The invention relates to a coupling device (2) which includes a coupling member (3) including a primary flow channel (11) and secondary flow channels (12) each provided with a proximal opening (13) intended for being in fluid communication with a respective tube for delivering medical treatment fluid and a distal opening (14), the distal opening (14) of the primary flow channel (11) being arranged between the distal openings (14) of the secondary flow channels (12), and a connection nozzle (4) to be connected to a catheter, the connection nozzle (4) including a mounting portion (15) in which the coupling member (3) is mounted, the coupling member (3) and the connection nozzle (4) defining an inner chamber (18) into which the distal openings (14) of the primary and secondary flow channels (11, 12) lead. The cross-section of the distal opening (14) of the primary flow channel (11) is larger than the cross-section of the proximal opening (13) of the primary flow channel (11).Ce dispositif de raccordement (2) comporte un organe de raccordement (3) comprenant un canal découlement primaire (11) et des canaux découlement secondaires (12) pourvus chacun dune ouverture proximale (13) destinée à être reliée fluidiquement à un tube dadministration de fluide de traitement médical respectif et dune ouverture distale (14), louverture distale (14) du canal découlement primaire (11) étant disposée entre les ouvertures distales (14) des canaux découlement secondaires (12), et un embout de connexion (4) destiné à être connecté à un cathéter, lembout de connexion (4) comprenant une partie de montage (15) dans laquelle est monté lorgane de raccordement(3), lorgane de raccordement (3) et lembout de connexion (4) délimitant une chambre interne (18) dans laquelle débouchent les ouvertures distales (14) des canaux découlement primaire et secondaires (11, 12). La section transversale de louverture distale (14) du canal découlement primaire (11) est supérieure à la section transversale de lo
