Insights from the NHS: adoption of High-throughput non-invasive prenatal testing for fetal RHD genotype at Musgrove Park Hospital

Aim:

• To target routine antenatal anti-D prophylaxis for women who are Rhesus D negative, instead of treatment with anti D for all pregnant women who are rhesus D negative.

Objectives:

• prevent unnecessary administration of blood products (anti D immunoglobulin) and their associated risk
• avoid unnecessary painful injections for women where the NIPT for fetal RHD genotype is negative
• reduce the number of antenatal anti-D prophylactic clinic appointments needed, and the amount of anti-D immunoglobulin used
• increase availability of anti-D immunoglobulin for use following potential sensitising events (PSEs) in pregnancy where the NIPT result for fetal RHD genotype is positive
• reduce the anxiety associated with potential sensitising events for D-negative women where the NIPT result for fetal RHD genotype is negative
• provide information to allow D-negative women to make an informed decision about whether to have treatment with anti-D immunoglobulin.

Taunton and Somerset NHS Foundation Trust provides hospital based and community services to a population of 340,000. The maternity department is based in Musgrove Park Hospital. 3300 babies are delivered annually and the midwifery service has integrated community and birth centre midwives.

The laboratory manager involved in the implementation is employed by Integrated Pathology Partnerships (iPP) which is part of a joint venture (Southwest Pathology Services LPP) with Taunton and Somerset and Yeovil District Hospital NHS Foundation Trusts and Integrated Pathology Partnerships. Pathology Services to both NHS Foundation Trust joint venture partners are provided by iPP.

Prior to implementation of this project, all women who were Rhesus D negative were treated with Routine antenatal anti-D prophylaxis (RAADP) as per NICE guidance on routine antenatal anti-D prophylaxis for women who are rhesus D negative which recommends that all pregnant women who are D-negative are offered prophylactic anti-D immunoglobulin in the third trimester. In Taunton this routinely happened as a single dose at the 28 week appointment. The new test is now used to determine the fetal RHD genotype which then directs prophylactic treatment with Anti D immunoglobulin. This is in line with NICE diagnostic guidance ‘High-throughput non-invasive prenatal testing for fetal RHD genotype’ (DG25). If the fetal RHD is negative the woman does not need prophylactic treatment with anti D, if it is positive then she will have the anti D injection at 28 weeks.

The project team predicted that there would be fewer Anti D clinic appointments required and less anti-D immunoglobulin used.

Methods:

In June 2015 SPS planned county wide implementation of free fetal DNA (ffDNA) which required aligning implementation plans for both the Taunton and Yeovil trusts. The project went live in February 2016.

The laboratory manager, transfusion practitioner and consultant haematologist presented a cost neutral cost benefit analysis to maternity managers and consultant obstetricians at both trusts. Input from the community midwives guided the development of a clinical guideline, a key aspect of which was a flow chart, which had very positive feedback.

Training was incorporated into the one of the biannual away days for community midwives which had an 80% attendance rate. Information packs regarding the new technology included literature from NHSBT were provided to all midwives.

The project team developed a staged communication plan from initial awareness raising to reminder emails in the weeks leading up to implementation, and suggest there are refresher communications at 4 and 6 months post implementation.

Musgrove Park offer the test as an option at the 16 week community appointment, not a change to the care pathway for all. The sample is sent to SPS where it is entered into the laboratory and diagnostic request system before being transferred to NHSBT via established transport links.

The results are returned via Sp-ICE and manually transferred to the local laboratory system as Positive, Negative, or indeterminate, and double checked by a second laboratory operator. In order to reduce the risk of human error associated with manual data entry a logic rule was written to auto-populate remaining information once Positive, Negative, or indeterminate is entered. Midwives are responsible for checking all blood requests.

A free fetal DNA (ffDNA) positive result is printed off and filed in hand held records prior to administration of anti-D immunoglobulin. Cord blood is taken for all babies delivered to D-negative women. Following delivery cord blood is taken from all babies and the maternity team cross check this with the ffDNA result. The local clinical guideline includes advice for false negative or false positive results, and the laboratory team are developing a reporting system process for cross-checking the cord blood against any previous ffDNA result. The laboratory refers a false positive or false negative to SHOT, the Serious Hazards of Transfusion haemovigilance scheme.

Data for the first 6 months following implementation show a steady increase in uptake rate for month 1-4 (46.8%-79.5%), as demonstrated in graph 1 in the supporting material. The project team are exploring possible reasons for the slight decline in uptake at month 5 and month 6 (74.3%-67.6%). The implementation of the test has been successful, however although there was not a target set for acceptance of the test; the uptake is lower than anticipated (mean= 67.4%). This has identified the need to send reminders to staff, update training within the community ‘Away Day’ and training to be included for all new community midwives.

The local project team are considering how to identify if the non-uptake group were offered and declined, or weren’t offered and also how to use data on rates of anti-D immunoglobulin administration to measure the impact of the technology on the anti-D usage.

A comparison of the use of Routine anti-D prophylaxis between the period before the test was introduced and the same period a year after the test was introduced has demonstrated a consistent reduction in the number of issues each month for the comparative periods (July-Dec 2015 Vs July-Dec 2016). A total 40% reduction in anti-D usage was observed between these comparative periods. See graph 2 in the supporting material.

• Maternity and laboratory services should work together to ensure processes to be incorporated in the guideline.
• Plan in advance to cross check ffDNA results with cord blood test results and develop a process for managing false negatives and false positives.
• If laboratory services are provided by a third party company or joint venture amend the costing spreadsheet to factor in an administration cost.
• Develop a local guideline to include an algorithm and patient pathway.
• Plan for refresher communications at 4 months and 6 months post implementation, for the staff that will care for the women at the point of delivery. The laboratory or maternity team will have a record of the EDD of the women who were tested.