Comparison of the total and hidden blood loss in patients undergoing single-level open and unilateral biportal endoscopic transforaminal lumbar interbody fusion: a retrospective case control study

Table 4 The result of perioperative blood changes in patient

Variable	ULIF	O-TLIF	P-value
Preoperative haematocrit (%)	39.49 ± 4.43	40.85 ± 4.25	0.000*
Postoperative haematocrit (%)	36.37 ± 4.24	36.64 ± 4.42	0.000*
Preoperative hemoglobin (g/L)	133.02 ± 18.14	138.04 ± 15.56	0.000*
Postoperative hemoglobin (g/L)	119.07 ± 15.70	120.23 ± 15.40	0.000*
Preoperative red blood cells (10^12/L)	4.48 ± 0.45	4.49 ± 0.48	0.000*
Postoperative red blood cells (10^12/L)	4.05 ± 0.38	3.96 ± 0.51	0.000*
Patient’s blood volume (ml)	4008.11 ± 626.59	4092.18 ± 833.09	0.558
Total blood loss (ml)	326.86 ± 223.45	427.97 ± 280.52	0.043*
Measured blood loss (ml)	99.00 ± 72.81	270.66 ± 102.34	0.000*
Hidden blood loss (ml)	227.86 ± 221.75	157.31 ± 268.08	0.143
TBL as a % of PBV	8.15 ± 5.37	10.45 ± 5.87	0.000*
HBL as a % of TBL	69.71 ± 23.72	36.76 ± 18.79	0.000*

Open transforaminal lumbar interbody fusion O-TLIF, Unilateral biportal endoscopic transforaminal lumbar interbody fusion ULIF, Total blood loss TBL, Hidden blood loss HBL, Patient’s blood volume PBV. Data are mean ± standard deviation, *P < 0.05

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