[Absence of portal bifurcation]

Since the first description in 1957, absence of the portal bifurcation has been reported by four different teams, which makes a total of 5 cases and a frequency of 1.90%. Serious complications may occur postoperatively, and this anomaly should be systematically detected. There is a huge portal ring: the main vessel enters the liver, looking like a large right paramedian vein, turns to the right within the parenchyma, reaches the umbilical fissure to send the usual branches of REX' recessus, and ends as a terminal branch for the caudate lobe. The right lateral vein appears as a collateral. Numerous anterior and posterior branches supply segments IV, V and VIII. Two main facts: the portal ring turns around the axis of the middle hepatic vein, which is in the center of the ring. There is a rupture in the portal triad of the left portal pedicle: the vein is intra-hepatic, the artery and biliary duct lie normally in the hilum. The detection of this anomaly should always be done by portography or ultra-sonography. When operating, it is easily detected: there is no portal bifurcation and the left portal vein is missing. The main difficulty is to perform a right hepatectomy. After total vascular by-pass, the portal system is skeletonized and resection achieved. Another solution is to interrupt the portal stem deep in the hilum, divide the main portal fissure along the right margin of the middle hepatic vein and cut the transversal portion of the portal ring.(ABSTRACT TRUNCATED AT 250 WORDS)