• Knowledge of the anatomy and physiology of the abdomen is important to avoid unexpected outcomes.

• 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 or the presence of bacteria or bile in the return fluid in the abdomen is 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 who have head injuries, are unconscious, or have 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 necessary 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 tomography (CT) scan frequently is used in trauma patients with hemodynamically stable conditions 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 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 Patients with hemodynamically unstable conditions may also go directly to the operating room (OR) for laparotomy.

• Complementary CT scan 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 radiography or penetrating abdominal trauma.

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

• Use caution when performing DPL in patients with suspected pelvic fractures (may use a supraumbilical site) because of false-positive results⁷; if DPL is performed in pregnant patients of more than 12 weeks’ gestation, use an open technique, superior to the uterus.⁷