Localization and pattern of inflammation spread
The fundamental rule of ulcerative colitis is that the lesion is strictly confined to the colon. Unlike other inflammatory bowel diseases, the process here is never discontinuous or "skip" in nature.
Inflammation always spreads continuously, moving in the proximal direction (ascending pattern of involvement), starting from the rectum and moving up the colon.
An important nuance for understanding the anatomy of the lesion: involvement of the terminal ileum (so-called backwash ileitis) is exclusively secondary in nature. The small intestine is affected only if a severe inflammatory process directly extends to it from the ileocecal valve. Primary independent foci in the ileum are atypical for this disease.
Acute (active) phase: endoscopic picture
During an exacerbation, the endoscopic and macroscopic picture looks maximally aggressive. The endoscopist visualizes the following classic signs of active inflammation:
- Mucosal changes: The mucous membrane becomes markedly edematous. Due to pronounced edema, the normal vascular pattern completely disappears. Pronounced contact bleeding is characteristic — the tissue begins to bleed at the slightest touch of the scope.
- Alteration of relief: There is a smoothing of the physiological sphincters and haustra of the colon.
- Formation of defects: Extensive damage forms in the lumen. Initially occurring erosions and ulcers rapidly coalesce with one another. The base of such confluent defects is densely covered with a fibrinosuppurative exudate and blood.
- Formation of pseudopolyps: These are not true tumors, but areas of fortuitously preserved mucosa located between deep confluent ulcers. Under the influence of inflammation, these tissue islands undergo marked inflammatory hypertrophy and rise above the level of the ulcerated base, creating a visual picture of polyposis.
Healing phase (remission) and bowel remodeling
When active inflammation subsides and the disease enters the healing phase (remission), the large intestine does not return to its original, healthy state. The main macroscopic result of a severe exacerbation is the loss of the normal anatomical structure of the bowel.
Endoscopically and radiologically, this is manifested by the formation of the classic "garden hose" sign. Due to the preceding inflammation and structural remodeling, the bowel becomes absolutely rigid, devoid of normal physiological haustrations. Visually, its walls flatten and thicken, and the lumen truly begins to resemble a smooth, rigid pipe.
To memorize the acute phase presentation, use the rule "C-B-U-P": Vascular pattern (absent) — Bleeding (contact) — Ulcers (confluent with fibrin) — Pseudopolyps.
Class and exam questions
Can the small intestine be affected in ulcerative colitis?
Yes, but only its very final segment (the terminal ileum). This occurs exclusively secondarily, when inflammation "creeps" onto it through the ileocecal valve from the colon.
What are pseudopolyps and why are they called that?
Pseudopolyps are islands of initially normal mucosa that remained between extensive ulcers. Against the background of surrounding inflammation, they hypertrophy and rise above the ulcers, outwardly resembling true polyps, although in essence they are simply inflamed tissue.
Why does the "garden hose" sign occur in the remission phase?
The sign forms due to the loss of the bowel's normal anatomical structure. Physiological haustra are smoothed out, the wall loses its elasticity and becomes rigid, acquiring the appearance of a smooth, straight pipe.
How does the mucosal vascular pattern change during an exacerbation?
In the acute (active) phase, the normal vascular pattern is completely absent due to marked and massive mucosal edema.
What else to study on this topic
- Clinical presentation and symptoms of various forms of the disease
- Microscopic (histological) picture of mucosal biopsies
- Etiology and pathogenesis of the inflammatory process development
- Systemic (extraintestinal) manifestations of ulcerative colitis
- Principles of conservative and surgical treatment
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