An indwelling needle assembly usable in combination with an infusion system for infusion into a patients body is disclosed. The indwelling needle assembly is comprised of a needle having a needlepoint insertable into the patients body a sleeve slidably fitted on the needle a catheter including a catheter tube slidably fitted on the sleeve a base body fixed to a proximal end of the needle and a slider fixed to the sleeve and slidably engaged with the base body so as to be movable between a first position to have the needlepoint projecting out of the sleeve and a second position to have the needlepoint retracted in the sleeve, wherein the needle, the sleeve, the base body and the slider are unitarily extractable from the catheter.一種留置針總成,可用來與一點滴注入病患身體之點滴系統組合。留置針總成由以下元件構成:一針,具有一可扎入病患身體的針尖;一套筒,可滑動地適配於針上;一導管,包含一可滑動地適配於套筒上之導管管子;一針座本體,固定於針之一近端;以及一滑件,固定於套筒,並可滑動地與針座本體啣合,俾可移動於針尖突出於套筒外之第1位置與針尖縮入套筒內之第2位置之間,其中針、套筒、針座本體及滑件可一體自導管拔出。10‧‧‧留置針總成11‧‧‧針12‧‧‧針座本體121‧‧‧抓握部122‧‧‧針座123‧‧‧凹槽13‧‧‧導管管子14‧‧‧導管配接器15‧‧‧導管16‧‧‧箍緊管17‧‧‧連接器18‧‧‧止血閥19‧‧‧套筒20‧‧‧滑件201‧‧‧彈性閂
