Biomedical Study Guide

Definitions and Explanations

Occult Stool

  • Definition: Occult Stool refers to hidden blood in feces not visible to the naked eye.

  • Detection Method: It is detected using the guaiac test or fecal occult blood test.

  • Clinical Implications: The presence of occult blood can indicate possible gastrointestinal (GI) bleeding, ulcers, or colon cancer.

Sputum Culture

  • Best Time to Collect: The best time to collect a sputum culture is early morning before eating or brushing teeth.

    • Reason: The mucus is thicker and more concentrated after sleeping, which improves the quality of the specimen.

Throat Culture

  • Swabbing Technique: For a throat culture, swab the tonsillar area and the back of the throat.

    • Important Note: Avoid touching the tongue or cheeks during the swabbing process to ensure accuracy in the sample.

Iodine and Contrast Media

  • Correlation: Contrast media, commonly used in diagnostic imaging, often contains iodine.

  • Allergy Consideration: Patients with allergies to iodine or shellfish may react to contrast media.

    • Important Protocol: Always check for allergies prior to administering contrast media.

Specimen Labels

  • Required Information on Labels:

    • Patient's full name

    • Date of birth

    • Collection date

    • Time of collection

    • Test type

    • Collector's initials

  • Label Placement: Specimen labels should go directly on the container, not on the lid.

Midstream Urine

  • Definition: A clean catch urine sample collected midway through urination to avoid contamination.

  • Usage: This method is utilized for urinalysis and urine culture.

Stool Specimen Transport

  • Immediate Laboratory Transport: Specimens for ova and parasites (D&P) or Clostridium difficile (C. diff) should go to the lab immediately.

    • Reason for Urgency: Delay in transporting these specimens can alter the results.

Stool Color Indicators

  • Bright Red Blood in Stool:

    • Implication: Indicates bleeding in the lower GI tract, such as from hemorrhoids or rectal bleeding.

  • Black Tarry Stool:

    • Implication: Signifies digested blood from an upper GI bleed, such as from a stomach or duodenal ulcer.