Postpartum Renal Cortical Necrosis: A Case Series.

Rationale & Objective: Postpartum renal cortical necrosis (postpartum RCN) is a severe form of obstetric acute kidney injury. This study aimed to identify clinicopathologic features in Chinese postpartum RCN cases to determine how pathologic findings may contribute to the treatment and prognosis.

Study Design: Single-center, case series.

Setting & Participants: Twelve patients with postpartum RCN had kidney biopsies at Peking University First Hospital between 2014 and 2021. The diagnosis of postpartum RCN was made according to typical magnetic resonance imaging or pathologic features. Clinical, laboratory, and pathologic data were compared between patients with estimated glomerular filtration rate <30 (poor outcome) and ≥30 mL/min/1.73 m after 6 months.

Observations: All patients with postpartum RCN presented with stage 3 acute kidney injury attributed to a probable atypical hemolytic uremic syndrome. Pregnancy terminations occurred at a median gestational age of 35.5 weeks. Kidney biopsy was performed from 18 days to 4 months from delivery. On biopsy, hemoglobin, platelet count, and lactate dehydrogenase levels had been restored to 137 g/L, 214 × 10/L, and 231.50 ± 65.01 U/L, respectively. Four patients exhibited poor outcome, demonstrating higher schistocyte count, serum creatinine, and mean arterial pressure at onset. Pathologically, glomerular segmental sclerosis was prevalent. The "not otherwise specified" variant was the most common type, followed by collapsing variant, cellular variant, and tip variant. Patients with poor kidney outcome had more glomerular coagulative necrosis, capillary thrombosis, extensive cortical coagulative necrosis, and pronounced arteriole/artery lesions including increased interlobular arteriole intimal edema and fibrin thrombosis, but a lower occurrence of segmental sclerosis.

Limitations: Limited sample size and retrospective design.

Conclusions: We identified key pathologic features in patients with postpartum RCN and atypical hemolytic uremic syndrome, highlighting the necessity for more effective therapeutic options. There is a clear demand for noninvasive biomarkers that can accurately track disease progression and inform treatment duration for long-term outcomes improvement.