Ascites: ultrasound guidance or blind paracentesis?

The classic site for paracentesis in generalized ascites is in the left lower quadrant of the abdomen at a position equivalent to McBurney's point. Its use has an average success rate of 58%, depending on the amount of liquid. To assess the efficacy of paracentesis at this site and to establish the ideal site for blind puncture, we studied 27 consecutive patients with ascites detected by abdominal ultrasonography. The amount of ascites was graded from 1 to 4. Free fluid had accumulated mostly in the perihepatic region, then around the bladder and in the right paracolic gutter, and finally in the left flank. In six of the eight patients in whom fluid was found in the left or right flank, air-filled bowel loops were observed between the abdominal wall and the fluid, in the expected path of a blind puncture. These findings suggest that the safety and efficacy of paracentesis would be greatly improved by ultrasonographic guidance.