Gastrointestinal Nursing.pdf

PATHOPHYSIOLOGY OF THE GALL BLADDERThe Biliary System 119Gall bladder diseases can either be short-term and easily manageable or longertermand debilitating. Generally diseases of the biliary system present duringmiddle age. In individuals aged 20–50, diseases of the biliary tract are sixtimes more common in women than in men, but over the age of 50 the incidencein men and women becomes equal (Summerfield 2000).Biliary tract disorders that are examined in this section include cholelithiasis,cholecystitis, choledocholithiasis, cholangitis and carcinoma.Gallstones (cholelithiasis)Gallstones are the presence of stones or calculi in the gall bladder. There aretwo types of gallstone: cholesterol stones and pigment stones. Cholesterolstones make up three-quarters of all gallstones. To understand the mechanismsof gallstone formation it is important to know their composition.Cholesterol stonesCholesterol stones contain cholesterol, calcium salts, bile acids, fatty acids,proteins and phospholipids. If the concentration of bile acids or phospholipidsdrops, cholesterol will not be held in micelles. This results in the bile becomingsupersaturated with cholesterol. When the cholesterol is not soluble in thissupersaturated system, it forms microcrystals. These microcrystals grow andcluster with one another and with other bile constituents to form gallstones.Cholesterol gallstones are more prone to develop when there is a high ratioof cholesterol to bile acids or lecithin in the bile. This can be due to highcholesterol levels related to a high fat diet. Gallstones also form when there isa reduction in bile acid secretion, as a consequence of bile acid malabsorptionor reduced lecithin secretion.Risk factors for the formation of both cholesterol and pigment stones areshown in Table 8.2.Table 8.2Risk factors for formation of gallstones.Cholesterol gallstonesIncreasing ageFemale sexPregnancy/use of oral contraceptiveObesityGall bladder staisisSpinal cord injuryPigment gallstonesIncreasing ageChronic haemolysisAlcohol abuse/cirrhosisBiliary infectionTotal parenteral nutritionGall bladder stasis