Investigators’ Meeting 2023 – Rearranged!

Date: 18th May

Venue: Crowne Plaza Hotel, Holiday Street, Birmingham, B1 1HH

Great news! We are re-booked for the Sunflower Investigators Meeting 2023! We hope to see all of you in person at the meeting in Birmingham on 18th May.

This will be a great day to learn all about activity across the study sites in the UK. We will be hearing updates from the Study Chief Investigator, the coordination team and a selection of site staff. There will be chance to network and share best practice and renew our efforts to make the study a success!

Get in touch on sunflower-study@bristol.ac.uk if you or any of your site team want to join us.


A randomised controlled trial to establish the clinical and cost effectiveness of expectant management versus pre-operative imaging with magnetic resonance cholangio-pancreaticogram (MRCP) in patients with symptomatic gallstones undergoing laparoscopic cholecystectomy at low or moderate risk of common bile duct stones: The Sunflower Study

In response to COVID-19, the study team are currently combining working from home and our office in Bristol. If you have any questions about the study, please email sunflower-study@bristol.ac.uk or call the study mobile on 07929 771395 (Monday-Friday: Office Hours). We continue to keep in touch with study participants. The UK government website provides up to date information on COVID-19.

What is the Sunflower study?

The Sunflower Study is what’s called a Randomised Controlled Trial, or RCT. It is investigating whether routinely testing all patients for common bile duct stones before gallbladder removal surgery is beneficial or not.

Why is this study being done, and why is it important to the NHS?

Gallbladder removal surgery (laparoscopic cholecystectomy) is one of the most common operations undertaken in the Western World, with around 70,000 operations performed annually in England. Patients require gallbladder removal when gallbladder stones are found using an ultrasound scan. Occasionally (in an estimated 2-5 in every hundred or 2-5% of patients), gallbladder stones may move in to the common bile duct, where they may remain without symptoms, cause problems or move spontaneously in to the stomach.  As such, when patients are checked for gallbladder stones, the common bile duct is also checked using an ultrasound scan.

If patients are found to be at a high risk of common bile duct stones, it is standard practice for patients to have further investigation using a type of scan called a magnetic resonance cholangiopancreatogram (MRCP). If common bile duct stones are identified during the MRCP scan, the stones are usually removed using a telescope procedure called an endoscopic retrograde cholangio-pancreatography (ERCP). However, for patients at low/medium risk of common bile duct stones (around 80 in every hundred, or 80% of patients), it is unclear whether further investigation with an MRCP is beneficial – fewer than 10 in every hundred (less than 10%) of these patients will have common bile duct stones.

The below summarises the possible advantages and disadvantages of testing and not testing for common bile duct stones before gallbladder removal surgery.

Testing for bile duct stones

Possible advantages

  • May detect and, if needed, treat bile duct stones that may become a problem.

Possible disadvantages

  • For approximately 5-10 in every hundred patients (5-10%), the scan may not detect bile duct stones even though they are there because they are too small to be seen. This means that some patients may have bile duct stones left behind after their gallbladder surgery, which could cause problems (e.g. jaundice, infection or pancreatitis) that require further treatment or readmission to hospital.
  • Bile duct stones often pass safely and spontaneously into the bowel meaning the scan and procedure to remove them will have been unnecessary.
  • Some patients may experience claustrophobia (fear of enclosed spaces) during the scan.
  • For some patients, the scan and the endoscope procedure (if required) may mean waiting longer for your gallbladder surgery, which may lead to problems with gallstones while waiting. The surgery will not always be delayed.

Not testing for bile duct stones

Possible advantages

  • Allows gallbladder surgery to go ahead without the possible disadvantages of testing for bile duct stones.

Possible disadvantages

  • Any bile duct stones that are present are not detected.
  • Undetected bile duct stones may cause problems after your gallbladder surgery (e.g. jaundice, infection, pancreatitis) and require further treatment or readmission to hospital. We estimate this to happen to approximately 2-5 patients in every hundred (2-5%).
  • If bile duct stones are suspected later, a scan and, if required, an endoscope procedure will likely be needed to remove them.

Risks of the endoscope procedure to remove bile duct stones

The following can occur: pancreatitis (approximately 3-4 patients in every hundred or 3-4%), bleeding (approximately 1 patient in every hundred or 1%), bowel perforation (a small hole in the bowel) (approximately 1 patient in every hundred or 1%) or infection.

Occasionally, the endoscope procedure may show a bile duct that is clear of stones, suggesting the stones have spontaneously passed into the bowel since having the scan and meaning the procedure to remove them was unnecessary.

Some patients may not have an endoscope procedure but will have a slightly different procedure or small operation instead. If this is the case for you, this will be explained.


What is the aim of the study?

We are undertaking a large research study to compare the proportion of patients at low/medium risk of common bile duct stones experiencing a gallstone related complication following their gallbladder removal surgery (laparoscopic cholecystectomy), whether they had imaging of their common bile duct with MRCP before surgery or did not. The Sunflower Study will provide evidence to inform policy and individual patient decision-making, will yield real benefits to future gallbladder removal surgery patients in the UK and throughout the world, and provide the NHS with information relating to the cost-effectiveness of these two different options.


Who can get involved in the Sunflower study?

The study is being carried out at hospitals in England, Wales, Scotland and Northern Ireland. The study is open to hospitals which undertake laparoscopic cholecystectomies. We aim to run this study in 50 hospitals.

If you are a SURGEON or RADIOLOGIST or SURGICAL TRAINEE interested in your hospital participating in The Sunflower Study, please click here for further information.

Patients who have gallstones and have been referred for a gallbladder removal (laparoscopic cholecystectomy) operation may be eligible to participate in The Sunflower Study. You will need to discuss with your surgeon whether your hospital is taking part in this study, and whether you may be a suitable participant.

If you are a patient interested in The Sunflower Study, please click here for further information.

Funding: This study is funded by the National Institute for Health Research (NIHR) Health Technology Assessment Programme (project number 16/142/04). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR HTA or the Department of Health. The study protocol is published on the NIHR website.

SUNFLOWER Protocol v6.0

Study Registration: This study is registered on the NHS Portfolio and ISRCTN.

Ethics Committee Approval: This study was approved by the Yorkshire & The Humber – South Yorkshire Research Ethics Committee.


Contact details

The Sunflower Study team can be contacted by email to sunflower-study@bristol.ac.uk, or by calling 07929 771395.

To access the patient database, please click the below link:


If you need help registering to the database, a short video can be found below:

 – How to Register to the Study Management System (1 minute)


Some descriptionSome descriptionSome description