What is chromoendoscopy (dye-spray) and why is it performed? 

Chromoendoscopy is the use of dyes during colonoscopy or gastroscopy to highlight abnormal areas in the bowel or stomach. Chromoendoscopy allows your doctor to examine the lining of the large bowel even more accurately than standard colonoscopy and in certain scenarios is the preferred method for performing colonoscopy. This is true for patients with long standing colitis or Crohn’s disease and patients with multiple polyps (polyposis syndromes), where chromoendoscopy has been shown to be more effective in detecting polyps and pre-cancer than standard colonoscopy. The short video below illustrates how chromoendoscopy can increase the likelihood of seeing flat polyps…

Chromoendoscopy VIDEO


What preparations are required? 

When performing chromoendoscopy in the colon, the colon has to be COMPLETELY cleared of stool. Some medications may need to be discontinued before colonoscopy. Specific details about how to prepare for colonoscopy can be found here.


What happens during colonoscopy with chromoendoscopy?  

Your doctor will first discuss the risks of the procedure with you and address any questions you may have. You will then meet your anaesthetist who will discuss all aspects of the anaesthetic. Following this you will be taken to the procedure room. You'll then lie on your side, and a needle will be placed in your hand or arm. This is used to administer the anaesthetic. Once you are completely asleep your doctor will pass the endoscope through your anus and into the rectum and also advance the colonoscope into the caecum or start of the large bowel. The procedure usually takes around 45-60 minutes. During the procedure special dyes are sprayed onto the surface of the colon using a purpose built spray catheter.


What happens after a colonoscopy with chromoendoscopy? 

You will be monitored until the anaesthetic has worn off. Your doctor will explain the results of the examination to you and will provide you with a written report of your procedure for your GP. You will be able to eat after you leave unless your doctor instructs you otherwise. Because of the anaesthetic, your judgement and reaction time will be impaired for the rest of the day. You will need someone to drive you home and stay with you. You may notice that your first bowel motions after a colonoscopy with dye-spray are blue coloured. This is normal and will settle down over the next few days.


What are the possible complications of colonoscopy with chromoendoscopy? 

Complications specific to chromoendoscopy are rare. Some patients with rare medical conditions have have adverse reactions o the dyes used during chromoendoscopy. Your Doctor will be able to advise you if chromoendoscopy is suitable for you.