Which lab tests are indicated if the diagnosis of small-bowel obstruction (SBO) is unclear?

Updated: Apr 28, 2017
  • Author: Mityanand Ramnarine, MD, FACEP; Chief Editor: Steven C Dronen, MD, FAAEM  more...
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Answer

If the diagnosis is unclear, admission and observation are warranted to detect early obstructions. Essential laboratory tests are needed, including the following:

  • Serum chemistries: Results are usually normal or mildly elevated; abnomal results early in the disease are generally due to vomiting or dehydration

  • Blood urea nitrogen (BUN)/creatinine levels: May be increased due to a decreased volume state (eg, dehydration)

  • Complete blood cell (CBC) count: The white blood cell (WBC) count may be elevated with a left shift in simple or strangulated obstructions; increased hematocrit is an indicator of volume state (ie, dehydration)

  • Serum lactate levels: Increased levels are suggestive of dehydration or tissue underperfusion

  • Lactate dehydrogenase studies

  • Urinalysis

  • Type and crossmatch as well as prothrombin time (PT), international normalized ratio (INR), and partial thromboplastin time (PTT): These are adjunctive laboratory tests used in the evaluation of SBO; the patient may require surgical intervention


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