Key Facts

SVCO is the obstruction of blood flow through the superior vena cava, causing venous congestion in the head, neck, upper limbs, and upper thorax. It is most commonly caused by malignancy but has an important differential of thrombotic and non-malignant causes.

Epidemiology

• Approximately 3-4% of patients with lung cancer develop SVCO
• Incidence of non-malignant SVCO increasing due to more central venous catheter and pacemaker use
• Male predominance (reflects lung cancer demographics)

Aetiology

• Malignant (85%):
  • Lung cancer: 70% (SCLC most common, followed by NSCLC)
  • Lymphoma: 15% (particularly NHL, mediastinal)
  • Other: thymoma, germ cell tumour, metastatic disease
• Non-malignant (15%):
  • Central venous catheter-related thrombosis
  • Pacemaker leads
  • Fibrosing mediastinitis
  • Retrosternal goitre
  • Aortic aneurysm

Pathophysiology

• External compression by mediastinal mass or invasion of SVC wall
• Intraluminal thrombosis (may be superimposed on compression)
• SVC is thin-walled, low-pressure vessel surrounded by rigid structures (sternum, trachea, bronchi, aorta, lymph nodes)
• Obstruction causes venous hypertension in the head, neck, and upper extremities
• Collateral venous circulation develops over days-weeks (azygos, internal mammary, subcutaneous)
• Cerebral oedema (rare): raised intracranial pressure in severe acute obstruction

Typical Presentation

• Facial swelling and plethora (worse in morning, improves with upright posture)
• Periorbital oedema
• Upper limb swelling (bilateral)
• Distended neck veins (non-pulsatile)
• Visible chest wall collateral veins
• Dyspnoea
• Headache (worse on bending forward, lying flat, or straining)

Severe Symptoms

• Stridor (tracheal compression)
• Hoarseness (recurrent laryngeal nerve involvement)
• Dysphagia (oesophageal compression)
• Confusion, visual disturbance (cerebral oedema)

Red Flags

• Stridor or airway compromise
• Altered consciousness (cerebral oedema)
• Papilloedema
• Rapid onset (more likely thrombosis or aggressive tumour)
• Known central venous catheter (thrombosis)

Bedside

• Observations (HR, BP, SpO2, RR)
• Examine for collateral veins, JVP, facial swelling
• Pemberton's sign
• Pulse oximetry

Bloods

• FBC, U&Es, LFTs, calcium, LDH
• Tumour markers (AFP, βhCG if germ cell tumour suspected)
• Coagulation screen (thrombosis assessment)
• Blood gas if respiratory symptoms

Imaging

• CT chest with IV contrast (CT venogram): investigation of choice; shows site and extent of obstruction, identifies underlying cause, guides stent placement
• CXR: mediastinal widening, right paratracheal mass (abnormal in 80%)
• CT head: if cerebral oedema suspected

Special Tests

• Tissue diagnosis: essential before treatment if no prior histology
  • CT-guided biopsy of mediastinal mass
  • Bronchoscopy with biopsy
  • Lymph node biopsy (cervical/supraclavicular)
  • Sputum cytology
• Venography: rarely needed; CT venogram usually sufficient

Non-pharmacological

• Elevate head of bed (30-45°)
• Avoid IV access in upper limbs if possible (poor venous return)
• Avoid constricting clothing

Pharmacological

• Dexamethasone 16mg IV stat then 8mg BD: reduces peritumoral oedema; particularly effective in lymphoma/thymoma
• PPI cover (omeprazole 20mg OD)
• Anticoagulation: if thrombotic component identified; LMWH initially
• Definitive treatment based on histology:
  • SCLC: chemotherapy (cisplatin/carboplatin + etoposide); rapid response expected
  • Lymphoma: chemotherapy ± steroids (R-CHOP for DLBCL)
  • NSCLC: radiotherapy or chemoradiotherapy

Surgical/Interventional

• SVC stenting: provides rapid symptom relief (within 24-48 hours in >90%)
  • Indicated for: severe symptoms, poor response to medical treatment, bridge to definitive therapy
  • Performed by interventional radiology under fluoroscopic guidance
• Radiotherapy: palliative (8-12 Gy in 1-2 fractions for rapid relief, or 20-30 Gy in 5-10 fractions)

Referral Criteria

• All suspected SVCO: urgent oncology referral
• Airway compromise: immediate anaesthetic/ENT assessment
• Stenting: interventional radiology referral
• Unknown histology: urgent tissue diagnosis required

• Depends on underlying cause and treatment response
• SCLC with SVCO: median survival approximately 6-12 months (chemosensitive)
• NSCLC with SVCO: median survival approximately 3-6 months
• Lymphoma with SVCO: good prognosis if chemosensitive (>50% 5-year survival for some subtypes)
• SVC stenting: symptom relief in >90% within 48-72 hours; re-occlusion rate 10-15%
• Non-malignant SVCO: good prognosis with anticoagulation and/or stenting

SVCO Management Algorithm

Causes of SVCO by Frequency