USMLE Guide: Cirrhosis

Introduction

Cirrhosis is a chronic liver disease characterized by the replacement of healthy liver tissue with scar tissue, leading to impaired liver function. This guide aims to provide a comprehensive overview of cirrhosis, including its etiology, pathophysiology, clinical features, diagnostic approach, and management.

I. Etiology

Cirrhosis can be caused by various factors, including:

1. Chronic alcohol abuse
2. Chronic viral hepatitis (Hepatitis B or C)
3. Non-alcoholic fatty liver disease (NAFLD)
4. Autoimmune hepatitis
5. Genetic disorders (e.g., hemochromatosis, Wilson disease)
6. Chronic biliary obstruction (e.g., primary biliary cirrhosis)
7. Drug-induced liver injury

II. Pathophysiology

The development of cirrhosis involves a complex process of liver injury, inflammation, and fibrosis. Key mechanisms include:

1. Hepatocellular injury: Repeated liver injury, such as from alcohol or viral hepatitis, leads to hepatocyte damage and apoptosis.
2. Inflammation: Chronic inflammation triggers an immune response, promoting the release of pro-inflammatory cytokines and recruitment of inflammatory cells.
3. Fibrosis: Activation of hepatic stellate cells results in excessive deposition of extracellular matrix components, leading to scar tissue formation and distortion of liver architecture.

III. Clinical Features

Patients with cirrhosis may present with a wide range of signs and symptoms, including:

1. Jaundice: Yellow discoloration of the skin and sclera due to impaired bilirubin metabolism.
2. Ascites: Accumulation of fluid within the peritoneal cavity, leading to abdominal distension.
3. Hepatic encephalopathy: Neurological symptoms caused by the liver's inability to detoxify ammonia, resulting in elevated blood ammonia levels.
4. Spider angiomas: Dilated cutaneous blood vessels resembling spider legs, commonly found on the upper body.
5. Gynecomastia and testicular atrophy: Hormonal imbalances due to impaired liver metabolism.
6. Palmar erythema: Redness of the palms due to increased circulating estrogen levels.
7. Caput medusae: Dilated abdominal wall veins resembling the head of Medusa.

IV. Diagnostic Approach

The diagnosis of cirrhosis involves a combination of clinical evaluation, laboratory tests, and imaging studies:

1. History and physical examination: Assess for risk factors, signs of liver disease, and complications.
2. Liver function tests: Evaluate liver synthetic function (albumin, prothrombin time) and liver injury markers (aspartate aminotransferase, alanine aminotransferase).
3. Imaging studies: Abdominal ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI) can assess liver size, nodularity, and the presence of complications.
4. Liver biopsy: In selected cases, a liver biopsy may be necessary to confirm the diagnosis and assess the degree of fibrosis.

V. Management

The management of cirrhosis focuses on addressing the underlying cause, managing complications, and preventing disease progression:

1. Lifestyle modifications: Alcohol cessation, weight loss in NAFLD, vaccination against hepatitis A and B.
2. Pharmacological interventions: Treatment of viral hepatitis with antiviral medications, immunosuppressive therapy for autoimmune hepatitis.
3. Complication management: Diuretics for ascites, lactulose and rifaximin for hepatic encephalopathy, beta-blockers for portal hypertension.
4. Liver transplantation: In cases of advanced cirrhosis with liver failure, transplantation may be the only curative option.

Conclusion

Cirrhosis is a chronic liver disease with various etiologies and a complex pathophysiology. Understanding its clinical features, diagnostic approach, and management is crucial for medical professionals. This USMLE guide aims to provide a comprehensive overview to assist students in preparing for their exams and developing a solid understanding of cirrhosis.