Final answer:
A trocar is a sharp needle used within the lymphatic system to allow drainage in medical procedures. It creates a pathway for fluids to be released and can be used to drain pleural effusions, remove ascitic fluid, or decompress a pneumothorax.
Step-by-step explanation:
A trocar is a sharp needle within the lymphatic system which is pushed into the body cavity to allow drainage. The lymphatic system is responsible for draining excess fluid and waste products from the body's tissues.
When a trocar is inserted, it creates a pathway for fluids to be released. This can be helpful in medical procedures such as removing excess fluid or performing a biopsy.
Examples of situations where a trocar may be used include draining a pleural effusion (fluid in the lungs), removing ascitic fluid (fluid in the abdominal cavity) or decompressing a pneumothorax (accumulation of air in the chest cavity).