Deep Vein Thrombosis (DVT) – GCC Nurse Clinical Guide

Overview

Wells Score

Treatment

VTE Prophylaxis

GCC Context

MCQ Practice

🩸 DVT — Overview

Deep Vein Thrombosis (DVT) is the formation of a blood clot (thrombus) in a deep vein, most commonly in the leg (proximal: femoral/popliteal; distal: calf veins). Together with pulmonary embolism (PE), it forms VTE (Venous Thromboembolism).

DVT → PE risk: Proximal DVT (above popliteal vein) has a ~50% risk of PE if untreated. Isolated distal (calf) DVT has a ~20% risk of proximal extension. PE is a medical emergency with up to 30% mortality if untreated.

Virchow's Triad — Risk Factors for DVT

Venous Stasis

Immobility (bed rest, long-haul flights >4 hours)
Paralysis, stroke
Obesity (BMI >30)
Varicose veins
Heart failure

Hypercoagulability

Malignancy (especially pancreatic, lung, haematological)
Inherited thrombophilia (Factor V Leiden, Protein C/S deficiency, antithrombin deficiency)
Antiphospholipid syndrome
Pregnancy and post-partum
OCP / HRT (oestrogen)
Myeloproliferative disorders

Vessel Wall Damage

Surgery (orthopaedic = highest VTE risk: hip/knee replacement)
Trauma
Central venous catheter
IV drug use
Vasculitis

Clinical Presentation of DVT

Unilateral leg swelling (most important sign)
Calf/leg pain — worse on dorsiflexion (Homans' sign — present in only 30–50%, not reliable)
Warmth and erythema over the affected area
Distended superficial veins
Pitting oedema

Upper limb DVT: Also occurs — especially with PICC lines, pacemaker wires, and subclavian catheters. Presents with arm swelling, pain, and prominent superficial veins. Same anticoagulation principles apply.

Investigations

Duplex compression ultrasound: Definitive investigation; non-compressibility of vein = DVT; sensitivity ~95% for proximal DVT
D-dimer: Highly sensitive but non-specific; useful for RULING OUT DVT when probability is low (negative predictive value >99%); elevated in many conditions (infection, pregnancy, post-op, cancer)
Wells score: Used to determine pre-test probability before ordering D-dimer or ultrasound

📊 Wells Score for DVT

⭐ Wells DVT Score

Active cancer (treatment ongoing or within 6 months, or palliative)+1

Paralysis, paresis, or recent plaster immobilisation of lower extremities+1

Recently bedridden >3 days OR major surgery within 12 weeks requiring GA+1

Localised tenderness along the distribution of the deep venous system+1

Entire leg swollen+1

Calf swelling >3 cm compared to asymptomatic leg (10 cm below tibial tuberosity)+1

Pitting oedema confined to symptomatic leg+1

Collateral superficial veins (non-varicose)+1

Previously documented DVT+1

Alternative diagnosis at least as likely as DVT-2

Score Interpretation

Score	Pre-test Probability	DVT prevalence in this group
≥2	High (likely DVT)	~28–53%
1	Moderate	~17%
0 or less	Low (DVT unlikely)	~5%

Diagnostic Pathway

Wells Score	First Step	If Negative D-dimer	If Positive D-dimer or High Probability
Low (0 or less)	D-dimer	DVT excluded — no further imaging	Compression ultrasound
Moderate (1)	D-dimer	DVT excluded	Compression ultrasound
High (≥2)	Compression ultrasound directly	N/A — go straight to ultrasound	Anticoagulate; if ultrasound negative, repeat in 1 week

D-dimer in special populations:
Pregnancy, post-op, active infection, malignancy — D-dimer is nearly always elevated, making it unhelpful for ruling out DVT. Go straight to compression ultrasound in these groups regardless of Wells score.

Age-adjusted D-dimer: For patients >50 years: upper limit = age × 10 µg/L (e.g., 70 years = 700 µg/L). This increases specificity while maintaining sensitivity.

💊 DVT Treatment

Anticoagulation — First-Line

Drug	Regimen	Notes
Rivaroxaban (DOAC)	15 mg BD × 21 days, then 20 mg OD	Most used in GCC; no monitoring needed; avoid if eGFR <15
Apixaban (DOAC)	10 mg BD × 7 days, then 5 mg BD	Preferred in CKD (safer at lower eGFR); no routine monitoring
LMWH → Warfarin	LMWH (e.g., enoxaparin 1 mg/kg BD) bridge until INR 2–3	Used if DOAC not suitable (antiphospholipid syndrome, severe renal impairment)
LMWH alone	Enoxaparin 1 mg/kg SC BD (adjust for renal function)	Preferred in cancer-associated DVT; pregnant patients

DOACs are now first-line for most DVT patients (simpler, no routine monitoring, similar or better efficacy and less bleeding vs warfarin).

Duration of Anticoagulation

Clinical Scenario	Duration
First provoked DVT (surgery, trauma, immobility)	3 months
First unprovoked DVT (no clear cause)	Minimum 3 months; consider extended (lifelong) based on bleeding risk
Cancer-associated DVT	Duration of active cancer + 3–6 months minimum
Second VTE event	Extended (indefinite) anticoagulation
Antiphospholipid syndrome	Lifelong warfarin (DOACs not recommended in triple-positive APS)

Compression Stockings

Class 2 below-knee compression stockings (30–40 mmHg) reduce post-thrombotic syndrome risk
Post-thrombotic syndrome: chronic venous insufficiency (leg ulcers, varicosities, chronic oedema) — affects up to 50% after proximal DVT
Apply stocking to affected leg from day 1 if patient mobilising

Ambulation

Contrary to historical practice, patients with DVT should be encouraged to ambulate as able (with compression stocking). Bed rest does NOT reduce PE risk and worsens venous stasis. Early ambulation reduces pain and swelling.

Anticoagulant reversal agents:

Warfarin: Vitamin K (slow) + Prothrombin Complex Concentrate (fast) for major bleeding
Dabigatran: Idarucizumab (specific reversal agent)
Rivaroxaban / Apixaban: Andexanet alfa (approved reversal agent) or 4-factor PCC (unlicensed but used)
LMWH: Protamine sulphate (partial reversal)

🛡️ VTE Prophylaxis in Hospitalised Patients

VTE is a leading preventable cause of in-hospital death. All patients should be assessed for VTE risk on admission and at 24–48 hours.

Risk Assessment — Caprini/Padua Score

Tools used to categorise VTE risk in medical and surgical patients. Most GCC hospitals use electronic risk assessment embedded in admission forms.

Pharmacological Prophylaxis

Low Molecular Weight Heparin (LMWH): Enoxaparin 40 mg SC once daily (most common in GCC)
Unfractionated Heparin (UFH): 5000 units SC BD/TDS — alternative if renal impairment (LMWH accumulates in severe CKD)
DOACs (rivaroxaban, apixaban) for extended post-surgical prophylaxis (hip/knee replacement)

Mechanical Prophylaxis

Graduated Compression Stockings (GCS)

Class 1 (18 mmHg) for general wards
Thigh-high or knee-high
Contraindicated in: peripheral arterial disease (ABPI <0.8), heart failure, ischaemia
Remove and inspect skin daily

Intermittent Pneumatic Compression (IPC)

Inflatable cuffs that cyclically compress calves
Used when pharmacological prophylaxis contraindicated (bleeding risk, recent surgery)
Can be combined with LMWH for highest-risk patients
Effective only when worn — patient compliance important

When to Withhold Pharmacological Prophylaxis

Active bleeding or very high bleeding risk (recent neurosurgery, spinal surgery, intracranial haemorrhage)
Platelet count <50 × 10⁹/L
Significant renal impairment (eGFR <15) — use UFH instead of LMWH, or adjust dose

High VTE Risk — Extended Prophylaxis

Total hip arthroplasty: LMWH/DOAC for 28–35 days post-op
Total knee arthroplasty: LMWH/DOAC for 10–14 days
Abdominal/pelvic cancer surgery: LMWH for 28 days post-op

Travel (Long-Haul Flight) Thrombosis Prevention

Flights >4 hours: walk regularly, stay hydrated, avoid alcohol, leg exercises in seat
High-risk travellers (previous DVT, known thrombophilia, recent surgery): graduated compression stockings; consider single-dose LMWH for very high-risk

🌍 GCC-Specific Context

DVT Risk in GCC Populations ▼

High prevalence of obesity, diabetes, and metabolic syndrome in GCC increases VTE risk
Long-haul international travel is common in GCC — both business and Hajj/Umrah travel
Hajj pilgrims — millions walk long distances in heat; risk of dehydration-related hypercoagulability; thrombosis reported in pilgrims
Domestic workers and migrant labourers often sit/stand for prolonged periods in heat-stressed conditions — venous stasis risk
Growing bariatric surgery programmes in GCC (UAE, KSA) — post-bariatric VTE prophylaxis protocols important

Anticoagulation During Ramadan ▼

Once-daily DOACs (rivaroxaban 20 mg OD) can be taken at Iftar (sunset meal) during Ramadan
Twice-daily apixaban: take at Iftar and Suhoor (pre-dawn meal)
LMWH injections can be given at Iftar and Suhoor for BID regimens
Dehydration during Ramadan may increase blood viscosity — DVT risk increases in susceptible patients; adequate hydration at Suhoor and Iftar is important
Warfarin INR monitoring should continue during Ramadan — dietary changes (dates, pomegranate juice) can affect INR

SCFHS / DHA / QCHP Exam Focus ▼

Virchow's Triad: Stasis + Hypercoagulability + Endothelial damage
Wells score ≥2 = high probability → compression ultrasound directly (skip D-dimer)
Wells score 0–1 → D-dimer first; if negative = DVT excluded
D-dimer is a sensitive rule-OUT test but NOT specific (elevated in many conditions)
First-line treatment: DOAC (rivaroxaban or apixaban)
Cancer-associated DVT: LMWH preferred (DOAC emerging evidence — edoxaban, rivaroxaban now also used)
Anticoagulation duration: 3 months provoked; ≥3 months unprovoked; indefinite if recurrent
VTE prophylaxis: enoxaparin 40 mg OD + IPC/GCS for all moderate-high risk inpatients
Post-thrombotic syndrome prevented by compression stockings
Dabigatran reversal: Idarucizumab; Factor Xa inhibitor (rivaroxaban/apixaban) reversal: Andexanet alfa

📝 MCQ Practice

1. A 58-year-old man presents with a swollen, painful right calf. Wells DVT score is calculated at 3. What is the MOST appropriate next step?

✅ B — Wells score ≥2 = high DVT probability. In high-probability patients, go directly to compression Doppler ultrasound. D-dimer is not used to rule out DVT when Wells score is high — a negative D-dimer in a high-probability patient is not reassuring enough to exclude DVT.

2. A 45-year-old woman is diagnosed with a proximal DVT and started on rivaroxaban. She asks whether she should rest in bed. What is the evidence-based advice?

✅ C — Early ambulation with adequate anticoagulation and below-knee compression stocking is the current evidence-based recommendation. Bed rest does NOT reduce PE risk and worsens venous stasis. Walking reduces pain and swelling and prevents post-thrombotic syndrome.

3. A post-operative hip replacement patient is prescribed enoxaparin 40 mg SC daily for VTE prophylaxis. On day 3, her platelet count drops from 210 to 68 × 10⁹/L. What is the most likely diagnosis and what should be done?

✅ C — A platelet drop of 30–50%+ on days 4–14 of heparin exposure = HIT until proven otherwise. HIT is a paradoxical prothrombotic state (not just bleeding risk). STOP all heparin products (including flushes). Switch to a non-heparin anticoagulant: argatroban, fondaparinux, or a DOAC once stable. Send HIT antibody test (anti-PF4 antibody).

4. A patient with known triple-positive antiphospholipid syndrome develops a DVT. Which anticoagulation is MOST appropriate for long-term treatment?

✅ C — Warfarin (target INR 2–3) is the anticoagulant of choice for VTE in antiphospholipid syndrome (APS), particularly triple-positive APS (lupus anticoagulant + anti-cardiolipin + anti-β2-glycoprotein I antibodies). DOACs have been shown to be INFERIOR to warfarin in APS (higher recurrence rates in TRAPS, RAPS, ASTRO-APS trials). Lifelong anticoagulation is indicated.