Info
🌱 來自: Huppert’s Notes
Other Conditions that Affect the Small Bowel🚧 施工中
Other Conditions that Affect the Small Bowel
Microscopic colitis
• Epidemiology: Age of diagnosis typically 45–65 yr; more common in females than males
• Etiology: Chronic inflammatory disease of the colon with two histologic subtypes: 1) Lymphocytic and 2) Collagenous colitis. Associated with autoimmune diseases, NSAIDs, tobacco use.
• Clinical features: Chronic, watery, non-bloody diarrhea.
• Diagnosis: Colonoscopy with biopsy showing lymphocytic or collagenous colitis. Workup should include ruling out infectious causes (check stool studies) and celiac sprue (check serologies).
• Treatment: 1) Stop NSAIDs (or other offending medications); 2) Loperamide for symptoms; 3) Budesonide for active disease. Second-line agents include cholestyramine, bismuth, and biologics if needed.
Irritable bowel syndrome (IBS)
• Pathophysiology: Idiopathic and multifactorial, sometimes considered a functional disorder. Associated with female sex, depression, anxiety, fibromyalgia.
• Clinical features: Subtypes are IBS-C (constipation), IBS-D (diarrhea), IBD with mixed bowel movements.
• Diagnosis:
- Exclude other organic etiologies through history and labs: Fecal calprotectin, stool studies, celiac disease studies.
- Colonoscopy is typically not needed, but should be considered for alarm features: Age >50 yr, GI bleeding, weight loss, progressive abdominal pain, lab abnormalities, family history of IBD, colon cancer.
- Rome IV criteria: Abdominal pain at least once per week for ≥3 months with ≥2 symptoms related to defecation, change in stool frequency, change in stool form.
• Treatment:
- For all subtypes: Education/reassurance, low FODMAP diet, dicyclomine for abdominal cramping, encapsulated peppermint oil
- IBS-D: Loperamide, cholestyramine, 5HT-3 antagonists, rifaximin, TCAs, SNRI
- IBS-C: Polyethylene glycol (MiraLAX), psyllium, prucalopride, plecanatide, lubiprostone, linaclotide, SSRI (not paroxetine), SNRI
- IBS-M: Fiber supplementation
Mesenteric ischemia
• Definition: Ischemia affecting the small intestine is generally referred to as mesenteric ischemia, while ischemia affecting the large intestine is referred to as colonic ischemia; mesenteric ischemia can be subdivided into acute and chronic subtypes.
Acute mesenteric ischemia
• Pathophysiology: Can be caused by arterial embolism (50%; e.g., Afib), arterial thrombosis (15–25%; e.g., atherosclerosis), venous thrombosis (5%; e.g., in setting of infection, hypercoagulability, malignancy), nonocclusive (20–30%; e.g., hypoperfusion, such as in hypotensive patient)
• Clinical features: Severe abdominal pain out of proportion to physical findings; anorexia, vomiting, mild GI bleed
• Diagnosis: CT angiogram
• Treatment: IV fluids, anticoagulation, broad-spectrum antibiotics. Arterial: Early surgical laparotomy with embolectomy. Venous: Anticoagulation. Nonocclusive: Treat underlying cause.
Chronic mesenteric ischemia
• Pathophysiology: Atherosclerosis can cause abdominal angina
• Clinical features: Dull pain that typically starts about one hour after eating; can cause food anxiety with subsequent weight loss
• Diagnosis: CT angiogram
• Treatment: Antiplatelet therapy, surgical revascularization
Carcinoid syndrome
• Pathophysiology: Neuroendocrine tumor that secretes serotonin
• Clinical features: 1) Flushing, 2) Diarrhea, 3) Wheezing, 4) Right-sided valvular heart disease (pathognomonic plaque-like deposits of fibrous tissue)
• Diagnosis: Increased urine 5-HIAA; imaging for tumor localization (e.g., CT, somatostatin receptor imaging) with EGD/colonoscopy if primary site remains undetermined
• Treatment: Surgical removal of the tumor. If not resectable, octreotide injection (long-acting release), telotristat, loperamide