Ulcerative colitis: 10 things you need to know

Ulcerative colitis (UC) is a chronic inflammatory disease affecting the lining of the colon and rectum, causing inflammation and ulcers. It can start at any age, but it is most common between 15 and 35 years old, with a second peak between 50 and 70.

At Clínica Eupnea, in Palamós, the digestology service diagnoses and treats ulcerative colitis with comprehensive follow-up including medical treatment, nutritional support, and, when needed, hospital referral for severe cases.

1. What is ulcerative colitis?

It is a chronic inflammatory bowel disease (IBD) exclusively affecting the colon and rectum. Inflammation is continuous, starts in the rectum, and extends proximally. It is limited to the mucosa (does not penetrate deeper layers) but can cause widespread ulcers.

2. Difference from Crohn's disease

• Ulcerative colitis: only colon and rectum; continuous superficial inflammation; common bloody stools
• Crohn's: any part of the GI tract (mouth to anus); 'patchy' transmural lesions; can cause fistulas and strictures

3. Main symptoms

• Bloody, mucous diarrhea (key symptom)
• Defecation urgency and tenesmus (sense of incomplete evacuation)
• Abdominal pain, especially in the left half
• Weight loss, fatigue, anemia
• Extraintestinal manifestations (10-30%): arthritis, erythema nodosum, spondylitis, uveitis, primary sclerosing cholangitis

4. Causes and risk factors

Origin is multifactorial: genetic predisposition + environmental factors (microbiota, diet, prior infections, tobacco with paradoxical protective effect) + abnormal immune response to microbiota components. Not contagious nor inherited in a Mendelian way.

5. Diagnosis

• Blood tests: CBC, CRP, fecal calprotectin (very useful marker)
• Stool cultures: rule out infections (Salmonella, Shigella, Campylobacter, C. difficile)
• Colonoscopy with ileoscopy and biopsies: reference test
• Imaging: ultrasound, MRI, CT in selected cases

6. Severity classification (Truelove-Witts)

• Mild: <4 stools/day, no systemic symptoms
• Moderate: 4-6 stools/day, moderate systemic symptoms
• Severe: >6 bloody stools/day, fever, tachycardia, anemia, elevated ESR

7. Medical treatment

• Aminosalicylates (mesalazine): first-line for mild-moderate UC, oral and/or topical (suppositories/enemas)
• Corticosteroids: for acute flares; time-limited use
• Immunomodulators: azathioprine, 6-mercaptopurine for maintenance
• Biologics: anti-TNF (infliximab, adalimumab), vedolizumab, ustekinumab — for moderate-severe UC
• JAK inhibitors (tofacitinib): newer option for refractory cases

8. When surgery is considered

Colectomy is considered in UC refractory to medical treatment, toxic megacolon, uncontrolled bleeding, perforation or dysplasia/cancer. Often with ileoanal anastomosis (J-pouch), allowing natural evacuations.

9. Diet and lifestyle

There is no single diet. During flares: low-residue, avoid lactose if intolerant. In remission: varied, balanced diet. Important factors: quit smoking (UC worsens with tobacco, opposite to Crohn's), stress management, regular exercise, and psychological support if needed.

10. Prognosis and complications

With proper treatment, most patients lead a normal life. Potential complications: chronic anemia, toxic megacolon (rare), increased colorectal cancer risk in extensive UC over 8-10 years (regular endoscopic screening).