Quantification (or titration) of red cell alloantibodies

Clinically significant maternal antibodies detected during initial antenatal group and antibody screening require referral to assist in the monitoring of antibody levels during the pregnancy.

Red cell antibodies of potential clinical significance in pregnancy can be monitored to see how strong they are and whether there is any change during the course of the pregnancy.

Negative (ie. no circulating antibodies)

Generally, the significance of anti-D and anti-c levels during pregnancy is as follows:

• anti-D less than 4 IU/mL: HDN unlikely;
• anti-D 4-15 IU/mL: moderate risk of HDN, referral to a specialist obstetric unit;
• anti-D greater than 15 IU/mL: high risk of HDN, referral to a specialist obstetric unit.
• anti-c less than 7.5 IU/mL: HDN unlikely, continue to monitor;
• anti-c 7.5 20 IU/mL: moderate risk of HDN, referral to a specialist obstetric unit;
• anti-c greater than 20 IU/mL: high risk of HDN, referral to a specialist obstetric unit.

This test may be referred to a reference laboratory for additional testing.
May be referred to the NHS Blood and Transplant service for confirmation if necessary.