The North Thames Anti-D Protocol Audit David R. Mold, Transfusion Data Manager, The Royal Free Hospital. Sasha Wilson, Specialist Practitioner of Transfusion, The Royal Free Hospital. Rachel Moss, Specialist Practitioner of Transfusion, St. Mary’s Hospital.

Introduction The development of anti-D antibodies generally results from fetomaternal haemorrhages (FMH) occurring in RhD negative women who carry an RhD positive fetus. Post-delivery immunoprophylaxis using anti-D Immunoglobulin (anti-D Ig) began in the UK in 1969. The programme has been an astounding success; deaths attributed to RhD alloimmunisation fell from 46/100,000 births before 1969 to 1.6/100,000 in 1990. Guidelines on Rh immunoprophylaxis were updated in 1976, 1981 and 1991. However RhD alloimmunisation continues to occur. There is clear evidence that the 1991 guidelines are not being fully applied. However the most important cause of anti-D antibodies is now immunisation during pregnancy where there has been no overt sensitising event. Late immunisation during a first pregnancy is responsible for 18-27% of cases. Immunisation during a second or subsequent pregnancy probably accounts for a similar proportion of cases, although in this situation it is impossible to distinguish late sensitisation from failure of prophylaxis at the end of the preceding pregnancy Source: Use of Anti-D Immunoglobulin for Rh Prophylaxis (22) - Revised May 2002 RCOG

Methodology A postal questionnaire was designed and sent to both the Consultants in charge of Transfusion and the Lead Obstetric Consultants at all hospitals covered by the North Thames Regional Transfusion Committee. Respondents were also asked to send a copy of their Trust’s protocol with the completed questionnaire and if they would like to participate in further audits and studies on the subject of anti-d prophylaxis

Audit Standards Royal College of Obstetricians and Gynaecologists Guideline - Use of Anti-D Immunoglobulin for Rh Prophylaxis (22) - Revised May 2002 National Institute of Clinical Excellence - Guidance on the use of routine antenatal anti-D prophylaxis for RhD-negative women

Questionnaire Response Questionnaires were sent to the Lead Obstetric Consultant and the Consultant in charge of transfusion at twenty seven hospitals. Total of twenty six (48%) questionnaires returned. Nineteen hospitals (70%) responded and there was seven (26%) hospitals where both obstetrician and haematologist responded. Responses by Speciality Obstetrician Or Haematologist Haematologist responsible for Transfusion 13 (50%) Obstetrician

Two trusts answered both yes (obstetrics) and no (transfusion) Does your trust have a protocol for the use of Anti-D Immunoglobulin for Rh prophylaxis ? Yes 19 One trust answered both yes (obstetrics) and no (transfusion). Yes assumed to be correct answer. Has the protocol been ratified/discussed by the Hospital Transfusion Committee? Yes 17 No 1 Unknown Two trusts answered both yes (obstetrics) and no (transfusion)

Do you give routine Anti-D Prophylaxis at 28 and 34 weeks? Yes 18 Other-26 + 34 1 Dose for routine antenatal prophylaxis 500 i.u. 9 1200 i.u. 1 1250 i.u. 8 1250 i.u. 26 weeks + 500 i.u. 34 weeks

Dose for routine postnatal prophylaxis 1200 i.u. 1 1250 i.u. 9 500 i.u.

Tests used for estimating FMH Kleihauer (6 both, 7 transfusion, 4 obstetrics) 17 Unknown (both obstetrics) 2 Confirm FMH with Flow Cytometry Yes (1 both, 11 transfusion, 2 obstetric) 14 No (both transfusion and obstetrics) 1 Unknown (Obstetrics) 4 Dose for additional Anti-D 125 i.u. per ml of FMH (10 transfusion) 10 No response (1 both, 12 obstetrics, 2 transfusion) 9

Are sensitising events stated in your protocol? Yes 18 No 1

Dose of Anti-D for sensitising events before 20 weeks 250 i.u. 7 500 i.u. 3 1250 i.u. 1200 i.u. 1 Unknown One trust answered with 250 i.u. (Obstetrics) and 500 i.u. (Transfusion). Answer given by transfusion used

Dose of Anti-D for sensitising events after 20 weeks 500 i.u. 10 1250 i.u. 8 1200 i.u. 1

Trusts using SD treated Anti-D Yes 7 No 5 Unknown Report adverse events to SHOT Yes 15 No 4

Protocols Respondents were asked to send a copy of their current trust protocol for the use of prophylactic anti-d. Thirteen trusts (45%) responded. The protocols were audited against the RCOG Green Top guidelines and NICE guidance.

Routine Prophylaxis Audit standard- Protocol should state that: at least 500iu of anti-D Ig should be given to non-sensitised RhD negative women at 28 weeks and 34 weeks of pregnancy. 12/13 trusts met the standard with one stating 26 and 34 weeks however 3/13 trusts did not specify any dose.

Sensitising Events Audit Standard- Protocol should state which dose to be given for sensitising events at: Pre 20 weeks gestation – 250 i.u. Post 20 weeks gestation– 500 i.u 10/13 trusts met the standard.

Post natal prophylaxis Audit Standard- Protocol should state: At least 500iu of anti-D Ig must be given to every non-sensitised RhD negative woman within 72 hours following the delivery of a RhD positive infant A test to detect FMH greater than 4ml must also be undertaken, so that additional anti-D Ig can be given as appropriate

Post natal prophylaxis 10/13 protocols stated that post natal prophylaxis is required. 9/13 protocols gave the dose 10/13 protocols stated a test to detect FMH greater than 4ml must be undertaken.

Issues raised by the audit. Areas where there was a consensus All Trusts have a protocol for the for the use of Anti-D Immunoglobulin for Rh prophylaxis but not all have had them ratified by their trust’s governance framework. Antenatal prophylaxis given at 28 and 34 weeks in 18 trusts. One trust gives prophylaxis at 26 and 34 weeks. Kleihauer tests used to estimate FMH in 17 trusts (2 unknown) Flow cytometry used confirm FMH in 14 trusts (1 trust –No and 4 trusts – unknown) 15 trusts report adverse events to SHOT (4 trusts- unknown)

Issues raised by the audit. Areas where there is variance in practice Dose for routine antenatal prophylaxis varied between 500 i.u. (9 trusts) and 1200/1250 i.u. (9 trusts). One trust gives 1250 i.u. at 26 weeks and 500 i.u at 34 weeks. Dose for routine post natal prophylaxis varied between 500 i.u. (9 trusts) and 1200/1250 i.u. (10 trusts) Dose for sensitising events before 20 weeks varied between 250 i.u. (7 trusts) 500 i.u. (3 trusts) 1200/1250 i.u. (8 trusts) and unknown (1 trust) Dose for sensitising events after 20 week varied between 500 i.u. (10 trusts) 1200/1250 i.u. (9 trusts) Use of Solvent detergent treated Anti-D varied between 7 trusts using it and 5 five trusts not using it. ( 7 trusts unknown)