What is the likelihood of cholecystitis in a patient with cholelithiasis and thickened gallbladder walls, considering a Hepatobiliary Iminodiacetic Acid (HIDA) scan?

From the Guidelines

A HIDA scan is recommended to confirm suspected cholecystitis in this case of cholelithiasis with thickened gallbladder walls. This nuclear medicine test evaluates gallbladder function by tracking how a radioactive tracer moves through the biliary system. The scan can determine if the gallbladder is obstructed, which is crucial for diagnosis when ultrasound findings are inconclusive 1. According to the 2019 WSES guidelines, HIDA scan has the highest sensitivity and specificity for acute cholecystitis than other imaging modalities, although its scarce availability, long time of execution, and exposure to ionizing radiations limit its use 1.

While waiting for the scan, the patient should remain NPO (nothing by mouth) except for clear liquids, and pain management with NSAIDs or opioids may be necessary. Antibiotics such as Piperacillin-Tazobactam 3.375g IV every 6 hours or Ceftriaxone 1g IV daily plus Metronidazole 500mg IV every 8 hours should be started if acute cholecystitis is strongly suspected, especially with fever or elevated white blood cell count. The HIDA scan works by measuring the ability of the gallbladder to fill with and release bile; non-visualization of the gallbladder after 4 hours suggests obstruction consistent with acute cholecystitis. This information will help determine if urgent surgical intervention (cholecystectomy) is needed or if conservative management is appropriate.

Some key points to consider in the management of acute cholecystitis include:

• The evaluation of the risk for elderly patient with ACC should include: mortality rate for conservative and surgical therapeutic options, rate of gallstone-related disease relapse and the time to relapse, age-related life expectancy, and consideration of patient frailty evaluation by the use of frailty scores 1.
• Cholecystectomy is the preferred treatment for ACC even in elderly patients, and laparoscopic approach should always be attempted at first except in case of absolute anesthetic contraindications and septic shock 1.
• Early laparoscopic cholecystectomy should be performed as soon as possible but can be performed up to 10 days of onset of symptoms, and earlier surgery is associated with shorter hospital stay and fewer complications 1.

It's worth noting that, in clinical practice, HIDA scan utilization is limited due to the required resources and time, and a study comparing the diagnostic sensitivities of US, CT, and HIDA scan confirmed the higher sensitivity of HIDA over US and CT 1. However, the 2020 World Society of Emergency Surgery updated guidelines for the diagnosis and treatment of acute calculus cholecystitis still support the use of HIDA scan in certain cases 1.

From the Research

Diagnostic Approaches for Cholelithiasis with Thickened Gallbladder Walls

• The presence of thickened gallbladder walls can be an indicator of cholecystitis, and diagnostic approaches such as ultrasonography (US) and hepatobiliary scintigraphy (HIDA scan) are considered for diagnosis 2, 3, 4.
• HIDA scan is found to be more sensitive than US in diagnosing acute cholecystitis, with sensitivities of 86% and 48% respectively, as reported in a study published in the Journal of the American College of Surgeons 2.
• Another study published in the International Journal of Surgery found that HIDA scan had a sensitivity and specificity of 87% and 79% respectively for acute cholecystitis, while US had a sensitivity and specificity of 26% and 80% respectively 3.

Comparison of Diagnostic Modalities

• A comparison of US, HIDA scan, and combined US/HIDA for diagnosing acute cholecystitis found that the combination of US and HIDA had the highest sensitivity of 97.7%, followed by HIDA scan alone with a sensitivity of 91.7%, and US alone with a sensitivity of 73.3% 4.
• The use of HIDA scan in patients with suspected acute cholecystitis is recommended as the first diagnostic modality, with US used to confirm the presence of gallbladder stones rather than to diagnose acute cholecystitis 2.

Clinical Implications

• The results of these studies have clinical implications for the diagnosis and management of patients with suspected acute cholecystitis, highlighting the importance of HIDA scan in the diagnostic workup 3, 4.
• A meta-analysis of cholecystectomy in symptomatic patients with positive HIDA scan results without gallstones found that surgical treatment was 15-fold more likely to result in symptom improvement compared to medical treatment 5.
• Hepatobiliary scan findings can also suggest chronic cholecystitis, and recognition of these patterns can increase suspicion of chronic disease and direct further management 6.