Collecting bone marrow for transplanting later on. It is done under general anaesthetic and usually means an overnight stay in hospital. Up to six punctures are made over the hip bones (and less usually, the chest bone). The marrow is sucked out of the puncture sites into a syringe. For adults, about a litre of bone marrow is taken. This is then frozen until it is needed for transplant. The after effects are bruising at the puncture sites for a few days. Paracetamol is usually given for this.