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Snapshot
  • A 73-year-old woman presents with severe abdominal pain and a recent history of passing bloody stools. The pain began about 3 days ago and is more concentrated at the left side of the abdomen. Physical examination shows decreased-to-absent bowel sounds, abdominal distention, and diffuse tenderness to palpation over her abdomen. A barium-enema study is performed which shows "thumb-printing" of the colon. 
Introduction
  • Clinical definition
    • medical condition characterized by inadequate blood supply to the large intestine leading to inflammation and injury of the colon
  • Epidemiology
    • demographics
      • more common in the elderly population
      • most common form of bowel ischemia
    • risk factors 
      • aortoiliac surgery/instrumentation
      • myocardial infarction
      • hemodialysis
      • hypercoagulable states (e.g., hereditary thrombophilia)
  • Pathogenesis
    • ischemic colitis is the result of blood flow reduction to the colon and is particularly prominent at the “watershed” areas of the colon where collateral blood flow is limited
      • the splenic flexure and rectosigmoid junction are particularly at risk for ischemia 
    • nonocclusive colonic ischemia
      • accounts for the mass majority of cases (95%)
      • typically transient hypoperfusion
      • examples include shock, systemic hypotension or atherosclerosis of SMA  
    • occlusive colonic ischemia
      • can be embolic (e.g., spontaneous or iatrogenic) or thrombotic secondary to atherosclerotic disease
    • mesenteric vein thrombosis
      • extremely rare and usually involves the small intestine
Presentation
  • Symptoms 
    • mild cramping abdominal pain commonly involving the left side  
      • less severe compared to mesenteric ischemia
    • hematochezia
      • usually follows within 24 hours after abdominal pain
    • diarrhea
    • vomiting
  • Physical exam
    • fever
    • abdominal tenderness
    • weight loss
Imaging
  • Abdominal radiograph
    • usually normal but may be useful in excluding other causes of abdominal pain
    • may also identify complications of mesenteric ischemia (e.g., necrosis)
  • Computed tomography (CT) without oral contrast
    • best initial test  
    • may see bowel wall thickening in a segmental pattern (thumbprinting), bowel dilation, mesenteric stranding, or intestinal pneumatosis 
  • Endoscopic evaluation
    • can be done via colonoscopy for flexible sigmoidoscopy
    • allows for biopsy of suspicious areas
    • positive findings include edematous, friable mucosa, erythema, and interspersed pale areas 
Studies
  • Laboratory studies
    • leukocytosis
    • elevated lactate
    • metabolic acidosis
Differential
  • Mesenteric ischemia 
    • differentiating factors
      • commonly presents with severe abdominal pain and does not accompany hematochezia
  • Colonic malignancy 
    • differentiating factors
      • will appear differently on endoscopy and abdominal CT
Treatment 
  • Management approach
    • treatment is dependent on its etiology, severity, and the clinical setting  
  • Mild colonic ischemia
    • supportive care
      • bowel rest and observation
      • nasogastric tube if ileus is present
      • monitor for persistent fever, leukocytosis, peritonitis, or other signs of clinical deterioration
    • most patients will recover within days
  • Moderate colonic ischemia
    • antibiotics
    • antithrombotic therapy
      • indicated for patients with mesenteric venous thrombosis or thromboembolism
  • Severe colonic ischemia
    • signs of peritonitis, pneumatosis on imaging, or gangrene on colonoscopy
    • exploratory laparotomy
      • inidicated in patients with signs of bowel ischemia
      • resected of necrotic bowel if applicable
Complications
  • Bowel necrosis
  • Perforation
  • Sepsis
  • Death
  • Stricture/obstruction
 

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Questions (2)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.GI.91) A 71-year-old Caucasian male presents to your office with bloody diarrhea and epigastric pain that occurs 30 minutes after eating. He has lost 15 pounds in 1 month, which he attributes to fear that the pain will return following a meal. He has a history of hyperlipidemia and myocardial infarction. Physical exam and esophagogastroduodenoscopy are unremarkable. What is the most likely cause of this patient's pain? Review Topic | Tested Concept

QID: 101148
1

Atherosclerosis

50%

(58/115)

2

Peptic ulcer disease

26%

(30/115)

3

Crohn's disease

3%

(4/115)

4

Amyloid deposition

5%

(6/115)

5

Diverticulosis

13%

(15/115)

M1 D

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(M1.GI.107) A 75-year-old male is hospitalized for bloody diarrhea and abdominal pain after meals. Endoscopic work-up and CT scan lead the attending physician to diagnose ischemic colitis at the splenic flexure. Which of the following would most likely predispose this patient to ischemic colitis: Review Topic | Tested Concept

QID: 101164
1

Increased splanchnic blood flow following a large meal

18%

(38/207)

2

Essential hypertension

20%

(42/207)

3

Obstruction of the abdominal aorta following surgery

51%

(106/207)

4

Hyperreninemic hyperaldosteronism secondary to type II diabetes mellitus

4%

(9/207)

5

Juxtaglomerular cell tumor

5%

(10/207)

M1 A

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