Exploratory celiotomy: Practical surgical anatomy (Proceedings)

Surgical exploration of the abdomen is performed for diagnostic, therapeutic, and prognostic purposes. With development of ultrasound diagnostic capabilities and ultrasound guided biopsy techniques the need for diagnostic surgical exploration has seemingly declined in our practice. Ultrasound diagnostic capabilities are not present in all practices and are operator sensitive therefore the principles for surgical exploration of the abdomen continue to be important. These principles include the need for complete and thorough exploration of all structures, biopsy and/or culture of appropriate tissues, and performance of a therapeutic operation when possible. Depending upon the goals of surgery, in some cases minimally invasive surgical techniques may be appropriate and may be used rather than conventional exploratory celiotomy.

Technique

A complete and thorough examination of all abdominal organs is indicated. Good operating room lights properly positioned aid the surgeon in accurate examination of the abdominal cavity. Surgery is initiated with a generous abdominal incision that allows access for palpation and visualization of all structures. The incision typically begins at the xiphoid cartilage and continues caudally to approximately halfway between the umbilicus and pubis. Extension to the pubis may be necessary especially for caudal structures such as the prostate and urethra. Entrance to the abdomen is accomplished and the falciform ligament removed by excision along its lateral attachments to the abdominal wall and ligation at its cranial aspect. Falciform excision is elective, however visualization and surgery, especially of the cranial abdomen is enhanced. In addition, closure of the abdominal wall at the conclusion of the celiotomy is also eased by falciform excision. Visualization of the abdomen is further enhanced by placement of Balfour self-retaining retractors after laparotomy pads moistened with saline have been placed to protect the abdominal wall. Other valuable instrumentation includes malleable retractors which are useful to retract abdominal viscous. A natural desire of the surgeon to focus on an obvious lesion is ignored initially in most cases in favor of a complete abdominal exploration. Large splenic or hepatic tumors may have to be treated initially to permit adequate exploration of the abdomen. Some surgeons routinely exteriorize the spleen and protect it with laparotomy pads which ease exploration of the remainder of the abdomen. Finally, disease that is treated aggressively before exploration includes active hemorrhage and leakage of gastrointestinal contents.

Exploration of the abdomen is performed in a systematic fashion either by a systems or anatomic "quadrant" approach. In a systems approach each system such as gastrointestinal, urinary, hepatobiliary, and lymphatic are examined thoroughly. In a quadrant approach the abdomen is divided into 4 quadrants and structures located in each area explored. Exploration includes examination of the pancreas and both adrenal glands in addition to the systems mentioned. Caution is advised regarding intraoperative decision-making based on the appearance of disease. For example, pancreatitis often takes on the appearance of and can be confused with aggressive disease (neoplasia). Intraparenchymal benign hepatic lesions may be nodular hyperplasia rather than metastatic disease.

The surgeon should be comfortable with common abdominal operative procedures such as gastrotomy, enterotomy, intestinal resection and anastomosis, splenectomy, and cystotomy. Hepatic neoplasia requiring lobectomy, biliary diversion techniques, gastrointestinal rerouting, adrenal masses, and ureteral surgery are examples of more advanced surgical techniques that may warrant referral to a surgical specialist.

If disease is encountered that the veterinarian is uncomfortable treating, i.e.- a large hepatic tumor, then incisional biopsy is often appropriate and may be useful in guiding further therapeutic decisions.

Practical Anatomy & Exploration

I.

• Exteriorize Spleen & Protect with Moistened Lap Pad

• Inspect diaphragm for integrity and presence of metastatic disease

• Inspect/Examine all liver lobes

o Left lateral, left medial, Quadrate, right medial, right lateral, Caudate

o Biopsy any questionable areas. DO NOT Euthanize mistakenly based on what may be hepatic nodular hyperplasia

• Examine gall bladder and bile duct. Express gall bladder if there's a question of whether gall bladder or bile duct is obstructed. Animal would be icteric. The BILE duct traverses the hepatoduodenal ligament from the gall ladder receiving Hepatic ducts from each liver lobe. The bile duct enters the serosal surface of the duodenum and empties on the major duodenal papilla about 3-5 cm distal to the pylorus. The bile duct can be catheterized from the major papilla in the proximal duodenum as necessary to relieve obstruction in some cases or to place a catheter for the bile duct to heal over if it is torn (incompletely)

II.

• Palpate gastroesophageal junction & stomach to the pylorus. The pylorus typically contracts as soon as it is palpated.

• Inspect and gently palpate the duodenum as it descends the right ventral abdominal cavity. Note the right limb of the pancreas, which is readily apparent next to the duodenum. Examine and gently palpate the left limb of the pancreas which courses dorsally in the root of the mesentery on the greater curvature of the stomach. Seemingly, the risk of clinical pancreatitis following palpation of the pancreas is small.

• Note that the duodenum is hard to exteriorize because of the hepatodudoenal ligament cranially and the duodenal-colic ligament located where the duodenum turns rostrally and starts ascending. This ligament is avascular and can be cut to mobilize the duodenum if necessary for resection or biopsy.

• The jejunum makes up most of the small intestine

• The ileum is marked by the presence of the antimesenteric vein and ends at the ileocolic junction where the cecum is located.

• NOTE the mesenteric lymph nodes at the ileocecal-colic junction. These nodes may be biopsied easily by wedge biopsy. Excisional biopsy is NOT performed as these nodes are at the root of the mesentery.

• Follow the colon to its entrance to the pelvic cavity. Remember, any foreign body that has made it to the colon will likely pass without problem and thus the need for colostomy is RARE to nonexistent.. Some foreign bodies can be "milked" further distal in the colon if desired.

III. Grasp the duodenum and mesoduodenum and use those structures to "pack viscera to the left side of the abdomen".

• Examine the right kidney and note the hepatodudenal ligament from the caudate liver lobe running to the kidney. This ligament is avascular and can be cut as necessary. The larger renal vein is usually easily visualized. The renal artery is dorsal and cranial to the vein and not typically visualized although palpation of the pulse is possible through the perihilar fat.

• Look for and examine the right ureter as it courses in the caudal retroperitoneal space and leaves the space to enter the lateral ligament of the urinary bladder before entering the serosal surface of the bladder and emptying at the trigone.

• Examine the right adrenal gland, which is located dorsal to the caudal vena cava just about at the level of the rostral pole of the right kidney. The adrenal can also be palpated through the wall of the vena cava.

• The epiploic foramen is located rostral and in the root of the mesoduodoenum. It is bounded by the portal vein ventrally, the vena cava dorsally, and the celiac artery caudally. Portosystemic shunts can often be visualized emptying into the vena cava in this area.

Grasp the colon and mesocolon and retract the viscera to the right side to visualize the left kidney.

• The anatomy of the left kidney is similar to the right except the left kidney may have more than 1 artery about 15-20% of time.

• Visualize the left ureter in the retroperitoneal space as it courses caudally.

• Just medial and rostral to the left kidney is the left adrenal gland. The phrenicoabdominal vein traverses directly over the middlle of the left adrenal gland.

• If the animal is female and unsprayed the uterus and ovaries can be inspected during this portion of the exploratory

IV.

• Examine and palpate the urinary bladder for the presence of masses and calculi.

• Biopsy rather than complete excision of masses is usually performed as masses (Transitional cell carcinoma (TCC) are typically located at the trigone making excision difficult.

• If stones are found and removed the urethra should be catheterized and inspected to assure patency and complete removal of all stones.

• Close the bladder with a single or double layer appositional or inverting pattern using absorbable suture and making an effort o NOT enter into the lumen.

V. If the dog is male, the prostate should be examined/palpated.

• If the dog is neutered the prostate should be difficult to palpate.

• In an intact dog, the prostate is typically bilobed with a raphe on its medial border. The prostate can be biopsied/culteured by making an incision into 1 lobe OFF the midline so as to avoid damaging the urethra. Passage of as catheter will assist in urethral identification if necessary.

VI. Feeding tube placement can be easily performed during exploratory celiotomy

1. Gastric feeding tubes are very effective in a variety of cases. A "purse-string Suture" is placed midway between the greater and lesser curvatures of the stomach in the gastric fundus. A "Pezzar" feeding tube is brought into the abdomen through a stab incision made about 1/3rd of the way from the ventral midline incision. The tube is passed into the gastric lumen through a stab incision made in the middle of the previously placed purse-string suture. The purse-string is tightened and several supporting sutures (pexy sutures) are placed between the gastric fundus and left abdominal wall. The tube is used for feeding blenderized food 2-3x daily. The tube should be maintained for a minimum of 10-14 days before removal even if the animal begins alimenting on its own. When the tube is removed, the gastric stoma and abdominal wall wound is allowed to heal by 2nd intention.

2. Jejunostomy tubes are useful in animals with upper GI disease including pancreatitis. A 6 French silastic feeding tube is brought into the abdomen through a right lateral incision. A purse-sting incision is placed in the serosal border of the jejunum and the tube passed into the jejunum through a stab incision in the middle of the purse-string. The tube is passed 12-20 cm aborad into the jejunum and the pusre-string tightened. Supporting pexy sutures are placed between the jejunum and the right abdominal wall. The tube is additionally secured to the external abdominal wall (skin) with a "Chinese finger trap". Typically, this tube allows feeding of enteral diets only. The tube is maintained for 10-14 days as a minimum, removed and the stoma allowed to heal by 2nd intention.

Biopsy Techniques

The surgeon should anticipate and assume that biopsies will be necessary during abdominal exploration. Abdominal viscous that is commonly biopsied in individual cases may include the liver, stomach, small intestine (duodenum, jejunum, ileum), kidney, lymph nodes, spleen, and prostate. A decision to take specific organ biopsies is based on the history, clinical signs, laboratory data, and appearance of tissue at the time of surgery. Due to its contaminated nature, the colon is not routinely biopsied unless a specific lesion is identified or suspected.

Liver is easily biopsied by the "guillotine" method in which a loop of absorbable suture is used to encircle a portion of liver on the periphery of a lobe. The suture is slowly tightened so as to strangulate a portion of tissue and the tissue is excised several millimeters distal to the ligature. Use of a skin biopsy punch is also quick and easy for obtaining hepatic biopsy especially when the lesion is more centrally located rather than the periphery of the liver. The instrument is inserted into the parenchyma to be biopsied and then slowly twisted partial thickness into hepatic tissue. The tips of scissors or a scalpel are used to free the deeper attachments of the tissue within the liver. Placing a small plug of gelatin hemostatic sponge within the biopsy site conveniently provides hemostasis.

Prior to biopsy, the gastrointestinal tract is packed off with moistened laparotomy pads from the remainder of the abdomen. The stomach and/or intestine are biopsied by making a full thickness 3-5 mm elliptical incision into the lumen either transversely or longitudinally with a number 15 or number 11 scalpel blade. The biopsy site is typically closed with interrupted appositional sutures of 3/0 or 4/0 monofilament absorbable suture (polydioxanone or polyglyconate) on a tapered needle. The intestine is "leak tested" by injecting saline into the biopsied segment while the area is occluded digitally or with Doyen forceps.

Lymph nodes may be biopsied by excisional or incisional methods. The mesenteric lymph nodes located at the ileocecal junction are often biopsied by incision since excision may disturb blood supply to the intestine. The spleen may be sampled by splenectomy, partial splenectomy or biopsied in a manner similar to the guillotine method described for liver biopsy.

The kidneys are biopsied with a Tru-cut biopsy needle or by incisional wedge biopsy. There is less hemorrhage with the needle technique but tissue sample size is small. Digital pressure is usually sufficient to stop any renal hemorrhage from needle biopsy. Incisional wedge biopsy of the kidney helps to ensure adequate tissue but there is increased hemorrhage and it is necessary to close the biopsy site with one to two mattress sutures of absorbable suture.

Abdominal Closure

Prior to closure the abdomen is lavaged with warm saline and the lavage completely removed by suction. The abdominal wall is closed with a simple continuous or simple interrupted suture of appropriate size. Absorbable suture is typically used however nonabsorbable suture such as nylon is also used successfully. When a continuous pattern is elected, suture one size larger than normal is often selected for abdominal closure. In either closure, the external rectus fascia is engaged and no effort is made to close the peritoneum or the internal rectus sheath. Exposed muscle is not included in the suture when avoidable. Dead space caused by subcutaneous tissue incision is closed and the skin apposed with staples or suture.

All tissue biopsies are submitted in 10% buffered formalin for histologic examination. The morbidity and mortality of exploratory celiotomy is directly related to the patient's condition preoperatively and the morbidity of any surgical procedure performed.