Hidden blood loss in unilateral open-door cervical laminoplasty for multilevel cervical spondylotic myelopathy.

Objectives: This study aims to evaluate the hidden blood loss (HBL) and its possible risk factors after unilateral open-door cervical laminoplasty (UOCL) in patients with multilevel cervical spondylotic myelopathy (MCSM).

Patients and methods: Between January 2018 and March 2023, a total of 105 patients (55 males, 50 females; median age: 76 years; range, 52 to 93 years) who underwent C3-7 UOCL for MCSM were retrospectively analyzed. Data of the patients were recorded, including age, sex, height, weight, plasma albumin, blood glucose, hematocrit, American Society of Anesthesiologists (ASA) score, surgical time, and intraoperative blood loss. The HBL was calculated according to the Sehat formula, and risk factors were identified.

Results: The median surgical time was 180.7 min. The median total blood loss (TBL) and median HBL were 507.4 mL and 201.7 mL, respectively. Correlation analyses revealed that body mass index and surgical time were correlated with HBL (p<0.05). However, multiple linear regression analysis showed that HBL was positively correlated with surgical time (β=0.293, p<0.05).

Conclusion: Our study results showed that surgical time is an independent risk factor for HBL. Therefore, HBL should not be overlooked in patients with MCSM undergoing UOCL, particularly in the patients with expected long surgical time.