Cholelithiasis & Choledocholithiasis
CHOLELITHIASIS
Definition:
“Gallstones”
“Sludge” (microlithiasis): super-concentrated mixture of bile acids, bilirubin, cholesterol, mucus, and proteins
Epidemiology:
>10% adults in U.S. have gallstones, however only 20% of these persons develop symptoms (1-2% chance per year)
↑ prevalence in women, Native Americans, and with increasing age, obesity and pregnancy
500,000 cholecystectomies are performed each year in the United States
Etiologies:
Drug/Medical therapies associated:
Pathophysiology:
Bile Physiology: Liver synthesizes 0.2-0.6 g/day; Pool of bile in body is about 3 grams
Biliary secretion = pool × (pool is 3 g, cycles occur 4-12 times/day, slowing during fasting, accelerating with meals)
Hence, there are 12-36 grams of bile secreted and absorbed per day
Bile composed of bile salts, phospholipids, cholesterol; ↑ cholesterol saturation in bile promotes gallstones
Enterohepatic circulation: Biliary secretion occurs, Ileal absorption returns 97% of intraluminal bile acid back into circulation via portal vein
(90% are extracted from portal circulation on their first pass through the liver)
Fecal excretion (0.2-0.6 g/day), Urinary excretion via systemic circulation (<0.5 mg/day)
In health, hepatic synthesis of bile acids is equivalent to enteric losses (0.2-0.6 g/day)
Gallbladder:
In health, the gallbladder concentrates bile 10-fold for efficient storage during fasting
Intraduodenal fat and protein release cholecystokinin (CCK) which stimulates gallbladder contraction, sphincter-of-Oddi relaxation
Principle factors involved in gallstone formation: cholesterol supersaturation, crystal nucleation, gallbladder hypomotility
Cholesterol supersaturation: result from deficient bile secretion or hypersecretion of cholesterol
Bile secretion reduced with age or liver disease, reduced enterohepatic circulation (TI disease)
Cholesterol secretion increased with hormones (female, sex, pregnancy, exogenous estrogens), obesity, liver disease
Nucleation: formation of insoluble deposits from supersaturated bile within biliary system
Gallbladder hypomotility: pregnancy, prolonged TPN, somatostatin therapy
Other influencing factors: bile transit time, gallbladder contraction, presence of bacteria, mucin, glycoproteins such as IgA
Types of gallstones; including color of stone
Mixed (80%): multiple stones, composed of 80% cholesterol and 20% unconjugated bilirubin, may calcify (15-20%); Yellow
Cholesterol (10%): usually single stone, large, uncalcified; Yellow
Pigment (10%): unconjugated bilirubin (hence seen in chronic hemolysis) and cirrhosis; Calcium too; Black & Radiopaque
Infectious: colonization of bile with enteric bacteria and/or parasites; Soft clay-like in ducts, not gallbladder; Asian population; Brown
Clinical Manifestations/Physical Exam:
Asymptomatic:
Most are found incidentally and remain asymptomatic in 80% of patients: require no treatment Prophylactic cholecystectomy: travel to remote areas (i.e. outer space!) or American Indians (stone associated cancer 20-fold ↑)
When symptoms do develop, only 2%/year present with acute cholecystitis or other complications
Biliary Colic: episodic RUQ or epigastric abdominal pain that begins abruptly, continuous, resolves slowly, lasts 30 min-6 hrsRelated posts:
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