Thrombin Generation During Abdominal Surgical Procedures: Effect of Prophylactic Anticoagulation Therapy
Authors: Fogerty Annemarie E. , Colwell Amy , Austen Jay William , Kuter David J. 
Published: October 2019

Abstract
Abstract 3183

Background:
One of the most serious complications of cosmetic surgery is a thromboembolic event (TE). Although the incidence of TE in most cosmetic procedures is <1 percent, the rate in massive weight loss patients presenting for circumferential contouring surgery is as high as 9 percent. Little evidence currently exists to determine the biochemical cause of this hypercoagulable process. Furthermore, there is little data to assess whether chemoprophylaxis prevents the hypercoagulable state. In this study, we use thrombin generation to assess activation of the coagulation cascade in patients undergoing excisional abdominal contouring procedures. Thrombin generation is a novel tool for studying the coagulation cascade and may better reflect in vivo coagulation activation than currently available laboratory measurements.

Methods:
Twenty-one consecutive patients from two surgeons were enrolled prospectively to assess thrombin generation at three time points: baseline/pre-operative, intra-operative after rectus plication or hernia repair, and 24 hours post-operative. Patients' intra-operative and post-operative values were normalized to their baseline value. All patients wore pneumatic compression devices for mechanical prophylaxis against TE. Nine patients received no chemoprophylaxis and 12 patients received pre-operative and post-operative chemoprophylaxis with unfractionated heparin or dalteparin according to surgeon preference based on the patient's risk profile.

Results:
Nine patients with a median age of 43 (range: 24–64) and BMI of 24.9 (range: 21.1–31.4) underwent abdominoplasty without TE chemoprophylaxis. Twenty percent had massive weight loss. Seventy-seven percent had liposuction and 67 percent had simultaneous procedures (liposuction as well as hernia repair or some other surgical intervention). The average operative time was 3.7 hours. In this group, the total thrombin generation increased by a mean (SD) of 997 (+/− 835) nM intra-operatively and 1404 (+/− 914) nM post-operatively. Twelve patients with a median age of 43 (range: 28–60) and BMI of 29.2 (range: 22.2–39.9) underwent panniculectomy or abdominoplasty with TE chemoprophylaxis. Eighty percent of these patients had massive weight loss. Fifty percent of patients had liposuction and 75 percent had simultaneous procedures. The average operative time was 5 hours. In this group receiving chemoprophylaxis, the total thrombin generation increased by a mean (SD) of 75 (+/− 781) nM intra-operatively and 186 (+/− 510) nM post-operatively. A t test was used to compare these two arms and the increase in thrombin generation was significantly less in patients receiving chemoprophylaxis compared to those who received no prophylaxis (intra-op: p<0.02 and post-op: p<0.004). There were no TEs or bleeding complications in any patient in the immediate post-operative period.

Conclusion:
Thrombin generation increases in patients undergoing abdominal contouring procedures. The magnitude of change may be decreased by giving peri-operative chemoprophylaxis. Further studies are warranted to determine the clinical relationship between thrombin generation, chemoprophylaxis and risk of thromboembolism and bleeding.

Disclosures:
No relevant conflicts of interest to declare.