It is very accurate in diagnosing or excluding gallstones, with a reported accuracy of 96% for the detection of gallstones [7], and helps differentiate cholelithiasis from gallbladder sludge, polyps, or masses. AC is the most common cause of right upper quadrant abdominal pain. However, assessment of more than one- third of patients initially suspected of having AC will result in an alternative diagnosis [16]. US is the most useful first-line imaging modality in evaluating AC, with the additional advantage of identifying alternate diagnosis of hepatic disease. The reported sensitivity and specificity of US range from 50% to 100% and from 33% to 100%, respectively, with summary estimates of 81% and 83%, respectively [25]. A 2019 study showed US sensitivity and specificity were 61.8% and 98.4%, respectively; the sensitivity of US reached 85.2% and 90% in patients with AC/biliary colic and urolithiasis, respectively [26]. US is also the most useful imaging modality for the diagnosis of biliary colic, with an accuracy of 90% for demonstrating cholelithiasis, which may develop into AC if untreated in up to 20% of patients [27]. Furthermore, choledocholithiasis can lead to biliary obstruction and subsequent cholangitis or acute pancreatitis, and US has a sensitivity of up to 91% in detecting stones within the common bile duct [28]. Liver abscess and metastatic disease may also cause right upper quadrant pain. Similarly, symptomatic hepatic masses causing bleeding or hemoperitoneum may also be easily picked up on US. US can also help identify renal pathology causing right upper quadrant pain with a sensitivity of 73% to 100% for the detection of hydronephrosis caused by renal obstruction with an overall improved sensitivity compared with radiography [27]. Adrenal pathology may also contribute to the list of causes of right upper quadrant pain. Adrenal hemorrhage can be easily identified as a mass without identifiable Doppler flow.
Right Upper Quadrant Pain. It is very accurate in diagnosing or excluding gallstones, with a reported accuracy of 96% for the detection of gallstones [7], and helps differentiate cholelithiasis from gallbladder sludge, polyps, or masses. AC is the most common cause of right upper quadrant abdominal pain. However, assessment of more than one- third of patients initially suspected of having AC will result in an alternative diagnosis [16]. US is the most useful first-line imaging modality in evaluating AC, with the additional advantage of identifying alternate diagnosis of hepatic disease. The reported sensitivity and specificity of US range from 50% to 100% and from 33% to 100%, respectively, with summary estimates of 81% and 83%, respectively [25]. A 2019 study showed US sensitivity and specificity were 61.8% and 98.4%, respectively; the sensitivity of US reached 85.2% and 90% in patients with AC/biliary colic and urolithiasis, respectively [26]. US is also the most useful imaging modality for the diagnosis of biliary colic, with an accuracy of 90% for demonstrating cholelithiasis, which may develop into AC if untreated in up to 20% of patients [27]. Furthermore, choledocholithiasis can lead to biliary obstruction and subsequent cholangitis or acute pancreatitis, and US has a sensitivity of up to 91% in detecting stones within the common bile duct [28]. Liver abscess and metastatic disease may also cause right upper quadrant pain. Similarly, symptomatic hepatic masses causing bleeding or hemoperitoneum may also be easily picked up on US. US can also help identify renal pathology causing right upper quadrant pain with a sensitivity of 73% to 100% for the detection of hydronephrosis caused by renal obstruction with an overall improved sensitivity compared with radiography [27]. Adrenal pathology may also contribute to the list of causes of right upper quadrant pain. Adrenal hemorrhage can be easily identified as a mass without identifiable Doppler flow.