From the Guidelines
A HIDA scan is ordered in a patient with gallstones, elevated WBC count, and positive Murphy's sign to confirm suspected acute cholecystitis despite the initial diagnosis suggesting otherwise. This nuclear medicine imaging test evaluates gallbladder function by tracking a radioactive tracer as it moves through the biliary system. In this clinical scenario, the combination of positive Murphy's sign (pain when pressing on the gallbladder area while the patient inhales) and elevated WBC count strongly suggests inflammation, even if initial imaging didn't show cholecystitis 1. The HIDA scan provides crucial diagnostic information by measuring the gallbladder ejection fraction and detecting blockages in the bile ducts. If the radiotracer fails to fill the gallbladder within 60 minutes, this indicates cystic duct obstruction, confirming acute cholecystitis with approximately 95% sensitivity.
Some key points to consider in this scenario include:
- The patient's clinical presentation, including a positive Murphy's sign and elevated WBC count, suggests acute cholecystitis despite initial imaging results 1.
- The HIDA scan is a sensitive test for detecting acute cholecystitis, with a sensitivity of 97% as reported in a meta-analysis by Shea et al 1.
- The distinction between acute cholecystitis and uncomplicated cholelithiasis is important, as acute cholecystitis typically requires urgent surgical intervention (cholecystectomy), while uncomplicated cholelithiasis may be managed conservatively.
- The HIDA scan helps resolve this diagnostic uncertainty when clinical signs and laboratory findings don't align with initial imaging results, as noted in the 2024 clinical practice guideline update by the Infectious Diseases Society of America 1.
Overall, the HIDA scan is a valuable diagnostic tool in this clinical scenario, providing crucial information to guide treatment decisions and improve patient outcomes.
From the Research
Patient Presentation
- The patient has cholelithiasis (gallstones) without cholecystitis (gallbladder inflammation)
- Elevated White Blood Cell (WBC) count
- Positive Murphy's sign
Reason for HIDA Scan
- A HIDA (Hepatobiliary Iminodiacetic Acid) scan is ordered to evaluate the function of the gallbladder and to check for any obstruction of the cystic duct 2
- The scan can help to determine if the patient's symptoms are related to the gallstones or if there is another underlying condition 3
- Although some studies suggest that HIDA scans may be overutilized in certain cases 4, they can still be a useful diagnostic tool in patients with atypical symptoms or inconclusive ultrasound results
Diagnostic Criteria
- The Tokyo guidelines recommend using clinical criteria, such as physical exam and laboratory findings, to diagnose acute cholecystitis 4
- However, a HIDA scan can be useful in cases where the diagnosis is unclear or if the patient has atypical symptoms 2, 3
- The scan can also help to identify patients who may benefit from surgery, such as those with chronic cholecystitis or biliary dyskinesia 5, 6
Clinical Implications
- The results of the HIDA scan will help to guide further management of the patient's condition
- If the scan shows an obstruction of the cystic duct or other abnormality, the patient may require surgery or other intervention 2
- The patient's elevated WBC count and positive Murphy's sign suggest that they may have an underlying inflammatory process, which the HIDA scan can help to evaluate 2