BACKGROUND: The piggy-back caval anastomosis technique is widely used in orthotopic liver transplantation although it carries an increased risk of complications, including outflow obstruction and Budd-Chiari syndrome. The aim of this study is to clarify the anatomy and variations of hepatic veins (HVs) draining into the inferior vena cava (IVC), and to classify the surgical techniques of piggy-back liver transplantation (PBLT) based on the anatomy of HVs which can reduce the occurrence of complications.

METHODS: PBLT was performed in 248 consecutive cases at our hospital from January 2004 to August 2011. The anatomy of recipients HVs was determined when removing the native diseased livers. Both anatomy of HVs and short HVs draining into the IVC were recorded. These data were collected and analyzed.

RESULTS: We classified anatomic variations of HVs in the 248 livers into five types according to the way of drainage into the IVC: type I (trunk type of left and middle HVs), 142 (57.3%) patients; type II (trunk type of right and middle HVs), 54 (21.8%); type III (trunk type of left, middle and right HVs), 14 (5.6%); type IV (non-trunk type of left, middle and right HVs), of which, type IVa, 16 (6.5%), in the same horizontal plane; type IVb, 18 (7.3%), in different horizontal planes; and type V (segment type), 4 (1.6%). The patients whose HVs anatomy belonged to types I, II and III underwent classical piggy-back liver transplantation. Type IVa patients had classical PBLT via HV venoplasty prior to piggy-back anastomosis, while type IVb patients and type V patients could only have modified PBLT.

CONCLUSION: This study demonstrates that HVs can be classified according to the anatomy of their drainage into the IVC and we can use this classification to choose the best operative approach to PBLT.