Objective: We studied the effect of prophylaxis for thromboembolism with low-molecular-weight heparin (LMWH) during hospitalization on the biological hemostasis system in patients who had undergone laparoscopic cholecystectomy.
Methods: This was a prospective paired cohort study without a control group (i.e., a before-after study). The subjects were 20 patients operated on laparoscopically for uncomplicated cholelithiasis. All patients received LMWH 2 h before the operation and 24 h after the first dose. Mean duration of surgery was 70 min. Pneumoperitoneum was accomplished at 14 mmHg, and all patients were operated on in the inverted Trendelenberg position (30 degrees). Patients were mobilized within 24 h, and were discharged within 48 h after surgery. As parameters of hemostasis we studied anti-Xa factor activity (anti-Xa), antithrombin III (AT III), partial active thromboplastin time (PTT) and fibrinogen. Samples were taken for laboratory analyses under basal conditions the day before the operation (first determination), 1 h after the first preoperative dose of LMWH was given (second), at the end of the operation (third), 24 h after surgery (fourth), and on postoperative day 7 (fifth).
Results: Mean basal values of all parameters were within the normal range. Mean anti-Xa activity was significantly higher in the second and third determinations than in the first and fifth measurements (p < 0.05). Mean PTT was significantly elevated on the second determination and decreased thereafter; however, none of the results differed significantly from the normal value. Mean AT III was significantly lower in the third determination in comparison with the first and fifth measurements. Fibrinogen was significantly higher in the fourth and fifth determinations than in the second and third measurements. Among all parameters and sampling times, the only values outside the normal range were anti-Xa activity on the second, third and fourth determinations.
Conclusions: Plasma anti-Xa factor activity was increased preoperatively, and remained elevated for 24 h after surgery, returning to basal values on postoperative day 7. Partial thromboplastin time was slightly prolonged after the first dose of LMWH, indicating good antithrombotic action.