Kleihauer–Betke (KB) positive test showing pink-stained foetal red cells. It is used to measure the amount of foetal haemoglobin containing red cells that entered maternal circulation. It is performed on Rhesus (D) negative mothers to determine the required dose of prophylactic Rho (D) immune globulin (RhIg) to prevent sensitization and formation of immune Rh (D) antibodies that can potentially cause haemolytic disease of the foetus and newborn in subsequent Rh(D) positive babies.