Exploratory Laparotomy Dr. Michael King, BVSc, MSc, DACVS

There are many indications for performing an exploratory laparotomy, both as a diagnostic and therapeutic procedure. These range from obtaining multiple gastrointestinal biopsies through to emergency surgeries such as GDV or hemoabdomen. It is important to be as prepared as possible for any finding intraoperatively, and work in a systematic manner to avoid missing any abnormalities.

Diagnostics: A variety of diagnostic techniques can be useful pre-operatively to identify the nature of any abdominal pathology.

• Abdominal radiography is probably the most commonly performed in general practice. Abnormalities to look for include pneumoperitoneum, ascites, or mass effects. In some cases it can be difficult to distinguish between excessive fluid production or especially large masses. • Ultrasonography more than any other tool has reduced the need for exploratory laparotomy as a diagnostic procedure. In cases such as abdominal masses or foreign bodies, depending on the skill of the ultrasonographer, it can provide extremely valuable preoperative information for surgical planning. • Abdominocentesis is an often overlooked diagnostic in ascitic patients. A needle or IV catheter is placed caudal to the umbilicus and aspirated. It can be difficult to obtain a sample in situations where there are pockets of fluid however. • Diagnostic Peritoneal Lavage (DPL) is similar, but involves infusing fluid into the abdomen first. 20ml/Kg of isotonic saline is injected through a catheter placed as for abdominocentesis. The patient is then gently rolled, and fluid aspirated back. Usually only a small amount of the infused saline is obtained, but DPL has been shown to be effectively 100% accurate in diagnosis of septic peritonitis.

Pre-operative Preparation: The patient should be clipped and prepped from cranial to the xiphoid to caudal to the pubis, with wide lateral margins. Even if the planned laparotomy is expected to be limited to a small incision, it is important to be prepared in the case of needing to extend the approach should there be unexpected complications or pathology encountered.

For the same reasons the clipped area should be draped widely enough to allow for incision from xiphoid to pubis.

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Canada West 2013 Symposium • October 6, 2013

Electrocautery is a very useful piece of equipment for efficient hemostasis during laparotomy, but not usually essential. Of more importance is access to suction, both to maintain visualization of the surgical field, and to completely remove lavage solution from the abdomen. All swabs and laparotomy pads should be counted prior to beginning the procedure, and at conclusion of it, to ensure none are left in the abdominal cavity. Additionally only swabs with radio-opaque markers should be used.

Laparotomy: In almost all cases, the incision should extend from xiphoid to pubis. As all incisions heal from side-to-side and not end-to-end there is no advantage to a smaller approach. In male dogs the incision curves laterally around the prepuce, with the preputial vessels ligated or cauterized.

Upon entering the abdomen, removal of the falciform ligament is recommended, as it both improves visualization, and minimizes adhesion formation. The ligament is dissected free from the body wall on each side of the incision and ligated cranially before transection. The incision should then be lined with moistened laparotomy pads, and a Balfour retractor placed.

Though the area of interest may be visible immediately on entering the abdominal cavity, a full exploration should be performed first. Obviously in cases where a life threatening situation exists (such as GDV or an actively bleeding splenic mass), immediate control of the problem is appropriate.

Exploration should be performed in a systematic manner, and the same order of examination should be used each time. Everyone has their own routine, but as long as the abdomen is explored thoroughly, the exact order is not important. My preference is as follows:

• Spleen • Liver & Gall Bladder • Esophagus & Stomach • Duodenum & Pancreas (both limbs) • Right Kidney and Adrenal • Left Kidney and Adrenal • Colon (from Descending to Ascending) • Cecum & Ileum • Jejunum (moving aborally to the Duodenum) • Bladder, Ureters & Reproductive Tract

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Canada West 2013 Symposium • October 6, 2013

Gastrointestinal Surgery The stomach and intestines consist of four layers; mucosa, submucosa, muscularis, and serosa. Though these are relatively indistinct in the intestine, in the stomach they form two separate layers; mucosa & submucosa, and muscularis & serosa. Upon biopsy of the stomach it is important to identify both layers, and sample each. Closure of the stomach is generally achieved with a double-layer pattern.

Enterotomy or enterectomies are usually closed with single-layer patterns, either interrupted or continuous. They should then be leak-tested with saline.

Biopsy of the pancreas should be performed with care, both to avoid interfering with its vascular supply, and to minimize any pancreatitis. Usually a small section can be isolated at the end of one of the limbs and ligated.

Hepatic biopsy: Several methods are described, with the guillotine technique most commonly performed. When biopsy of a lesion not present within the periphery is needed, a Keyes Biopsy Punch can be used. The defect can be filled with gelfoam, surgicell, or omentum. The larger hepatic vessels are present along the dorsal aspect, so biopsy using this technique should be limited to two- thirds of the way through the parenchyma.

Kidney & Splenic biopsy: Though not part of a routine biopsy collection, samples of the renal cortex are most safely obtained using a Tru-Cut needle. Significant hemorrhage can still occur, though generally stops following a period of digital pressure.

Biopsy, or even partial removal of the spleen can be difficult due to the texture and vascularity of its parenchyma. Generally a complete splenectomy is preferable when pathology is present. Vessels should be ligated close to the spleen, in order to avoid compromising the pancreatic blood supply.

Abdominal Closure: Prior to closure the abdomen should be lavaged with warmed saline, the volume of which depends on the procedure that has been performed, and the contamination that may have occurred. As a general rule, the abdomen is lavaged until the fluid suctioned out is clear. Inflammatory cells within the abdomen are surface-activated, making them ineffective in large volumes of fluid. It is therefore important to remove as much of the lavage fluid as possible.

Closure of the linea can be with either a continuous or interrupted pattern, with a continuous suture at least as strong. Monofilament absorbable suture such as PDS or Maxon are most appropriate, and with continuous patterns six throws should be placed at each end to ensure a

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Canada West 2013 Symposium • October 6, 2013 secure knot. The rectus fascia is the strength holding layer of the abdominal wall, so incorporating a substantial bite of this tissue is important. Including muscle does not add to the strength, and with subsequent necrosis may actually lead to a more loose closure. Peritoneum also does not add any strength and should not be incorporated within the suture. It heals within a matter of hours by adherence of mesothelial cells.

Post-operative Care: Abdominal incisions heal over a 10-14 day period, though the linea is still somewhat weak at this time. The suture line should be protected with a sterile dressing, and an Elizabethan collar used when necessary.

In most cases continuing intravenous fluids for 24 hours post-operatively is indicated, and generally continued until the patient is eating.

Opioids such as morphine and buprenorphine are used for the initial 48 hours following surgery, followed by a switch to oral analgesics once they are eating.

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Canada West 2013 Symposium • October 6, 2013