Neonatal renal vein thrombosis: review of the English-language literature between 1992 and 2006.

Renal vein thrombosis is a complication that occurs in neonates with various underlying risk factors. It carries a grave prognosis for affected kidneys. Anticoagulant and fibrinolytic therapies have been promoted in the past with anecdotal success in some circumstances. However, prospective controlled trials are still lacking, and to date there have been no evidence-based guidelines available for the treatment of neonates with renal vein thrombosis. We retrospectively reviewed all the available medical literature pertaining to renal vein thrombosis published in English during the past 15 years. A total of 271 patients from 13 case series were identified by using the terms "renal vein thrombosis" and "neonates" via PubMed and Cochrane Library searches. Data then were extracted from each of the studies for analysis. During the past 15 years, a male predominance (67.2%) in neonatal renal vein thrombosis has been reported. More than 70% of patients had unilateral renal vein thrombosis, which was more prevalent on the left side (63.6%). The thrombus involved the inferior vena cava and was associated with adrenal hemorrhage in 43.7% and 14.8% of neonates, respectively. Forty percent of the patients were treated conservatively with supportive care alone. Among those patients who received anticoagulation therapy, unfractionated heparin and low molecular weight heparin were used alone in 21.6% and 20.7% of the patients, respectively. Fibrinolytic treatment alone was used in 11.2% of the patients. Only a minority of patients were treated with antithrombin (1.7%), warfarin alone, (0.9%) or underwent surgical intervention (0.3%). The majority (70.6%) of the involved kidneys became atrophic. A total of 9 neonates died with non-renal vein thrombosis-related conditions during the study period. Evidence-based recommendations on treatment cannot be made at the present time. Cooperative prospective studies that involve multiple centers are needed to elucidate the optimal treatment for neonatal renal vein thrombosis.