Patients will undergo the planned bariatric intervention according to the standard of treatment. A solution of 20 ml of the local anesthetic Ropivacaine (0.25%) is then injected for postoperative pain control according to the allocated procedure (TPA).

Patients will undergo the planned bariatric intervention according to the standard of treatment. A solution of 20 ml of the local anesthetic Ropivacaine (0.25%) is then injected for postoperative pain control according to the allocated procedure (PSI).

The laparoscopic-assisted Transversus Abdominis Plane (TAP) block will be done just after the optic trocar placement as follow: as landmarks we use the anterior axillary line, in the middle between the iliac crest and the costal margin. After insertion of the optic trocar the peritoneum is visualized. A 14 Gauge needle is inserted 2 cm cranially respect the taken landmark through the skin until the penetration of the internal and external oblique fascias, identified as sudden lowering of resistance. Laparoscopy allows to confirm that the needle did not pass the peritoneum.

A solution of 20 ml of Ropivacaine (0.25%) is then injected, observing the formation of a bulge posterior to the transversus abdominis muscle.

The procedure is then repeated identically on the contralateral side.

Postoperative pain on the visual analogue scale (VAS) This visual analogue scale measures the subjective pain: patients indicate a position along a continuous line between two end-points to specify their level of pain. Absence of pain is represented by 0 while 10 corresponds to the maximum of pain.

Postoperative pain on the visual analogue scale (VAS) at 3, 6, 12, 18 hours. This visual analogue scale measures the subjective pain: patients indicate a position along a continuous line between two end-points to specify their level of pain. Absence of pain is represented by 0 while 10 corresponds to the maximum of pain.