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Pathology smear review process

20 Aug 2017

By: Calvin Smith, MLS (ASCP), senior lab specialist-hematology, with Clark McDonald, MD

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The laboratory has recently added an order in EPIC for a Pathologist Smear Review. With the addition of this test, there has been a significant increase in the number of physician requests for pathologist reviews, many of which may be unnecessary.

The lab has defined criteria and a process for determining when hematology specimens require a pathologist's review.  This process is outlined below. The intention of this information is to brief clinicians regarding laboratory procedures and help support their decision when determining if a pathologist review will provide additional clinical information other than that already provided by the laboratory testing process.

The EPIC order for the PSRV has recently been updated to require a reason for the PSRV request. This was added to help the pathologist by providing information on the reason for the physician requested review. Specific information can be added by selecting the “Other” box and including specific reasons the slide is being sent for review.

The primary hematology analyzer used in the Salem Health laboratory is the Sysmex XN-3000, which reports up to 30 parameters on 88 ul of whole blood.

Primary Hematology Orders:

  • H&H – Hemoglobin and hematocrit
  • Hemogram – includes cells counts (WBC, RBC, PLT), H&H, and indices (i.e. MCH, MCHC, RDW)
  • CBC – includes hemogram and automated 6 part diff. (Neuts, Lymphs, Monos, Eos, Basos, IG [Immature grans – meta, myelo and promyleocytes])
  • CBCM – Hemogram with a manual differential.


Instrument Flagging:

The XN-3000 evaluates results using 136 flags and rules to determine if further evaluation by a technologist is required. Based on these rules a tech may need to perform further work, which often includes a smear review (see below).  Results that do not generate any flags are automatically released to EPIC.

Microscopic Review: Smear review vs. manual differential

Smear Review Process:       

The technologist is verifying the accuracy of the automated differential based on a review of a peripheral blood smear. When reviewing a smear the technologist evaluates all three cell lines:

  • White blood cells
  • Red blood cells
  • Platelets

Based on their findings they will report the automated differential results or perform and report a manual differential.

To report the automated differential the slide review must meet specific criteria. In general the instrument’s automated count must match what the tech is seeing on the slide. The presence of immature or abnormal cells will require a manual differential to be reported. 

RBC and Platelet morphology is reviewed and abnormal morphology reported whether a smear review or manual differential is reported. If no abnormal morphology is present results are reported as normal.

Manual Differential:

To perform a manual differential, the tech must count and classify 100 WBCs. They will also report RBC and PLT morphology, which is reported on a smear review as well.

The only difference between a smear review and a manual differential is for a manual differential, the tech must count and classify 100 WBCs.

Compare this to the automated differential, which will count and classify thousands of WBCs using the XN’s fluorescent labeled flow cytometry technology.

The Sysmex automated differential combined with the Sysmex rules and flagging criteria adds a significant level of reliability to the instrument differential.

PSRV (Pathology Smear Review)

Based on the results of the smear review or differential, a pathologist review may be required. Laboratory procedure has defined criteria that require a slide to be sent for evaluation by a pathologist. These criteria include findings for first time blasts, suspect lymphoproliferative disorders, erythroblastic reactions, dsyplastic changes or any suspicious or abnormal cells present. When any of the required criteria are met, a PSRV is ordered and sent for pathologist review.

If you have any questions on the PSRV process contact me at or 503-814-1348