Pocket Medicine

GASTROENTEROLOGY

BILIARY TRACT DISEASE

CHOLELITHIASIS (GALLSTONES)

Epidemiology & pathogenesis (J Hep 2008;48:S124)

•  >10% adults in the U.S. have gallstones; a/w ↑ overall mortality (Gastro 2011;140:508)

•  Bile = bile salts, phospholipids, cholesterol; ↑ cholesterol saturation in bile + accelerated nucleation + gallbladder hypomotility → gallstones

•  Risk factors: ; South, Central, Native American; ↑ age (>40 y), obesity, pregnancy, TPN, rapid ↓ wt; drugs (OCPs, estrogen, clofibrate, octreotide, ceftriaxone); ileal disease

•  ? statin use >1 y ↓ risk of sx gallstones & cholecystectomy (JAMA 2009;302:2001)

Types of gallstones

•  Cholesterol (90%): 2 subtypes

mixed: contain >50% cholesterol; typically smaller, multiple stones

pure: 100% cholesterol; larger, yellow, white appearance

•  Pigment (10%)

Black: unconjugated bilirubin (chronic hemolysis, cirrhosis) and calcium

Brown: stasis & infection in bile ducts → bacteria deconjugate bilirubin → precipitates w/ calcium; seen w/ duodenal diverticula, biliary strictures, parasites

Clinical manifestations

•  May be asx; biliary pain in ~2%/y; once sx, rate of complications ~2%/y

•  Biliary pain (“colic”) = episodic RUQ or epigastric abd pain that begins abruptly, is continuous, resolves slowly and lasts for 30 min–3 h; ± radiation to scapula; nausea

•  May be precipitated by fatty foods

•  Physical exam: afebrile, ± RUQ tenderness or epigastric pain

Diagnostic studies

•  RUQ U/S: Se & Sp >95% for stones >5 mm; can show complications (cholecystitis); should be performed only after fasting ≥8 h to ensure distended, bile-filled gallbladder

Treatment

•  Cholecystectomy (CCY), usually laparoscopic, if symptomatic

•  CCY in asx Pts w/: GB calcification (~7% risk of ca) (Surgery 2001;129:699), GB polyps >10 mm, Native American, stones >3 cm or bariatric surgery or cardiac transplant candidates

•  Ursodeoxycholic acid (rare) for cholesterol stones w/ uncomplicated biliary pain or if poor surgical candidate; also reduces risk of gallstone formation with rapid wt loss

•  Biliary pain: NSAIDs (eg, diclofenac 50 mg IM) drug of choice, efficacy  opiates & ↓ complications (Aliment Pharmacol Ther 2012;35:1370)

Complications

•  Cholecystitis: 20% of sx biliary pain → cholecystitis w/in 2 y

•  Choledocholithiasis → cholangitis or gallstone pancreatitis

•  Mirizzi’s syndrome: common hepatic duct compression by cystic duct stone → jaundice, biliary obstruction

•  Cholecystenteric fistula: stone erodes through gallbladder into bowel

•  Gallstone ileus: SBO (usually at term ileum) due to stone in intestine that passed thru fistula

•  Gallbladder carcinoma (~1% in U.S.)

CHOLECYSTITIS (NEJM 2008;358:2804)

Pathogenesis

•  Acute cholecystitis: stone impaction in cystic duct → inflammation behind obstruction → GB swelling ± secondary infection (50%) of biliary fluid

•  Acalculous cholecystitis: gallbladder stasis and ischemia → inflammatory response; occurs mainly in critically ill, hosp. Pts (postop major surgery, TPN, sepsis, trauma, burns, opiates, immunosuppression, infxn [eg, CMV, Crypto, Campylobacter, typhoid fever])

Clinical manifestations

•  History: RUQ/epigastric pain ± radiation to R shoulder/back, nausea, vomiting, fever

•  Physical exam: RUQ tenderness, Murphy’s sign = ↑ RUQ pain and inspiratory arrest with deep breath during palpation of R subcostal region, ± palpable gallbladder

•  Laboratory evaluation: ↑ WBC, ± mild ↑ bilirubin, AΦ, ALT/AST and amylase; AST/ALT >500 U/L, bili >4 mg/dL or amylase >1000 U/L → choledocholithiasis

Diagnostic studies

•  RUQ U/S: high Se & Sp for stones, but need specific signs of cholecystitis: GB wall thickening >4 mm, pericholecystic fluid and a sonographic Murphy’s sign

•  HIDA scan: most Se test (80–90%) for acute cholecystitis. IV inj of HIDA (selectively secreted into biliary tree). In acute cholecystitis, HIDA enters BD but not GB. 10–20% false  (cystic duct obstructed from chronic cholecystitis, lengthy fasting, liver disease).

Treatment

•  NPO, IV fluids, nasogastric tube if intractable vomiting, analgesia

•  Antibiotics (E. coliKlebsiella and Enterobacter sp. are usual pathogens) ([2nd- or 3rd-generation cephalosporin or FQ] + MNZ) or piperacillin-tazobactam

•  Early CCY (usually w/in 72 h). Delaying surgery 2–3 mo ↓ operative time w/o Δ rate of complications or conversion to open procedure (Am J Surg 2008;194:40).

•  If unstable for surgery, EUS-guided transmural or ERCP-guided transcystic duct drainage is equivalent to cholecystostomy (Gastro 2012;142:805)

•  Intraoperative cholangiogram or ERCP to r/o choledocholithiasis in Pts w/ jaundice, cholangitis or stone in BD on U/S

Complications

•  Gangrenous cholecystitis: necrosis w/ risk of empyema and perforation

•  Emphysematous cholecystitis: infection by gas-forming organisms (air in GB wall)

•  Post CCY: bile duct leak, BD injury or retained stones, cystic duct remnant, sphincter of Oddi dysfxn

CHOLEDOCHOLITHIASIS

Definition

•  Gallstone lodged in bile duct (BD)

Epidemiology

•  Occurs in 15% of Pts w/ gallbladder stones; can form de novo in BD

Clinical manifestations

•  Asymptomatic (50%)

•  RUQ/epigastric pain due to obstruction of bile flow → ↑ BD pressure, jaundice, pruritus, nausea

Diagnostic studies

•  Labs: ↑ bilirubin, AΦ; transient spike in ALT or amylase suggests passage of stone

•  RUQ U/S: BD stones seen ~50% of cases; usually inferred from dilated BD (>6 mm)

•  ERCP preferred dx modality when likelihood high; cholangiogram (percutaneous, operative) when ERCP unavailable or unsuccessful; EUS/MRCP to exclude BD stones when suspicion low

Treatment

•  ERCP & papillotomy w/ stone extraction (± lithotripsy)

•  CCY typically w/in 6 wk unless contraindication (>15% Pts will develop indication for CCY if left unRx’d)

Complications

•  Cholangitis, cholecystitis, pancreatitis, stricture

CHOLANGITIS

Definition & etiologies

•  BD obstruction → infection proximal to the obstruction

•  Etiologies: BD stone (~85%)

Malignant (biliary, pancreatic) or benign stricture

Infection w/ fluke (Clonorchis sinensisOpisthorchis viverrini)

Clinical manifestations

•  Charcot’s triad: RUQ pain, jaundice, fever/chills; present in ~70% of Pts

•  Reynolds’ pentad: Charcot’s triad + shock and Δ MS; present in ~15% of Pts

Diagnostic studies

•  RUQ U/S

•  Labs: ↑ WBC, bilirubin, AΦ, amylase;  BCx

•  ERCP; percutaneous transhepatic cholangiogram (if ERCP unsuccessful)

Treatment

•  Antibiotics (broad spectrum) to cover common bile pathogens (see above) ampicillin + gentamicin (or levofloxacin) ± MNZ (if severe); carbapenems; pip/tazo

•  ~80% respond to conservative Rx and abx → biliary drainage on elective basis

•  ~20% require urgent biliary decompression via ERCP (papillotomy, stone extraction and/or stent insertion). If sphincterotomy cannot be performed (larger stones), decompression by biliary stent or nasobiliary catheter can be done; otherwise percutaneous transhepatic biliary drainage or surgery.