• Knowledge of the anatomy and physiology of the abdomen is needed.

• The Intestines and the bladder lie immediately beneath the abdominal surface. In children, the bladder is an abdominal organ. In adults, a full bladder is raised out of the pelvis.

• The cecum is relatively fixed and is much less mobile than the sigmoid colon; therefore, bowel perforations are more frequent in the right lower quadrant than in the left.

• A distended stomach can extend to the anterior abdominal wall.

• Peritoneal fluid is normally straw-colored, serous fluid secreted by the cells of the peritoneum.

• Grossly bloody fluid, a red blood cell (RBC) count of greater than 100,000/mm³,^2,5,9 and the presence of bacteria or bile in the return fluid in the abdomen are abnormal. A white blood cell (WBC) count greater than 500,000/mm and the presence of bile or amylase in the lavage fluid are parameters, in addition to the RBC count, that can lead to operative intervention.^2,5,9

• Diagnostic peritoneal lavage is a highly sensitive tool for diagnosis of visceral injuries in the abdominal cavity.^1,5,8

• Diagnostic peritoneal lavage is used after blunt abdominal trauma or in trauma patients with head injuries, those who are unconscious, or those with preexisting paraplegia to determine the presence of the following²:

• Therapeutic lavage is used to:

• For trauma patients with stab wounds and gunshot wounds to the lower chest or anterior abdomen, diagnostic peritoneal lavage is controversial; most trauma centers operate on patients with gunshot wound injuries to the lower chest or anterior abdomen.¹

• Diagnostic peritoneal lavage can be used as a tool in patients with hypotension of uncertain etiology, in the presence of trauma.⁶

• Diagnostic peritoneal lavage is not needed if abdominal surgery is already indicated.^7,9

• Because it is an invasive procedure, diagnostic peritoneal lavage does have a small risk of visceral injury (0.6%).⁵

• Diagnostic peritoneal lavage is 95% sensitive and 99% specific for intraperitoneal blood; however, it cannot exclude retroperitoneal hemorrhage, disruption of the diaphragm, or hollow viscus perforation.^5,7

• Computed tomographic (CT) scan frequently is used in hemodynamically stable trauma cases as the diagnostic procedure of choice.⁵ Also, abdominal ultrasound scan and focused abdominal sonography in trauma (FAST) have been increasingly used to screen blunt abdominal trauma cases for hemoperitoneum.⁹

• In patients with hemodynamically unstable conditions, diagnostic peritoneal lavage (DPL) may be preferred by some practitioners because of its high sensitivity.^1,2,5,9 DPL is quick, inexpensive, safe, and highly sensitive to the presence of blood in the peritoneal cavity.⁵ Hemodynamically unstable cases may also go directly to the operating room for laparotomy.

• Complementary CT and DPL decreases nontherapeutic laparotomy rates and allows nonoperative management of those patients with solid-organ injury.⁹

• Peritoneal lavage is absolutely contraindicated in an acute abdomen that needs immediate surgery as indicated by free air on radiograph or penetrating abdominal trauma.

• Relative contraindications for DPL include the following^5,6:

• Practitioners should use caution when performing DPL in patients with suspected pelvic fractures (a supraumbilical site may be used) because of false-positive results⁷