Hidden blood loss in percutaneous endoscopic lumbar discectomy via the posterolateral approach.

Objectives: The study aimed to evaluate the hidden blood loss (HBL) and its possible risk factors in patients with lumbar disc herniation undergoing percutaneous endoscopic lumbar discectomy (PELD) via posterolateral approach.

Patients and methods: The clinical data of 170 lumbar disc herniation patients (101 males, 69 females; mean age: 57.7±18.0 years; range, 19 to 87 years) treated with PELD via posterolateral approach between January 2021 and January 2023 were retrospectively analyzed. Demographic characteristics, laboratory data, and surgery-related clinical data of the patients were collected, including age, sex, height, weight, body mass index, albumin, blood glucose, hemoglobin (Hb), hematocrit (Hct), American Society of Anesthesiologists (ASA) score, surgical time, number of puncture, and the need for foramenoplasty. Hidden blood loss was calculated, and multiple linear regression analysis was performed to identify risk factors.

Results: The mean Hb in patients with preoperative anemia was 115.8±8.6 g/L. The mean postoperative Hb loss and Hct loss were 7.0±4.5 g/L and 0.02±0.01%, respectively. The mean number of punctures (1-3 punctures vs. >3 punctures) was 2.4±0.7 and 4.6±0.6, respectively. Satisfactory localization was achieved within three punctures in nearly 60% of the patients. More than half (55.3%) of the patients underwent foraminoplasty. The mean surgical time was 110.9±32.0 min. The mean HBL was 178.4±66.5 mL. The mean follow-up time was 6.9±2.2 months. When comparing the preoperative and postoperative incidence of anemia, we found that the incidence of anemia was significantly associated with HBL (p<0.001). Multiple linear regression analysis showed that HBL was positively correlated with the number of punctures, foraminoplasty, and surgical time.

Conclusion: Our results suggest that the number of punctures, foraminoplasty, and surgical time are independent risk factors for HBL after PELD via posterolateral approach. Therefore, HBL should not be ignored in patients with these risk factors to ensure patients' safety in the perioperative period.