Table 3 Studies examining the clinical value of peripheral blood smear review

Fairbanks et al. [4] 1971

Mayo Clinic, Rochester, Minnesota

2 blood smears per subject (24 normal controls + 38 patients with IDA) reviewed, for the purposes of the study, by 9 staff and resident hematologists

Among all interpretations:

• False positives (IDA reported on a control patient): 5.8%

• False negatives (IDA not reported on IDA case): 51.0%

• Consensus among all 9 reviewers: 5 of 38 blood smears from IDA patients

Average intra observer variability (discrepancy when a reviewer reviewed the same smear twice): 22%

“Except when morphologic changes are pronounced, the diagnosis of iron deficiency anemia from examination of the peripheral blood film is difficult and not very reliable.”

Jen et al. [5] 1983

Brigham and Women’s Hospital, Boston, Massachusetts

288 anemic inpatients with blood smears reviewed in the context of clinical care by laboratory staff, with or without physician review

• Only 5 of 11 (45%) common RBC morphologic abnormalities showed both inter- and intra-observer reproducibility better than chance.

• Among patients evaluated for iron, folate, or B12 deficiency, red cell indices showed similar or better specificity and positive predictive value than blood smear interpretation.

• Among smears interpreted by laboratory staff, additional physician interpretation yielded “unique” diagnostic information in no cases and “helpful” information in 2.2% of cases.

• “Blood smear readings are poorly reproducible, are no better than RBC indices for screening for possible deficiency states, and only occasionally provide unique information.”

• “The physician’s reading is most important for the confirmation of abnormal WBC morphology and is most likely to add incremental value in patients whose elevated reticulocyte counts suggest hemolysis.”

Simmons et al. [6] 1989

Walter Reed Army Medical Center, Washington, DC

12 cases of anemia with blood smear and clinical and CBC data reviewed, for the purposes of the study, by 65 residents, fellows, and staff physicians

• Access to a peripheral smear did not significantly change the number or appropriateness of tests ordered.

• Access to a peripheral smear did not significantly improve the reviewer’s ability to make a correct diagnosis.

“RBC review, even when accurate, does not improve clinical problem solving across a variety of common anemias and among a broad cross section of residents, internists, and hematologists.”

Kurt-Mangold et al. [7] 2018

University of Iowa Hospitals and Clinics

Chart review of patients associated with 277 clinician-ordered peripheral blood smear reviews

• 68% of smear review reports included unique data beyond that already described in the medical record.

• 52% of smear review results were not mentioned in patients’ clinical notes.

• Data obtained from peripheral smear review impacted clinical decision making in 1% of cases.

“Only rarely do [data from peripheral blood smear review] appear to be clinically significant and the information frequently overlaps with information already provided by laboratory-initiated smear reviews.”