Gallstones for the PA Exam
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Gallstones (Cholelithiasis) for the Physician Assistant Licensing Exam
Overview
- Gallstones, or cholelithiasis, are solid particles formed in the gallbladder due to imbalances in bile composition.
- Gallstones are classified into:
- Cholesterol stones: Most common, formed due to cholesterol supersaturation.
- Pigment stones: Composed of bilirubin, often linked to hemolytic diseases.
Pathophysiology
Cholesterol Stones
- Form due to cholesterol supersaturation in bile, decreased bile salts, or gallbladder stasis.
- Risk factors include:
- Obesity: Increases cholesterol secretion.
- Rapid weight loss: Mobilizes cholesterol from adipose stores.
- Estrogen: Increases cholesterol saturation; common in pregnancy and hormone therapy.
- Metabolic syndrome: Associated with insulin resistance and hyperlipidemia.
- Genetics: Native Americans have higher prevalence due to genetic predisposition.
Pigment Stones
- Result from excess bilirubin in bile, forming black or brown pigment stones.
- Commonly associated with:
- Chronic hemolytic states (e.g., sickle cell anemia, hereditary spherocytosis).
- Cirrhosis: Reduces bile flow, increasing the risk of stone formation.
- Biliary infections: Bacterial enzymes hydrolyze bilirubin glucuronides, promoting stone formation.
Clinical Presentation
- Most patients with gallstones are asymptomatic.
- Biliary colic: Characterized by RUQ or epigastric pain, often after a fatty meal, due to temporary cystic duct obstruction. The pain is steady and may radiate to the right shoulder or back, lasting up to several hours.
- Nausea and vomiting often accompany biliary colic.
Complications
Acute Cholecystitis
- Inflammation of the gallbladder due to persistent cystic duct obstruction by a stone.
- Symptoms: Persistent RUQ pain, fever, and Murphy’s sign (pain on inspiration during palpation of the RUQ).
- Diagnosis: Ultrasound shows gallbladder wall thickening and pericholecystic fluid.
- Requires prompt management with antibiotics and potential cholecystectomy.
Choledocholithiasis
- Gallstones obstructing the common bile duct (CBD), leading to bile flow obstruction.
- Symptoms: Jaundice, RUQ pain, and elevated bilirubin and ALP.
- May progress to cholangitis (infection of the bile duct), which presents with fever, jaundice, and RUQ pain (Charcot’s triad). Severe cases may develop Reynold’s pentad (Charcot’s triad plus hypotension and altered mental status).
- Managed with ERCP for stone removal.
Gallstone Pancreatitis
- Occurs when gallstones obstruct the pancreatic duct, leading to pancreatic inflammation.
- Symptoms: Epigastric pain radiating to the back, nausea, and vomiting.
- Diagnosis: Elevated amylase and lipase levels.
- Management includes supportive care and possibly ERCP for stone extraction.
Diagnosis
- Ultrasound: First-line imaging for detecting gallstones, showing echogenic foci with posterior acoustic shadowing.
- CT or MRI: May detect complications such as abscesses or perforation but are less sensitive for gallstones.
- Liver function tests (LFTs): Elevated in choledocholithiasis, particularly bilirubin, ALP, and GGT.
Management
Asymptomatic Gallstones
- Observation: No treatment is required unless the patient develops symptoms.
Symptomatic Cholelithiasis (Biliary Colic)
- Laparoscopic cholecystectomy: The definitive treatment for symptomatic gallstones to prevent recurrence and complications.
- Medical therapy: Ursodeoxycholic acid may be used to dissolve cholesterol stones in patients who cannot undergo surgery, though this is less effective and requires long-term therapy.
Acute Cholecystitis
- Antibiotics: Administered to cover gram-negative and anaerobic organisms.
- Cholecystectomy: Performed within 72 hours to prevent complications like perforation.
Choledocholithiasis and Cholangitis
- Endoscopic retrograde cholangiopancreatography (ERCP): Both diagnostic and therapeutic for common bile duct stones, followed by cholecystectomy to prevent recurrence.
Key Points
- Cholesterol stones are the most common type of gallstones, and risk factors include obesity, rapid weight loss, and pregnancy.
- Biliary colic presents as RUQ pain after meals and resolves when the stone moves away from the cystic duct.
- Complications of gallstones include acute cholecystitis, choledocholithiasis, cholangitis, and gallstone pancreatitis.
- Ultrasound is the first-line imaging for gallstones, and ERCP is used for diagnosing and removing stones in the bile ducts.
- Laparoscopic cholecystectomy is the definitive treatment for symptomatic gallstones.