COLITA ISCHEMICA Flashcards
What is ischemic colitis?
inflammation of the large intestines leading to injury and ischemia
eldery
What are the general categories of causes for reduced blood flow in ischemic colitis?
Changes in the systemic circulation (e.g., low blood pressure).
Local factors (e.g., constriction of blood vessels or a blood clot).
What is the most common form of bowel ischemia?
Ischemic colitis.
What is the most common mechanism leading to ischemic colitis?
non-occlusive low flow state in microvessels, which occurs in the setting of hypovolemia or hypotension.
most vulnerable arteries?
inferior and superior mesenteric arteries
By how much does blood flow to the colon need to drop for ischemia to develop?
More than about 50%
very sensitive arteries
What happens to the arteries feeding the colon during periods of low blood pressure?
They clamp down vigorously.
What types of drugs can cause vasoconstriction in the colon?
Ergotamine, cocaine, or vasopressors.
What are the most exposed areas of the colon in ischemic colitis?
The junction between the descending and sigmoid colon, and the splenic flexure.
What are the two main mechanisms that can lead to ischemia in the colon?
Decrease in arterial flow and venous stasis.
In what contexts can colon hypoperfusion occur, leading to ischemic colitis?
Coronary bypass surgery.
Aortic valve surgery.
Prolonged physical exertion (e.g., long-distance runners).
Any cardiovascular event accompanied by hypotension.
What are identified risk factors for ischemic colitis related to medication and conditions?
Oral contraceptives.
Drugs (e.g., cocaine).
Vasculitis.
Hypercoagulability states.
Other causes include
➢ embolic disease
➢ vasculitis, fibromuscular hyperplasia
➢ aortic aneurysm
➢ blunt abdominal trauma
➢ disseminated intravascular coagulation
➢ irradiation
➢ hypovolemic or endotoxic shock.
What are the common presenting symptoms of ischemic colitis?
Sudden colic abdominal pain (mild/moderate, left lower quadrant).
Urgent defecation.
Rectal bleeding (diarrheal stools with blood, occasionally melena).
What are the common findings on clinical examination in ischemic colitis?
Sometimes slight tenderness in the affected colonic segment.
Abdominal flatulence with present bowel sounds.
No signs of peritoneal irritation.
What are the rare, but serious, signs that indicate gangrenous intestine, perforation, or transmural necrosis in ischemic colitis?
Hypovolemia and peritonitis.
What are the two major clinical patterns of ischemic colitis?
Gangrenous (15-20% of cases)
Non-gangrenous (80-85% of cases)
What are the potential outcomes of non-gangrenous ischemic colitis?
Transient and reversible lesions.
Chronic and irreversible strictures (10-15%).
Chronic segmental colitis (20-25%).
What factors determine the pattern of clinical presentation in ischemic colitis?
Cause.
Extent of vascular obstruction.
Speed of ischemic insult.
Degree of collateralization.
Comorbid conditions.
What associated colonic pathology may be present in patients with ischemic colitis?
Up to 20% of patients may have associated colonic pathology such as cancer.
DIAGNOSIS
OF
COLONIC ISCHEMIA
▪ CT SCAN
▪ COLONOSCOPY along with histopathologic biopsy is the current
standard modality for diagnosis.
▪ ANGIOGRAPHY is rarely helpful
Angiography has a limited role in cases of colonic ischemia, but it may be
invaluable in a few specific indications, such as arteriovenous fistulas
What is a limitation of ultrasonography (US) in diagnosing ischemic colitis?
Pneumatosis, a poor prognostic indicator, is difficult to identify on US.
What is a strength of ultrasonography (US) in diagnosing ischemic colitis?
US is sensitive to early structural changes in the colon walls caused by ischemia
When can ultrasonography (US) be considered as an alternative to colonoscopy?
In patients who are high risk or have contraindications to colonoscopy.
What type of CT scan is used to diagnose ischemic colitis?
oral and IV contrast.
Why is a CT scan considered the best test after plain radiography for diagnosing ischemic colitis?
It can exclude many other causes of abdominal pain.
It can establish the diagnosis of intestinal ischemia.
What are the manifestations of ischemic colitis on a CT scan?
Colonic wall thickening.
Edema.
Thumbprinting.
Bowel dilatation.
Effusion of intestinal circumference.
When is multiphasic CT angiography (CTA) recommended?
For patients with suspected acute mesenteric ischemia or isolated right-sided ischemia.
Which form of ischemic colitis is most frequently encountered?
The non-gangrenous form (relative frequency is 80-85%).
Where do anatomopathological changes begin in ischemic colitis?
At the level of the mucosa, the area furthest from the recta vassa
What is the typical evolution of ischemic colitis?
Most often self-limiting.
