With certain preventive measures, incidence of deep vein thrombosis after general surgery appears low, possibly catheter-related

A blood clot that forms in a deep vein, DVT occurs in up to 40 percent of general surgery patients with an associated death risk of 1 percent unless protective steps (prophylaxis) are taken, according to background information in the article. Historically, some surgeons have been resistant to using anticoagulant (anticlotting) medications that protect against DVT because of concern about bleeding, although recent research suggests that prevention is associated with significant reductions in DVT and a low rate of major bleeding. "Few data exist regarding the specifics of DVT formation when general surgical patients receive adequate prophylaxis," write the authors.

Brian R. Smith, M.D., and colleagues in the Department of Surgery at University of California, Irvine Medical Center, Orange, Calif., reviewed data from the National Surgical Quality Improvement Program from January 2008 to December 2009. The researchers evaluated medical records to assess patient characteristics and demographics, whether a central catheter was in place, the location of DVT, the time of diagnosis from the index operation, whether any DVT were associated with clots in the lungs (pulmonary embolism) and how many deaths occurred.

During the study period 2,189 patients underwent general operations (including surgeries of the pancreas, esophagus, stomach, intestines, colon and rectum, as well as other body parts) and 35 (1.6 percent) developed DVT. Most cases (94.3 percent) of DVT were detected because patients experienced DVT symptoms; the rest were found through routine screening. Similar numbers of patients developed upper-extremity DVT (40 percent) or lower-extremity DVT (45.7 percent), and 14.3 percent developed DVT in both areas. DVT was diagnosed a mean (average) of 8.6 days after the operation, and in 83 percent of cases was diagnosed in the inpatient setting. DVT associated with catheters occurred in 60 percent of patients. Other underlying health problems were noted in 62.9 percent of patients, including pulmonary embolism in 11.4 percent. At 30 days, the death rate was 14.2 percent. The researchers reported an average 93 percent compliance with prophylaxis criteria during the study period.

"The incidence of DVT after general surgical operations is low, with most cases diagnosed as inpatients," the authors conclude. "With more than half of DVTs being caused by central catheters, efforts toward DVT prevention should include closer scrutiny to the need for central catheters, including limiting the duration of central catheters, and consideration of the added use or perhaps higher dose of anticoagulation when central catheters are present."