Evaluation of Clinical Indications and the Reviewed Diagnoses from Bone Marrow Aspirate Examinations in Paediatric Patients at a Central Hospital in Zimbabwe

Introduction

There are a few haematological disorders whose diagnosis can be revealed using a bone marrow aspirate examination.

Bone marrow is the viscous tissue found in the confines of the long bones. The bone marrow contains haematopoietic cells, composed in their majority by haematopoietic precursors of the megakaryocyte lineages [1]. Haematological disorders arise mostly due to problems originating from the bone marrow stem cells and microenvironment.

Examination of the bone marrow can help in the diagnoses of many haematological disorders and gives a comprehensive intel on the disorder being investigated and it has been extensively revised to reflect the significant advances that have occurred in molecular biology and genetics [2] Some of the triggers for BMA examination include; diagnostics of unexplained fevers, hepatosplenomegaly, haematological malignancies, follow up after and during chemotherapy and assessment of iron level if biochemical iron studies are not conclusive. Staging of certain malignancies is also a common reason for bone marrow examination [3].

Bone marrow aspirate examination can reveal a normal picture, dry tap, haemodilute or bone marrow infiltration and each of these has its own contributions to the report and ultimately patient care. A haemodilute BMA may be difficult to analyse for the haematologist and unsuitable leading to a delayed diagnosis for the patient, which may lead to further progression of the disease. Pediatric patients differ from adults anatomically and physiologically in various ways, which requires special skill when analysing their bone marrow abnormalities. The results from bone marrow examination may vary from one case to another depending on the clinical indication or suspected condition [4].

Bone marrow examination is the pathological analysis of a bone marrow resemblance acquired through bone marrow biopsy and or bone marrow aspirate. Several staining techniques are used for examination on a microscope. A bone marrow biopsy is a cut section of the bone that contains marrow in it. A bone marrow aspirate is a small amount of bone marrow fluid and cells removed from the bone marrow through a needle. It is also used in follow-up of patients with haematological diseases and for investigating various non-haematological conditions including storage diseases, inborn errors of metabolism, metastatic cancer, and infection that has spread to the bone marrow [2].

Materials and Methods

Demographic and BMA examination data for pediatric patients at Parirenyatwa Group of Hospitals (PGH) medical records were collected and captured directly into an excel sheet. The study cases were from pediatric patients (less than 12 years old) who had a bone marrow examination done between 2016 and 2022 and their demographics and BMA results available.

Data collected were stored on an encrypted excel sheet and patients were assigned a code for confidentiality and security. The data were retrieved from files of request forms in which bone marrow examination results are stored. All results and request forms for BMA are stored in the Haematology department at PGH. The forms were taken and all pediatric request forms that met the criterion of the study were put aside for capturing into an excel document. Each request form was filed accompanied by a result sheet. The request forms selected included the following indication for BMA examination, age, and thesuspected condition if available. Convenience sampling method was used in the collection of data, depending on the ward of admission, age and consideration of the inclusion criterion.

Approval to carry out the research study was sought from the Department of Laboratory Diagnostics and Investigative Sciences, Medical Laboratory Sciences unit, Faculty of Medicine, and Health Sciences at the University of Zimbabwe. Permission to conduct the study was sought from the respective management. Clearance on ethics of the study was sought by application to the Joint Research Ethics Committee (JREC Ref: 65/2022) to obtain approval. Access to subject information was strictly available only to the researchers.

Diverse clinical indications such as; pancytopenia, anaemia, concern for lymphoma, anaemia with thrombocytosis, aplastic anaemia, anaemia with lymphocytosis, bicytopenia and concern for haematological malignancy, were extracted from the records of bone marrow examinations.

The reviewed final laboratory diagnoses were classified into either complete or incomplete reports. The complete reports were those BMA examination results that could be used for patient management. Incomplete reports were those which were found to be unsuitable for reporting and a repeat sample recommended due to procedural or technical errors. The suspected conditions or clinical indications were matched with the final reviewed laboratory results. These were grouped into discordant and concordant. The discordant results are those that were found not matching the clinical suspicion. The matching results are those that had a positive result after having a bone marrow examination reviewed.

The Graph Pad prism 9 program and Microsoft excel were used for data analysis that included descriptive statistics (percentage, range, mean and standard deviation) and comparisons according to the distribution of the data in all variables. A Chi-Square test was used to determine association at p less than 0.05 significance level.

Discussion

A retrospective study of 76 pediatric bone marrow examination reports was carried out to evaluate the correlation between clinical suspicion and the reviewed laboratory diagnosis. Medical records for the cases were analysed and summarized statistically. The study was done at Parirenyatwa Group of Hospitals. The median age of the study participants was 7 years with an inclusive age range of 1 to 12 years. Most of the cases were bone marrow aspirate performed after the age of 6 and this was after presenting with a range of indications repeatedly that led to the bone marrow aspirate being done. Forty-three (57%) of the cases were males and 33 (43%) females.

Out of the 76 cases that were recruited into the study, 62 (81.6%) of them had a diagnostic contribution to the case’s haematological profile. The remaining 14(18.4%) had incomplete laboratory reports due to technical errors. If a bone marrow aspirate specimen is found to be giving an undesired result, the search for the disease-causing agent has to be found elsewhere. However, the patient would have already incurred a cost on the procedure that turned out to be of little or of no use. This means that there was extended investigation time and increased cost in both cases of incomplete reporting and those that were found with no disorder. The hospital stay for these cases is also extended including the cost of the stay in hospital.

Four groups of the triggers for BMA examination were created as follows; 5(6.6%) aplastic anaemia, 21(27.6%) anaemia with variation, 14(18.4%) pancytopenia, and 36(47.4%) with suspected haematological malignancies. This distribution confirms the investigation of haematological malignancies as the most common trigger.

It also demonstrates that Zimbabwe (a low-income country) has an increasing prevalence of haematological conditions in pediatrics. However, other than BMA examination there are other more accurate diagnostic methods that could have been used such as; flow cytometry, immunohistochemistry, molecular genetics, fluorescence in situ hybridization (FISH) and cytogenetics. Unfortunately, PGH did not have those methods during the period studied, which could have reduced the probability of having a BMA examination for morphology as the sole investigative tool.

The burden of anaemia in pediatrics was also evident in the study with a cumulative proportion of 52.6% (aplastic anaemia, pancytopenia and other anaemias) of the cases. Similar trends have been reported in other studies from the region, for example a study done in South Africa concluded that pancytopenia and B cell lymphoma were indications of the highest frequency with 47.8% and 21.7% respectively5. However, there are many factors that can be attributed to the development of pancytopenia in pediatrics such as; infections (including HIV), malnutrition and mutations6. Despite concerted efforts in the fight against HIV, Zimbabwe remains burdened by this problem.

The 62 complete laboratory reports in our study comprised of; 34(54.8%) haematological malignancies, 2(3.2%) with no significant diagnostic features, 5(8.1%) aplastic anaemia, 17(27.4%) with no evidence of neoplasm or infiltration, 3(4.8%) bone marrow hypoplasia, and 1(1.6%) with non haematological bone marrow metastasis. The 34 haematological malignancies were dominated by acute lymphoblastic leukemia (ALL; contributing 45.2% alone; Table 3). This finding is consistent with the general observation that ALL is the most frequent malignant disease in childhood and adolescence, with an annual incidence of approximately 3-4 cases per 100,000 children under 15 years of age [7, 8].

The concordance analysis between clinical suspicion and the revealed laboratory report was poor (Table IV) in our study, for example; in cases that were suspected to have anaemia with thrombocytosis, aplastic anaemia, and lymphadenopathy had a discordance ranging from 66.67% to 100%. Bone marrow examination can be classified as of poor diagnostic value in cases with a discordance of greater than 50% [5, 9, 10, 11]. However, the poor concordance in our study could be attributed to the limited diagnostic test available and the fact that some of the indications given were non-specific and could not be followed up since the study was a retrospective design.

In our study setting, the clinical diagnosis (indications), collection of BMA sample, laboratory processing and reporting of the BMA are done by independent professionals. This could be a possible cause for the increased discordance. However, these findings highlight the need for coordinated workflow and more training for the professionals to have a functional system with a better yield and guidelines on the indications for a BMA examination because a standard or improved system would be important in the reduction of human and technical errors.

There was no statistically significant correlation (p=0.275) at 0.05 significance level to conclude that there is concordance between triggers for BMA examination and BMA examination diagnosis. Nevertheless, there is need to introduce the monitoring and improved standardization of haematological procedures on the clinical side and quality improvement by the laboratory. Furthermore, 14 (18.4%) of 76 cases that had incomplete results reported as either haemodilute for diagnosis or unsuitable for diagnosis meaning no diagnostic report was issued due to poor sample collection is a cause for concern. Therefore, training of junior clinical staff in bone marrow aspirate collection by qualified haematology specialists to reduce trauma, disease burden and cost to the patient and improve on quality.

Conclusion

Haematological malignancies were the most common indications for a bone marrow examination in our study. Haematological malignancies were also found to be the commonest outcome in the BMA examinations done in pediatric patients with the major form being acute lymphoid leukemia. Although the percentage diagnostic yield between the bone marrow examinations and the clinical indications was 62/76 (81.6%), statistically there was not enough evidence to conclude that there is concordance between clinical indications and BMA examination reports.

Limitations

The sample size between the period January 2016 and January 2022 was affected by the global strike of the covid-19 pandemic which came with lockdowns in the years 2020 and 2021 hence not many bone marrow aspirates were done in 2020 and 2021. The study was done based on available laboratory data as the availability of specialised expertise in bone marrow aspirate and trephine biopsy collection was limited in the years before 2020.There was also no control over the specimen in this study as this was a retrospective design.

Recommendations

Further studies need be done to improve and give a confident diagnostic value to bone marrow examinations in pediatrics. Laboratory personnel should be consistently consulted in the making of the smears and sample collection to improve and reduce the technical errors in the bone marrow aspirates that are collected. The health system also needs improvement in the technical methods of analysis for both laboratory and clinical diagnosis as advancements have been made with regards to bone marrow analysis.

Funding

This research was supported by the Fogarty International Center of the National Institutes of Health under Award Number D43 TW011326. However, the content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.