Obstructive Jaundice PDF

Obstructive jaundice/ Dr. Yousif Al-Jubori OBSTRUCTIVE JAUNDICE Jaundice is defined as; a yellowish discoloration of the skin and mucous membranes due to raised serum bilirubin. It gives a yellow tinge to the sclera. Metabolism of bilirubin (bile pigment): 1. Haem and globin are liberated from...

Obstructive jaundice/ Dr. Yousif Al-Jubori OBSTRUCTIVE JAUNDICE Jaundice is defined as; a yellowish discoloration of the skin and mucous membranes due to raised serum bilirubin. It gives a yellow tinge to the sclera. Metabolism of bilirubin (bile pigment): 1. Haem and globin are liberated from RBCs after haemolysis in the spleen. 2. Haem is converted to indirect (unconjugated) bilirubin, which is lipid soluble. 3. The indirect (unconjugated) bilirubin conjugates with liver enzyme to form the direct (conjugated) bilirubin. It is water soluble. 4. The direct (conjugated) bilirubin is excreted with the bile to the intestine. 5. The direct (conjugated) bilirubin is converted to urobilinogen (water soluble) by colonic bacteria. 6. Urobilinogen: a. Some urobilinogen is excreted with the stool. b. Some urobilinogen is absorbed by the portal vein to the liver to be excreted into the bile (enterohepatic circulation). c. Some urobilinogen is excreted in the urine. N.B. Normally, the indirect bilirubin (lipid soluble) is found in the blood only, and not found in the urine. The direct bilirubin (water soluble) is found in the blood, excreted with the bile to the intestine, and to the urine. It gives the normal colour of stool and urine. Urobilinogen is the converted product of direct bilirubin. So, it is same as the direct bilirubin; (found in the, stool, blood, and urine). OBSTRUCTIVE (POST-HEPATIC) JAUNDICE The normal total serum bilirubin is below 1.2 mg/ dL, which is of two types. Direct (conjugated) bilirubin is 0.3 mg/ dL, and the remainder is indirect (unconjugated) type. Jaundice is three types; pre-hepatic, hepatic, and obstructive (post-hepatic) jaundice. Causes of obstructive jaundice: 1. Causes in the lumen; (e.g., gallstones). 2. Causes in the wall; (e.g., Stricture or tumour of the common bile duct). 3. Causes outside the wall (external compression); (e.g., Tumour of the head of the pancreas, and liver abscess). 1  Obstructive jaundice/ Dr. Yousif Al-Jubori Pathophysiology of obstructive jaundice: 1. Any obstruction to the common bile duct prevents excretion of the direct bilirubin. The direct bilirubin will be absorbed into the blood in high amounts and excreted in the urine. So, the stool becomes pale clay coloured, and the urine becomes dark brown tea coloured. 2. Moreover, the function of liver cells will be affected in prolonged obstruction. So, the hepatic and post hepatic forms of jaundice may co-exist. For example, a stone in the common bile duct may produce jaundice mainly by obstructing the outflow of bile (obstructive jaundice), and partly by secondary damage to the liver (hepatic jaundice). Similarly, tumour deposits in the liver and liver cirrhosis may result in jaundice; both mainly by damage of the liver tissue and partly by duct obstruction. N.B. In obstructive jaundice, the direct bilirubin is raised in the blood, and the urine, but low in the stool; (stool is pale clay coloured, and urine is dark brown tea coloured). Moreover, urobilinogen is neither found in the stool, nor in the blood, and the urine. Preoperative preparation of a patient with obstructive jaundice: 1. Special investigations: a. Total serum bilirubin and direct serum bilirubin are raised. b. Serum urobilinogen is decreased. c. Liver enzymes especially alkaline phosphatase is raised. d. Prothrombin time is prolonged. e. Complete blood count, and ESR. f. Blood urea, serum creatinine and electrolytes to check renal function. g. Ultrasound (US) of the abdomen to show the dilated bile ducts and the obstructing lesion. 2. Rehydration with intravenous fluids to prevent renal failure. 3. Parenteral vitamin K is given for three days prior to surgery to prevent bleeding tendency; as clotting factors II, VII, IX, and X depend on their synthesis on vitamin K in the liver. 4. Preparation of fresh blood for suspected bleeding. 5. Antibiotics to prevent infection. Treatment: According to the obstructing cause and remove it. 2