Total and Hidden Blood Loss in Biportal Endoscopic Versus Tubular-Based Minimally Invasive Transforaminal Lumbar Interbody Fusion.

BACKGROUND

The purpose of this study was to compare total blood loss (TBL) and hidden blood loss (HBL) between biportal endoscopic transforaminal lumbar interbody fusion (BE-TLIF) and tubular-based minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) using hematocrit-based calculations. The study aimed to compare blood loss outcomes between the 2 techniques during their respective initial adoption phases to ensure a fair comparison of hemostatic control.

METHODS

This retrospective study included 72 patients who underwent single-level lumbar fusion. Thirty-six consecutive BE-TLIF cases (June 2023-July 2025) were compared with 36 early-period MIS-TLIF cases (2016-2021) to ensure comparable learning curve stages. TBL was calculated using Nadler's and Gross's formulas based on hematocrit changes. HBL was derived by subtracting estimated blood loss and drainage from TBL.

RESULTS

The BE-TLIF group underwent more additional adjacent-level decompression procedures and longer operative times than the MIS-TLIF group. However, the BE-TLIF group showed consistently lower TBL at the immediate postoperative time point (0.42 vs. 0.62 L, p = 0.001) and at the time point of maximum calculated loss (0.87 vs. 1.05 L, p = 0.025). HBL was similar between the groups (0.32 vs. 0.43 L, p = 0.262), suggesting that reduced TBL in the BE-TLIF group resulted from decreased intraoperative bleeding rather than postoperative extravasation differences. No patients in either group required blood transfusion.

CONCLUSIONS

Despite longer operative times and more extensive adjacent-level decompression procedures, BE-TLIF resulted in significantly lower TBL. HBL was comparable between the techniques, indicating that BE-TLIF's hemostatic advantages are achieved through improved intraoperative control. Even during the initial adoption phase, BE-TLIF demonstrated superior hemostatic control.