Percutaneous core needle biopsies: the yield in spinal tuberculosis.

BACKGROUND Current recommendations for spinal tuberculosis (TB) not requiring open surgery include core needle biopsy to confirm TB and determine drug sensitivity. International figures show the positive culture yield from core needle biopsies is 50 -- 83%.Objectives. To (i) assess the yield of percutaneous needle biopsies; (ii) identify factors that may lead to a negative result; and (iii) determine whether, TB being suspected, needle biopsy is justified. METHODS We conducted a multicentre retrospective review of 44 patients treated for suspected spinal TB between January 2009 and April 2012, who did not require open surgery. Data captured included demographics, relevant history, outcome of investigations and histopathological findings in patients. RESULTS The overall positive TB culture rate was 59%. Age, duration of symptoms, HIV and neurological status, erythrocyte sedimentation rate and core size had no statistical influence. Of the 7 patients receiving TB treatment at the time of biopsy, 3 were culture-positive. Multidrug resistance was evident in 12% of positive cultures. The positive culture yield was 40% at Tygerberg Hospital and 75% at Groote Schuur Hospital, with no difference in histological yield. This was attributed to the practice of decontaminating specimens prior to culture at Tygerberg Hospital. The highest culture yield (32%) came from samples showing non-necrotising chronic inflammatory changes. CONCLUSION Percutaneous biopsy remains an important tool to diagnose and manage spinal TB. The yield of transpedicular biopsies in this study was comparable with international figures. Specimen decontamination prior to culture had a direct negative influence on biopsy culture yield, as did prior TB treatment.