Conditions of Pancreas and Biliary System PDF

Conditions of pancreas and biliary system Lecture Number 6.2 Status Done Type Lecture 6.2 Conditions of pancreas and biliary system Overview This lecture covers the formation and composition of gallstones, complications arising from gallstone disease, and pa...

Conditions of pancreas and biliary system Lecture Number 6.2 Status Done Type Lecture 6.2 Conditions of pancreas and biliary system Overview This lecture covers the formation and composition of gallstones, complications arising from gallstone disease, and pathologies affecting the biliary tree. It also provides a thorough look at jaundice, including its classification into pre-hepatic, hepatic, and post-hepatic types, with explanations of bilirubin metabolism and the causes of each type. The lecture concludes with an analysis of liver function tests (LFTs), their significance, and their interpretation in diagnosing hepatic and biliary conditions. Emphasis is on high-yield, exam-relevant material and clinically significant knowledge. Learning Objectives Objective 1: Describe the formation and composition of gallstones. Objective 2: Explain the pathology and clinical presentation of gallstone complications, including biliary colic, acute cholecystitis, ascending cholangitis, and acute pancreatitis. Objective 3: Define jaundice and explain its relation to haem/bilirubin metabolism. Objective 4: Identify common causes of jaundice (pre-hepatic, hepatic, post-hepatic) and interpret abnormal LFTs in the context of jaundice. Objective 5: Recognize pancreatic malignancy and other obstructive causes as contributors to post-hepatic jaundice. Key Concepts and Definitions Gallstones: Crystalline structures formed primarily from cholesterol, bile pigments, and phospholipids within the gallbladder or biliary tree. Mnemonic: "Gallstones Clog Pipes" for Cholesterol, Pigments, and Phospholipids. Composition : Cholesterol Stones: Most common in Western populations, appear yellowish. Pigment Stones: Form from bilirubin, usually black or brown. Mixed Stones: Combine cholesterol and pigment elements. Formation : Imbalances in bile components lead to crystallization, with stones forming in layers due to cholesterol and bile pigment deposits. Biliary Colic: Sudden onset of right upper quadrant (RUQ) pain due to a transient obstruction by a gallstone in the cystic or common bile duct. Pain is intermittent, correlating with gallbladder contractions attempting to dislodge the stone. Mnemonic: "Biliary colic comes and goes like a rolling stone." Acute Cholecystitis: Inflammation of the gallbladder due to persistent gallstone obstruction in the cystic duct. Key sign is RUQ tenderness and a positive Murphy's Sign (inspiratory arrest upon palpation during a deep breath). Ascending (Acute) Cholangitis: Infection and inflammation of the biliary tree, often due to bacterial invasion following ductal obstruction. Charcot’s Triad: RUQ pain, fever, and jaundice, indicative of acute cholangitis. Mnemonic: "Pain, Pyrexia, Pigment" (Jaundice) for Charcot's Triad. Jaundice: Yellowing of the skin, sclera, and mucous membranes due to elevated bilirubin levels in the blood. Types: Pre-Hepatic: Elevated unconjugated bilirubin due to excess haemolysis. Hepatic: Mixed bilirubin elevation due to impaired conjugation by hepatocytes. Post-Hepatic: Elevated conjugated bilirubin due to biliary obstruction. Mnemonic: "Pre-Hepatic Precedes, Hepatic Happens, Post-Hepatic Post-Blockage." Clinical Applications Case Study 1: A patient with recurrent RUQ pain after fatty meals, fever, and nausea. Physical exam shows positive Murphy's sign, indicating acute cholecystitis. Case Study 2: A patient with RUQ pain, jaundice, and fever, presenting Charcot’s Triad for ascending cholangitis due to CBD obstruction. Diagnostic Approach: Ultrasound (US): Imaging modality of choice for detecting gallstones, thickened gallbladder wall in cholecystitis, and ductal dilatation. LFTs: Evaluate bilirubin and enzyme levels to determine liver and biliary tree function. CT/MRI: Used in acute pancreatitis to assess the extent of pancreatic necrosis and exclude other causes. Treatment Options: Biliary Colic: Pain management with NSAIDs, possibly followed by elective cholecystectomy. Cholecystitis: Initial conservative management (IV fluids, antibiotics), followed by cholecystectomy if indicated. Ascending Cholangitis: IV antibiotics, fluids, and surgical or endoscopic relief of obstruction (ERCP). Complications/Management: Acute Pancreatitis: Often secondary to gallstones or alcohol use, treated with fluids, supportive care, and gallstone management if causative. Pathophysiology Gallstone Formation : Results from bile component imbalances, leading to insoluble crystals. Cholesterol crystals accumulate into stones in the gallbladder, where they can obstruct the cystic or common bile duct. Biliary Obstruction : Stones can obstruct bile ducts, leading to various conditions: Biliary Colic: Transient cystic duct blockage. Cholecystitis: Persistent cystic duct blockage with inflammation. Ascending Cholangitis: Infection from the duodenum ascending into the biliary tree. Acute Pancreatitis: Occurs if stones block the pancreatic duct or ampulla of Vater. Jaundice Mechanisms: Pre-Hepatic: Increased haemolysis raises unconjugated bilirubin levels, overwhelming the liver’s conjugation capacity. Hepatic: Damage to hepatocytes results in impaired conjugation and mixed bilirubin elevation.  Post-Hepatic: Obstruction of bile flow leads to a build-up of conjugated bilirubin, which can be excreted in urine, leading to dark urine and pale stools. Pharmacology Pain Management: NSAIDs and opioids for biliary colic; NSAIDs preferred due to reduced risk of spasm. Antibiotics: For ascending cholangitis, commonly IV broad-spectrum antibiotics (e.g., piperacillin/tazobactam). Relevant Enzyme Elevations: ALT and AST: Indicators of hepatocyte injury. ALT rises higher in acute liver damage. AST predominates in chronic liver conditions (e.g., alcoholic hepatitis, cirrhosis). ALP: Elevated in biliary obstruction and cholestasis, indicating post-hepatic jaundice. Mnemonic: "ALT is Acute, AST is Sustained." Differential Diagnosis Biliary Colic vs. Cholecystitis: Biliary Colic: RUQ pain without fever or signs of inflammation. Cholecystitis: Persistent RUQ pain, fever, and positive Murphy’s sign. Jaundice Types: Pre-Hepatic: Conditions like sickle cell anaemia, thalassemia, causing unconjugated hyperbilirubinemia. Hepatic: Conditions like hepatitis and cirrhosis, presenting mixed hyperbilirubinemia. Post-Hepatic: Obstructive causes like gallstones or pancreatic tumours, presenting with conjugated hyperbilirubinemia. Investigations Ultrasound: Preferred for identifying gallstones, ductal dilatation, and cholecystitis. LFTs: Bilirubin Levels: Elevations indicate jaundice; pattern (conjugated vs. unconjugated) guides diagnosis. ALT/AST: Acute Liver Damage: ALT > AST (e.g., hepatitis). Chronic Liver Damage: AST > ALT (e.g., alcoholic liver disease). ALP: High in post-hepatic jaundice, biliary obstruction, or cholestasis. Albumin : Decreased in chronic liver disease, indicating reduced synthetic function. Blood Amylase and Lipase: Elevated in acute pancreatitis. Key Diagrams and Visuals Summary and Key Takeaways Gallstones: Form from imbalances in cholesterol, bile pigments, and phospholipids. Key complications include biliary colic (intermittent RUQ pain without inflammation), acute cholecystitis (persistent RUQ pain with inflammation and positive Murphy’s sign), ascending cholangitis (Charcot’s triad of RUQ pain, fever, and jaundice), and acute pancreatitis (caused by stones obstructing the pancreatic duct). Jaundice: Classified into three types based on bilirubin metabolism and excretion:  Pre-Hepatic: Elevated unconjugated bilirubin due to excess haem breakdown (e.g., hemolytic conditions like sickle cell anemia). Hepatic: Mixed conjugated and unconjugated bilirubin due to hepatocyte damage (e.g., hepatitis, cirrhosis). Post-Hepatic: Elevated conjugated bilirubin due to biliary obstruction (e.g., gallstones, pancreatic cancer). Exam Tip: Recognize jaundice type by the pattern of bilirubin levels in LFTs—conjugated vs. unconjugated. Liver Function Tests (LFTs): Key to identifying liver and biliary tree health: ALT: More liver-specific, elevated in acute hepatic injury. AST: Elevated in chronic liver diseases, such as alcoholic liver disease, where it often exceeds ALT. ALP: Elevated in post-hepatic jaundice due to biliary obstruction. Albumin : Decreased in chronic liver disease, indicating impaired synthetic function. Mnemonic: "ALT is for Acute Liver Trauma; AST for Sustained Trouble in chronic liver disease." Further Reading/References Patient.info: Comprehensive overview of gallstones and cholecystitis Link Liverpool University Resource: Detailed bilirubin metabolism and jaundice pathways Link Geeky Medics: Guide to interpreting Liver Function Tests (LFTs) Link Questions/Clarifications Question 1: In differentiating biliary obstruction due to gallstones vs. pancreatic tumour, what imaging or lab markers would be most indicative of each? Question 2: How does Charcot’s Triad differ from Reynold’s Pentad in severe cholangitis, and what is the clinical significance of each? Question 3: For jaundice presentation in darker skin tones, what visual signs should be noted for clinical diagnosis? Question 4: Given the prevalence of gallstone disease, what preventive measures or lifestyle modifications are recommended to reduce risk, particularly in at-risk populations?