An Attempt to Reach Consensus Regarding Management of Neonatal Renal Vein Thrombosis: The Canadian Pediatric Hemostasis and Thrombosis Network Experience.

Background: Renal vein thrombosis (RVT) is the most frequent site of primary venous thrombosis in neonates. At present, there is no conventional therapeutic regimen for this condition.

Objective: To establish current clinical guidelines based on data from the Canadian Pediatric Hemostasis and Thrombosis Network (CPHTN).

Materials and Methods: A standardized questionnaire was sent to CPHTN members involved with pediatric thrombosis care. Clinical variables included thrombus location (unilateral vs. bilateral), severity (non-occlusive vs. occlusive), extension to the inferior vena cava (IVC+), and concomitant bleeding at diagnosis [i.e. hematuria with thrombocytopenia (H/T+), with/without ≥ grade 2 intraventricular hemorrhage (IVH+/−)].

Results: A total of 16 pediatric hematologists participated, with a response rate of approximately 80%. Regarding diagnostic imaging, the most utilized methods were the following: a) Doppler ultrasound (U/S) in 14/16 (87.5%); b) U/S without Doppler in 1/16 (6.25%); and c) contrast venography in 1/16 (6.25%). 12/16 (75%) of the physicians would have ordered a thrombophilia work up. For unilateral, non-occlusive, H/T− or H/T+ cases, management included, respectively: 1) no therapy in 11/16 (68.75%) and 9/16 (56.25%); 2) low-molecular-weight heparin (LMWH) in 2/16 (12.5%) (3-month-course) and 3/16 (18.75%) (14-day or 3-month course); and 3) therapy based on radiologic follow up (f/u) in 3/16 (18.75%) and 4/16 (25%). For unilateral, occlusive, H/T+, IVH− or IVH+ cases, management included: 1) no therapy in 5/16 (31.25%) and 10/16 (62.5%); 2) LMWH in 6/16 (37.5%) and 4/16 (25%); and 3) treatment based on f/u findings in 5/16 (31.25%) and 2/16 (12.5%). For bilateral, occlusive, IVC−, IVH− cases, management included: 1) LMWH (2 weeks to 3 months) in 12/16 (75%); 2) tissue-plasminogen activator (t-PA) in 1/16 (6.25%); 3) LMWH and t-PA in 2/16 (12.5%); and 4) therapy based on f/u in 1/16 (6.25%). Finally, for bilateral, occlusive, IVC+, IVH− or +, the responses were, in that order: 1) LMWH (6 weeks to 3 months) in 10/16 (62.5%) and 11/16 (68.75%); 2) t-PA in 3/16 (18.75%) and 0/16; 3) LMWH and t-PA in 2/16 (12.5%) and 0/16; 4) treatment based on f/u in 1/16 (6.25%) in both groups; 5) no therapy in 2/16 (12.5%) of the latter group only; and 6) unknown in 2/16 (12.5%) of the latter group only. The anti-Xa level (0.5 to 1.0 range) was the only assay suggested for monitoring LMWH. Standard heparin was monitored by anti-Xa levels in only 3/16 (18.75%) of cases. Consultation sources included 1) combined sources (i.e. books, protocols, journals) in 10/16 (62.5%) cases; 2) journals in 4/16 (25%) cases; and 3) 1-800-NO-CLOTS in 2/16 (12.5%) cases. 15/16 (93.75%) of the participating physicians supported the idea of developing therapeutic protocols.

Conclusions: Currently, there are no standard therapeutic practices with respect to neonatal RVT. It would be difficult to successfully complete a randomized clinical trial due to small numbers. However, multicenter, prospective studies utilizing consistent therapeutic approaches would be extremely helpful in this clinical setting.