Background: Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy caused by ADAMTS13 deficiency and disproportionately affects women. Pregnancy can precipitate TTP due to the physiological decline in ADAMTS13 during the second trimester. TTP in pregnancy is associated with pregnancy loss, maternal mortality and poorer neonatal outcomes.
Case report: We report the case of a 39-year old gravida 2 para 2 woman with a history of acquired TTP initially diagnosed at age 22, with recurrent clinical relapses previously treated with immunosuppression including plasma exchange. She was in clinical and serological remission prior to this pregnancy. Monthly monitoring revealed a reduction in ADAMTS13 activity (nadir 30.9%) beyond that of the expected physiological decline. An anti-ADAMTS13 inhibitor assay confirmed the presence of an 1.6 Bethesda unit inhibitor. She received four doses of rituximab and oral prednisolone pre-emptively from 27-weeks, resulting in normalisation of ADAMTS13 activity (105.3%) at Day 14 post-rituximab. She did not experience clinical TTP. She delivered a 2.1kg female infant at 34-weeks via emergency C-section due to premature rupture of membranes. The neonate developed transient hypoglycaemia due to maternal gestational diabetes, and mild jaundice managed conservatively. Postpartum the mother was treated with oral antibiotics for an operative wound infection. At 6-weeks post-partum she remains in serological remission with normal ADAMTS13 activity at 94.2%.
Conclusion: In this case, pre-emptive treatment with rituximab and corticosteroids in the second and third trimesters rapidly normalised ADAMTS13 activity and prevented clinical TTP relapse. Both maternal and neonatal outcomes were favourable, with no significant infective complications.