This single center prospective study over a 4-year period illustrates the intensity of pain and incidence of serious adverse events following a BMAB from an academic center in India. Our study identifies pain intensity as low when performed in our hands. Though pain following BMAB has been reported as moderate to severe in up to one third of the patients; it is well recognized that sensitivity to and tolerance of pain differs amongst ethnic groups(9–11). The mean pain score of 2.7 (± 1.39) in our study reflects a low pain score and is similar to a recent Italian national survey (12) This is but in conflict to experience with other procedures that, amongst ethnic groups; Indians have a higher mean pain score and need more medications for pain control.(10) This could be because of our policy of premedication with tramadol. Opioids have been reported to reduce pain associated with the vacuum aspiration of bone marrow.(9) Intravenous tramadol is a safe agent and is known to reduce procedural pain when given pre procedure.(13)
Our study also confirms the safety of the procedure with no infectious complications or death. Reported complications following BMAB include trauma to neighboring structures, infection and hemorrhage(14) Though it can be a potentially hazardous procedure; and deaths have been reported; serious complications have been rare.(6, 15, 16) In our series 2 (0.2%) patients had serious hemorrhage. Both these patients had retroperitoneal hemorrhage and needed transfusion. One was managed conservatively while the second one required surgical excision of the retroperitoneal hematoma and ligation of right internal iliac artery. This adverse event has been reported and both conservative and surgical approaches have been utilized to manage this complication(3, 17–19). Thrombocytopenia and anticoagulant therapy have been reported as potential factors for this complication. Both our patients had neither thrombocytopenia nor were on anticoagulant therapy. Both these patients had a myeloproliferative neoplasm. This is similar to the experience from UK where this diagnosis was associated with higher risk of bleeding during bone marrow biopsy(6). The mechanisms that may be involved with the risk of bleeding in chronic myeloproliferative neoplasms include acquired Von Willebrand disease or an acquired platelet dysfunction and storage pool defects compounded by the hypersplenism.(20)
Our final objective was to determine factors associated with lower pain perception that help improve the patient experience in our population. A small proportion of patients experienced severe pain, but clearly the vast majority were comfortable with the procedure. Factors which have been previously explored in possible connection to pain in BMAB include gender, age, level of education, information prior to procedure, Prior BMAB, indication, operator experience, duration, and difficulty of the procedure.(9) Though a prior BMAB has been associated with unbearable pain in an earlier report; in our experience this is associated with a lower pain score.(21) This possibly could be due to a more informed patient due to their earlier experience and also supported by the detailed explanation prior to each procedure. It has been observed that patients with information about the procedure or who had previous personal experience with bone marrow examination could arrange a mental strategy and experience lesser pain.(21)
We found no relation to pain with operator experience or indication. In our study the number of attempts influenced pain. Higher number of attempts was associated with a higher pain score. This in likely due to an increase in anxiety or reflective of the observation that patients undergoing lengthy procedures( due to repetitive attempts) report higher pain scores than patients undergoing shorter uncomplicated procedures. (22) In our series patients who had a meal intake or a juice prior to the procedure reported lower pain scores. This is a novel association. Evidence does support an analgesic effect of sweet solutions for newborns and infants and has been explored in older children(23). However, data is scarce on food intake and pre procedural pain in adults. A report on healthy volunteers showed a better pain threshold and tolerance in subjects after food intake as compared to before intake of food postulating that intake of food could stimulate the release of hormones and endorphins leading to the observed hypoalgesia.(24) This novel association needs to be explored since most patients who visit a clinic in India report empty stomach in anticipation of investigations.
Strength & Limitations
We present some of the first information on procedural pain in BMAB and its complications from India. We were able to identify factors which might help improve the experience of the procedure and be alert to complications.
The findings of the study should be interpreted with several limitations in mind. We had a diverse group of patients who underwent a BMAB. We included patients with both malignant and benign diseases of the blood and marrow. We did not account for / have data on the baseline pain threshold from comorbidity prior to procedure, meaning that some patients may have had a higher threshold that contributed to varied pain perception. There is also likely to be significant heterogeneity in pain perception across the various ethnicities and a larger prospective study from multiple centers in India is required to conclusively state that our results are representative of the country.