Perioperative coagulation shifts after degenerative lumbar surgery and exploratory lower-limb thrombosis signals.

Background: Degenerative lumbar disease surgery is associated with perioperative blood loss, tissue injury, postoperative immobility, and activation of hemostatic pathways. Although venous thromboembolism after spine surgery has been investigated extensively, less attention has been given to the integrated perioperative shift of routine hematologic and coagulation markers in degenerative lumbar surgery. Methods: This single-center retrospective observational study consecutively included patients undergoing surgery for degenerative lumbar disease at Beijing Luhe Hospital, Capital Medical University, between January 1, 2021 and December 31, 2022. After source verification and construction of the locked patient-level analytic cohort, 143 patients were included. Paired preoperative and postoperative day 1 hematologic and coagulation markers were analyzed. Postoperative lower-limb venous thrombosis status was available for 142 patients and was ascertained by clinical records and routine bilateral lower-limb venous ultrasonography, usually performed after drainage tube removal on postoperative day 2 or 3. Thrombosis-stratified comparisons, descriptive ROC analyses, and limited Firth logistic regression were performed only as exploratory and hypothesis-generating analyses. Results: Ten asymptomatic calf muscular vein thromboses were recorded among 142 patients with available thrombosis status, corresponding to an event rate of 7.0%, and no pulmonary embolism was recorded. Core paired laboratory analyses included 143 preoperative and postoperative day 1 pairs. Hb decreased from 141.00 to 115.00 g/L, HCT from 0.42 to 0.34, and PLT from 216.00 to 201.00 × 10^9/L. APTT shortened from 29.40 to 25.90 s, whereas FIB increased from 2.85 to 3.45 g/L and D-dimer from 0.08 to 0.53 μg/mL DDU; all paired comparisons were statistically significant. In exploratory thrombosis-stratified analyses, patients with ultrasound-detected asymptomatic calf muscular vein thrombosis had higher postoperative D-dimer than those without thrombosis, 1.16 vs. 0.51 μg/mL DDU, lower postoperative APTT, 24.35 vs. 26.00 s, and lower postoperative AT-III, 88.50% vs. 99.00%. In a descriptive ROC analysis, postoperative D-dimer yielded an AUC of 0.715 with bootstrap 95% CI 0.533-0.905. Conclusions: Routine laboratory markers demonstrated expected perioperative hematologic and coagulation shifts after surgery for degenerative lumbar disease. Exploratory differences in postoperative D-dimer, APTT, and AT-III among patients with ultrasound-detected asymptomatic calf muscular vein thrombosis require prospective validation and are not sufficient for screening, risk stratification, threshold derivation, or prophylaxis decisions.