Renal vein thrombosis in neonates: a case series of diagnosis, treatment and childhood kidney function follow-up.

Abstract

Neonatal renal vein thrombosis (NRVT) is a rare condition with little data available. We retrospectively analyzed newborns diagnosed with NRVT admitted to3 pediatric nephrology units in Paris from 2005 to 2020. Twenty-seven patients were analyzed (male = 59%). The median age at diagnosis was2.5days (1 - 4.5). Diagnosis was suspected based on at least one of the three cardinal signs of renal vein thrombosis in 93%: flank mass (67%), hematuria(67%) and thrombocytopenia (70%). In all patients, diagnosis was confirmed by ultrasound. All patients had at least one known perinatal risk factor. A prothrombotic risk factor was found in 13 patients (48%). NRVT was unilateral in 70%, involving the left renal vein in 58%. Among 25 treated patients, 19 (76%) received low molecular weight heparin (LMWH) as initial therapy, 2 (8%) received unfractionated heparin and4 (16%) received fibrinolysis. Median duration of treatment was 8weeks (4 - 12). Bleeding occurred significantly more often with fibrinolysis than with LMWH/supportive therapy (3 of 4: 75% vs 0 of 4: 0%, p = 0.05). Clot resolution in patients treated with fibrinolysis did not differ significantly from those treated with LMWH/supportive therapy. After a median follow-up of 5.7years (3years-9.9years), pathological kidney features were observed in 73% of the patients (19 of 26), kidney atrophy in 18 (69%), hypertension in 2 (8%), chronic kidney disease(CKD) in 1 (4%) and proteinuria in2(8%). NRVT remains a challenging condition, which still requires further study because of its associated morbidity. A higher resolution version of the Graphical abstract is available as Supplementary information.