot of these patients land in the scanner for vague belly pain and get diagnosed there anyway. CT is also the better tool for spotting the complications below — gas, gangrene, and perforation hide better on ultrasound.
The complications, a.k.a. "now it's an emergency"
Uncomplicated cholecystitis is a manageable problem. The trouble starts when the wall, starved of blood by all that pressure, begins to fail. These are the words that make a radiologist sit up straight.
- Gangrenous cholecystitis — the wall is dying. On imaging it looks irregular, with sloughed membranes floating inside and patchy spots where the wall stops enhancing. The Murphy's sign can paradoxically vanish as the nerves die off, which is a cruel little trap.
- Emphysematous cholecystitis — gas-forming bugs set up shop and you get air in the wall of the gallbladder. On CT it's unmistakable; on ultrasound, gas makes bright, dirty, shifting reflections. Disproportionately tied to diabetes, and it moves fast.
- Perforation — the wall gives way. You may see a focal defect in the wall and fluid (or a frank abscess) tracking around it.
Don't let a disappearing Murphy's sign reassure you. In gangrenous cholecystitis the tenderness can fade as the wall necroses and the nerve endings die. A sicker-looking patient with a less tender belly is a setup, not a recovery.
Emphysematous cholecystitis — gas in the gallbladder wall — is a surgical emergency, not a "let's recheck tomorrow." It carries a much higher risk of gangrene and perforation and often hits diabetic and older patients hard. See gas in that wall and the surgeon should already be on the phone.
A quick word on the stone-free version
Not every angry gallbladder has a stone. Acalculous cholecystitis shows up in critically ill, fasting, or post-surgical patients — the gallbladder gets sluggish and inflamed without an obstructing stone. It's easy to miss precisely because the obvious culprit is absent, and it tends to march toward gangrene faster, so it deserves a low threshold of suspicion in the ICU crowd.
The one thing to carry out
When the bile backs up further down the line, you cross into choledocholithiasis and its infected cousin, ascending cholangitis — different problems, same family. But for acute cholecystitis itself, anchor on this: ultrasound first, hunt the constellation of stone-plus-thick-wall-plus-fluid-plus-Murphy, and the moment you see gas, dying wall, or a breach, stop thinking "antibiotics" and start thinking "operating room."