Timing of symptomatic venous thromboembolism after surgery: meta-analysis.

Hundreds of millions of surgical procedures are performed annually worldwide. Blood clots in legs and lungs represent serious, and sometimes fatal, complications of surgery. To prevent these complications, clinicians often give blood thinners to patients. To optimize the starting time and duration of use of blood thinners, it is crucial to know when blood clots occur after surgery. This study summarized the timing of blood clots after surgery based on a systematic review and meta-analysis of 22 prospective studies including thousands of patients with blood clots from various surgical fields. Of blood clots occurring within 4 weeks after surgery, 47 per cent occurred by the first, 74 per cent by the second, and 90 per cent by the third week after surgery. These research results are useful for patients, clinicians, and guideline developers to guide the starting time and duration of use of blood thinners after surgery.