Verification of abnormal results from Coulter instrumentation

Transcription

1 Created Lisa Senzel Asst. Prof. - Clinical 5/9/2008 Path Revised Bruce Kube Day Heme Tech 1 10/24/2012 Reviewed Jay Bock M.D. 4/10/2012 Procedure: Approved Lisa Senzel Asst. Prof. - Clinical Path Replaces 9/07 ID 16 HEM Verification of abnormal results from Coulter instrumentation 1/10/2013 Many of the flags listed below may be generated when a sample is clotted or partially clotted. As part of the verification process, the sample should be manually checked for the presence of a clot. Clot checking is to be done as follows: Remove the top of the tube and visually inspect the inside of the top for the presence of a clot attached to it. Following inspection of the top, check the sample using 3 applicator sticks to allow for additional surface are for any clots present to adhere to. Place the sticks into the tube until they touch the bottom and ring the tube several times. Remove the sticks and inspect them for any evidence of clotting (visible clot, fibrin stands) For additional information about when to perform manual review of the peripheral smear, see HEM 3.3.x, Procedure for review of peripheral smear-when to perform. ABNORMALITIES COVERED IN THIS PROCEDURE WBC elevated or with flags Pages 1-2 RBC elevated or with flags Page 2 H&H not matching Pages 2-3 Reticulocytes elevated, flagged, or known hemoglobinopathy Page 3 NRBCs or megakaryocytes on smear Pages 3-4 Platelets decreased, elevated, or with flags, clumps, or no MPV Pages 4-5 SAMPLES TO BE VERIFIED BY REPEAT RUN Rerun all specimens with the following results, on new patients only as determined by inquiry. Be sure to record additional workload in MISYS. WBC <2.5 >30.0 Hgb <7.0 >18.0 PLT <40 >800 H&H not matching (Normal ratio of 1:3:9 for RBC:Hb:Hct is not present). WBC WBC>30,000 Repeat sample for verification. WBC>99.9 Reject the original results, do not place in preliminary. Prepare 1:5 dilution (100ul blood/400ul Isoton). Coulter LH Series analyzers On the LH workstation select the predilute (CBC) checkbox. Enter 5.0 for the dilution factor. Run the sample as per HEM 2.1.X Operation of the LH 785. Report result in OEM. If the sample is ordered as a CBCD Enter HIDE for the differential parameters. Perform a manual differential if necessary. In the event of an H&H mismatch, compare the RBC to the HGB these parameters are generally related in a 1:3 ratio. If the ratio is met, compare RBC to HCT (1:9 ratio). If these ratios are met, and the difference between the HGB/HCT is +/-3.5 the Page 1 of 6

2 results may be released, otherwise if the RBC/HGB ratio is acceptable release the HGB and not the HCT. WBC with associated flags: CHECK SAMPLE FOR CLOT, INDICATE ON SCATTERPLOT AND APPEND NCD TO THE RESULT. In the absence of a clot, place WBC, Platelet and MPV into preliminary and verify counts on peripheral smear. Discrepant counts must be performed manually. Whenever a flag next to the WBC is displayed examine the scatterplot for evidence of cryoglobulins. Check peripheral smear for interferences such as nucleated red cells, parasites, megakaryocytes and clumped platelets. RBC RBC> Posted linearity MCV R Dilute 1:2 (or higher). Multiply by dilution factor and report the dilution. Correct RBC indices as described in HEM 3.6.x, Manual Calculation of RBC Indices. HCT= Corr RBC X MCV 10 MCV 65fl or less also R next to RBC, HCT, MCH, MCHC, RDW, PLT and MPV. Verify the platelet count on the smear, do a manual platelet count if necessary since very small RBC may be counted as platelets creating a spuriously high count. HH H&H not matching means that the ratio generally exhibited of 1:3:9 for RBC:Hgb:Hct is not present. In the event an appropriate match is not obtained after completing the following instances, report only the parameters indicated. In the event of an H&H mismatch, compare the RBC to the HGB these parameters are generally related in a 1:3 ratio. If the ratio is met, compare RBC to HCT (1:9 ratio). If these ratios are met, and the difference between the HGB/HCT is +/-3.5 the results may be released, otherwise if the RBC/HGB ratio is acceptable, release the HGB and not the HCT. In the absence of Lipemia the Hgb is the parameter least subject to interference. Do not report results for erroneous parameters; report using the text code INTF which translates to Interfering substance prevents accurate reporting of this parameter. HH not matching, (Low RBC high MCV, high indices) HH not matching, Possible cold agglutinin. Check for hemolysis and adequate sample volume. Warm blood for 30 minutes at 37 o C and repeat the sample. Append the text code AGGL to all results that correct by warming. If still unable to obtain match after warming, report WBC, Hgb, Pltc, and MPV and differential. Perform slide verification if necessary prior to reporting any flagged reviewable parameters. Result all non-reportable parameters with the code INTF. Possible lipemic specimen. Page 2 of 6

3 (Hgb high, RBC and indices appear normal.) Centrifuge an aliquot of blood (1-2ML). Run the plasma through the Coulter. Subtract the plasma Hgb from the whole blood Hgb to get the corrected Hgb. This should match the HCT. Do not report MCH, MCHC unless requested, then calculate as described in HEM 3.6.x, Manual Calculation of RBC Indices. If the plasma appears to be hemolyzed, you can only report WBC, Hgb and MCV. All RBC calculated parameters are incorrect. All non-reportable parameters are to be resulted with the text code INTF. HH not matching, (Low MCV <55 fl, RBC histogram shift to left (take off above origin). Report WBC, HGB, verify PLTC and perform manually if necessary. HCT low) Very small RBC may be counted as platelets, creating a spuriously high platelet count. Report MCV as MCV<55. Result RBC, HCT, MCH, MCHC as Cannot report due to markedly decreased MCV. Do not perform spun HCT because plasma trapping makes spun HCT unreliable. All non-reportable parameters are to be resulted with the text code INTF. Reticulocytes R flags Repeat sample. If R flag persists perform manually >10.0 Repeat sample for verification of critical value >26.0 Verify manually Known hemoglobinopathy Perform manually CORRECTION FOR INTERFERING PARTICLES (N-RBC OR MEGAKARYOCYTES) Count the number of nucleated interfering particles (NRBC or Megakaryocytes) seen per 100 WBC count/differential. Correct the WBC count using the formula: Corr WBC = Uncorr WBC X 100 #particles When reviewing a sample for NRBCs, adhere to the following guidelines. a. If a CBC is ordered: i. NRBCs are seen upon scan 1) Do not order a manual differential. Review the slide counting the number of NRBCs/100 WBCs and perform the correction to the WBC count if 10 or more NRBCs are seen. Enter the corrected WBC count into Sunquest with the following text appended to it. ADJ-;##NRBCs Seen/100 WBCs. ## is the number of NRBCs counted. ii. If a manual differential is requested by the patient care area on to a sample for which the WBC has previously been corrected for NRBCs 1) Order the differential through REI on Sunquest using the accession number of the previously resulted sample. 2) Print out an IRA for the sample and highlight or circle the correction statement on the WBC that denotes the presence and quantity of NRBCs. Page 3 of 6

4 3) Perform the manual differential. Enter the number of NRBC used to originally correct the WBC into the NRBC field of the manual differential. Do not re-correct the WBC. b. If a CBCD is ordered: 1. The WBC is within limits and only a scan is required (Autodiff is released) and NRBCs seen on the scan are appear greater than 30% different from the number reported by the Coulter. Perform a manual differential enumerating the NRBC and correct the uncorrected WBC as indicated in the equation above. If upon scan you agree with the NRBC number report the corrected WBC and append the text code ADJ to the WBC. 2. A manual differential is required based on the WBC. Perform the differential as normal using the Sunquest keyboard to count the NRBCs. If the number of NRBC differs 30% or more from the Coulter, apply the manual correction to the uncorrected WBC from the Coulter. Refer to the LIS procedure for differentials if not familiar with the available methods of ordering. PLATELET All samples with platelet clump, giant platelet, cellular interference, Platelet R or WBC R flags must be checked for clots prior to reporting any results. Indicate on scatterplot and in Sunquest by appending the test with NCD that the check was performed and no clot was detected. All samples prior to running should be inspected for proper collection volume. Particular attention should be given to cases where there are platelet counts that are vastly lower than a previous count or critical check for proper draw volume. Grossly under drawn samples are to be cancelled (less than ½ full draw). (See flowchart below) < 100,000 First occurrence. Check for clot using procedure outlined above. Ctl-click here to review the procedure >2X change from previous If below 30,000, check for a clot using the procedure outlined above. At or above 30,000, check for clot and check labels on the current and previous sample. 40,000 All samples tubes yielding platelet counts 40,000 must always be carefully and thoroughly checked for a clot prior to either resulting or placing the count into preliminary. If no clot is detected in the tube, It is to be indicated on the scatterplot by writing NCD as well as appending the information to the test in the LIS < 40,000 or >800,000 or Are to be verified on smear (counted manually if discrepancy With R flag noted) as described in HEM 3.3.x Procedure for review of peripheral smear-when to perform and HEM 3.7.x Platelet estimation > Posted Linearity Dilute 1:2 (higher if necessary), multiply by 2 (or dilution factor) and report calculated value. Page 4 of 6

5 MPV is... Clumped plts Verify count on peripheral smear. Perform manual count on all discrepant samples. Enter a Result of HIDE for the MPV during CBC data verification session. HEM 3.3.x Procedure for review of peripheral smear-when to perform describes reporting of clumped platelets. Namely, If clumped platelets are present on the smear and the automated platelet count is >50, report as >(instrument count) with platelet clumps If clumped platelets are present and the automated count is <50, report as clumped Request a fresh specimen (in a blue top tube) if an accurate platelet count is necessary. You can also try 40% citrate (.1ml in 10ml blood) or 0.8M sodium citrate with 0.8M citric acid added (.5ml with 4.5ml of blood), or a 37 o C incubator. When reviewing results that have platelet flags: 1. The tube for samples that yield platelet R flags or WBC * must be manually, carefully and thoroughly checked for a clot prior to releasing any results. If no clot is present, indicate that on the scatterplot by writing NCD. The hemogram results can be released and the platelet and MPV put in preliminary. 2. All samples that are to be reviewed for platelets only must have a scan ordered. The scan should be ordered through the piggyback (OEM) for CBCD and in REI for CBC. 3. When flagged, platelet counts must always be verified on the peripheral smear. If there is any question as to the accuracy of the platelet count, a phase count should be performed. Refer to Platelet Estimation, HEM 3.7.x. Manual count is described in WBC-PLT Determination by Manual Method, HEM 3.9.x 4. When the MCV is <50 fl verify the platelet count on smear, do a phase if necessary (very small RBC may be counted as platelets, creating a spuriously high platelet count). Page 5 of 6

6 Appendix: Major Changes in Criteria Sept 2007 Manual WBC or platelets only required if the automated count does not agree with the slide estimate May Peripheral smear verification is no longer required for WBC<3 in the absence of flags Reporting of clumped platelets has changed (see Procedure for review of peripheral smear How to Perform, HEM 3.3.2) November Perform 1:5 dilution to correct red cell parameters when WBC>99.9 April Defined text code to be used when resulting non-reportable parameters. INTF = Interfering substances prevent accurate reporting of this parameter. Clarified which parameters can be reported in the presence of interfering substances. August 2010 Added instruction to make sure clot checking for clots is documented on scatterplots and in Sunquest by appending NCD to the test so that there are 2 checkpoints prior to finalizing the result. In platelet section, added instruction to check for QNS when platelets are low. December 2011 Modified range of reticulocytes to be verified manually to 26.0 from 10.0 based on CAP linearity study (LN19). Reticulocytes results with R flags and from patients with known hemoglobinopathies will continue to be performed manually. The critical value remains at 10.0 and samples with critical results will be repeated for verification. January 2013 Modified level of platelet count that triggers sample clot checking and clarified proper procedure for clot checking. Page 6 of 6