PEDIATRICS

M.O. Stormon¹, A. Shun², E.V. O'loughlin¹, D. Verran³, G. Thomas², D. Lord⁴, M. Chennapragada^4
1Gastroenterology, Children's Hospital Westmead, Sydney/NSW/AUSTRALIA, ²Surgery, Children's Hospital Westmead, Sydney/NSW/AUSTRALIA, ³Transplant Surgery, Australian National Liver Transplant Unit, Sydney/NSW/AUSTRALIA, ⁴Medical Imaging, Children's Hospital Westmead, Sydney/NSW/AUSTRALIA

Body: Introduction Hepatic venous outflow tract obstruction (HVOO) is uncommon after pediatric liver transplantation. We report 7 children with post liver transplant HVOO; their clinical features, investigations, management and outcomes. Methods Retrospective chart review of children with HVOO, transplanted at Australian National Liver Transplant Unit, Sydney, Australia (1985-2009). Demographics Of 228 transplants performed in 197 children, 7(3%) developed HVOO. 5 male, 4.5 years mean age). Indications: alpha-1-antitrypsin deficiency(3), biliary atresia(1); retransplant(3). Grafts all reduced size: 6 cut-downs (2 left lobe; 4 left lateral segment (LLS), II and III); in-situ split LLS 1). 2 were urgent transplants, one of which included an urgent re-transplant. The same surgical team has performed the vast majority of the total pediatric liver transplants from our centre. The hepatic vein-inferior vena cava anastomosis was performed by piggy-backing the donor hepatic vein(s) to the recipients hepatic venous confluence via the triangulation technique, with modifications as required. Results HVOO diagnosed 20 months (mean) post transplant (range 1 month to 8.2 years). Symptoms often subtle: abdominal pain(3), diarrhea(1); 2 children asymptomatic. Clinical signs: splenomegaly(6), ascites(5), edema(3), hepatomegaly(3), rapid marked weight gain(2). Jaundice unusual(1). Liver function tests were minimally deranged. The bilirubin was normal in 5 patients, with mild elevations in the other two (total/conjugated 110/25 and 31/17). Transaminases (AST, ALT) were normal(3), and ranged from 1-2 x normal(3), to > 4 x normal (1 patient). Serum albumin was usually low, mean 20 g/L. Other laboratory parameters included full blood counts, with abnormal values seen in 4 patients, usually reflecting hypersplenism (low platelets, white cell count). Coagulation was abnormal (despite near normal LFT), mean INR of 1.9. Diagnostic imaging with doppler ultrasound (US) was unreliable in identifying HVOO - reports of normal hepatic veins (HV) in 3, while patency of the HV (4) but with flow anomalies (dampened trace, loss of triphasic pattern, monophasic character). CT (2) and MRI (1) scans had "normal HV" when performed. Hepatic venogram the gold standard investigation for HVOO. All seven patients had a stricture at the HV/IVC anastomosis, and when measured there was significant pressure gradient across the anastomosis. Liver biopsy when performed (3) directly led to hepatic venograms and the diagnosis of HVOO. Management was balloon dilatation in all 7 patients: once only (1), 1-5 (3), >5 (3). HV stents were placed (3); two patients required x 3 stents. Outcomes: retransplant (4) for graft failure due to HVOO. Three of these had already undergone 2nd transplant, and all had required stenting. 1 has evolving cirrhosis (multifactorial including HVOO), another requires regular dilatations (x 9 over 4 year period). Conclusion HVOO post pediatric liver transplant results in significant morbidity and graft loss. The clinical presentation can be subtle. LFT are often minimally abnormal, and doppler US is unreliable. Diagnosis requires a high index of clinical suspicion, and is confirmed by hepatic venography. Treatment is with balloon dilatation; stenting in our experience has not been successful. All our patients with HVOO had received reduced size grafts; three who developed HVOO after their 2nd graft required a 3rd graft.

Disclosure: All authors have declared no conflicts of interest.