Hidden Blood Loss in Percutaneous Endoscopic Lumbar Discectomy (PELD): a Prospective Study

Abstract Background: Percutaneous endoscopic lumbar discectomy (PELD) is a minimally invasive technique for treatment of lumbar disc herniation (LDH) that requires only an eight-mm skin incision and promotes faster recovery. It is widely believed that the procedure is associated with minimal blood loss. However, significant perioperative hidden blood loss (HBL) is frequently unaccounted for. This study aimed to investigate HBL and peri-operative factors contributing to HBL in a series of individuals undergoing PELD.Methods: As a prospective observational study, 156 patients, mean age 41.6 years (ranged from 17 to 71), undergoing PELD were finally enrolled between May 2019 and November 2020. The analyzed factors included gender, age, body mass index (BMI), symptom duration, operation approach/technique, operation duration, the presence of associated chronic diseases (e.g., hypertension, rheumatoid arthritis, and diabetes mellitus), and improvements in Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA), and Oswestry Disability Index (ODI) scores. Gross’s formula was applied to calculate blood loss from recorded values for patient height, weight, and hematocrit levels before and after surgery. Multivariate linear regression analysis and t test were performed to identify factors that contributed significantly to HBL.Results: The mean HBL during PELD was 201 ± 126 mL, and the Hb reduction observed post-operatively was 7.4 ± 4.5 g/L. A lateral surgical approach was associated with greater HBL compared with an interlaminar approach. However, no significant differences in VAS, JOA, and ODI score improvements were noted between the two surgical approaches. Increased surgical times and foraminal decompression were identified by multivariate linear regression analysis as linked to increased HBL. As expected, the occurrence of post-operative anemia was significantly associated with HBL. Age, gender, BMI, symptom duration, and associated chronic diseases showed no association with increased HBL during PELD. Conclusions: HBL is increased in PELD patients with long surgical times and lumbar foraminal decompression.