Paracentesis.  The procedure to remove abnormal collection of fluid from the peritoneal cavity.

• Differential diagnosis of ascites
• Intraabdominal pressure causing respiratory distress
• Differential diagnosis of acute peritonitis

CONTRAINDICATIONS:

• Acute abdomen requiring immediate surgery (absolute contraindication)
• Coagulopathy (relative contraindication)
• Thrombocytopenia (relative contraindication)
• Severe bowel distension (use extra caution or open technique)
• Previous abdominal surgery, especially pelvic surgery
• Pregnancy (necessitates using open technique above umbilicus after first trimester)
• Distended bladder that cannot be emptied with a Foley catheter
• Obvious infection at intended site of insertion (cellulitis or abcess)

COMPLICATIONS:

• Bladder perforation
• Small or large bowel perforation
• Stomach perforation
• Lacerations of major vessels (mesenteric, iliac, aorta)
• Laceration of catheter or guide wire and loss in peritoneal cavity (might require laparotomy to recover catheter)
• Abdominal wall hematomas 
• Incisional hernias
• Wound infection
• Wound dehiscence
• Inability to retrieve majority of instilled fluid