Factors affecting the results or processing of Haematology tests - Manchester University NHS Foundation Trust

All sections of Haematology

Test	Factor affecting result/processing	Outcome
All Tests	Failed Specimen Acceptance Policy (Routine samples and Blood Transfusion samples)	Would not process
	Unlabelled	Would not process
	Poorly printed label	Would not process
	Label not straight on sample	Would not process
	Wrong sample for requested test	Would not process
	Wrongly labelled	Would not process
	Sample leaked in transit	Would not process (If multiple samples were put in the specimen bag ALL samples would not be processed)
	Sample broke in transit	Would not process (If multiple samples were put in the specimen bag ALL samples would not be processed)

Coagulation

Test	Factor affecting result/processing	Outcome
Routine clotting tests	Under filled sample	Would not process
Routine clotting tests	Haemolysis	Would process Depending on the degree of haemolysis an estimated result may be reported off the analyser with a comment ‘? Validity of result due to haemolysis’
Routine clotting tests	Lipaemia	Would process Depending on the degree of lipaemia an estimated result may be reported off the analyser with a comment ‘? Validity of result due to lipaemia’
All clotting tests	Clotted	Would not process
Clotting assays	Secondary clot in frozen sample	Depending on size of clot would process and add comment ‘? Validity due to secondary clot’ or would not process and add comment ‘Clotted’

Blood counts

Test	Factor affecting result/processing	Outcome
FBC	Small sample	Paediatric- minimum required sample volume – 500µl otherwise comment ‘Insufficient’ Neonate- minimum required sample volume – 160µL-otherwise comment ‘Insufficient’ Adult – minimum required sample volume – 1.5ml- otherwise comment’ Insufficient’
FBC & ESR	Small sample	Paediatric – separate sample ESR. FBC + ESR requires 2.5ml in FBC tube otherwise will be reported as ‘Insufficient’
FBC & Film	Old sample (Greater than 24 hours)	FBC would not be processed and comment-‘Too old for analysis’ Film would be reported as –‘Too old for morphology’
FBC, ESR & Retic	Clotted Sample, or severe case of Cold Agglutination	Would not be processed Severe cases of Cold Agglutination the sample must be sent warm (37⁰C) to the laboratory
FBC	EDTA may cause clumping of platelets	This would result in a falsely low platelet count- laboratory will check a blood film and ask for citrated (Coag) sample to attempt an accurate measurement of the platelets
CSF	Contaminated with red cells	Would process-appropriate comment will be added
Bone marrow smears	Not enough marrow material to perform stains on	Could not perform stains – repeats would be requested

Blood transfusion

Test	Factor affecting result/processing	Outcome
X-Match Samples & Grouping Samples	Extreme Haemolysis	Would not use – repeats will be requested
Grouping Sample	Clotted Sample	Would not process
Samples for Cold Agglutinins	Sent to the lab ‘cold’ i.e. not in warm water	Would not process

Haematinics and Red cell investigations

Test	Factor affecting result/processing	Outcome
Haematinic assays	Haemolysis	Would process and add appropriate comment
Haemolytic assays	EDTA clotted	Would not process
Plasma Viscosity	Sample stored in fridge	Would not process
G6PD Assay	Temperature during transit	Depends on the results from the travel control sample.

G6PD Assay and the testing of travel controls from external sites

When referring tests to MFT we require a completely anonymised sample, that is suspected to be normal but taken under similar circumstances and of similar age to accompany the test samples as a “travel control”. The travel control will only be tested in the event of abnormal results on the patient test samples in order to ascertain that abnormal results are not due to unknown issues which may affect samples during transit. Should the travel control then also show abnormal results the patient test results will be rejected, and a repeat sample requested as it may be assumed that the test results are not reliable due to poor travel conditions. No results will ever be reported on the anonymised travel control. It is a UKAS requirement that the influence of travel conditions is considered when interpreting results.

This list is not exhaustive – there may be other factors affecting the reporting of results which are not listed

(Last reviewed July 2024)