Remove the introducer, and attach the syringe. Draw the fluid into the syringe. If no fluid returns, rotate, slightly withdraw, or advance the catheter until fluid is obtained. If still no fluid returns, abort the procedure, and try an alternative site or method. Ascites fluid may be removed by attaching a three-way stopcock or one-way valve, a 60-cc syringe to one arm, and drainage tubing and bag to the other arm. If lavage is desired, such as for detecting hemoperitoneum after trauma, connect intravenous tubing to the three-way stopcock. Remove excess fluid and then infuse 700 to 1,000 mL of Ringer lactate or normal saline into the abdominal cavity. Gently roll the patient from side to side. Then, remove the fluid as described above or using a trap-suction arrangement.