Read the French translation: Péritonites: Décisions Durant l'Opération

Introduction

Peritonitis is a life threatening condition in dogs and cats that causes serious metabolic alterations and organ dysfunction. This inflammatory process involves all, or a portion, of the peritoneal cavity. It results in contamination of the abdominal cavity by either inflammatory chemicals or microorganisms. The septic abdomen is defined by the presence of germs (bacteria) in the peritoneal cavity. This may result from traumatic injury, surgical induced lesions, strangulation-necrosis of the gastrointestinal tract, perforation of the bowel, rupture of gastrointestinal ulcers, incarcerated loop of intestine, mesenteric volvulus, or pyometra rupture. Inflammation of the peritoneal cavity may also result from release of neoplastic tissues, blood, urine, or bile into the abdominal cavity. Pancreatitis can also trigger peritonitis by local inflammation.

Early diagnosis of peritonitis is a key issue in small animals as peritonitis is not always characterized by acute abdominal pain. Several imaging modalities are helpful to refine the diagnosis. Survey radiographs can evidence ascites or pneumoperitoneum. Contrast studies should be limited to the assessment of the integrity of the urethra and bladder. Contrast studies of the digestive tract should be avoided. Ultrasonography is a key element in the diagnosis of peritonitis as it also allows collection of fluid for further analysis (ultrasound-guided abdominocentesis). If a peritoneal effusion is present in sufficient amount (> 5-7 ml/kg), it can be collected by simple abdominocentesis or by the "4-quadrant" method.

When a septic peritonitis is suspected, some values on the effusion fluid can help confirm the diagnosis. The same measurements can be done perioperatively.

Biochemical criteria evocative of a septic peritonitis:

 Difference between blood and effusion glucose > 0.2 g/l

 Effusion glucose < 0.5 g/l

 Difference between blood and effusion lactates > 2 mmol/l

 Effusion lactates > 5.5 mmol/l

 Effusion pH < 7.2

Treatment

Treatment of peritonitis has 4 goals:

 Administer appropriate supportive medical treatment (antibiotics, fluid therapy, shock therapy)

 Lavage the abdominal cavity with sterile warm saline to flush bacteria or debris

 Correct surgically the primary problem

 Prepare post-operative care

Exploratory Laparotomy and Lavage

The exploratory laparotomy must be performed as soon as the animal is stable enough to undergo surgery. Surgery starts with a thorough examination and immediate lavage of the cavity. The source of the peritonitis is controlled by excising whole or a portion of the involved organ, by repairing it if possible, or by debriding and draining it if not. Specifically, this is achieved through the use of the following techniques: splenectomy, enterectomy, liver lobectomy, partial pancreatectomy, ovariohysterectomy, prostatic or hepatic abscess drainage, etc. The damage secondary to the infection is then addressed. The abdomen is debrided as required. Any infected affordable tissue (Omentum) is excised. Adhesions and compartments in the peritoneal cavity are ruptured and flushed. After the last lavage is performed, the lavage fluid is carefully removed as any remaining fluids are an obstacle to opsonisation.

Abdominal Closure

If contamination is mild and the source of the peritonitis can be well controlled, then the abdomen can be closed after thorough lavage. If the peritonitis has a tendency to be very productive (for instance after a bile peritonitis) or the source cannot be well controlled, then multi-fenestrated large-diameter Jackson Pratt tubes can be placed between the liver and the diaphragm, and on the latero-caudal part of the inner face of the abdominal wall. Omentectomy or omentopexy can be performed to prevent premature obstruction of draining systems. These drains can be connected to a closed suction device or even used to flush the peritoneal cavity. They are maintained until the daily cytology of the abdominal fluid shows significant improvement.

If the contamination of the abdominal cavity is severe or if the source of the contamination is not controlled or if a lot of foreign material is present, the abdomen can be left open. Benefits include a more efficient drainage, a further opportunity to inspect and debride the abdomen, and increase in oxygen tension which hampers anaerobic bacteria proliferation. It entails a risk for iatrogenic contamination which could aggravate the initial septic peritonitis. Also hypoproteinemia, hypoalbuminemia and anaemia are classically associated complications, especially when OPD is prolonged. In a study, 63% of the patients treated with an open abdomen died in the early postoperative period from complications associated with the open abdomen. Then benefits and disadvantages from the technique should therefore be weighted before opting for OPD. When resorting to OPD, the bandage is changed under strict aseptic conditions once or twice daily. Most commonly, provided the initiating cause is treated, the abdomen's condition usually improves over a few days and the abdomen can be closed after 3 to 5 days of OPD.

Another option to consider when an OPD is not wished is a planned re-exploration. This second exploration, often advocated in human surgery, will aim at further rinsing and draining the abdominal cavity, as well as reassessing all tissues which were questionable during the first intervention. This should minimise the risks of Hospital-Acquired-Infections and nursing care demands of an OPD.

Enteral Feeding

Because of high energy demands as well as gastro-intestinal motility disorders and risks for bacterial translocation, placement of enteral feeding-tubes should be considered before closing the abdomen.

Gastrostomy tubes allow feeding through the stomach and post-operative decompression of the stomach. Jejunostomy tube shall be considered when a bypass of the upper part of the gastrointestinal is required. A loop of jejunum is selected distal to the part of the intestine that needs to be bypassed. A purse-string of 3-0 monofilament absorbable suture is placed on the antimesenteric border of the jejunum. The jejunostomy tube (3 to 5 French) is first inserted through the abdominal wall. A stab incision is made in the middle of the purse-string and the jejunostomy tube is introduced in the jejunum 20 cm aborally. The purse-string is tied. Then, 4 jejun pexy sutures are placed evenly around the jejunostomy tube between the abdominal wall and the jejunum. Alternatively, because jejunostomy tube placement carries more risk than gastrostomy tube, a gastro-jejunostomy tube can be placed. Thanks to this technique, feeding can be provided distal to the pancreas and the stomach can still be decompressed. Alternatively, non-surgical naso-jejunal tubes or endoscopic gastro-jejunal tubes can also be applied.

Before Leaving the Theater

Before leaving the surgical theater, the surgeon dealing with peritonitis should ask himself:

 Did I get adequate samples for cytology, histology, bacteriology?

 Did I identify and control the source of the peritonitis?

 Did I lavage thoroughly the abdominal cavity?

 Did I think about the different drainage options?

 Did I place a feeding tube?

And finally, based on the perioperative findings, the surgeon should conduct a thorough discussion with his team regarding post-operative issues. What complications are we expecting (DIC, MOF, sepsis, septic shock, heart rhythm problems, anemia, hypoproteinemia,...) and how can we anticipate and control them before they actually occur.