HDN of varying degrees of severity has been reported in association with anti-M and can even lead to intrauterine deaths or requiring treatment with exchange transfusion. If the mother has a history of prior intrauterine deaths, abortion, hydrops fetalis, severe fetal anemia or infertile, MN blood group and anti-M antibodies should be tested after excluding the possibility of other causes and HDN due to ABO or Rh blood group incompatibility. As the efficacy of phototherapy increases, the role of exchange transfusion in acute management is rapidly decreasing. High-dose intravenous immunoglobulin and/or intramuscular metalloporphyrins may further reduce the need for exchange transfusion. The exchange transfusion may be performed through peripheral arterial (drawn out) and venous (infused in) lines.