Deep vein thrombosis can be a silent killer, presenting with no visible symptoms or with symptoms that are barely noticeable to the recovering patient who's been discharged 1 or 2 days ago. Symptoms can include pain, swelling, redness or excessive warmth on the skin of — or on the veins closest to the surface of — the legs, ankles or feet. Any kind of pain or swelling in the calf area should raise suspicions very high. Complaints of chest pain or shortness of breath could indicate that the DVT has progressed to the pulmonary embolism stage, and while any of these symptoms demand medical examination, a patient suffering from PE should be taken to the emergency room immediately. Read on as we review this circulatory condition.

Risk factors
The development of DVT isn't limited to surgical patients, of course. But the 3 ways that it occurs — through a decrease in blood flow, through damage to blood vessel walls and through an increased tendency of blood to clot — cover many situations in the surgical environment and in the medical histories of its primary patient population.

DVT is most often seen among patients 40 years of age or older who suffer from poor circulation and whose medical histories show previous experiences with DVT or PE. But even patients who fall outside of that demographic may find themselves at increased risk of DVT if their health histories include such factors as obesity, prolonged immobility (such as hospital stays, bed rest, a sedentary lifestyle, recent lengthy air travel or paralysis), varicose veins, compressed veins or swollen legs.

Smoking, the use of birth control pills or hormone replacement therapy, and intravenous drug use also up the risks, as do infections, physical trauma, previous heart failure or a family history of blood clotting disorders. Cancer in general fosters thrombophilic conditions, and women who are pregnant, who have recently given birth or who have a history of miscarriage may also have clotting risks.

On the surgical side of the equation, general anesthesia is a risk right out of the gate. Its vasodilatory effect lowers blood pressure, which increases the possibility of a clot. The longer a patient is under, the greater the risk of DVT.

Any surgery in which the patient is on the table for 45 minutes or longer can present elevated risks for DVT. Abdominal surgeries, and laparoscopic procedures in particular, require special attention. The pressure created by an inflated peritoneum for laparoscopic surgery can obstruct the flow of blood out of the legs. This increase in stasis results in an increased risk of clotting.

The incidence of DVT following elective hip and knee replacement surgeries has been estimated at about 10% to 15%. This is largely due to patients' inhibited ambulation after the procedures, but also on account of the joint and vein manipulation that takes place during surgery, as well as the possibility that retractors or other surgical instruments might have caused direct trauma to blood vessels.

Preventive measures
Preventing DVT among surgical patients begins with risk stratification. Compiling a history and physical can help to form an assessment of a patient's risk of developing clots, whether she's likely to need or to benefit from an anti-DVT prophylaxis and how aggressive that prophylaxis will be.

A young, healthy female patient undergoing a tubal ligation procedure, for example, is at low risk and may not require any intervention other than early ambulation. On the other hand, it may be advisable to treat an elderly patient undergoing total joint replacement surgery and exhibiting several of the risk factors we've cited as though she's already suffering a clot.

Ideally, the aim is to mobilize the patient as early as possible following surgery to stimulate blood flow in the lower extremities. But an anti-DVT prophylaxis can include a combination of compression and pharmaceutical efforts, pre-, intra- and post-operatively.

Having your patients put on compression stockings, also known as TED (thrombo-embolic deterrent) stockings, is a very simple method for preventing clots, especially if they're not at high risk. Alternatively, a mechanical compression device that blows air into plastic booties or sleeves to sequentially squeeze a patient's feet, ankles and calves can mimic the circulatory stimulation that occurs when we walk.

Pharmaceutically, your physicians' anti-coagulant options include the orally dispensed warfarin (such as Bristol-Myers Squibb's Coumadin) or an injectable low-molecular weight heparin such as enoxaparin sodium (marketed by Sanofi-Aventis as Lovenox). While heparin is frequently given in low doses for prevention, warfarin is more often used among high-risk patients and for clot treatment.

Since warfarin's dose levels can be adversely affected by a patient's diet or other medications, its administration requires blood to be drawn perhaps weekly to accurately monitor the levels. Many pharmaceutical firms are developing more stable alternatives to warfarin. In March, an FDA advisory panel recommended that the agency approve one of them, Rivaroxaban, a joint venture between Bayer Healthcare Pharmaceuticals and Johnson & Johnson.

If your physicians are going to thin a patient's blood against the risk of clots, they begin doing so pre-operatively, since clots can start to form during surgery, and continue the prophylaxis through to post-op.

Detection and treatment
If a patient complains of symptoms conferring with those of DVT, there are several ways to determine whether they're suffering from a clot, including blood tests for elevated levels of D Dimer (a protein fragment that is present in the blood after a clot is broken down), venography (the injection of radiographic contrast material into the leg, followed by fluoroscopic imaging) and CT or MRI scans. But ultrasonic imaging of the veins in the affected area is at present the gold standard for detection, given its accessibility and the fact that the blood test's levels may be affected by a post-surgical patient's naturally occurring higher levels of D Dimer.

If a patient is diagnosed with DVT, it's important to treat the condition before the clot grows or breaks loose. The methods of treatment include the pharmaceutical methods of prevention, warfarin and low-molecular weight heparin, but can also include the intravenous administration of thrombolytic clot-busters or the implantation of filters. A filter, which resembles an open umbrella without the cloth, is placed via a catheter into a patient's inferior vena cava, for example, to catch pieces of a clot and prevent them from moving further upstream while the body breaks them down. They can also be used preventatively in cases where a high-risk patient's blood cannot be thinned, such as for neurosurgery and some spinal surgeries.

The surgical removal of clots is rarely recommended, however, especially among surgical patients who've suffered DVT, since new surgeries would present another risk of forming new clots.

Increased exposure
While DVT has long been overlooked, both outside and inside the healthcare industry, it's gained a measure of exposure in recent years due to its appearance among airline travelers and as the culprit in some high-profile deaths. Still, many cases are improperly diagnosed and venous thromboembolism remains a leading cause of in-hospital death.