Hi , and thanks for reaching out with such a great question! While plenty of people do get diagnosed via a colonoscopy, there are other tests / procedures that are done to help determine and diagnose an inflammatory bowel disease like Crohn's. I'm sharing a link to an article with more information about how a diagnosis is made, https://inflammatoryboweldisease.net/diagnosis.
Crohn's itself can present anywhere in the digestive tract, so it's possible that a colonoscopy will not accurately determine whether or not someone has Crohn's (unlike Ulcerative Colitis which only presents in the colon). (Here's an article with some information on different types of Inflammatory Bowel Diseases, if you're interested, https://inflammatoryboweldisease.net/types-of-ibd)
That being said, I imagine it depends on your doctor (as well as your symptoms) as to what procedure or test they think would make sense. Are you wondering about a diagnosis for yourself or someone you know?
I hope this help answers your question, and please let us know if you have any other questions.
Wishing you a gentle day! -- Warmly, Christine (Team Member)