From the Guidelines
A HIDA scan should be ordered when ultrasound is inconclusive in patients with suspected acute cholecystitis, particularly if CT is also equivocal, as it is considered the gold standard for diagnosing acute cholecystitis. This recommendation is based on the most recent and highest quality study available, which suggests that HIDA scans have the highest sensitivity and specificity for the diagnosis of acute calculus cholecystitis compared to other imaging modalities 1. The benefits of HIDA scans include their high diagnostic accuracy, lower cost compared to MRI/MRCP, and ability to provide a clear picture of the biliary system. However, patients must fast for several hours before undergoing a HIDA scan, and certain medications like opioids and anticholinergics should be discontinued to avoid false-positive results.
Some key points to consider when ordering a HIDA scan include:
- The patient's clinical presentation, including right upper quadrant pain, abnormal liver function tests, and suspected biliary obstruction or dysfunction
- The results of previous imaging studies, such as ultrasound and CT
- The need for a definitive diagnosis of acute cholecystitis, particularly in cases where other imaging modalities are inconclusive
- The potential benefits and limitations of HIDA scans, including their high diagnostic accuracy and requirement for patient fasting
It's also important to note that HIDA scans are not the first-line imaging modality for suspected acute cholecystitis, and ultrasound and CT should be considered first 1. However, in cases where these imaging modalities are inconclusive, a HIDA scan can provide valuable diagnostic information and help guide treatment decisions. Additionally, HIDA scans can be useful in evaluating bile leaks after hepatobiliary surgery, assessing biliary atresia in infants, and determining the patency of biliary-enteric anastomoses.
From the Research
Indications for HIDA Scan
- A HIDA scan is typically ordered when there is a high clinical suspicion for cholecystitis, but ultrasonography (US) results are inconclusive 2.
- It can be used to assess biliary drainage in jaundiced patients with surgically altered biliary tract anatomy 3.
- In cases of "acute abdomen" with suspected gallbladder disease, a HIDA scan can be a useful first-line investigation to support or exclude the diagnosis of acute gallbladder disease 4.
- HIDA scans can also be used to evaluate congenital gallbladder and biliary duct anomalies, as they can provide functional information about the biliary tree 5.
Specific Clinical Scenarios
- In patients with suspected acute cholecystitis, a HIDA scan can help confirm the diagnosis if US results are unclear 2, 4.
- In infants with persistent jaundice, a HIDA scan can be used as an initial diagnostic test to evaluate for biliary atresia, although percutaneous transhepatic cholecysto-cholangiography (PTCC) and liver biopsy may be more effective in excluding this condition 6.
- In patients with complicated gallbladder disease, a HIDA scan may not be necessary if clinical criteria for cholecystitis are already met 2.
Limitations and Precautions
- HIDA scans should be reserved for cases with high clinical suspicion for cholecystitis and inconclusive US results, as overutilization can increase healthcare costs and delay care 2.
- The scan may not be useful in patients with hepatocellular disease or biliary obstruction, as poor uptake or secretion of the HIDA can lead to false-negative results 3, 4.