Crohn’s and ulcerative colitis are both inflammatory conditions involving the digestive system. While UC causes inflammation only in the lining of the colon (the large intestine), Crohn’s disease commonly affects the small intestine and the large intestine, and can occur anywhere from the mouth to the anal canal. Both diseases often present with diarrhea, abdominal pain, and rectal bleeding, and can cause severe weight loss in kids.
Blood and stool laboratory testsColonoscopyCT scan or MRI of the abdomen
Not every patient needs every test, however. Both UC and Crohn’s also tend to develop in teenagers and young adults, and affect men and women equally, according to UCLA Center for Inflammatory Bowel Disease. Despite these similarities, there are a few key differences that allow doctors to differentiate the two diseases. Telltale symptoms of ulcerative colitis are blood in the stool with mucus, frequent diarrhea, loss of appetite, and tenesmus, or a strong urge to use the bathroom without necessarily having a bowel movement. Crohn’s can present the same way, but it may also be marked by nausea, weight loss, and bloating, with minimal, if any, rectal bleeding and diarrhea. Both diseases may also cause inflammation of the eyes, joints, and skin. While it is usually obvious to a gastroenterologist if a person has Crohn’s disease or ulcerative colitis, there are some cases where it is not totally clear which one is causing the inflammation. This is called indeterminate colitis and may affect around 10 percent of people with IBD, according to UCLA.
2. Where Inflammation Occurs
Both illnesses are caused by inflammation in the GI tract, but where the inflammation occurs can lead a doctor to the correct diagnosis. “The most basic difference is that Crohn’s disease can involve the entire GI tract, from the mouth all the way down to the anus, whereas ulcerative colitis is restricted to the colon,” says Louis Cohen, MD, an assistant professor of gastroenterology at Icahn School of Medicine at Mount Sinai in New York City. According to the UCLA Center for Inflammatory Bowel Disease, Crohn’s disease usually results in healthy stretches of the intestine between inflamed areas. People who suffer from colitis experience continuous inflammation that starts at the lower part of their colon.
3. Diagnostic Tests
Doctors may inspect a stool sample for signs of mucus or blood, which could indicate UC. Stool samples can also help doctors rule out other issues, like pathogens or bacteria. The gold standard for diagnosing IBD is colonoscopy, in which a small camera attached to a thin tube is inserted into the colon, allowing a doctor to see the entire colon and take biopsies. If the doctor sees that the inflammation starts at the rectum and moves continuously up the colon and then stops, this could be a sign of ulcerative colitis. In Crohn’s, inflammation can occur anywhere in the digestive tract, and there are typically patches of healthy tissue interspersed with patches of inflamed tissue. Crohn’s sometimes creates clusters of immune cells called granulomas, whereas ulcerative colitis does not. Granulomas are the result of your body’s attempt to get rid of foreign material, and the cells are visible under a microscope, according to a research article published in StatPearls in September 2022. If the doctor suspects that the small intestine is involved in Crohn’s, she or he can use an imaging test, including a magnetic resonance imaging (MRI) or CT scan, to get a better look. If part of the upper GI tract, such as the stomach, is involved, your doctor may perform an upper endoscopy to determine where the inflammation is. Today, many IBD patients take a class of drugs called biologics, which are live antibodies that help immune cells fight inflammation. Other classes of drugs include immunomodulators, which help tamp down the immune system’s inflammatory response, and aminosalicylates, the oldest class of drugs, which are used to keep the disease in remission. A newer type of drug, called Janus kinase inhibitors, or JAK inhibitors, are small molecule compounds that are absorbed into the bloodstream and can block multiple pathways of inflammation. “JAK inhibitors are being used most frequently in patients with moderate to severe disease that have failed other therapies,” Dr. Cohen says. “There is an active area of research considering the potential use of JAK inhibitors as first line therapies, especially in patients with more severe disease due to their rapid onset of action.” Diet is another important factor in flare-ups of both diseases. While everybody is different, high-fiber vegetables like broccoli and cauliflower, uncooked produce, and unpeeled fruit are typically foods that people with IBD have difficulty digesting. Dairy and fatty or greasy foods can also trigger symptoms in some people. Work with a dietitian to determine which foods you can safely eat and which you should avoid.
When Surgery Is Needed
If medication isn’t reducing the inflammation and IBD progresses, surgery may be needed. This is where people with ulcerative colitis tend to fare better. “If the colon gets bad enough in ulcerative colitis, it’s removed and replaced with an internal pouch, which functions like a colon,” says Cohen. According to the Mayo Clinic, colectomy surgery usually requires additional procedures that reconnect the remaining portions of the digestive system so they can still rid the body of waste. But that option is becoming less common. A study published in December 2019 in the Journal of Gastrointestinal Surgery found that due to advances in medicine and medical care for IBD patients over the past decade, the number of hospitalized patients with ulcerative colitis who require a colectomy decreased by nearly 50 percent between 2007 and 2016. According to the Crohn’s and Colitis Foundation, proctocolectomy with ileal pouch–anal anastomosis — usually called J-pouch surgery — is the most common surgery performed on people with UC who have not responded to medication. Surgeons remove the rectum and colon and then create a temporary opening in the abdomen, called a loop ileostomy, which allows waste to move from the small intestine into an ostomy bag that sits outside the body while the digestive system heals from the surgery. In some cases a stoma, or permanent opening in the abdomen that funnels waste into an external bag, is required, notes Mayo Clinic. Since Crohn’s can occur anywhere in the digestive tract, simply removing the colon won’t cure the disease. According to the Crohn’s and Colitis Foundation, up to 75 percent of people with Crohn’s disease will eventually require some kind of surgery. Typically in people with Crohn’s, smaller pieces of the colon will be removed to try and preserve as much of the healthy intestines as possible. This requires more frequent surgeries. In severe cases, Crohn’s creates holes in the bowel, causing a fistula, or a tunnel that leads from one section of the bowel to another. Fistulas are serious and need to be repaired. About one-half of Crohn’s patients will require surgery within 10 years of diagnosis, according to a research analysis published in December 2017 in the American Journal of Gastroenterology, while about 30 percent of adults with ulcerative colitis will need surgery at some point in their lives, Cleveland Clinic reports. “More recent data reflecting therapies introduced in the last 10 years suggest rates potentially decreasing to 10 percent in UC and 30 percent for CD (for intestinal resections),” Cohen notes, “but we will need more data over time to understand fully how medications introduced in the last five years impact these rates even further.” Additional reporting by Ashley Welch.
