Perianal fistulizing Crohn’s disease (PCD) is a complication of Crohn’s that affects up to 40% of Crohn’s patients. Fistulas form when abnormal connections form between the intestine and surrounding tissue.  Specifically, in the presence of inflammation, ulcers extend through the entire intestinal wall, creating a tunnel that drains pus away from the inflamed area. Fistulas may occur anywhere along the GI tract and are very painful and difficult to treat.

In good news for patients, a 2025 study published in The Journal of Clinical Investigation identifies new factors that contribute to fistulas. Examining samples of patients with PCD, researchers found that a specific immune signal--interferon gamma (IFN-γ)—was highly active in patients with PCD. This over-activation was linked to inflammation and changes in tissue that allow fistulas to form and persist.

The study also identified high numbers of a type of white blood cell, Th17 immune cells, which help protect the body from infections. In PCD, however, these cells produced large amounts of IFN-γ, fueling inflammation and tissue damage. Together with other immune cells, they created a cycle that drives fistula formation.  Combined, these new findings may pave the way for more effective treatments of fistulas and much needed relief for patients.

References

​Crohn’s & Colitis Foundation

Revealing hyperactivated IFN-γ pathways in perianal fistulizing Crohn’s disease using single-cell and spatial multi-omics, J Clin Invest. 2025; 135(17):e193413.

1.  Fasting: Some MRIs require you to fast (stop eating and drinking) the night before.  We recommend eating a healthy, filling dinner the night before and drinking plenty of water.  It helps if your MRI is scheduled first thing in the morning and luckily most centers give priority to kids for these early time slots so you won't be hungry too long.  Its also helpful to ask your family not to eat in front of you while you are fasting!

2. Leave Your Metal At Home:  MRIs have big magnets that will attract certain metal objects.  To be safe, remove all the metal from your body and leave it at home.  This includes jewelry, watches, and any removable dental appliances.  If your parents are coming into the MRI with you, they need to do the same.  Mom won't be happy about leaving her engagement ring in a hospital locker, so its best everything precious stay at home. Once at the MRI offices you and your parents will also be asked lots of questions about your medical history and any possible metal inside your body (orthodonture, orthopedic pins, staples, hearing aids, pacemakers, etc.)  As a final check you may also be screened by a metal detector to ensure nothing has been missed.

3.  Funny Pajamas:  Once you get to the MRI offices a nurse or assistant will probably ask you to put on some funny pajamas and socks.  If the offices are cold you may also want to ask for a blanket.  

4.  Drinking the Mix: To prepare for the MRI you may be asked to drink a mix of Miralax and Gatorade.  It doesn't taste great, but its not that bad either.  Its kind of hard to drink it all in the short time they give you and it may make you feel yucky.  It was easier to get down if we timed a few sips every minute.  

5. Lying Down on the Table: Usually, your mom and dad can stay in the room with you, so even if you can't seem them while you're lying down, you can still talk to them and know they are close by.  The nurse and/or technician will help you get on the table and show you the best position to lie in.  They may also put straps on your legs or waist to help you lie still.  After you are in the right position the nurse or technician will leave the room you're in and watch you from a special room with a window so they can see you. They will also be able to talk to you through a speaker  telling you when its ok to move and when its important to stay still. 

6. Plugging Your Ears:  The most surprising thing about an MRI is how LOUD it is.  It doesn't hurt at all, but it does make a whirring, chop chop chop sound a lot like a helicopter and sometimes like a fire alarm.  The noises can be so loud that the nurse will likely give you either earplugs or headphones.  The only problem with these is that it makes it hard to hear what other people are saying, but you get used to it. 

7: Getting the IV: During the MRI you may get a contrasting dye injected through your veins.  The dye helps the doctor see everything inside more clearly.  To prepare for this, the nurse may insert the tube in your arm ahead of time while you are waiting.  The nurse might rub a numbing cream on your arm so the needle prick doesn't hurt, but even if s/he doesn't it only pricks for a second and then she takes the needle out.  A little tube stays in your arm but it gets taped down and doesn't hurt.   In some people, the injection of the dye makes them feel sick to their stomach.  The feeling is intense and awful, but it usually passes quickly -- within 2-3 minutes.  The nurse gave me a plastic bowl in case I needed to throw up, but I ended up not needing it.

8.  Settling In:  The MRI can take a really long time.  Ours usually lasted 45-60 minutes.  I even fell asleep once! Its important to stay still when the machine is taking pictures so that you don't have to do them again. But if you do have to take some pictures again, its no big deal, it just takes a little longer.

9. When Its Over: Congratulations! When its over you will be relieved and also probably a little surprised that it wasn't as big a deal as you thought it would be.  You might even get a prize at the end for your bravery.  We got a stuffed animal and we got to keep our funny socks.  Now we wear the socks as a weird memento of our not-such-a-big-deal-MRIs. 

When I look at pictures of our son at the beach  last summer it is startling.  How could I look at those protruding ribs and thin limbs and not realize our son had Crohn's Disease?  Unfortunately, at the time I didn't even know what Crohn's Disease was.   Although I was always vaguely worried that Ben didn't eat enough or get enough sun, when I saw him without his shirt at the beach I was taken aback.   But somehow, I managed to talk myself out of my concerns, remembering old photos of his Dad -- who was also very thin as a boy but filled out as a teenager.  The paleness was easily explained in my mind too.  Ben didn't  play outside much -- like many boys his age he mostly preferred computer games.   

In addition to not knowing about Crohn's Disease, what we also didn't yet know that Ben was having severe diarrhea.  He was shy about telling us and didn't clue us in until the start of the school year.  We figured he was nervous about starting school and chalked up his symptoms to irritable bowel syndrome (IBS), an anxiety-driven condition that is pretty common in our family.  We tried not to pressure him to eat too much and let him pick many of our menus but when dinner after dinner was merely picked at, mealtimes became tense.  We wondered if he was having some trouble at school he wasn't telling us about or whether he might have an anxiety disorder.  We knew SOMETHING was wrong, but we didn't know what.  

At the same time, our daughter Isabelle was also complaining of stomach pains almost every morning.  She was admittedly excited and nervous about the start of school, so I attributed the complaints to nerves and didn't give it much thought at all.  Occasionally I would give her a TUMS, even if I didn't believe she had a "real" stomachache  I figured they were a good source of calcium.  She also intermittently complained about sores in her mouth.  In my experience, too much sugar, nuts, or citrus will give me mouth sores, so I assumed it was the same for her and tried to cut back on the sugary drinks she loved so much (e.g. chocolate milk at lunch, fruit juice box for snacks).  When the sores got particularly bad so that it hurt to eat, I took Isabelle to a walk-in clinic where the nurse practitioner diagnosed "hoof and mouth disease."  

If I knew then what I know now, its obvious none of this was normal and both kids were in early stages of Crohn's Disease.  They say hindsight is 20/20, so with my 20/20 hindsight I'll share the symptoms that our kids had that we ultimately learned are signs of Crohn's Disease:

• Frequent diarrhea and/or constipation
• Rectal bleeding
• Abdominal cramps and pain
• Loss of appetite
• Weight loss
• Weakness in the limbs and joints
• Fatigue
• Anemia
• Mouth sores/ulcerations in the digestive tract
• Skin rashes

Although every person is different, if any of these symptoms persist in your child, ask your pediatrician about testing for IBD.   When you know something is wrong, trust your instincts and ask specific questions about what could be causing your child's symptoms.  In most cases it will be a passing virus or food sensitivity but if its more, the sooner you get the right treatment the better.  

See also At 12, he had stopped growing. The reason was a surprise, Washington Post, Feb. 6, 2017.

To read more about the signs and symptoms of the disease we recommend the Crohn's and Colitis Foundation of America website, ccfa.org.