Depends. I was diagnosed with perianal Crohn's first. That one is more obvious because there's physical and visually apparent symptoms. I went to the Colorectal Surgeon, she took a look and just told me that it's obviously perianal Crohn's, no doubt about it. I mean, I had a perianal abscess that was drained and then a fistula developed... I had hemorrhoids, fissures, skin tags, proctitis, pruritus... so, it was just visually apparent.
The other doctors that I went to (including a gastro) all told me that they thought I just had IBS. I mean, my symptoms were very mild and were mostly perianal related. The only real symptom of Crohn's that I had was constant diarrhea (I mean, like, 10-30 times a day). It was so bad that I couldn't sleep at night because I would wake up every hour to run to the bathroom. But because I had no pain and no bleeding, they just kept telling me it was IBS.
It wasn't until I went to the ER due to discomfort in my bladder and in my lower back, did I finally get told like "Yeah, this is 100% Crohn's." I had like flu symptoms, I felt so bad.... one minute chills next minute sweating, I was so weak that I would nearly faint every time I stood up, I just felt absolutely miserable. After a couple of days of those flu-like symptoms and the bladder discomfort increasing, I went to urgent care (I assumed it was just a UTI and I needed antibiotics). Urgent Care said yeah probably a UTI and they gave me Cipro. I took it for 2 days and symptoms were worsening. Went back to Urgent Care, they told me go to the hospital because they thought it was appendicitis (which is crazy because I didn't even have pain, I kept telling them it was just a discomfort, I specifically said it felt like something was pressing on my bladder).
Long story short, I went to the hospital and they checked for a UTI, negative. They did a transvaginal ultrasound to see if it might be caused by ovarian or uterine cysts, negative. Then they did a CT Scan and lo and behold... so many things came up and my radiology report literally says Crohn's, like, they told me the characteristics were so clear that it's definitely Crohn's. And basically the reason why I felt the bladder discomfort was because my bowels were pressing on my bladder.