Cholelithiasis

Introduction

• Description: Cholelithiasis is the formation of stones in the gallbladder or biliary collecting system. Most stones (80%) are the result of precipitation of supersaturated cholesterol.

• Prevalence: 9% of women; 1 million cases per year.

• Predominant Age: 70% of patients are older than 40 years.

• Genetics: Ratio of women to men is 3:1; some races at greater risk (eg, Pima Indians). Pigment gallstones affect men and women equally. A mutation in the gene ABCG8 significantly increases a person’s risk of gallstones.

Etiology And Pathogenesis

• Causes: The metabolic alteration leading to cholesterol stones is thought to be a disruption in the balance between hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase and cholesterol 7α-hydroxylase. HMG-CoA controls cholesterol synthesis, whereas cholesterol 7α-hydroxylase controls the rate of bile acid formation. Patients who form cholesterol stones have elevated levels of HMG-CoA and depressed levels of cholesterol 7α-hydroxylase. This change in ratio increases the risk of precipitation of cholesterol as stones.

• Risk Factors: Age, female gender, parity (75% of affected women have had one or more pregnancies), obesity (15–20 lb overweight is associated with a 2-fold increase in risk; 50–75 lb excess weight is associated with a 6-fold increase in risk) and weight cycling, pregnancy, estrogen use (oral), cirrhosis, diabetes, and Crohn disease. A family history of cholelithiasis in siblings or children results in a 2-fold increase in risk. Vegetarians are at a 9-fold lower risk.

Signs And Symptoms

• Asymptomatic (60%–70%; 50% become symptomatic; 20% develop complications)

• Fatty food intolerance

• Variable right upper quadrant pain with radiation to the back or scapula especially after meals

• Belching, nausea, or vomiting (often mistaken for “indigestion”)

• Fever usually associated with cholangitis

Diagnostic Approach