Beyond visible blood loss: Rethinking perioperative bleeding in endoscopic spine surgery

Table 1 Hidden blood loss patterns across endoscopic spine procedures

Procedure type	Typical HBL pattern	Main drivers	Practical implication
UBE/BESS decompression[12,13,21]	Often > 50% of total blood loss; commonly 250-500 mL	Operative time, BMI, hypertension, preoperative Hct	Visible blood loss markedly underestimates true perioperative burden
PELD/endoscopic discectomy[14,15]	Increases with access complexity and additional decompression	Foraminoplasty, number of punctures, operative time	“Minimal access” does not guarantee minimal blood loss
Cervical endoscopic procedures[4]	Present despite smaller operative field	Number of levels, operative time	HBL is not confined to lumbar procedures
Endoscopic lumbar fusion (endo-TLIF/UBE-LIF)[16-18]	More variable; often higher than decompression-only cases	Fusion levels, operative duration, comorbidity burden	Fusion should be considered a distinct bleeding profile
Endoscopic vs open surgery[5,19,20]	Lower total blood loss, but hidden component remains substantial	Technique, surgical extent, measurement method	“Low blood loss” depends on how it is measured

HBL: Hidden blood loss; UBE: Unilateral biportal endoscopy; BESS: Biportal endoscopic spine surgery; BMI: Body mass index; PELD: Percutaneous endoscopic lumbar discectomy; TLIF: Transforaminal lumbar interbody fusion; LIF: Lumbar interbody fusion.