Adequacy of Bone Marrow Trephine Biopsy in a Tertiary Care Center

OBJECTIVES: To review the bone marrow trephine biopsies analyzed at the Health Sciences Centre in Winnipeg, Canada in 2007 and evaluate them in terms of published criteria for adequacy.

METHODS: The Health Sciences Centre (HSC) is the largest tertiary care centre in the province of Manitoba, and houses the only leukemia treatment/bone marrow transplant ward. It also provides pathology services to the adjacent clinics of the provincial cancer agency. One thousand and twelve (1012) bone marrow aspirates and biopsies were identified from January 1 – December 31, 2007 through pathology records. Bone marrow biopsies performed on children (age <18 years) and specimens referred from other centers were excluded. A total of 770 bone marrow aspirates and biopsies were identified as meeting the inclusion criteria and 67 were unavailable for evaluation. 703 biopsies were included in the final analysis. Data was collected on location of procedure (HSC ward vs. outpatient cancer clinic), operator and indication of biopsy. The total length of each biopsy and length of interpretable bone marrow were measured. The bone marrow biopsies were compared to published criteria for adequacy: 16 mm total length prior to processing (11 mm after processing), and 8 mm of interpretable marrow after processing.

RESULTS: Using 8 mm of interpretable marrow as the criterion of adequacy, the overall adequacy rate was 67% (472/703). There was a significant difference in the percentage of adequate biopsies between operators. Hematologists obtained an adequacy rate of 81% (220/272), Registered Clinical Assistants (RCA) 63% (169/268), oncologists 56% (5/9), residents 50% (71/141), and medical students 54% (7/13), p<0.001). The mean overall length of biopsy after processing was 14.5 mm (SD 5.3 mm), with 10 mm (SD 5.4 mm) of interpretable bone marrow. Hematologists obtained samples with a mean length of interpretable bone marrow of 12.4 mm (SD 5.8 mm), RCA 8.6 mm (SD 3.9 mm), oncologists 10 mm (SD 4.1 mm), residents 8.4 mm (SD 5.7 mm), and medical students 8.2 mm (SD 4.5 mm). There is a significant difference in length of core biopsies obtained by different operators. Hematologists get longer biopsies than residents (p≪0.01), RCA (p≪0.01) and medical students (p<0.05). When looking specifically at those cases (n = 294) in which the requisition submitted at the time of the procedure stated an indication for which an adequate biopsy is crucial (detection of infiltration, diagnosis and staging of lymphoma) or when there was an inadequate/dry aspirate (n = 74), there was no significant difference in percentage of adequate biopsies when compared to the overall adequacy rate (70% vs. 67%, p=NS). When the biopsy was performed at the outpatient cancer clinic, the adequacy rate was 72.5% (342/472), whereas biopsies performed on HSC wards had an adequacy rate of 56.4% (133/236).

CONCLUSIONS: A large proportion of bone marrow biopsies performed during the study period were of inadequate size. There was a significant difference in quality of bone marrow biopsies obtained by different operators, and among biopsies performed at different locations. The proportion of adequate samples was no better in cases where the aspirate was dry or where the suspected diagnosis should have mandated collection of an adequate sample. A multidimensional intervention including education and procedural changes will be implemented in order to improve the quality of bone marrow biopsies performed.