Expansion
A valveless network connecting thoracic, pelvic and vertebral veins
Expansion
Batson’s plexus is a network of valveless veins surrounding the vertebral column, connecting:
- Intercostal and lumbar veins
- The azygos system
- Pelvic veins, including the prostatic and uterine plexuses
- Intracranial dural sinuses
Because there are no valves, flow direction depends on pressure gradients. Coughing, straining or lifting raises intrathoracic and intra-abdominal pressure and drives blood into the vertebral plexus rather than towards the heart.
This provides a direct route for tumour cells to reach the vertebrae and skull without first traversing the pulmonary capillary bed. It explains the characteristic pattern of bony metastasis in prostate, breast, lung, thyroid and renal carcinoma, and the occurrence of spinal metastases in the absence of lung deposits.