Ischemic colitis: causes and pathogenesis
The disease develops as a result of impaired normal blood supply to the large intestine. The main factors are circulatory disorders, such as atherosclerotic lesions of the mesenteric arteries (vascular occlusion), arterial hypotension, and venous stasis. An additional risk factor is hypercoagulation occurring against the background of malignant tumor growth or oral contraceptive use.
The pathogenesis is based on the formation of segmental ischemia of the intestinal wall. In severe cases, the process leads to extremely dangerous manifestations—arterial or venous intestinal infarction and the development of gangrene.
Morphological picture of chronic ischemia
With chronic blood flow disruption in the large intestine, the following changes develop:
- Necrosis of the superficial layers of the mucous membrane.
- Formation of acute erosions capable of repair.
- Focal accumulation of hemosiderosis in the lamina propria of the mucosa.
- Spread of the inflammatory process to the deep layers of the wall with granulation tissue formation, resulting in fibrosis and the formation of constrictions — strictures.
Microscopic examination demonstrates a characteristic feature: the epithelium is completely preserved only in the deep parts of the crypts, accompanied by marked submucosal edema.
Pseudomembranous colitis
This pathology is an infectious enterocolitis etiologically associated with the activity of the microorganism Clostridium difficile.
The pathomorphological picture is characterized by the development of fibrinous inflammation in the large intestine wall. In areas of mucosal necrosis, superficial plaques called pseudomembranes are formed. Histological examination reveals an important diagnostic sign: viable epithelium is preserved exclusively at the very base of the crypts.
Briefly: answers to topical questions
What are the macroscopic changes in the intestinal wall in acute infarction resulting from ischemia?
In acute intestinal infarction resulting from ischemia, wet gangrene develops. The macroscopic changes in the intestinal wall are characterized by the following features:
- Tissue swelling — the wall becomes edematous.
- Foul odor — occurs due to the action of putrefactive microorganisms.
- Absence of a demarcation line — the boundary of the lesion is undefined.
Which zones of the large intestine are most frequently affected in ischemic colitis?
In ischemic colitis, the splenic flexure of the colon is most frequently affected. Depending on hemodynamic conditions, the following typical involvement zones are distinguished:
- Splenic flexure (splenic flexure) — serves as a watershed zone of blood supply and is most frequently affected.
- Left hemicolon — the disease as a whole is characterized by predominantly left-sided involvement.
- Right hemicolon — more frequently involved in the pathological process during low-flow states (low-flow states).
Class and exam questions
What are the main causes leading to the development of ischemic colitis?
Key causes include circulatory disorders (atherosclerosis of the mesenteric arteries, hypotension, venous stasis) and hypercoagulable states associated with tumors or oral contraceptive use.
What is the main morphological outcome of chronic intestinal ischemia?
Chronic ischemia leads to the spread of inflammation to the deep layers of the wall, proliferation of granulation tissue, and progression to fibrosis with subsequent stricture formation.
What is the causative agent of pseudomembranous colitis and what is its morphology?
The disease is caused by Clostridium difficile. Morphologically, it manifests as fibrinous inflammation and the formation of superficial plaques (pseudomembranes) in areas of necrosis.
What else to study on this topic
- Anatomic features of large intestine involvement in vascular occlusion
- Differential diagnosis of erosions and ulcers in ischemic injury
- Mechanisms of fibrinous deposit formation in infectious colitis
- Pathogenetic connection between hypercoagulation and mesenteric vessel thrombosis
- Morphological changes in colonic diverticulosis
Master the entire topic in the "Pathological Anatomy" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Ischemic and pseudomembranous colitis" and 4,414 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 153 video lessons on the subject
Other topics in the «Digestive System Diseases» section
Free video lessons: pathological anatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.