01OverviewDefinition, clinical context and the essential points that orientate the chapter.
These conditions share gallstones but not the same obstruction. In Mirizzi syndrome, an impacted stone at the gallbladder neck or cystic duct compresses the adjacent common hepatic duct and may erode into it, creating a cholecystobiliary fistula. The person can present with jaundice, pain, cholangitis or an apparent hilar stricture. Dense inflammation distorts Calot anatomy and greatly increases injury risk during routine laparoscopic dissection.
Gallstone ileus is a bowel obstruction caused by a stone that has traversed a chronic fistula, usually between gallbladder and duodenum. It often affects older, frail patients and may be intermittent as the stone tumbles before impaction. Vomiting, distension, dehydration and aspiration risk dominate. CT is the most useful broad study because it can demonstrate the transition point, ectopic stone and pneumobilia while assessing perforation. Bouveret syndrome is proximal gastric-outlet obstruction by a migrated stone.
Management must fit physiology and anatomy. Mirizzi with cholangitis needs drainage and antibiotics, followed by specialist surgery planned from duct involvement; subtotal cholecystectomy or reconstruction may be necessary. Gallstone ileus with obstruction usually requires removal of the enteric stone. Adding fistula closure and cholecystectomy prolongs surgery and is selected only for appropriate patients and operative findings. Always examine the bowel for additional stones and verify that decompression and perfusion have recovered.
Key points
- Mirizzi syndrome is extrinsic common-hepatic-duct compression or erosion by an impacted gallbladder-neck or cystic-duct stone.
- Suspect Mirizzi when gallstones accompany obstructive jaundice and proximal duct dilatation but the distal common duct is not comparably enlarged.
- Map anatomy with ultrasound followed by MRCP, CT, EUS or ERCP according to stability and need for drainage; careless cholecystectomy risks dividing an adherent bile duct.
- Gallstone ileus results when a large stone enters bowel through a biliary-enteric fistula and becomes impacted, commonly in distal small bowel.
- CT can show mechanical obstruction, an ectopic stone and gas in the biliary tree, although not every stone is densely calcified.
- Operate urgently for bowel compromise; in frail obstructed patients, enterolithotomy alone may be safer than adding fistula repair and cholecystectomy during the same physiological insult.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Impacted neck stone
Long-standing stone impaction in the gallbladder neck or cystic duct causes Mirizzi compression and inflammatory adherence to the hepatic duct.
Biliary-enteric fistula
Chronic pressure and inflammation can erode the gallbladder into duodenum or bowel, allowing a large stone to migrate and impact distally.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Extrinsic duct compression
The impacted stone and surrounding inflammation narrow the common hepatic duct, producing proximal cholestasis and infection risk.
- 2Fistula erosion
Pressure necrosis creates an abnormal communication; duct wall involvement can progress from compression to a true cholecystobiliary fistula.
- 3Mechanical bowel blockage
A large migrated calculus travels until bowel calibre narrows, causing proximal distension, vomiting, fluid sequestration and possible ischaemia.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Gallstones with jaundice and proximal duct dilatation should raise suspicion for extrinsic hilar compression or cholecystobiliary fistulation.
A contracted gallbladder densely adherent to the common hepatic duct makes conventional cystic-duct dissection dangerous.
Gallstone ileus may cause intermittent obstructive symptoms before a stone finally impacts and produces complete small-bowel obstruction.
CT may reveal bowel obstruction, pneumobilia and an ectopic gallstone, but absence of one component does not exclude the diagnosis.
Peritonism, continuous severe pain, metabolic deterioration or free gas suggests ischaemia or perforation requiring immediate surgery.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Liver blood testsFirst step - Why
- Characterise obstruction and infection in suspected Mirizzi syndrome.
- Interpretation and limitations
- Cholestatic abnormality supports impaired hepatic drainage, while inflammatory and organ-function tests determine urgency for drainage.
- 02
Ultrasound - Why
- Identify gallstones and compare proximal and distal duct calibre.
- Interpretation and limitations
- An impacted neck stone and intrahepatic dilatation can suggest Mirizzi, but inflammation and bowel gas may prevent complete mapping.
- 03
MRCP - Why
- Map non-invasively the stone, bile ducts and suspected fistula.
- Interpretation and limitations
- MRCP helps prevent hazardous routine dissection, though ERCP or operative imaging may still be needed for drainage and exact fistula definition.
- 04
Contrast CT abdomen - Why
- Locate bowel obstruction and its cause while assessing complications.
- Interpretation and limitations
- An ectopic stone, pneumobilia and transition point support gallstone ileus; radiolucent stones and incomplete triad can make interpretation harder.
- 05
ERCP - Why
- Drain cholangitis and delineate selected biliary obstruction.
- Interpretation and limitations
- ERCP may stent or clarify Mirizzi anatomy but cannot by itself remove most impacted gallbladder-neck stones; procedure risk and surgical planning remain.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Hilar cholangiocarcinoma
Malignant hilar obstruction can mimic Mirizzi with proximal dilatation; tissue strategy and cross-sectional imaging are crucial before radical decisions.
Adhesional small-bowel obstruction
Previous surgery commonly causes obstruction without pneumobilia or an ectopic stone, though both mechanisms can coexist.
Gastric or duodenal tumour
Proximal obstruction and weight loss may reflect malignancy rather than Bouveret syndrome, requiring endoscopic inspection and tissue diagnosis.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Worked case: Mirizzi cholangitisMap before cuttingFirst stepA patient with gallstones develops jaundice and fever; imaging shows an impacted neck stone, dilated intrahepatic ducts and a relatively normal distal common duct.+
- 1Recognise probable Mirizzi syndrome with cholangitis and begin sepsis treatment and urgent biliary drainage planning.
- 2Use MRCP or therapeutic ERCP to define and decompress the anatomy according to stability and local expertise.
- 3Refer to an experienced biliary surgeon and avoid routine dissection through the inflamed duct interface.
- 4DefinitiveVerify bilirubin, fever and perfusion response after drainage and document the definitive cholecystectomy or reconstruction plan.
02Worked case: gallstone ileusRelieve bowel obstructionAn older adult has vomiting, distension and CT evidence of small-bowel obstruction, pneumobilia and an ectopic ileal stone.+
- 1Resuscitate with fluids and electrolyte correction, provide aspiration prevention and nasogastric decompression when indicated.
- 2Assess for ischaemia or perforation and move urgently to surgery when compromised.
- 3Perform enterolithotomy to relieve obstruction, tailoring any concurrent fistula and gallbladder procedure to physiology and expertise.
- 4Inspect for additional enteric stones and verify return of bowel function and correction of dehydration postoperatively.
03Bouveret variantTreat proximal impactionA migrated gallstone obstructs the duodenum, causing gastric retention and recurrent aspiration.+
- 1Decompress the stomach and correct fluid, chloride and potassium losses.
- 2Use endoscopic extraction or lithotripsy when feasible with experienced teams.
- 3Proceed to surgery if endoscopic therapy fails or perforation and instability require it.
- 4Reassess nutrition, aspiration risk and the residual fistula after obstruction is relieved.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Ascending cholangitis
Bile stasis above Mirizzi compression permits bacterial proliferation and rising duct pressure, potentially causing bacteraemia and septic organ dysfunction.
Bowel ischaemia or perforation
Pressure at the impacted stone and severe distension can compromise bowel wall, leading to contamination and emergency resection.
Bile-duct injury
Unrecognised fusion of gallbladder and hepatic duct creates a high risk of transection, leak and later stricture during cholecystectomy.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- In Mirizzi syndrome, trend bilirubin, inflammatory markers and symptoms after drainage before definitive surgery.
- After gallstone-ileus operation, monitor nasogastric losses, urine output, electrolytes, bowel function and aspiration risk.
- Inspect for persistent sepsis, missed additional stones, enterotomy leak or recurrent obstruction.
- Document whether a biliary-enteric fistula remains and whether later biliary review is appropriate for the person’s fitness.
- Following complex Mirizzi surgery, monitor for bile leak, stricture, recurrent cholangitis and liver dysfunction.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Two levels of obstruction
Mirizzi blocks bile flow outside the bowel; gallstone ileus blocks the bowel after a fistula has formed.
Distal duct calibre helps
Proximal dilatation with a relatively normal distal duct points toward compression near the common hepatic duct.
The full CT triad is optional
A non-calcified stone or subtle pneumobilia can make gallstone ileus visible only through careful transition-point review.
Shorter surgery may be safer
In a frail obstructed patient, relieving the bowel obstruction alone can be preferable to a longer one-stage biliary reconstruction.
11Common pitfallsFrequent interpretation and management errors.
- 01
Attempting routine cystic-duct dissection through unrecognised Mirizzi inflammation.
- 02
Excluding gallstone ileus because the ectopic stone is not densely calcified.
- 03
Repairing the fistula automatically during emergency enterolithotomy without considering physiological reserve.
- 04
Failing to inspect for a second enteric stone after removing the obstructing calculus.