Late pregnancy complications as a triggers of obstetric atypical hemolytic uremic syndrome

Obstetric atypical hemolytic-uremic syndrome (aHUS) is considered as a classic complement-mediated TMA, the trigger of which is pregnancy itself. However, there is reason to believe that in women who do not have a genetic defect in the complement system, the induction of acute thrombotic microangiopathy (TMA) requires the presence of additional complement-activating states (CAS) that may complicate pregnancy. The aim of our study was to assess the effect of pregnancy complications on the development, course, and prognosis of obstetric ASH in a large group of patients Methods: 69 patients aged 16 to 44 years with aHUS diagnosed were observed from 2011 to 2019, which developed during pregnancy or immediately after childbirth. Results: in all cases, additional CAS preceded the development of aHUS. The amount of CAS did not signifi cantly differ between patients with pathogenic mutations of complement genes and without them and did not affect the severity of the course of aHUS. The most common combination of CAS was preeclampsia - cesarean section - bleeding. 40 out of 69 patients (58%) received treatment with the complement-blocking drug Eculizumab. Almost a half of them (19 out of 40, 47.5%) received only 1 to 5 infusions. Among 40 patients treated with Eculizumab, complete recovery of renal function was observed in 26 (65%) women, four (10%) retained signs of CKD 4-5 stages, five (12.5%) reached terminal renal failure and 5 patients (12.5%) died. Among 29 women who received only plasma therapy, renal function restoration was noted only in10 (34.5%). An analysis of the development conditions and features of the aHUS course indicates a heterogeneity of the obstetric aHUS. The latter can develop both in genetically predisposed women and in patients without a genetic defect in the complement system. In the latter case, complement activity apparently arises as a result of the interaction of several CAS. This explains the effectiveness of the short-term course of Eculizumab. © 2020 JSC Vidal Rus. All rights reserved.