Maternal morbidity and mortality in pregnant/postpartum women with suspected HELLP syndrome identifiable as probable thrombotic thrombocytopenic purpura or atypical hemolytic uremic syndrome by high LDH to AST ratio

Abstract

Objective To describe findings in 8 women initially diagnosed as presumptive HELLP Syndrome, eventually confirmed as TTP/aHUS as distinguished by elevated calculated LDH:AST ratio > 22:1. Methods All medicolegal files of patients evaluated between 1986 and 2015 with presumptive HELLP syndrome but later determined to have TTP/aHUS had LDH:AST ratios evaluated throughout care. Results Fifty‐eight pregnant/postpartum women presented with a diagnosis of presumptive HELLP syndrome. In the final analysis, 8 women had TTP/aHUS characterized by severe thrombocytopenia (<20 000/μl) at admission, rare epigastric pain, and the consistent demonstration of a very high calculated total LDH to AST ratio. This calculation greatly exceeded 22:1 with TTP/aHUS (mean = 32:1) versus 2:1 with HELLP and could be consistently demonstrated throughout care. Six of 8 women with TTP/aHUS died. Conclusion Correctly distinguishing between HELLP syndrome versus an imitator disorder continues to challenge obstetric specialists. This medicolegal data supplements prior findings supporting the concept of the LDH:AST ratio as a useful screening tool for clinicians to differentiate TTP/aHUS apart from HELLP syndrome in order to facilitate earlier hematology consultation, patient referral to tertiary care and emergent hemotherapy for these mothers.

Features of Postpartum Hemorrhage-Associated Thrombotic Microangiopathy and Role of Short-Term Complement Inhibition

“…Many obstetric complications such as (pre)eclampsia/HELLP, PPH, and cesarean delivery can be considered complement-activating conditions. 6 , 9 , 10 , 11 , 12 The delivery of the placenta during the postpartum phase eliminates its complement-inhibiting effect via CD55 (decay accelerating factor) and further predisposes for TMA. 4 , 13 , 14 The heme molecule itself has been identified as complement activator in aHUS.…”

Pregnancy as a susceptible state for thrombotic microangiopathies

“…A recent study suggests that serum creatinine levels ≥1.9 mg/dL, LDH levels ≥1,832 units/L, or a combination of LDH levels ≥600 units/L and serum creatinine level ≥ 1.9 mg/dL can effectively differentiate CM-HUS from HELLP syndrome in the postpartum period ( 59 ). Furthermore, it has been suggested that a high LDH to AST ratio > 22 may indicate a higher likelihood of TTP rather than HELLP syndrome in a third-trimester pregnant patient suspected of having TMA ( 60 , 61 ).…”