Makindo Medical Notes

Related Subjects: | Pulmonary Embolism | Deep Vein Thrombosis | DVT/PE in Pregnancy | CTPA

🩺 The subclavian vein lies beneath the clavicle and continues from the axillary vein, merging with the internal jugular vein to form the brachiocephalic vein. ⚠️ Thrombosis here (SCVT) is an important form of upper-extremity DVT.

📖 About

• 🩸 Subclavian vein thrombosis (SCVT) = upper-limb DVT.
• 🔗 Causes: trauma, catheters, malignancy, or inherited clotting disorders.

🧬 Aetiology (Virchow’s Triad)

• 🩸 Hypercoagulability (blood composition changes).
• 🌀 Stasis/turbulent flow.
• 🧱 Endothelial injury/damage to the vessel wall.

📌 Causes

• Primary SCVT 🏋️‍♂️ (Effort-Induced):
  • 💪 Paget–Schroetter Syndrome: Young, healthy, after vigorous activity.
  • ❓ Idiopathic: sometimes due to hidden malignancy.
• Secondary SCVT 🏥:
  • 🦴 Trauma (clavicle fracture, compression).
  • 💉 Central venous catheters, pacemakers, dialysis lines, TPN.
  • 🛏️ Prone positioning during surgery.
  • 🧬 Inherited thrombophilia (e.g., Factor V Leiden, Protein C/S deficiency).
  • 🎗️ Lung cancer (esp. Pancoast tumours).

🩺 Clinical Features

• 💪 Arm swelling, oedema, heaviness.
• 🌐 Dilated veins (neck, shoulder, arm).
• 🔵 Cyanosis in fingers/hand.
• 📈 Possible lymphadenopathy (cervical/axillary).
• 👩‍⚕️ Breast exam if malignancy suspected.

🧪 Investigations

• 🧾 Bloods: FBC, U&E, ESR/CRP, ↑ D-dimer.
• 🧬 Thrombophilia screen (esp. young pts).
• 🖼️ Imaging: CXR, CT/MRI venography.
• 🔊 Duplex ultrasound = first-line.
• 💉 Contrast venography = gold standard.
• 🎗️ Mammography if breast cancer suspected.

⚠️ Complications

• 🫁 Pulmonary embolism (PE).
• 🦵 Post-thrombotic syndrome (chronic swelling, stasis ulcers).
• 🦠 Septic thrombophlebitis.
• 🫀 Superior vena cava (SVC) syndrome.
• 🚫 Loss of central venous access (catheter occlusion).

🔍 Differential Diagnoses

• 🫀 Superior vena cava syndrome.
• 🧬 Lymphatic obstruction.
• 🔥 Cellulitis.
• 🪓 Thoracic outlet obstruction.
• 🎗️ Pancoast tumour.
• ☠️ Necrotizing fasciitis.
• 🩸 Superficial thrombophlebitis.

🛠️ Management (Cause-Dependent)

• 💉 Anticoagulation: Start LMWH → warfarin/DOACs.
• 🧼 Thrombolysis: Catheter-directed in effort-induced/catheter-related cases.
• 🪡 Stenting: For significant venous narrowing.
• 🕵️ Investigate: Underlying malignancy or thrombophilia.
• ❌ Remove catheter: If device is the culprit (after acute phase).

📚 References

• Subclavian Vein Thrombosis – StatPearls (NCBI)

🧑‍⚕️ Case Examples — Subclavian Vein Thrombosis (SCVT)

• Case 1 (Effort-induced / Paget-Schroetter syndrome): 🏋️ A 22-year-old competitive rower presents with sudden swelling, heaviness, and cyanosis of the right arm after intense training. Dilated superficial chest wall veins are visible. Analysis: “Effort thrombosis” of the subclavian vein due to repetitive overhead arm activity causing venous compression. Diagnosis: Duplex ultrasound confirms acute SCVT. Management: Anticoagulation, catheter-directed thrombolysis if severe, and later surgical decompression (first rib resection) to prevent recurrence.
• Case 2 (Catheter-related SCVT): 💉 A 65-year-old man with a central venous catheter for chemotherapy develops left arm swelling, pain, and erythema over 48 hours. Analysis: Indwelling catheters are the commonest cause of secondary SCVT, provoking local thrombosis. Diagnosis: Duplex/CT venography shows thrombus around catheter in the left subclavian vein. Management: Anticoagulation (LMWH/DOAC), remove catheter if no longer essential, oncology team review.
• Case 3 (Malignancy-associated SCVT): 🎗️ A 58-year-old woman with known breast cancer presents with right arm swelling, facial plethora, and dilated chest wall veins. Analysis: Cancer is a strong pro-thrombotic state; extension towards the SVC suggests SVC obstruction. Diagnosis: CT venography shows right subclavian vein thrombosis with proximal extension. Management: Anticoagulation, oncology input, consider stenting if symptomatic SVC obstruction.