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Snapshot
  • A 40-year-old man presents to the emergency room soon after arriving back from a vacation on a cruise ship. He reports feeling unwell and losing his appetite in the past few days. He has had several episodes of nausea and vomiting, but today had an episode of bloody diarrhea. He is otherwise healthy and is concerned about the amount of blood. He has also had subjective fevers. (Infectious colitis)
Introduction
  • Overview
    • lower gastrointestinal bleed results from bleeding from the colon or rectum
  • Epidemiology
    • incidence
      • very common
    • epidemiology
      • elderly patients with comorbid conditions
    • risk factors
      • diverticulosis
      • angiodysplasia
      • ischemic colitis
      • neoplasm
      • inflammatory bowel disease
      • infection
        • Salmonella
        • Shigella
      • hemorrhoids
      • anal fissure
  • Pathogenesis
    • mechanism
      • depends on the etiology
  • Prognosis
    • can be inconsequential or life-threatening
Presentation
  • Symptoms
    • common symptoms
      • rectal bleeding
        • hematochezia
          • bright red (originating from left side of colon)
          • maroon blood (originating from right side of colon)
        • has the potential to be fatal and cause massive hemorrhagic shock
        • fecal occult blood test is positive
      • a fever may indicate infectious etiology
      • painless bleeding may indicate angiodysplasia or diverticular bleeding
      • abdominal pain may indicate ischemic colitis
  • Physical exam
    • inspection
      • dehydration
Imaging
  • Radionuclide scan
    • indications
      • often performed before angiography as it is not invasive and a negative result negates a need for further invasive procedures
      • high sensitivity
  • Angiography
    • indications
      • hemodynamically unstable patients
      • if colonoscopy does not reveal a bleeding site in hemodynamically stable patients
      • can also be therapeutic
Studies
  • Serum labs
    • complete blood count
    • serum electrolytes
    • coagulation studies
  • Invasive studies
    • colonoscopy/anoscopy/sigmoidoscopy  
      • indication
        • first-line for patients who are hemodynamically stable
        • patients require bowel preparation  
        • can also be used therapeutically for hemostasis
        • in patients > 40 years of age, must rule out malignancy with colonoscopy
Differential
  • Upper gastrointestinal bleed
    • key distinguishing factor
      • source of bleeding from stomach or small intestine
      • may also present as bright red blood if there is rapid hemorrhage
Treatment
  • Medical
    • resuscitation
      • modalities
        • large-bore intravenous access
        • crystalloid fluid replacement
        • blood transfusions if needed
  • Surgical
    • colonoscopy/anoscopy/sigmoidoscopy
      • indication
        • both diagnostic and therapeutic
        • colonoscopy specifically for all patients over 40 to rule out malignancy
      • modalities
        • hemostasis via
          • coagulation i.e., electrocoagulation
          • clip placement
    • angiography
      • indication
        • both diagnostic and therapeutic
        • used when colonoscopy is unrevealing or contraindicated
        • hemodynamically unstable patients
      • modalities
        • embolization
        • vasopressin drip
    • surgical exploration
      • indication
        • hemodynamically unstable patients refractory to resuscitation
        • persistent or recurrent bleeding
Complications
  • Death
  • Shock
 

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Questions (4)
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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(M3.GI.2) A 71-year-old woman is brought to the emergency department following a syncopal episode. Earlier in the day, the patient had multiple bowel movements that filled the toilet bowl with copious amounts of bright red blood. Minutes later, she felt dizzy and lightheaded and collapsed into her daughter's arms. The patient has a medical history of diabetes mellitus and hypertension. Her temperature is 99.0°F (37.2°C), blood pressure is 155/94 mmHg, pulse is 82/min, respirations are 15/min, and oxygen saturation is 99% on room air. The patient's exam is notable for fecal occult blood positivity on rectal exam; however, the patient is no longer having bloody bowel movements. The patient's lungs are clear to auscultation and her abdomen is soft and nontender. Labs are ordered as seen below.

Hemoglobin: 7.1 g/dL
Hematocrit: 25%
Leukocyte count: 5,300/mm^3 with normal differential
Platelet count: 182,500/mm^3

Two large bore IV's are placed and the patient is given normal saline. What is the best next step in management?
Review Topic

QID: 102631
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Colonoscopy

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CT abdomen

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Fresh frozen plasma

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Packed red blood cells

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Type and screen

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M2

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SUBMIT RESPONSE 5

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(M2.GI.80) A 72-year-old male with a past medical history significant for aortic stenosis and hypertension presents to the emergency department complaining of weakness for the past 3 weeks. He states that, apart from feeling weaker, he also has noted lightheadedness, pallor, and blood-streaked stools. The patient's vital signs are stable, and he is in no acute distress. Laboratory workup reveals that the patient is anemic. Fecal occult blood test is positive for bleeding. EGD was performed and did not reveal upper GI bleeding. Suspecting a lower GI bleed, a colonoscopy is performed after prepping the patient, and it is unremarkable. What would be an appropriate next step for localizing a lower GI bleed in this patient? Review Topic

QID: 106153
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Nasogastric tube lavage

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Technetium-99 labelled erythrocyte scintigraphy

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Ultrasound of the abdomen

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CT of the abdomen

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Flexible sigmoidoscopy

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