• Incomplete request forms & improper sample labelling to blame 
• Capacity building progs. for MOs/nurses/health staff & guidelines on sample collection/acceptance/rejection criteria, needed 

The overall rejection rate for the blood specimens at the Laboratory of the National Institute of Infectious Diseases in Sri Lanka was 71.15%, while incomplete request forms accounted for the majority of rejection rates (54.2%) and the rejection rate of haematology (blood and bone marrow cells) samples was 34.21% due to improper sample labelling.

These findings were made in an updated review article on the ‘Identification of pre-analytical errors in the Laboratory of the National Institute of Infectious Diseases, Sri Lanka’ which was authored by P.D. Koggalage, M.P.G.D. Madhubhashini, D.U. Abeysinghe and G.R.D.M. Abeywickrama (all four attached to the National Institute of Infectious Diseases) and published in the Sri Lankan Journal of Medical Administration's 24th volume's second issue, this month (May, 2024).

Laboratory reports play a major role in effective patient management. Therefore, the accuracy and precision of laboratory results should be maintained. The quality of the laboratory procedures, per V. Bhat, M. Tiwari, P. Chavan and R. Kelkar's ‘Analysis of laboratory sample rejections in the pre-analytical stage at an oncology centre’, is associated with three main phases, namely, pre-analytical, analytical, and post-analytical. According to S.F. Green's ‘The cost of poor blood specimen quality and errors in pre-analytical processes’, up to 75% of total laboratory errors occurred in the pre-analytical phase, thus influencing the quality of the laboratory reports. 

The most important pre-analytical variables are specimen collection, handling, and transportation. All the samples that are received in the laboratory should be assessed for acceptability by the laboratory. According to Koggalage et al., some errors in the samples received at the National Institute of Infectious Diseases Laboratory include haemolysed (the pathological process of the breakdown of red blood cells in the blood) samples, clotted samples, samples received in improper containers, samples mismatched with the request forms, improperly labelled samples, leaking samples, and overfilled and under-filled samples (for the erythrocyte sedimentation rate [measures how quickly red blood cells settle to the bottom of a test tube] {ESR} and coagulation studies) that may lead to erroneous laboratory results. These errors are the most common reasons for repeat sample collection that may affect patient care and delay turnaround time.

Hence, Koggalage et al. sought to determine the sample error rate and identify the causes of sample errors at the Laboratory of the National Institute of Infectious Diseases, Angoda. The study was a cross sectional one. Each rejected specimen's data sheet contained information about the blood samples that were rejected. Over the course of two weeks from 14 August of last year (2023) to 24 August 2023, data of the samples received at the said Laboratory were gathered on 14 consecutive weekdays from 8 a.m. to 4 p.m. The total sample rejection rate and the rejection rates according to the rejection criteria and the investigation were calculated. A formula was used to calculate the rejection rates: the sample rejection rate equaled the number of samples rejected divided by the total number of samples received, and multiplied into 100. 

Results

Within 14 consecutive weekdays, the Pathology Laboratory received 2,000 samples in total, of which 1,423/71.15% met the rejection criteria. The cause of errors in the Biochemistry tests and the rejection criteria included insufficient volume, haemolysed samples, there being no signature and date in the request form, there being no ward number in the request form, there being no patient name in the request form, there being no gender in the request form, and being unclearly labelled. The cause of errors in the Full Blood Count (FBC) test included insufficient volume, illegible request forms, mismatched samples, incorrect labelling, clotted samples, and the outer surface of the tube being contaminated with blood. The cause of error for other tests (the Prothrombin Time [measures how quickly the blood clots] / the International Normalised Ratio [tells how long it takes for the blood to clot] {PT/INR}; the Activated Partial Thromboplastin Time [measures how long it takes the blood to form a clot] {APTT}; the ESR; and the Urine Full Report {UFR}) included insufficient volume, overfilled samples, the sample being collected into an improper container, and incorrect labelling. Out of all the rejection criteria, incomplete request forms accounted for the majority of rejections (54.2%) of the blood samples. The highest rejection rate was found for requests for Biochemistry analysis, where the medical officer's signature and the date of request were not mentioned on the request form. Incorrect labelling had the highest rejection rate (30.1%) for the FBC tests, and among other rejection criteria, incorrect labelling had the highest rejection rate (5%) for other tests as well.

Discussion

Laboratory reports, as an Indian study (R. Chawla, B. Goswami, D. Tayal and V. Mallika's ‘Identification of the types of pre-analytical errors in the Clinical Chemistry Laboratory: One year study at the Govind Ballabh Pant Hospital) emphasises, play a major role in modern medicine which relies highly on clinical diagnosis data. The rejection of laboratory samples may lead to the delay in proper patient management. The rejection of laboratory samples may be caused by an increase in the turnaround time of the laboratory reports. In the case of the increased turnaround time of laboratory investigation reports, it may, as a South African study involving a tertiary laboratory in the Capital points out (L.A. Jacobsz, A.E. Zemlin, M.J. Roos and R.T. Erasmus's ‘Chemistry and hematology sample rejection and clinical impact in a tertiary laboratory in Cape Town’), affect the productivity of the healthcare services. The overall rejection rate of the haematology samples in the current study was 34.21%. 

In the current study, out of all the rejected samples, 30% of the rejection rate was due to the improper labelling of the sample. Out of all the biochemistry samples, 50% of the rejection rate was due to incomplete request forms. From the rejected samples (three) for the PT/INR test, about 12.9% were rejected due to overfilling. L.K. Dilshika, W.V. Bandara and A.D. Karunanayaka's ‘A study on sample rejection rates due to pre-analytical errors: Associated factors and knowledge, attitudes and practices of nurses on blood sample collection for haematology at a Teaching Hospital (Karapitiya)’ recorded the rejection rate of the overfilled samples in the PT/INR test as 90% out of the total rejected samples in the PT/INR test. 

In contrast to sample collection procedures, the current study's highest rejection rates were found to be the result of incorrect request forms and improper sample labelling. The accuracy of the laboratory reports may be primarily impacted by mislabelled items and incomplete request forms. Inaccurate request forms, such as those that omit the ward or the department, can result in lost laboratory reports and needless patient specimen duplication. The study also revealed that request forms were lacking the medical officer's (MO) signature and the requested date, which are serious issues. This could end up in audit queries and ambiguous situations for laboratory professionals.

Therefore, Koggalage et al. recommended a continuous educational programme of laboratory sample collection, storage, and transportation in order to improve the productivity of the laboratory service. This study shows that the knowledge of nurses still needs to be updated in certain aspects such as the suitable specimen collection containers for several investigations, the amount of blood needed for several tests, the importance of mixing anticoagulant and blood in the container, and the importance of mentioning proper patient details in both the request forms and the labels. Finally, the findings of the current study encouraged laboratory staff to prepare and distribute specimen rejection criteria documents for nursing officers in all wards at the National Institute of Infectious Diseases, Angoda. 

The overall rejection rate for the blood specimens was 71.15%. Incomplete request forms accounted for the majority of the rejection rates (54.2%), while the rejection rate of haematology samples was 34.21% due to improper sample labelling.

Therefore, the relevant healthcare workers should pay more attention to patient investigations relevant to the blood samples in order to provide appropriate patient management with minimal errors in the investigation reports.

Recommendations

Capacity building programmes for MOs, nursing officers and other relevant health staff categories on blood sample collection, storage, and transportation were recommended along with the need for guidelines on sample collection, sample acceptance, and rejection criteria.