Bain identified a number of clinical situations which should prompt the clinician to order an examination of the peripheral blood smear. These findings may be missed if only an automated differential is performed. The author is from St. Mary's Hospital in London.


Reasons to request examination of a peripheral blood smear:

(1) unexplained anemia, microcytosis or macrocytosis

(2) unexplained jaundice

(3) findings suggestive of sickle cell disease or unstable hemoglobinopathy

(4) unexplained thrombocytopenia or clinical findings suggestive of thrombocytopenia

(5) unexplained neutropenia or clinical findings suggestive of neutropenia

(6) findings suggestive of a lymphoproliferative disorder

(7) findings suggestive of a myeloproliferative disorder

(8) findings suggestive of disseminated intravascular coagulation (DIC), hemolytic uremic syndrome (HUS), or thrombotic thrombocytopenic purpura (TTP)

(9) acute or recent onset of renal failure

(10) acute or recent onset of renal enlargement

(11) hemorrhages, exudates, optic atrophy or signs of hyperviscosity on retinal examination

(12) findings suggestive of a bacterial or parasitic infection (Malaria, Babesia, Ehrlichia, other) that can be identified on a blood smear

(13) signs of infectious mononucleosis or other viral infection

(14) unexplained general ill health, with malaise, fever and/or weight loss

(15) findings suggestive of a disseminated malignancy with bone pain (looking for a leukoerythroblastic picture)


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