Hidden blood loss following 2- to 3-level posterior lumbar fusion

Patients undergoing single-level posterior lumbar decompression and fusion (PLDF) usually do not need transfusions. However, patients undergoing two or three-level PLDF occasionally require transfusion postoperatively even when estimated blood loss (EBL) or blood loss from drains appears acceptable. Estimating the volume of HBL is critical in perioperative fluid management.

To determine the volume of hidden blood loss (HBL) in two- or three-level PLDF.

Single-center, multisurgeon, secondary analysis from a prospective randomized clinical trial of cell saver use.

Patients enrolled in a prospective randomized trial of cell saver undergoing two- or three-level PLDF were included in this analysis.

Total blood loss was calculated using four estimation formulas including Bourke's, Gross', Camarasa's, and Lopez-Picado's formulas. HBL was determined by subtracting the visible loss (EBL and blood loss from drains) from the calculated total blood loss.

A total of 89 patients (36 males, mean age 62 years) were included. Seventy-five patients underwent open two-level fusion while 14 had three-level fusions. Intervertebral fusion was performed in 20 patients. Mean surgical time was 261 minutes, and EBL was 685 mL. Mean blood loss from drains was 824 mL. Seventy patients received allogenic blood whereas 47 cell saver blood reinfused intraoperatively. HBL was calculated to be 678 mL, 963 mL, 1,267 mL, and 819 mL using each formula.

HBL following two or three-level PLDF was substantial and more than EBL. Postoperative management of blood loss should take HBL into account.