Policy/Principle: | Certification: | Testing Prerequisites: | Materials: | Specimen: | Procedure: | Results Derivation: | Expected Values: | Quality Control: | Infection Control: | References:
The Gastroccult® test is performed as a rapid screen to ascertain if “occult’ (not grossly visible) blood is present in gastric aspirate or vomitus. The pH is used as a guide to determine if the specimen is gastric. The Gastroccult® slide includes both a specially buffered guaiac test for occult blood and a pH test based on the principle that certain dyes change color with changes in hydrogen ion concentration. If blood is present in the gastric specimen, the peroxidase-like activity of its heme moiety will catalyze oxidation of the guaiaconic acid impregnated into the paper of the slide by the H2O2 developer solution, creating a distinctly blue colored conjugate.
1. Orientation, authorization and competency of staff and licensed practitioners performing POCT are provided by the director’s (named on the CLIA certificate) designee as indicated in the “Point of Care (POCT) Program” procedure.
2. Gastroccult® screening will be performed by Nursing Service personnel who have been specifically certified:
A. To be certified, the requirements of the Gastroccult®, Gastric Occult Blood and pH screening; POCT Self-Instructional/Competency documentation packet must be completed. The primary goal here is to make sure that the materials are properly managed, test timing is correct and documentation is in order.
B. If the individual seeking certification is unable to demonstrate acceptable performance of Quality Control, he/she must be retrained and successfully re-tested for authorization to perform Gastroccult® testing.
C. Re-certification is required annually:
a. Re-certification for an individual may be required more often if deemed necessary. When an instructor observes improper technique, he/she may decertify the operator on the spot. Arrangements for re-certification of that individual must then be made through their immediate supervisor.
b. Re-certification requires an operator to successfully complete the Gastroccult®, Gastric Occult Blood and pH; POCT Self-Instructional Competency documentation packet.
D. The certification record for operators and instructors will be maintained on the unit.
4. This test requires blue-spectrum differentiation; it should not be attempted by individuals with blue colorblindness. If you have not been tested for colorblindness, contact Employee Health Services before proceeding.
5. Physicians performing waived testing are exempt from training and competency documentation.3
1. Physician orders can call for gastric occult blood, gastric pH or "Gastroccult®" testing.
2. The Gastroccult® test cannot be run on feces.
3. The only laboratory-sanctioned gastric occult blood screen is the Beckman/Coulter Gastroccult® brand with on-slide controls.
4. Charging for the Gastroccult® screen:
A. At Mercy Medical Center:
a. The nurse performing the test is responsible for processing the charge.
b. Order a Gastroccult® screen in the H.I.S. Order Communication system.
B. At the Finley Hospital:
the Gastroccult® is not charged.
1. The three Gastroccult® components, plastic applicators, slides and developing solution, are obtained from the laboratory on an as-needed basis. Nursing stations where testing is likely to occur can keep 3-4 slides and a bottle of developing solution on hand. Strict adherence to the open-expiration dating and storage specifications is required. Testing material will be stored long term in the laboratory under optimum storage conditions.
2. Gastroccult® reagent components are to be stored out of the light and at room temperature. Gastroccult® slides must be kept sealed inside special wrapper until ready to use. Do not store near ammonia or halogen compounds (iodine, chlorine, bromine).
3. If either of the Gastroccult® labile components is not used before their open-expiration dating, they must be exchanged for fresh material from the laboratory. The laboratory may redirect this material to sites that have a more rapid rate of use once reagent integrity has been re-verified.
1. Two drops of gastric aspirate obtained by nasogastric intubation or vomitus are required.
2. In the hospital setting, the Gastroccult® slides should be developed immediately after sample is added to the slide. The pH must be read within 30 seconds of adding sample.
3. Antacid products containing magnesium hydroxide (e.g., Mylanta II and Maalox Plus) exhibit the most inhibitory effect on the test. Gastric samples should be collected at least 60 minutes after antacid ingestion. It is unlikely that there will be any inhibition of the occult blood test by antacids if gastric samples are tested no sooner than 60 minutes after last antacid administration and stomach irrigation.
4. Many foods (e.g., incompletely cooked meat, raw fruits and vegetables, etc.) have peroxidase activity which can produce a positive Gastroccult® test result. Thus, a positive test result does not always indicate the presence of human blood.
5. Ascorbic Acid (vitamin C) has been shown to cause false-negative test results for occult blood.
1. Make sure you have properly identified the patient according to established protocol.
2. Obtain a Gastroccult® slide and developer solution from its storage space on the unit; check to make sure the testing materials are within the open-expiration dating.
3. Open the slide cover. Using a plastic applicator, apply one drop of gastric sample to the pH test area and one drop to the occult blood test area. Do not allow gastric sample drop to come in contact with the Performance Monitor area.
4. Determine the pH of sample by visual comparison of the test area to the pH color comparator. Read the pH results within 30 seconds after applying sample.
5. Apply two (2) drops of Gastroccult® Developer directly over the sample in the occult blood test area, and one (1) drop between the "Pos." and "Neg." Performance Monitor Areas.
6. Read occult blood results within 60 seconds of applying the developer solution. Wait a full 60 seconds on specimens that appear negative. Do NOT attempt to read after 60 seconds. The development of any trace of blue color in the occult blood test area is regarded as a positive result.
Some gastric samples may be highly colored and appear as blue or green on the test area. Test results should only be regarded as positive if additional blue is formed after Gastroccult® Developer is added.
7. Read the control results in the Performance Monitor area of the slide. A blue color should appear in the "Pos." Performance Monitor area. No blue color should appear in the "Neg." Performance Monitor area.
8. Place the patient identification label or record the patient name and birthdate on the Gastroccult Log. Record the patient and control results and the Gastroccult Card lot # on the Gastroccult Log.
9. If the on-board controls are not satisfactory, do not report the patient result at all. Contact the laboratory. Label the slide that failed with the patient's name, date, your initials and your in-house location. Send this slide along with the developer and any other slides stored at the nursing station to the laboratory for assessment.
1. Within 60 seconds of applying the developing solution, positive specimens will show a blue color. Wait a full 60 seconds on specimens that appear negative. Do NOT attempt to read after 60 seconds.
2. Positive occult blood: Any trace of blue color in the occult blood test area indicates a positive result. Some gastric samples may be highly colored and appear as blue or green on the test area. Test results should only be regarded as positive if additional blue is formed after Gastroccult® Developer is added.
3. Negative occult blood: No blue color in the occult blood test area indicates a negative result.
4. pH: Determination of pH is made by visual comparison of test area to pH color comparator.
The pH is used as a guide to determine if the specimen is gastric. Gastric aspirates have decidedly acidic pH values, preferably 4 or less, compared with intestinal aspirates that are usually greater than 4, or respiratory secretions that are usually greater than 5.5.
Note: if the patient has received an antacid, the pH of the gastric specimen may be greater than 4.5.
5. If the on-board controls (Performance Monitor) are satisfactory, record the results on the patient's chart as either "Positive for occult blood" or "Negative for occult blood".
6. If the on-board controls are not satisfactory, do not report the patient result at all. See the Q.C. section that follows.
1. Occult Blood: Negative (no detectable blue color)
2. pH: 1.5-3.5
Note: Expected value in normal subjects after 12 hour fast (in absence of smoking or chewing gum).
1. The laboratory will manage the ordering and distribution of testing materials. Nursing personnel certified to perform the testing will come to the laboratory to pick up reagent (kits/packs) for their unit when needed and will, at that time, perform QC using external controls as specified by the manufacturers.
Nursing service will ensure that those individuals who are authorized to run POCT come to the laboratory on a rotational basis to pick up the reagent for their unit and run the assigned controls.
A. Develop controls on a representative slide and record results on the Gastroccult QC Log.
B. If opening a new box of Gastroccult slides, refer to the laboratory “Gastroccult” procedure for instructions on pH QC.
C. Nursing staff will record their control results in a log, which documents their identity, the date/time and allowable tolerances.
D. Logs will be kept in the laboratory and will be reviewed periodically by the local laboratory managers and the office of the Technical Director for compliance and to ensure that task is being routinely rotated among the personnel who perform the tests.
2. As specified in the written procedure above, for each and every test, the person running the test will check the Performance Monitor control spots on the slide and record results on the Gastroccult Log:
A. One drop of the developer solution is applied between the "Pos." and "Neg." spots in the Performance Monitor area of the slide. The results are read within 60 seconds.
B. The integral control spots provide assurance that the guaiac paper and developer are functional. The spot marked "Pos." contains a hemoglobin derivative and will turn blue within 10 seconds when exposed to the H2O2 of the developer and the color will remain stable for at least 60 seconds. The spot marked "Neg." contains no hemoglobin derivative and will not turn blue in the face of peroxide.
C. If the on-board controls are satisfactory, record the result on the Gastroccult Log and the patient's chart as either "Positive for occult blood" or "Negative for occult blood".
D. If the on-board controls are not satisfactory, do not report the patient result at all. Contact the laboratory. Label the slide that failed with the patient's name, date, your initials and your in-house location. Send this slide along with the developer and any other slides stored at the nursing station to the laboratory for assessment.
1. Staff will wear a fresh pair of gloves while performing the Gastroccult® test and will wash their hands after the procedure using established protocol.
2. Residual gastric specimen, testing slide and gloves will be disposed of in accordance with the hospital's approved waste management policy.
1. December 2000. S. Raymond; Technical Director, Dubuque Pathology Associates.
2. Gastroccult® package insert. Beckman Coulter, Inc. Fullerton, CA. November 1999.
3. Susie McBeth, JCAHO Regional Agent. JCAHO Division of Research. Oakbrook Terrace, IL 60181. (630) 792-5000 4/9/2001.
i. January 2001 L. McGovern
ii. April 2001 S. Raymond/L. McGovern (Revised: II.4, XI.3. added)
iii. November 2001 L. McGovern (Revised: IX.2)
iv. January 2006 L. McGovern (Revised: IX.2-3.)
v. February 2007 L. McGovern (Revised: I.)
vi. October 2009 L. McGovern, S. Raymond (Revised: II.1. added)
vii. November 2009 L. McGovern, S. Raymond (Revised: VI.7-9.; IX.6.)
viii. December 2009 L. McGovern (Revised: IX.)
Medical Director; P.A.:
Technical Director; P.A.:
Representative: Nursing Service Finley
Representative: Nursing Service Mercy
Interim Review: January 2011 L. McGovern (no changes)