Prevention of Venous Thromboembolism - Covidien

gery, we recommend starting either 6 to 8 h
after surgery or the next day (Grade 1A).
3.5.2 Screening for DVT Before Hospital Discharge
Historically, some clinicians have advocated for
high-risk orthopedic surgery groups the routine
screening for and subsequent treatment of asymptomatic
DVT before the thrombus could extend to
produce symptomatic DVT or PE. 432 We do not
advocate this approach because it has not been
shown to be effective in preventing clinically important
VTE. Routine screening for asymptomatic DVT
using DUS was not shown to be beneficial in five
large studies 297,379,433–436 of THR and TKR patients.
Only 3 of 1,936 arthroplasty patients (0.15%) who
received in-hospital LMWH thromboprophylaxis
were found to have asymptomatic DVT on prehospital
discharge DUS. 297 Another study 434 found
asymptomatic proximal DVT in only 0.9% of 441 hip
or knee arthroplasty patients, using DUS before
hospital discharge. The strongest evidence against
routine screening comes from a trial 379 in which hip
and knee arthroplasty patients were randomized to
receive prehospital discharge DUS or sham ultrasound.
Active DUS screening detected DVT in 2.5%
of patients, who then received therapeutic anticoagulation.
However, this strategy was not associated
with a reduction in symptomatic VTE. These findings
were confirmed in another trial, 433 in which 346
hip and knee arthroplasty patients received LMWH
thromboprophylaxis for 10 days and were then randomized
to continue LMWH for another 3 weeks, or
to have prehospital discharge DUS screening, with
anticoagulant therapy if the findings were positive.
DUS screening identified almost twice as many
proximal thrombi but did not reduce the rate of
symptomatic VTE over the subsequent 3-month
follow-up. Finally, another study 435,436 showed that
proximal DVT rates were similar irrespective of
whether screening DUS was performed 3 days or 2
weeks after surgery among 2,364 patients who underwent
hip or knee arthroplasty. Each of the 6
symptomatic pulmonary emboli detected in this
study occurred in patients in whom the screening
DUS result was negative for DVT. Therefore, prehospital
discharge screening using contrast venography
or DUS has not been shown to predict which
patients do or do not require posthospital discharge
thromboprophylaxis. 115,295,435–438 Furthermore, this
strategy would be very costly, logistically impractical
for many hospitals, uses a technique that has considerable
interobserver variability and the potential to
falsely diagnose DVT, and often identifies patients
with asymptomatic thrombi in whom treatment may
not be necessary. The failure of routine prehospital
discharge screening for asymptomatic DVT to do
more good than harm lends support for the practice
of extended postdischarge thromboprophylaxis as
the best means to prevent clinically important
thromboembolic complications in major orthopedic
surgery.
Recommendation: Screening for DVT Before
Hospital Discharge
3.5.2. For asymptomatic patients following major
orthopedic surgery, we recommend against
the routine use of DUS screening before hospital
discharge (Grade 1A).
3.5.3 Duration of Thromboprophylaxis
The duration of thromboprophylaxis after surgery
has been discussed previously. 1,439 Although thromboprophylaxis
is routinely administered to patients
who have undergone major orthopedic surgery, it is
frequently stopped at the time of hospital discharge.
440 However, a substantial proportion of these
patients leave the hospital with clinically silent DVT,
including proximal DVT. For example, when inhospital
thromboprophylaxis with LMWH was administered
for 1 to 2 weeks, 15 to 20% of THR
patients had venographic evidence of DVT at hospital
discharge. 115,441,442 There is evidence that activation
of coagulation persists for at least 4 weeks after
THR, 443,444 and the increased risk of symptomatic
VTE continues for up to 3 months after
THR. 299,302,303,305,320,443,445–448 In one epidemiologic
study 303 of almost 24,000 THR patients, in which the
mean length of stay was 7 days, 76% of the thromboembolic
events were diagnosed after hospital discharge.
Among the 26,000 TKR patients also studied,
the rate of posthospital discharge VTE (2.1%)
was only slightly lower than after THR (2.7%),
although this diagnosis was made earlier following
discharge from hospital in TKR patients (mean time,
7 days for TKR and 17 days after THR). These
observations suggest that the optimal duration of
thromboprophylaxis might be shorter for TKR than
for those undergoing THR. In an analysis 449 of
patients undergoing THR, the risk factors for rehospitalization
for symptomatic VTE were a body mass
index � 25 kg/m 2 , a history of previous VTE, and age
� 85 years. Ambulation before the second postoperative
day and the use of warfarin after hospital
discharge were protective factors against VTE.
Four large prospective cohort studies 291,297,298,309
and one randomized clinical trial 379 examined the
in-hospital use of LMWH or warfarin thromboprophylaxis
for an average of 7 to 15 days after THR or
TKR. Symptomatic VTE occurred in only 1 to 3% of
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