A puncture assistance device for use in connection with an ultrasound probe to guide a Veress needle through the layers of the wall into a bodily cavity is provided. The puncture assistance device comprises a tenaculum-like forceps, a needle guide body provided with a slot for guiding the Veress needle within the scan plane of the ultrasound probe, attachment means to the ultrasound probe, and attachment means of the needle guide to the tenaculum-like forceps. Also provided is a balloon catheter for use as a retractor in gaining access into the abdominal cavity, presenting at its distal end an inflatable balloon membrane and an framework of non-distendable flexible fibers disposed in a specific arrangement. A method access the abdominal cavity with the aid of said devices under ultrasound guidance is also provided.