Some men who had been vasectomised previously or have an obstruction in their spermatic ducts will have no sperm in their ejaculate. Sperm can then be surgically extracted by an operation such as micro-epididymal sperm aspiration (MESA) or Testicular sperm extraction (TESE). Testicular sperm has very poor motility and must be combined with the ICSI procedure to fertilise an egg.