This document provides information on deep vein thrombosis (DVT), including:
- DVT occurs when a blood clot forms in a deep vein, most often in the leg. Part of the clot can break off and cause a pulmonary embolism.
- Risk factors include pregnancy and immobilization. Ultrasound is the main imaging method used to diagnose DVT.
- Ultrasound findings of DVT include non-compressible veins, lack of flow, and visualization of thrombus within the vein. Differential diagnoses when DVT is ruled out include muscle injuries, hernias, cysts, and arterial diseases. Proper patient positioning and knowledge of anatomy are important for accurate ultrasound evaluation.
2. WHAT IS VENOUS THROMBOEMBOLISM?
• When a blood clot (thrombus) forms in a
deep vein, this is called deep vein
thrombosis (DVT) - If it happens it
happens most frequently in the leg
• Thromboembolism occurs when part of
a clot breaks away and enters the
bloodstream – When this happens the
blood clot is called an embolus
• Pulmonary embolism is the third most
common cause of mortality by cardiovascular
disease after coronary artery disease and
stroke.
3. EPIDEMIOLOGY
DVTs occur in about 1 per 1000 persons per year.
100,000 deaths may be directly or indirectly related to these diseases
• In pregnant women, it has an incidence of 0.5 to 7 per 1,000 pregnancies, and is
the second most common cause of maternal death in developed countries after
bleeding
Journal of Internal Medicine volume 232 Issue 2, Pages 155 -
160
4. PRESENTATION AND CLINICAL EXAMINATION
• PAIN AND TENDERNESS
• SWELLING (USUALLY IN ONE LIMB)
• REDNESS
• WARMTH
• EDEMA
• CYANOSIS
• HOMANS SIGN ( dorsiflexion of foot
while knee is extended)
6. VEINS OF LOWER LIMB
Superficial veins
Deep veins
Perforating veins
Superficial veins includes great and small sephanous veins and their
tributaries. They drain into deep veins through perforating veins.
The greater saphenous vein joins the femoral vein at afixed point in the
groin 2.5 cm below and lateral to the pubic tubercle, and the lesser
saphenous vein terminates at avariable site in the popliteal fossa.
Blood passing up the superficial veins enters the deep veins at the
saphenopopliteal and saphenofemoral junctions..
7. ULTRASONOGRAPHY
color-flow Duplex scanningis the imaging
test of choice for patients with suspected
DVT
inexpensive,
noninvasive,
widely available
Ultrasound can also
distinguish other
causes of leg
swelling, such as
tumor, popliteal
cyst,
abscess, aneurysm, or hematoma.
10. POPLITEAL VEIN
Leg allowed to hang over the edge off the bed with
the probe positioned in the popliteal fossa
Ma OJ, Mateer JR. Blaivas M. Emergency Ultrasound, 2nd Edition
11. NORMAL VENOUS FLOW
1. Spontaneity: Spontaneous flow without augmentation
2. Phasicity: Flow changes with respiration
3. Compression: Transverse plane
4. Augmentation: Compression distal to site of examination patency below
site of examination patency below site of examination
5. Valsalva: Deep breath strain while holding breath patency of
abdominal & pelvic vein
17. COMPRESSION TEST AT LEVEL OF ADDUCTOR CANAL
Compression test inadequate at level of adductor canal. Rather, examiner additionally presses
the vein against transducer from below the flat hand.
27. DIFFERENTIAL DIAGNOSIS OF DVT
Useche JN et al. Radiographics 2008: 28 : 1785-1797.
• 7 of 10 patients could have cause other than DVT.
• Ancillary findings detected in only 10% of Doppler study.
• 90% of incidental findings related to patients symptoms.
• Anatomic approach is the most useful strategy for dd.
Make every effort to establish a diagnosis when DVT is
ruled out
28. DIFFERENTIAL DIAGNOSIS OF DVT
ANATOMIC APPROACH
• Groin From inguinal ligament to 10cm below.
• Thigh From this line to Hunter canal.
• Popliteal From hunter canal to 10cm below pop crease.
• Lower leg 10cm from popliteal crease to ankle
Useche JH et al. RadioGraphics 2008 : 28 : 1785 – 1797.
29. DIFFERENTIAL DIAGNOSIS OF DVT
Region Differential Diagnosis
1. Inguinal Hernias: Femoral – Inguinal.
Hiopsoas & Heopectineal bursitis.
Adenopathy (inflammatory & neoplastic)
Pseudo aneurysm – AVI – anticoagulation hematoma.
2. Thigh Sports-related lesions (conclusions, muscle tears, hematoma) Muscle herniation –
myositis – abscess.
3. Popliteal Ruptured Baker’s cyst.
Para meniscal cyst – pes anserinus bursitis.
Popliteal artery thrombosis –aneurysm – adventitial cyst.
4. Lower Leg PA entrapment syndrome – thrombophlebitis
Tennis Leg
Cardiac and renal failure.
Useche JH et al. RadioGraphics 2008 : 28 : 1785 – 1797.
30. NORMAL INGINAL ANATOMY
RT INGUINAL REGION – PARALLEL TO & CRANIAL TO INGUINAL
LIGAMENT
Jamadar DA et al. AJR 2007: 188 : 1356-1364.
31. RT INGUINAL REGION – PARALLEL TO & CRANIAL TO INGUINAL
LIGAMENT
INDIRECT INGUINAL HERNIA
Pre-Valsalva maneuver Post-Valsalva maneuver