Study design:

This was a retrospective study.

Objective:

The objective of this study was to evaluate the volume of hidden blood loss (HBL) and analyze its influential factors in single level oblique lateral interbody fusion (OLIF) surgery.

Summary of background data:

OLIF is a minimally invasive spine surgery and is increasingly used to treat lumbar degenerative disk diseases. It is generally believed that there is less bleeding during OLIF. However, HBL during the perioperative period is commonly ignored.

Materials and methods:

From January 2018 to December 2019, a total of 70 patients underwent single level OLIF surgery were retrospectively reviewed. The values of preoperative and postoperative hematocrit (Hct) were recorded to reckon HBL in accordance with Gross formula. The influential factors included sex, age, height, weight, body mass index, hypertension, diabetes mellitus, American Society of Anesthesiologists classification, disease etiology, surgery type, operative time, surgical corridor distance, psoas cross-sectional area, thickness of abdominal wall soft tissue, coagulation panel value, platelet count, values of Hct and hemoglobin, and intraoperative blood loss. Independent sample t test, Pearson correlation, Spearman correlation, and multivariate linear regression analysis were performed to investigate the risk factors related to HBL.

Results:

The average volume of HBL was 809 mL and the average hemoglobin loss was 27.1 g/L in OLIF procedure. Multiple linear regression analysis revealed that thickness of abdominal wall soft tissue was the independent risk factor for HBL (P=0.008). Whereas age (P=0.414), activated partial thromboplastin time (P=0.314), preoperative value of Hct (P=0.854), disease etiology (P=0.362), operative time (P=0.389), and intraoperative blood loss (P=0.912) were not statistically associated with HBL.

Conclusions:

HBL was substantial and the average volume of HBL was 809 mL in single level OLIF surgery. The thickness of abdominal wall soft tissue was the risk factor of HBL. Accurate assessment of HBL can prevent perioperative complications and ensure patients’ safety.