Superior vena cava obstruction

Overview

Superior vena cava obstruction (SVCO) occurs when flow through the SVC is partially or completely blocked, causing venous hypertension in the head, neck, and upper limbs. Malignancy is the most common cause; iatrogenic causes (central lines, pacemakers) are increasingly recognised.

Causes

•Malignant (majority) - lung cancer (most common, especially small cell), lymphoma, mediastinal metastases

•Benign/iatrogenic - central venous catheter or pacemaker lead thrombosis, fibrosing mediastinitis

Presentation

•Facial oedema - worst in the morning after lying flat

•Distended neck veins - non-pulsatile jugular venous engorgement; does not collapse on inspiration

•Dyspnoea - reduced venous return and/or tracheal compression

•Arm and upper chest oedema - dilated subcutaneous collateral veins across chest wall

•Headache and visual disturbance - raised intracranial venous pressure; worsened by bending forward or lying flat

•Cough, hoarseness, dysphagia - recurrent laryngeal nerve or tracheal/oesophageal compression

•Pemberton's sign - elevation of both arms above the head reproduces/worsens facial plethora and cyanosis

•Symptoms worsen on bending forward, lying flat, or raising arms

🚨

Stridor indicates laryngeal oedema or significant tracheal compromise - a red flag requiring urgent airway management. Altered consciousness or seizures indicate cerebral oedema from critically elevated intracranial venous pressure.

Investigations

🥇 First-line

•chest X-ray (widened mediastinum, right-sided mass); bloods (FBC, U&E, LFTs, LDH, tumour markers); upper extremity Doppler ultrasound

🏆 Gold standard

•contrast-enhanced CT thorax - defines site, extent, and cause; identifies mass, lymphadenopathy, or thrombus; guides biopsy planning

🥈 Second-line

•MRI chest (if contrast contraindicated); tissue biopsy to confirm histology before disease-directed treatment - bronchoscopy (>70% yield), CT-guided biopsy, or mediastinoscopy (>90% yield, higher anaesthetic risk); venography if endovascular stenting planned

⚠️

Do not commence radiotherapy or other tissue-destructive treatments before a histological diagnosis is obtained - except in a genuine life-threatening emergency.

Management

•Supportive: sit patient upright; high-flow oxygen; dexamethasone - reduces peritumoural oedema

•Endovascular stenting - first-line for rapid symptom relief regardless of cause; high technical success rate; can be performed before histological diagnosis in emergency

•Anticoagulation - if intraluminal thrombus identified

•Definitive (malignant cause): chemotherapy (e.g. platinum-based for small cell lung cancer), radiotherapy, or combined - guided by histology

⚠️

Never give IV fluids via upper limb or neck veins in SVCO - they cannot drain effectively and will worsen oedema. Use femoral or lower limb venous access instead.

Complications

•Laryngeal oedema - stridor, airway compromise

•Cerebral oedema - confusion, seizures, coma

•Reduced cardiac output - obstructed venous return → reduced preload

•Pulmonary embolism - secondary SVC thrombus embolising

Prognosis

•Determined by underlying cause - malignant SVCO reflects advanced disease and carries a poor overall prognosis

•Stenting achieves symptom relief in the majority and improves quality of life even in incurable malignancy

•Benign SVCO has a much better long-term outlook with successful endovascular intervention