By Dr. Richard Nguyen, DO, FACS, FACOS | Board-Certified Surgeon | San Jose & Los Gatos, CA
If your doctor has ordered a HIDA scan because of gallbladder pain without obvious gallstones, the result known as the "ejection fraction" can feel like a mystery number. In our San Jose and Los Gatos practice, we see many patients holding a report that says "low ejection fraction" and wondering what it means for them. This guide explains what a HIDA scan measures, how to read the percentage, and how that number fits into the decision about gallbladder removal (cholecystectomy).
A HIDA (hepatobiliary iminodiacetic acid) scan, also called cholescintigraphy, is a nuclear medicine imaging test. A small amount of a radioactive tracer is given through an IV. The tracer travels through the liver, into the bile ducts, and then into the gallbladder and small intestine. A special camera follows its path, allowing your care team to see whether bile is flowing normally and whether the gallbladder fills and empties as it should.
The radiation dose is low and comparable to many routine imaging studies. The test usually takes one to several hours, and you will be asked to fast beforehand.
After the gallbladder fills with tracer, you may be given a medication (commonly cholecystokinin, or CCK) or a fatty meal to make it contract. The scan then measures how much of the tracer the gallbladder squeezes out. That percentage is the ejection fraction (EF).
A single number should never decide your care. A low EF is a clue, and its importance depends on your symptoms. Surgeons generally weigh the result alongside:
Some people have a low EF and few symptoms. Others have classic symptoms with a borderline EF. This is why a careful history and exam matter as much as the scan. For a deeper look at this condition, see our article on gallbladder pain without stones and biliary dyskinesia.
Because several conditions can mimic gallbladder pain, a thorough workup is important before surgery is recommended. Depending on your situation, your physician may consider acid reflux or a hiatal hernia, peptic ulcer disease, irritable bowel syndrome, pancreatitis, liver conditions, or medication effects. Certain medications, including some opioids, can themselves slow gallbladder emptying and affect scan results, so tell your care team everything you take.
Surgery may be a reasonable option when a patient has persistent, typical gallbladder-type symptoms, a reduced ejection fraction, and no other explanation after appropriate testing. The goal is to relieve symptoms, and the decision is shared between you and your surgeon. Watchful waiting, dietary changes, and addressing other conditions are legitimate approaches for patients with mild or infrequent symptoms.
When surgery is recommended, gallbladder removal is typically performed with minimally invasive laparoscopic techniques as an outpatient procedure. Many patients go home the same day. Published studies suggest that patients with typical symptoms and a low EF often improve after cholecystectomy, but outcomes are not guaranteed. Individual results vary.
When you meet with a surgeon in San Jose or Los Gatos, consider asking: What ejection fraction cutoff does this facility use? Did the scan recreate my pain? What else has been ruled out? What are the benefits and risks of surgery versus continued observation for my case? What can I expect during recovery? Our guide to gallbladder surgery recovery, diet, and timeline covers the weeks after surgery in detail.
Many facilities use about 35 to 40 percent or higher as normal, but the exact threshold depends on the protocol used. Your physician interprets the number alongside your symptoms.
No. A low value is one piece of information. Surgery is considered when symptoms are typical and persistent and other causes have been excluded. Individual results vary.
The test involves an IV placement and lying still under a camera. The radiation exposure is low. Some patients feel cramping when CCK is given, which can actually help reproduce symptoms for the evaluation. Allergic reactions to the tracer are rare.
Many patients find that smaller, lower-fat meals ease symptoms while they are being evaluated. Seek urgent care for severe pain, fever, yellowing of the skin or eyes, or persistent vomiting.
Dr. Richard Nguyen, DO, FACS, FACOS, is a board-certified general and bariatric surgeon serving San Jose and Los Gatos, California. Fellowship-trained in minimally invasive and bariatric surgery at Vanderbilt University, he has performed more than 15,000 procedures and is nationally recognized for non-mesh and advanced hernia repair. At Lifetime Surgical he combines advanced surgical technique with personalized, patient-centered care.
Wondering which surgical procedure might be right for your condition? We're here to help you understand your treatment options and develop a personalized surgical plan. Contact our office today to schedule a consultation.
Your path to improved health may be more achievable than you think—with advanced surgical techniques leading to faster recovery, reduced complications, and a significantly enhanced quality of life.
.avif)
