Peripheral Blood Smear

What it does

Peripheral Blood Smear reads the nucleated cells of a stained blood film. Smear review follows an abnormal complete blood count or an analyser flag, and its most important job is safety: not missing blasts or abnormal lymphocytes among otherwise ordinary cells.

The run locates and classifies each nucleated cell as neutrophil, lymphocyte, monocyte, eosinophil, basophil, immature granulocyte, blast, erythroblast or atypical cell, and turns the counts into a differential in percent. Every cell appears in a gallery grouped by class, so the reviewer sees the cells behind each number. When blasts or abnormal lymphocytes are found, the result raises an alert with "refer for haematology review" guidance.

Intended use

Decision support for the laboratory morphology review: a pre-classified differential with every cell in view, and a safety net that puts suspicious smears first. Red-cell and platelet morphology are not graded by this model.

Who it is for

Haematology laboratory scientists and technologists, haematologists, clinical pathologists, and labs without a digital morphology analyser. Developers use the run to add a structured differential and an abnormal-cell alert to a laboratory information system.

Accepted input

Two kinds of input describe the same smear:

• Whole-slide image of the monolayer of a Wright- or May-Grünwald-Giemsa-stained smear, as DICOM VL Whole Slide Microscopy Image or a scanner file (SVS, NDPI, MRXS, CZI, OME-TIFF and others).
• Single-cell images exported by a digital morphology analyser, as JPEG, PNG or TIFF crops of individual cells.

Requirements

Requirement	Why
Romanowsky-type stain (Wright, MGG)	Granules, nuclear chromatin and cytoplasm colour separate the cell classes
Readable monolayer on whole slides	Cells are classified where they lie singly, not in thick or feathered areas
Pixel spacing on whole slides	Cell size helps separate blasts from lymphocytes and monocytes

Optional context

The full blood count, analyser flags, age and the clinical question can be passed in clinical_context; the guidance reads the differential against them.

The result

Section	Content
WBC differential	Class of every nucleated cell, differential percentages, cell gallery by class and the blast or abnormal-cell alert
Draft report	Opt-in (options.report): an English narrative that interprets the result for the reader (findings, impression, limitations); every number is checked against the findings

Counts and percentages sit in measurements; each gallery cell keeps a link to its position on the slide or to its source image.

Standards

• Morphology: ICSH 2015 recommendations for the standardisation of nomenclature and grading of peripheral blood cell morphological features.
• DICOM: classified cells as Microscopy Bulk Simple Annotations on whole slides, the differential in SR TID 1500, an Encapsulated PDF.
• Interoperability: FHIR R4 DiagnosticReport with one LOINC-coded Observation per cell class.

The blast alert

The alert names the cells classed as blasts or abnormal lymphocytes, shows them in their own gallery and carries the "refer for haematology review" guidance.

Works with

When blasts are flagged, Bone Marrow Aspirate (path/bone-marrow) reads the follow-up aspirate with a full myelogram and blast percentage.