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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: H. pylori by CLO Test

Test Code(s): CLO / HCCLO

CPT Code(s): 87077

Methodology: Enzymatic

Clinical Significance: The H. pylori CLO test detects the urease enzyme of Helicobacter pylori in gastric mucosal biopsies.  It is intended for the presumptive diagnosis of H. pylori infection.

Days Performed: Mon-Fri.

Turnaround Time: Stat: Not available stat.
Routine: Up to 24 hours.

Specimen Requirements

Specimen: Tissue

Patient Preparation: Patients should discontinue the use of antibiotics and bismuth preparations three weeks before the biopsy.  These agents may suppress but not eradicate the presence of H. pylori making the organism difficult to detect.  Patients should not have ingested proton pump inhibitors two weeks prior to the test as these drugs have been shown to inhibit the growth of H. pylori in some people.

Collection Instructions: The recommended gastric area to biopsy is at least 2 cm away from the pylorus along the lesser or greater curve of the antrum.  Excise tissue that appears normal- avoid tissue that is eroded or ulcerated as H. pylori may be present in smaller numbers around those areas.

Collection Container: Preferred: CLO Test slide

Specimen Transport: Transport CLO test slides to the Microbiology laboratory at ambient temperature.  

Unacceptable Criteria: 1) Biopsies that are too large to be completely imbedded in the CLO test slide.
2) Samples from intestinal metaplasia (H. pylori does not colonize intestinal mucosa).
3) Samples contaminated with formalin.
4) Refrigerated or frozen test slides.

Stability: Ambient: 72 hours
Refrigerated: Not acceptable
Frozen: Not acceptable


Expected Results:


Test Limitations:

False negative results may occur due to:

  • Recent ingestion of antibiotics, bismuth, proton pump inhibitors or sucralfate.
  • Low numbers of H. pylori in tissue sample.
  • H. pylori not captured in the biopsied area (patchy distribution).

False positive results are rare, but may be due to:

  • Failure to completely imbed the biopsy into the gel which allows contaminating organisms to grow in the tissue.
  • Patients who have achlorhydria from bacterial overgrowth (may occur in patients with a history of pernicious anema, gastric surgery, or recent use of proton pump inhibitors).


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