Cholecystitis – Top USMLE Diseases

Cholestasis in neonates and young infants is conjugated hyperbilirubinemia in the 1st 3 months of life due to impaired bile excretion. Biliary tract malformations involving the gallbladder and bile duct are grouped into cystic and noncystic obliterative cholangiopathies, the most common of which is biliary atresia. Less common causes include the genetic Alagille syndrome, infectious causes, and metabolic disorders. Clinical presentation is with obstructive jaundice. Ultrasonography and MRCP are useful diagnostic tools, and a prenatal diagnosis is sometimes made with ultrasonography. Cystic causes frequently require surgery to correct the defect and allow for normal child growth. Liver transplantation may be needed in cases of biliary atresia with portal hypertension.

The hepatobiliary system is composed of the liver, gallbladder, and bile ducts (within the liver and external to the liver). The liver produces bile, which is a fluid made of cholesterol, phospholipids, conjugated bilirubin, bile salts, electrolytes, and water. Bile, which assists in digestion and helps eliminate waste products, is stored in the gallbladder. The hepatobiliary system can be affected by infections, cysts, solid masses, ischemia, and mechanical flow obstruction, which mandate the presence of reliable imaging tests to determine the etiology. The methods that evaluate structural changes in the liver and biliary tract include ultrasonography, CT scan, and MRI (including magnetic resonance cholangiopancreatography). Additionally, cholescintigraphy, a functional imaging study, helps identify gallbladder pathology by tracking the biliary pathway.

Chronic pancreatitis is due to persistent inflammation, fibrosis, and irreversible cell damage to the pancreas, resulting in a loss of endocrine and exocrine gland function. The most common etiologies are alcohol abuse and pancreatic duct obstruction. Patients often present with recurrent epigastric abdominal pain, nausea, and features of malabsorption syndrome (diarrhea, steatorrhea, and weight loss). Characteristic computed tomography (CT) findings include pancreatic atrophy, dilated pancreatic ducts, and pancreatic calcifications. Therapy focuses on alcohol cessation, diet changes, pain management, and treatment of pancreatic insufficiency.

Acute pancreatitis is an inflammatory disease of the pancreas due to autodigestion. Common etiologies include gallstones and excessive alcohol use. Patients typically present with epigastric pain radiating to the back. Diagnosis requires 2 of 3 criteria, including: characteristic abdominal pain, serum amylase and lipase 3 times the upper limit of normal, or characteristic radiology findings. Ranson’s criteria is commonly used to assess the severity. Management includes aggressive intravenous (IV) hydration, analgesia, nutritional support, and treatment of the underlying cause.

Cholecystectomy is a surgical procedure performed with the goal of resecting and extracting the gallbladder. It is one of the most common abdominal surgeries performed in the Western world. Cholecystectomy is performed for symptomatic cholelithiasis, cholecystitis, gallbladder polyps > 0.5 cm, porcelain gallbladder, choledocholithiasis and gallstone pancreatitis, and rarely, for gallbladder cancer. Over 90% of cholecystectomies are now completed laparoscopically because of the procedure’s enhanced recovery time and decreased postoperative pain. Cholecystectomy has a low-risk profile, but the most dreaded complications include vascular and biliary ductal injuries.

The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Bile is secreted by hepatocytes into thin channels called canaliculi. These canaliculi lead into slightly larger interlobular bile ductules, which are part of the portal triads at the “corners” of hepatic lobules. The bile leaves the liver via the right and left hepatic ducts, which join together to form the common hepatic duct. The common hepatic duct joins with the cystic duct to form the common bile duct, which empties into the small intestine. If the sphincters leading into the intestines are closed, bile will travel via the cystic duct into the gallbladder for storage.

Cholecystitis is the inflammation of the gallbladder (GB) usually caused by the obstruction of the cystic duct (acute cholecystitis). Mechanical irritation by gallstones can also produce chronic GB inflammation. Cholecystitis is one of the most common complications of cholelithiasis (calculous cholecystitis) but inflammation without gallstones (acalculous cholecystitis) can occur in a minority of patients. The acute type usually presents with right upper quadrant (RUQ) pain, fever, and leukocytosis. The diagnosis is made clinically and confirmed via ultrasound (US). The definitive management is cholecystectomy, preferred to be performed within 72 hours. This condition can present as a mild condition or as a severe disease (with complications such as gallbladder gangrene, perforation, empyema) which require emergent intervention.

Cholelithiasis (gallstones) is the presence of stones in the gallbladder. Most gallstones are cholesterol stones, while the rest are composed of bilirubin (pigment stones) and other mixed components. Patients are commonly asymptomatic but may present with biliary colic (intermittent pain in the right upper quadrant). The diagnosis is established by ultrasound. Management options include supportive care to prevent and control associated symptoms. When indicated, cholecystectomy is the definitive treatment. Gallstones may lead to complications such as choledocholithiasis (a stone trapped in the common bile duct), cholecystitis (inflammation of the gallbladder), or cholangitis (biliary sepsis). These conditions require urgent medical attention.