Renal venous thrombosis (RVT) in children occurs mainly in the neonatal period. To date, no unbiassed epidemiological data are available. The impact of different therapies on the outcome of RVT has not been studied in unselected patients.

Aim of the study was to estimate the incidence and to document the current therapy and outcome of neonatal RVT in Germany.

Between 1992 and 1994, the German registry on rare pediatric diseases(ESPED) carried out a nationwide survey on thrombosis in the neonatal period. 101 cases were reported, 35 of which were classified as RVT based on typical ultrasonographic and urinary findings. Therapy and outcome were assessed by a standardized questionnaire mailed to the treating physicians.

The incidence of neonatal RVT was 2.2 per 100,000 live births. In 43%, RVT occurred in preterm babies. RVT was unilateral in 80%. Caval occlusion was reported in 23%. Therapy was supportive in 23%, low dose heparin was used in 40%, full heparinization in 26% and thrombolytic therapy in 10%. 80% of children with caval occlusion received either high dose heparin or thrombolytic therapy reflecting a more aggressive approach in this subgroup. Outcome could be assessed in 32 patients with a median follow-up of 11.5 months. Two children were in end-stage renal failure while the remainder had normal kidney function (serum creatinine < 50 μmol/l). Arterial hypertension (RR > 110/70 mmHg) was present in three. Renal atrophy was noted in 67% of 39 kidney units affected by RVT. There was no difference in the occurrence of renal atrophy between the different treatment groups.

There is no generally accepted treatment of neonatal RVT. Renal morbidity is high. Because of the low incidence of neonatal RVT a large multi-center therapeutic trial is planned to determine the optimal treatment of neonatal RVT.