Small-for-size syndrome in the rat: does size or technique matter?

The incidence of the small-for-size syndrome (SFSS) is inversely correlated to the size of the remnant liver or the partial graft. The relevance of factors besides the absolute liver mass is discussed controversially. It is the aim of this study to test the effect of two different mass ligation techniques in comparison with our newly developed parenchyma-preserving vessel-oriented liver resection technique on the induction of a SFSS after extended 90% liver resection in the rat.

Ninety percent liver resections were performed using three surgical techniques, two mass ligation techniques, and a vessel oriented technique. Diagnosis of SFSS was based on the combination of biochemical and morphological criteria on the first postoperative day and was related to the outcome on postoperative day 7 and the regenerative capacity of the liver.

Only the use of mass ligation techniques was associated with a low 1-wk survival rate (<40%), more pronounced histomorphological signs of liver damage at 24 h postoperatively, and a delayed onset of hepatocyte proliferation. Histological analysis revealed an extended stump necrosis in the paracaval liver and signs of sinusoidal damage in the remaining caudate lobes as morphological correlates of a putative outflow obstruction as the possible underlying reason. The lesions added up to a high small-for-size score in rats operated according to mass ligation techniques.

These results indicate that preservation of functional liver mass and prevention of an outflow obstruction by delicate surgery is essential to prevent a SFSS in a size-reduced liver.