Peritoneal lavage is a medical procedure in which fluid is introduced into the abdominal cavity, then drained and analyzed. It is most commonly associated with trauma care, where it helps detect internal bleeding after an injury to the abdomen. But the same basic technique, flushing the abdominal cavity with fluid, also has therapeutic uses ranging from treating severe infections to rewarming patients with dangerously low body temperatures and even staging certain cancers.
How Diagnostic Peritoneal Lavage Works
In the diagnostic version of this procedure (often called DPL), you lie flat on your back while the area around your belly button is numbed with a local anesthetic. A catheter and tube are placed to empty your bladder and stomach first, which reduces the risk of accidentally puncturing either organ. The skin just below (or above) the belly button is then opened with a small incision, and a thin catheter is guided into the peritoneal cavity, the space that surrounds your intestines, liver, spleen, and other abdominal organs.
Once the catheter is in place, warm saline is infused into the cavity. After the fluid has had time to mix with whatever is inside, it drains back out through the same catheter and is sent to a lab. If the returned fluid contains blood, bile, digestive enzymes, or elevated white blood cell counts above certain thresholds, the test is considered positive, meaning there is likely significant internal injury that may need surgery.
Three Approaches to the Procedure
There are three ways the catheter can be placed, and the choice depends on the clinical situation and the physician’s preference.
- Open technique: A small vertical incision is made below the belly button, and the surgeon cuts directly through each tissue layer under direct vision until reaching the abdominal cavity. This gives the clearest view and the lowest risk of accidentally injuring nearby structures.
- Closed technique: A needle is inserted through the skin into the abdominal cavity without an incision through the deeper layers. A guidewire is threaded through the needle, and the catheter slides over the wire. It is faster but relies entirely on feel rather than sight.
- Semi-open technique: This is a middle ground. The skin and fat are opened with a small incision so the surgeon can see the tough connective tissue layer underneath, but the catheter is then placed using the guidewire method rather than cutting all the way through. As the needle passes through the connective tissue and then the lining of the abdominal cavity, two distinct “pops” are typically felt, confirming correct placement.
Why DPL Is Used in Trauma
DPL was once the primary way emergency teams evaluated blunt abdominal trauma, such as from car accidents or falls. Its main strength is speed: the entire procedure can be done at the bedside in minutes and does not require moving an unstable patient to a scanner. It is also highly sensitive, meaning it rarely misses significant bleeding inside the abdomen.
Today, bedside ultrasound (the FAST exam) has largely replaced DPL as the first-line tool in most trauma centers because it is completely noninvasive and even faster. CT scans offer far more anatomical detail. But DPL still has a role when ultrasound results are inconclusive, when CT scanning is not available or the patient is too unstable to be moved to the scanner, or when the clinical picture simply does not add up. Some guidelines recommend it as a follow-up step after a negative or unclear ultrasound in a patient whose condition is deteriorating.
The complication rate for DPL is low, around 0.9% in large studies. The most common problems are technical errors during catheter placement and, less frequently, false-negative or false-positive results. Serious complications like bowel perforation or blood vessel injury are rare.
Therapeutic Uses: Treating Infection
Peritoneal lavage is not only a diagnostic tool. When severe peritonitis develops, meaning widespread infection inside the abdominal cavity (often from a ruptured appendix, perforated ulcer, or bowel injury), surgeons may flush the cavity with large volumes of warm saline during or after an operation. The goal is mechanical: physically washing out bacteria, pus, and debris to reduce the infectious load the body has to fight.
Animal research has shown that lavage with large volumes of warm saline significantly reduces the early inflammatory response that spreads from the abdomen to the lungs, one of the most dangerous complications of severe peritonitis. Both normal saline and higher-concentration saline solutions appear to offer this protective effect on lung tissue.
Rewarming in Severe Hypothermia
When someone’s core body temperature drops to dangerous levels, external warming methods like blankets and warm air are often too slow. Peritoneal lavage offers a way to warm from the inside. Heated fluid is infused into the abdominal cavity, where it transfers heat directly to the core of the body, and then drained and replaced with fresh warm fluid in repeated cycles.
In experimental studies, peritoneal lavage rewarms the body at a rate of roughly 6°C per hour per square meter of body surface area. That is substantially faster than surface warming alone and makes it a valuable option in emergency departments treating patients with severe or profound hypothermia, particularly when more advanced rewarming methods like heart-lung bypass are not available.
Cancer Staging With Peritoneal Lavage
In oncology, peritoneal lavage plays a completely different role. During staging laparoscopy for gastric (stomach) cancer, surgeons flush the abdominal cavity with fluid and then examine it under a microscope for cancer cells. This technique has become a cornerstone of gastric cancer staging because standard imaging, including CT and PET-CT scans, has limited ability to detect small amounts of cancer that has spread to the abdominal lining.
Finding cancer cells in the lavage fluid, even when no visible tumor deposits are present on the abdominal surfaces, is significant enough to reclassify the cancer as stage IV. This changes the treatment plan considerably, often shifting the approach from curative surgery to other strategies. Current guidelines recommend this lavage for patients with more advanced tumors, positive lymph nodes, or a diffuse-type growth pattern.
One challenge is consistency. A recent multicenter survey of high-volume Japanese cancer centers found more than a tenfold variation in how often lavage cytology came back positive, largely driven by differences in how labs collected, processed, and interpreted the samples rather than by true differences in disease rates. Standardizing these methods remains an active priority in surgical oncology.
What the Experience Is Like
If you are having a diagnostic peritoneal lavage, the procedure is done with local numbing of the skin and, in many cases, mild sedation through an IV. You will feel pressure near your belly button and possibly a brief cramping sensation as fluid enters the abdominal cavity. The entire process, from prep to fluid drainage, generally takes 15 to 30 minutes. Results from the lab can come back quickly, sometimes within the hour, which is part of what makes DPL valuable in urgent situations.
Therapeutic lavage during surgery for peritonitis happens while you are already under general anesthesia, so you would not feel it. Lavage for hypothermia rewarming is typically performed on patients who are already critically ill and often sedated. In cancer staging, the lavage is part of a laparoscopic procedure done under general anesthesia, and the fluid collection itself adds minimal time to the operation.