Obstructive jaundice and suspected biliary obstruction

ACR AC Jaundice; ACR AC Radiologic Management of Biliary Obstruction

A two-question pathway: is the jaundice mechanical, and if so at what level and from what cause. Ultrasound answers the first cheaply; the second usually needs cholangiography, and the choice between MRCP and a pancreas-protocol CT depends on whether a mass is suspected.

Jaundice with a cholestatic biochemical pattern, with or without pain, itching or weight loss.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Haemodynamic state

The fact that lets a pathway waive its own requirements. A crashing patient does not wait for a score.

Fever or sepsis

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

Ultrasound abdomen — full survey

Ultrasound abdomen

What we'd amend, and why

The first decision is mechanical versus hepatocellular, and duct calibre answers it. Bile is anechoic and the dilated ducts run alongside portal vein branches, so the parallel-channel appearance is conspicuous at almost no cost and with no radiation. Ultrasound also gives the gallbladder, gross liver texture and portal flow in the same sitting, which is enough to direct everything that follows.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwayadult — Adults

Decision support only. Local protocol takes precedence.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Cholangitis with haemodynamic instability — decompression, not diagnosis

Role	Study & protocol	Why this answers the question
First line	Ultrasound abdomen Ultrasound abdomen — full survey usually appropriate	Jaundice, fever and shock is obstructed, infected bile under pressure, and the treatment is decompression — endoscopic in almost all cases, percutaneous where endoscopy fails or is not available. Imaging has one job in the next hour, which is to confirm that the system is obstructed and to say at what level so the endoscopist or the interventional radiologist knows what they are going to. A bedside ultrasound does that without moving the patient out of a resuscitation area. Everything else waits. The specific failure this arm exists to prevent is the well-intentioned MRCP: a good study, twenty to forty minutes in a scanner, breath-held, away from the team, in a patient whose deterioration is measured in the same units — and it changes nothing about the decision, because the decision is already drainage. Cholangiography earns its place after decompression, when the residual question is what caused the obstruction.
Second line	CT Abdomen and Pelvis CT Abdomen and Pelvis — Portal Venous Phase	Where the ultrasound does not explain the picture — a non-dilated system in a patient who is clearly septic, or a septic source that may not be biliary at all — portal-venous CT is the study that resolves it quickly, and it also finds the things that change the drainage plan: a liver abscess, portal venous gas, an infarcted gallbladder, a duodenal perforation. It is a fast acquisition in a patient who cannot cooperate, which is exactly why it precedes cholangiography here. It is not a substitute for drainage and it should never be the reason drainage is deferred.
Problem solving	MRCP (MR Cholangiopancreatography) MRCP — standard unenhanced	After decompression and once the patient is stable, cholangiography answers what is left — the cause, any residual stones, and a stricture that needs characterising. Deliberately last, because performing it first is the error this arm exists to catch, not because the study is wrong for this disease.

Nothing in this arm withholds imaging. It re-sequences one study out of the way of a treatment that is already indicated, and puts it back once the treatment has happened.

Jaundice with fever or sepsis — suspected cholangitis

Role	Study & protocol	Why this answers the question
First line	Ultrasound abdomen Ultrasound abdomen — full survey usually appropriate	The study is the same as for painless jaundice and the timetable is not. Cholangitis carries a defined window for biliary drainage — the Tokyo Guidelines put urgent decompression at within roughly twenty-four hours for moderate disease and immediately, alongside organ support, for severe disease — and the patient who is stable now is the patient who declares Grade III disease overnight, so the ultrasound is an emergency request rather than a next-available slot: obstructed and infected is enough to refer for decompression, and duct calibre plus the level is what that referral needs. A non-dilated duct is not reassurance in this setting — early or intermittent obstruction, a stone that has passed and a sclerotic tree all present this way — and it should escalate rather than close the question.
Second line	MRCP (MR Cholangiopancreatography) MRCP — standard unenhanced	Cholangiography is the right next study for the febrile but stable patient, and its value is that it is specific about what the endoscopist will find: a stone in the distal duct, a benign stricture, or an anastomotic problem in a patient with previous biliary surgery. It is worth doing when it will change whether and how the duct is instrumented; it is not worth doing when the referral for drainage has already been made on clinical and ultrasound grounds, because it will not change it.
Problem solving	CT Abdomen and Pelvis CT Abdomen and Pelvis — Portal Venous Phase	Portal-venous CT is for the febrile jaundiced patient in whom the source is not clearly biliary, or in whom a complication is suspected: a hepatic abscess, an infarcted gallbladder, portal venous gas or portal vein thrombosis. It is also the practical answer when MRI cannot be delivered in a useful timeframe. Where the ultrasound has raised a mass, the question changes from sepsis to resectability and the pancreas-protocol study on the default pathway is the correct one.

Adults

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	Ultrasound abdomen Ultrasound abdomen — full survey usually appropriate	The first decision is mechanical versus hepatocellular, and duct calibre answers it. Bile is anechoic and the dilated ducts run alongside portal vein branches, so the parallel-channel appearance is conspicuous at almost no cost and with no radiation. Ultrasound also gives the gallbladder, gross liver texture and portal flow in the same sitting, which is enough to direct everything that follows.
Second line	MRCP (MR Cholangiopancreatography) MRCP — standard unenhanced	Heavily T2-weighted imaging exploits the fact that static bile is the brightest thing in the upper abdomen, so a stone appears as a filling defect in a bright duct and a stricture as an abrupt calibre change, without instrumenting the biliary tree. The distal common bile duct — where ultrasound is defeated by duodenal gas — is exactly where MRCP performs best, which is why this is the standard problem-solving study for intermediate-probability choledocholithiasis and for an unexplained level of obstruction.
Problem solving	CT Pancreas Protocol CT Pancreas — Dual Phase with Water Distension	Where the ultrasound suggests a mass, or the picture is painless jaundice with weight loss, the question is no longer only the level of obstruction but resectability. A pancreatic parenchymal acquisition plus a portal venous acquisition gives tumour conspicuity, arterial and venous contact, and liver metastases in one study, which cholangiography alone cannot do.

Pitfalls

Sending the patient straight to MRCP without an ultrasound, which sometimes buys an expensive study for a hepatocellular cause that never needed cholangiography.
Accepting a routine portal-venous abdominal CT for painless jaundice, which is the wrong phase for a pancreatic head tumour.
Reading a non-dilated system as excluding obstruction in early or intermittent obstruction, or in primary sclerosing cholangitis where fibrosis prevents dilatation.
Letting imaging delay decompression in a patient with cholangitis and shock. The commonest form of this is the well-intentioned MRCP: twenty to forty minutes in a scanner, away from the team, to answer a question that has already been settled by the decision to drain.
Booking an MRCP in a patient already committed to ERCP. Cholangiography earns its place when it will change whether or how the duct is instrumented, and duplicates the diagnostic part of the therapeutic procedure when it will not.
Overlooking pneumobilia from a previous sphincterotomy or a biliary-enteric anastomosis and reporting it as new.

Priors — what to pull first

Previous cholecystectomy, sphincterotomy or stenting reshapes the differential completely; find the endoscopy record before vetting.
Compare duct calibre with any earlier study — a duct can remain mildly dilated for years after stone passage or sphincterotomy.

What makes a good request

Painless progressive jaundice with weight loss is a malignancy pathway until proven otherwise and should not sit in a routine ultrasound queue.
Jaundice with fever and rigors is cholangitis, a drainage emergency in which imaging must not delay decompression. Antibiotics, resuscitation and a referral for endoscopic — or, where endoscopy fails or is unavailable, percutaneous — drainage all start on the clinical picture, and the Tokyo Guidelines timetable is urgent drainage within about twenty-four hours in moderate disease and immediately in severe disease.
A non-dilated duct does not exclude obstruction early in its course or in a sclerotic biliary tree, and in cholangitis it is not a reason to stand the drainage referral down.

Scoring this once it is done

The classification and risk tools this question ends in.

eGFR (CKD-EPI 2021 Creatinine)LI-RADS v2018 (CT/MRI)Child-Pugh Score (Child-Turcotte-Pugh)RECIST 1.1 Tumor Response

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

Ultrasound abdomen — full survey CT Abdomen and Pelvis — Portal Venous Phase MRCP — standard unenhanced CT Pancreas — Dual Phase with Water Distension

Confirm locally

Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.