PB0307 - Results of a Single-centre Targeted Screening Approach to Identify Potential Occult Cases of Pregnancy-associated Thrombotic Thrombocytopenic Purpura (TTP).

Sunday, July 10, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

Lucy Neave, MBBS MRCP FRCPath

Clinical Research Fellow
UCLH Hospitals NHS Trust / Haemostasis Research Unit, University College London
London, England, United Kingdom

Co-Author(s)

Mari Thomas, MD, PhD

Consultant Haematologist
University College Hospitals London NHS Foundation Trust
London, England, United Kingdom
CV

Chiara Vendramin

Research Fellow
University College London
London, England, United Kingdom
KM

Katarzyna Maksym

Clinical Research Fellow
Fetal Medicine Unit, UCLH Hospitals NHS Trust /Institute for Women's Health, University College London
London, England, United Kingdom
RS

Rebecca Spencer

Clinical Research Fellow/ Clinical Lecturer
Elizabeth Garrett Anderson Institute for Womens Health, University College London / Discovery and Translational Science Deprtment, Univeristy of Leeds
Leeds, England, United Kingdom
AD

Anna L. David

Professor of Obstetrics and Maternal Fetal Medicine
Elizabeth Garrett Anderson Institute for Women's Health, Univerisity College London
London, England, United Kingdom
Andrew J. Doyle, MBChB MRCP FRCPath

Consultant Haematologist
Guy's & St Thomas' NHS Foundation Trust
London, England, United Kingdom
MW

Melissa Whitten

Consultant in Maternal and Fetal Medicine
Elizabeth Garrett Anderson Institute for Women's Health
London, England, United Kingdom
Marie Scully, MD

Professor of Haemostasis and Thrombosis
Department of Haematology, University College London Hospitals, London, UK
London, England, United Kingdom

Background: Pregnancy-associated TTP can be associated with hypertension, proteinuria, fetal growth restriction and fetal loss, and cases may be initially diagnosed as preeclampsia +/- HELLP syndrome. Meanwhile, a subset of cases of ‘unexplained’ fetal growth restriction, stillbirth, or thrombocytopenia in pregnancy may represent undiagnosed TTP. Given that effective treatment of TTP drastically improves fetomaternal outcomes, it is vital that cases are not missed.

Aims: We sought to screen for TTP in women with obstetric complications possibly compatible with underlying TTP.

Methods: Women with a current or previous history of unexplained fetal growth restriction or stillbirth ( +/- suspected uteroplacental insufficiency), preeclampsia, HELLP syndrome, or new onset thrombocytopenia (nadir < 75 x109/L) were recruited at a regional centre. In cases with additional features ‘suspicious’ for TTP (1+ of: (i) >25% fall in platelet count; (ii) features of haemolysis (iii) features of uteroplacental insufficiency and (iv) additional adverse obstetric history), ADAMTS13 activity (FRETS-VWF73 assay) was measured. ADAMTS13 activity >10 iu/dL excluded TTP. ADAMTS13 activity was also measured in all cases of severe early onset fetal growth restriction recruited to the multicentre prospective EVERREST study. Regional ethics committee approval was obtained (18/NW/0552, 13/LO/1254) and informed consent sought in accordance with the Helsinki Declaration.

Results: Of a total of 218 women recruited, 211 met the criteria for ADAMTS13 activity measurement. One case initially presenting with severe early onset fetal growth restriction and preeclampsia was subsequently diagnosed with TTP. Figure 1 summarises the results.

Conclusion(s): Fetal growth restriction may in some cases be the initial presenting feature of pregnancy-associated TTP and there is potential for misdiagnosis as preeclampsia/HELLP. Whilst larger scale screening for TTP in complicated pregnancies may not be feasible/ justified, education of healthcare professionals to raise awareness of TTP is of paramount importance in reducing missed cases.