Liver biopsy remains the gold standard for diagnosing nonalcoholic fatty liver disease (NAFLD). However, ultrasound is utilized as the first-line imaging test for individuals with suspected NAFLD. 

A study estimated the accuracy of ultrasound as a screening test for NAFLD contrasting it with liver biopsy in patients with class II and III obesity undergoing bariatric surgery. 

The study included patients undergoing Roux-en-Y gastric bypass who were screened for NAFLD with standardized ultrasound and liver biopsy. 

The following observations were made-

• 227 patients were included in the study with 84% female and 83.6% white individuals.
• The mean age of the enrolled subjects was 42.5 ± 10.2 years and the mean preoperative body mass index was 49.5 ± 8.4 kg/m2. 
• Liver biopsies diagnosed 67.4% of the patients having NAFLD, with 18% having fatty liver and 49.3% having nonalcoholic steatohepatitis. The sensitivity and specificity of ultrasound was 88.9% and 44.6% respectively. 
• Similarly, Positive and negative predictive values were found to be 76.8% and 66.0%, respectively. 
• Furthermore, the positive and negative likelihood ratio was 1.6 and 0.25 respectively. 
• Thus, nearly three of every four subjects with an ultrasound indicating NAFLD were true positives. 

So, it was inferred that Ultrasound shows good sensitivity in detecting NAFLD in patients with class II and III obesity.

Source- Obesity Research & Clinical Practice, 2021;15(5):461-465

https://doi.org/10.1016/j.orcp.2021.09.002.