Updated: 6/23/2019

Small Bowel Obstruction

Topic
Review Topic
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Questions
4
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Evidence
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Snapshot
  • A 45-year-old woman presents to the emergency room for abdominal pain, nausea, and nonbloody vomiting for the past day. She has not had any flatus during this time. She also endorses decreased appetite. She has a past surgical history of cesarean section. On physical exam, there is diffuse tenderness to palpation of her abdomen but no rebound tenderness or guarding. An abdominal radiograph shows dilated loops of small bowel, which is confirmed with a CT abdomen and pelvis. There are no masses identified. She is admitted to the inpatient floor and a nasogastric tube is placed.
Introduction
  • Overview
    • partial or complete blockage of the small intestines
  • Epidemiology
    • incidence
      • common
    • risk factors
      • prior abdominal surgeries (most common)
        • post-operative adhesions
      • masses/malignancy
      • hernias
      • inflammatory bowel disease
      • intussusception (in children)
  • Prognosis
    • partial SBOs often self-resolve
    • complete SBOs may also self-resolve but often require surgical intervention
Presentation
  • History
    • decreased appetite
    • lack of flatus
    • constipation
  • Symptoms
    • common symptoms
      • nausea and vomiting
      • abdominal pain
  • Physical exam
    • inspection
      • abdominal distention
    • motion
      • generalized tenderness to palpation
Imaging
  • Abdominal radiographs
    • indications
      • best initial test
    • findings
      • dilated loops of small bowel
      • free air may indicate need for immediate surgery
  • Computed tomography (CT) of abdomen and pelvis
    • indications
      • diagnosis of SBO
    • findings
      • dilated loops of small bowel
      • transition point
      • any masses present
Studies
  • Serum labs
    • lactic acid to monitor for bowel necrosis if suspected
  • Invasive studies
    • small bowel follow-through with gastrograffin
      • indication
        • patients who fail to improve clinically after 48 hours of nonoperative treatment
        • may rule out need for surgery
Differential
  • Appendicitis
    • distinguishing factor
      • imaging shows enlarged appendix with signs of inflammation instead of dilated loops of bowel with transition point
Treatment
  • Conservative and lifestyle
    • supportive care
      • modalities
        • intravenous fluids
  • Medical and pharmacologic
    • treat underlying condition
    • nasogastric decompression and bowel rest
      • indications
        • partial SBO
        • no signs concerning for bowel strangulation
  • Surgical and interventional
    • surgical intervention with correction of cause of SBO, i.e., lysis of adhesions
      • indications
        • peritonitis
        • signs concerning for bowel strangulation
          • systemic signs i.e., fever
          • metabolic acidosis
          • continuous pain
Complications
  • Bowel necrosis
  • Peritonitis
  • Bowel perforation
 

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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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(M2.GI.4685) A 69-year-old female presents to the emergency department with crampy abdominal pain. She has a past medical history of hypertension, dyslipidemia, and cholelithiasis status post cholecystectomy. The patient states she has not passed stool or gas for 48 hrs. On physical exam vitals are T 98.4 F HR 105 bpm BP 155/101 mmHg RR 16 SpO2 96%, abdominal exam is notable for distension, tympany to percussion, and tenderness to palpation without rebound or guarding. Which of the following findings are most likely on radiograph? Review Topic

QID: 107359
1

Free air under the diaphragm on upright abdominal radiograph

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2

Apple core defect after lower GI series

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3

Multiple punctate mucosal outpouchings through the serosa on lower GI series

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4

Ladder-like series of distended bowel loops with air-fluid levels on abdominal radiograph

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5

Loss of haustral markings and "lead pipe" appearance to the descending colon on lower GI series

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M2

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(M2.GI.43) A 76-year-old female is brought to the emergency department after being found unresponsive in her room at her nursing facility. Past medical history is significant for Alzheimer's disease, hypertension, and diabetes. Surgical history is notable for an open cholecystectomy at age 38 and multiple cesarean sections. On arrival, she is non-responsive but breathing by herself, and her vital signs are T 102.9 F, HR 123 bpm, BP 95/64, RR 26/min, and SaO2 97% on 6L nasal cannula. On physical exam the patient has marked abdominal distension and is tympanic to percussion. Laboratory studies are notable for a lactic acidosis. An upright abdominal radiograph and CT abdomen/pelvis with contrast are shown in Figures A and B respectively. She is started on IV fluids and a nasogastric tube is placed to suction which returns green bilious fluid. Repeat vitals 1 hour later are T 101F, HR 140 bpm, BP 75/44, RR 30/min, and SaO2 is 100% on the ventilator after she is intubated for airway concerns. What is the next best step in management? Review Topic

QID: 104585
FIGURES:
1

Therapy with levofloxacin and metronidazole

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2

Immediate laparotomy and surgical management

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3

Continue IV fluid hydration, nasogastric suction, NPO

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4

Pneumatic enema

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5

Sigmoidoscopy, attempted derotation and rectal tube placement

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