Document 6586255

is the formation of a blood clot ("thrombus") in a
deep vein. It is a form of thrombophlebitis
(inflammation of a vein with clot formation).
Deep vein thrombosis commonly
affects the leg veins (such as the
femoral vein or the popliteal vein)
or the deep veins of the pelvis.
Occasionally the veins of the arm
are affected (if spontaneous, this
is known as Paget-Schrötter
disease).
DVTs occur in about 1 per 1000
persons per year. It is estimated
that approximately 350,000 to
600,000 Americans each year
suffer from DVT and pulmonary
embolism and at least 100,000
deaths may be directly or
indirectly related to these diseases.
DVT is much less common in the
pediatric population. About 1 in
100,000 people under the age of 18
experiences deep vein thrombosis,
possibly due to a child's high rate of
heart beats per minute, relatively
active lifestyle when compared with
adults, and fewer comorbidities .
Iincluding :
 *the use of estrogen-containing methods of
hormonal contraception,
 *recent long-haul flying (economy class
syndrome),( risk of DVT is higher in travellers
who smoke, are obese, or are currently taking
contraceptive pills)
 * intravenous drug use .

*a
history of miscarriage (which is
a feature of several disorders that
can also cause thrombosis).
Women have an increased risk
during pregnancy and in the
postnatal period

A family history can reveal a hereditary factor
in the development of DVT. Approximately 35
percent of DVT patients have at least one
hereditary thrombophilia, including
deficiencies in the anticoagulation factors
protein C, protein S, antithrombin, or
mutations in the factor V and prothrombin
genes.
*The
most common risk factors
are recent surgery or
hospitalization. 40% of these
patients did not receive heparin
prophylaxis.
*Other risk factors include
advanced age, obesity, infection,
immobilization, tobacco usage
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*certain inflammatory diseases and specific
conditions such as stroke, heart failure or
nephrotic syndrome.
*Immobilization (such as when orthopedic
casts are used).
*certain drugs (such as estrogen or
erythropoietin) .
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According to Virchow's triad, venous
thrombosis occurs via three mechanisms:
1-decreased flow rate of the blood,
2-damage to the blood vessel wall and
3-an increased tendency of the blood to clot
(hypercoagulability). Several medical
conditions can lead to DVT, such as
compression of the veins, physical trauma,
cancer, infections

It is recognized that thrombi usually develop
first in the calf veins, "growing" in the
direction of flow of the vein. DVTs are
distinguished as being above or below the
popliteal vein. Very extensive DVTs can
extend into the iliac veins or the inferior vena
cava. The risk of pulmonary embolism is
higher in the presence of more extensive
clots

There may be no symptoms referable
to the location of the DVT, but the
classical symptoms of DVT include
pain, swelling and redness of the leg
and dilation of the surface veins. In up
to 25% of all hospitalized patients,
there may be some form of DVT,
which often remains clinically
inapparent (unless pulmonary
embolism develops).
 There
are several techniques
during physical examination to
increase the detection of DVT,
such as measuring the
circumference of the affected and
the contralateral limb at a fixed
point (to objectivate edema), and
palpating the venous tract, which
is often tender.
Physical examination is
unreliable for excluding
the diagnosis of deep
vein thrombosis
 the
leg is pale and cool with
a diminished arterial pulse
due to spasm. It usually
results from acute occlusion
of the iliac and femoral
veins due to DVT.
 there
is an acute and nearly
total venous occlusion of the
entire extremity outflow,
including the iliac and femoral
veins. The leg is usually
painful, cyanosed and
oedematous. Venous gangrene
may supervene.
 It
is vital that the possibility
of pulmonary embolism be
included in the history, as
this may warrant further
investigation .
I-Physical examination:
 Homans' test: Dorsiflexion of foot elicits pain
in posterior calf. However, it must be noted
that it is of little diagnostic value and is
theoretically dangerous because of the
possibility of dislodgement of loose clot.
 Pratt's sign: Squeezing of posterior calf elicits
pain.
 However,
these medical
signs do not perform well
and are not included in
clinical prediction rules that
combine best findings in
order to diagnose DVT.

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Active cancer (treatment within last 6 months or palliative)
-- 1 point
Calf swelling >3 cm compared to other calf (measured
10 cm below tibial tuberosity) -- 1 point
Collateral superficial veins (non-varicose) -- 1 point
Pitting edema (confined to symptomatic leg) -- 1 point
Swelling of entire leg - 1 point
Localized pain along distribution of deep venous system—
1 point
Paralysis, paresis, or recent cast immobilization of lower
extremities—1 point
Recently bedridden > 3 days, or major surgery requiring
regional or general anesthetic in past 4 weeks—1 point
Alternative diagnosis at least as likely—Subtract 2 points
 Score
of 2 or higher - deep
vein thrombosis is likely.
Consider imaging the leg
veins. Score of less than 2 deep vein thrombosis is
unlikely. Consider blood test
such as d-dimer test to further
rule out deep vein thrombosis.
 II-
intravenous venography, which
involves injecting a peripheral
vein of the affected limb with a
contrast agent and taking X-rays,
to reveal whether the venous
supply has been obstructed.
Because of its invasiveness, this
test is rarely performed.


D-dimer
In a low-probability situation, current practice
is to commence investigations by testing for
D-dimer levels. This cross-linked fibrin
degradation product is an indication that
thrombosis is occurring, and that the blood
clot is being dissolved by plasmin. A low Ddimer level should prompt other possible
diagnoses (such as a ruptured Baker's cyst, if
the patient is at sufficiently low clinical
probability of DVT.
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Other blood tests :
Other blood tests usually performed at this
point are:
complete blood count
Primary coagulation studies: PT, APTT,
Fibrinogen
liver enzymes
renal function and electrolytes .
 Impedance
plethysmography,
Doppler ultrasonography,
compression ultrasound scanning
of the leg veins, combined with
duplex measurements (to
determine blood flow), can reveal
a blood clot and its extent (i.e.
whether it is below or above the
knee).
 Duplex
Ultrasonography,due to its
high sensitivity, specificity and
reproducibility, has replaced
venography as the most widely
used test in the evaluation of the
disease. This test involves both a
B mode image and Doppler flow
analysis.
 1-The
most serious complication
of a DVT is that the clot could
dislodge and travel to the lungs,
which is called a pulmonary
embolism (PE). DVT is a medical
emergency, present in the lower
extremity there is 3% chance of a
PE killing the patient

2- A late complication of
DVT is the post-phlebitic
syndrome, which can
manifest itself as edema,
pain or discomfort and skin
problems.
Therapy:

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Treatment at home is an option .
Hospitalization should be considered in
patients with more than two of the following
risk factors as these patients may have more
risk of complications during treatment:
bilateral DVT,
renal insufficiency,
body weight >70 kg/154 lbs,
recent immobility,
chronic heart failure,
and cancer.
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Anticoagulation is the usual treatment for DVT. In
general, patients are initiated on a brief course
(i.e., less than a week) of heparin treatment while
they start on a 3- to 6-month course of warfarin
(or related vitamin K inhibitors).
Low molecular weight heparin (LMWH) is
preferred,
though unfractionated heparin is given in
patients who have a contraindication to LMWH
(e.g., renal failure or imminent need for invasive
procedure).
 In
patients who have had
recurrent DVTs (two or
more), anticoagulation is
generally "life-long."
 An
abnormal D-dimer level
at the end of treatment
might signal the need for
continued treatment among
patients with a first
unprovoked proximal deepvein thrombosis
 Thrombolysis
is generally
reserved for extensive clot,
e.g. an iliofemoral
thrombosis. But there may
be an increase in serious
bleeding complications.
 Elastic
compression stockings
should be routinely applied
"beginning within 1 month of
diagnosis of proximal DVT and
continuing for a minimum of 1
year after diagnosis". Starting
within one week may be more
effective. Most trials used kneehigh stockings.
 Inferior
vena cava filter reduces
pulmonary embolism and is an
option for patients with an
absolute contraindiciation to
anticoagulant treatment (e.g.,
cerebral hemorrhage) or those
rare patients who have objectively
documented recurrent PEs while
on anticoagulation

An inferior vena cava filter (also
referred to as a Greenfield filter) may
prevent pulmonary embolisation of
the leg clot. However these filters are
themselves potential foci of
thrombosis,IVC filters are viewed as a
temporizing measure for preventing
life-threatening pulmonary embolism.

Post-phlebitic syndrome occurs in 15% of
patients with deep vein thrombosis (DVT). It
presents with leg oedema, pain, nocturnal
cramping, venous claudication, skin
pigmentation, dermatitis and ulceration
(usually on the medial aspect of the lower
leg).
 is
advised in many medical and
surgical inpatients using
anticoagulants, graduated
compression stockings (also
known as thromboembolic
deterrent stockings) or
intermittent pneumatic
compression devices.
 Clinical
practice guidelines
by the American College of
Chest Physicians (ACCP)
provide recommendations
on DVT prophylaxis in
hospitalized patient:

"In acutely ill medical patients who have been
admitted to the hospital with congestive heart
failure or severe respiratory disease, or who
are confined to bed and have one or more
additional risk factors, including active
cancer, previous VTE, sepsis, acute
neurologic disease, or inflammatory bowel
disease, prophylaxis with low-dose
unfractionated heparin-LDUH or LMWH is
recommended.
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In patients who have undergone surgery, low
molecular weight heparins (LMWH) are routinely
administered to prevent thrombosis. LMWH can
only currently be administered subcutaneously .
Prophylaxis for pregnant women who have a
history of thrombosis may be limited to LMWH
injections or may not be necessary if their risk
factors are mainly temporary.
Early and regular ambulation (walking) is a
treatment that predates anticoagulants and is
still recognized and used today
There is clinical evidence to suggest that
wearing compression socks or compression
tights while travelling also reduces the
incidence of thrombosis in people on long
haul flights