Chapter 2 · Blood film review and morphology

Not all flagged samples require a blood film — the laboratory must have documented blood film review criteria. Blood films must be prepared and examined by a trained haematology scientist or pathologist when criteria are met. Morphology findings must be documented in a structured format: RBC morphology, WBC differential and morphology, platelet morphology. The authorising scientist must sign the morphology report. Films must be retained for a defined period.

Chapter 2 · Practical example

Blood film morphology — specific comments, not generic flags

Morphology comments on blood films must be specific enough for the clinician to act on. Generic comments describing findings without clinical context transfer risk back to the requester.

▲ The situation

A blood film made on a sample showing Hb 79 g/L and MCV 62 fL shows microcytic hypochromic red cells, target cells, and pencil cells. The scientist writes: abnormal red cell morphology — recommend clinical review.

Reference: ISO 15189:2022 Clause 7.5

✓
Good practice

The section head reviewing the film asks the scientist to make the comment clinically specific: Microcytic hypochromic anaemia with target cells and pencil cells. This morphological pattern is consistent with iron deficiency or beta thalassaemia trait. In this patient’s demographic context, haemoglobin electrophoresis and serum ferritin/iron studies are recommended to differentiate between these diagnoses. This gives the GP specific investigations to order immediately.

✗
Poor practice

The generic comment is released. The GP, not a haematologist, knows the morphology is abnormal but does not know which investigations to order. She refers to haematology. The haematologist orders iron studies and haemoglobin electrophoresis — investigations that could have been ordered directly by the GP six weeks earlier with a specific laboratory comment.

● What this means for your practice

A morphology comment must answer two questions: what did you see, and what does it mean clinically. A comment that answers only the first question is incomplete. The laboratory’s interpretive expertise is part of the clinical service.