Bellies, Bladder, and Bowels: Exploring the abdomen and perfecting the "otomies" in your practice
Written by Michael B. Mison, DVM, Diplomate ACVS Staff Surgeon - Seattle Veterinary SpecialistsAffiliate Assistant Professor - University of Washington School of Medicine
Abdominal surgery is a common procedure in modern veterinary practice. It is important for the practitioner to become familiar with the procedure to develop confidence in performing an exploratory celiotomy. Doing so minimizes morbidity associated with surgery. There are currently no controlled veterinary studies that quantify the risk: benefit ratio of abdominal surgery in companion animals. It is important to consider the clinical indications for abdominal surgery in order to minimize needless surgery. Abdominal surgery is indicated to provide a diagnosis, to establish a prognosis, to provide treatment, or to perform elective procedures. Timing of surgery must be based on the patient's need for preoperative stabilization and the progression of the disease. As in most cases, a complete history, physical examination, and appropriate pre-surgical laboratory tests are essential parts of a successful surgery. Further clinical investigations such as endoscopy, abdominal ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), and minimally invasive surgery (MIS) may be warranted in individual patients prior to anesthesia and surgery.
Abdominal surgery should be regarded as an opportunity to examine the entire abdominal cavity, and surgeons should avoid the temptation to treat only the obvious lesion prior to closure of the abdomen. Although no further abnormalities are detected for the majority of the time, other significant pathology may be identified and either influences the anticipated surgical procedure or warrant tissue sampling. The abdominal cavity may be divided into five regions for the purposes of exploration, ensuring that all organs and tissues are examined. These regions are: cranial abdomen, gastrointestinal tract, right abdominal gutter, left abdominal gutter, and caudal abdomen. In addition, the abdominal wall, peritoneal surface, and mesenteries should be evaluated. Abnormalities in location, shape, size, texture, and color of organs and tissues should be noted, and appropriate tissue or fluid samples taken. Appropriate surgical training and guidance, in addition to up-to-date knowledge of anatomy, pathophysiology, and surgical methods, with close adherence to Halstead’s surgical methods, will all contribute to a successful surgical outcome.
Halstead’s principles of surgery:
- Asepsis and aseptic surgical technique
- Sharp anatomical dissection
- Atruamatic tissue handling and surgical technique
- Removal of devitalized tissue from the surgical wound
- Precise hemostasis with preservation of tissue blood supply
- Accurate tissue apposition and minimize dead space without excessive tension on tissues.
Abdominal exploratory is usually performed with the patient positioned in dorsal recumbency. The prepuce in male dogs may be clamped to one side of ventral midline with a sterile Backhaus towel clamp. A ventral midline incision is most frequently used for abdominal surgery and may extend from the xyphoid process, through the umbilicus to the pubic symphysis. Ventral midline is demarcated by the linea alba. Upon entering the abdominal cavity, the falciform fat may be large and difficult to retract during examination of the cranial abdomen. Complete transection and removal of the falciform fat will facilitate exposure of the abdominal contents. Protect the wound edges from desiccation, contamination, or bruising with moistened surgical swabs during surgery. As mentioned before, the abdominal cavity should be systematically explored.
Closure of abdominal surgical incisions is fairly straightforward. The only tissue layer with suture holding strength is the external fascial sheath of the rectus abdominus and the combined aponeurosis of the other abdominal muscles. Closure of the subcutaneous fat, intradermal layer, and skin is routine.
Liver biopsy is indicated during most exploratory celiotomies. Diagnosis of hepatic lipidosis, lymphoma, metastatic neoplasia, and other hepatic diseases may be obtained using hepatic biopsy. A suture fracture technique is appropriate for liver biopsy when a protruding point of liver is identified. A ligature of 4-0 absorbable suture is looped around the protruding section of liver and tightened to cut through the liver parenchyma while ligating any vessels. Scissors are used to transect the tissue distal to the ligature leaving the ligature to control hemorrhage. If all lobes have a rounded configuration, a transfixation suture fracture technique is used. This method is also used if a specific section of liver is desired for biopsy because of the presence of a lesion. The needle (atraumatic) is passed through the liver parenchyma and the suture is tied to cut through the liver on one side. The second throw on the suture is made to cut through the liver on the other side ligating the vessels supplying the liver distal to the ligature. The tissue is then transected distal to the ligature allowing excision of the biopsy specimen. Any residual hemorrhage is controlled with a hemostatic agent. For a focal lesion within the parenchyma, a core biopsy needle or skin biopsy punch can be used to obtain small pieces of liver tissue. The biopsy site can be packed with a small piece of Gelfoam or omentum following removal of hepatic tissue to facilitate hemostasis.
Splenomegaly is a common finding during an abdominal exploratory and may be incidental or indicative of disease. A spleen that increases rapidly in size over a very short period of time or one that is irregular in shape, painful or so large that it interferes with abdominal viscera function is cause for concern. Conditions that cause focal or diffuse splenomegaly in companion animals include infiltrative diseases (hemangiosarcoma, lymphoma, mast cell tumor, etc.), infectious diseases, splenic hyperplasia (hypersplenism or immune-mediated hemolytic anemia), or congestive diseases (splenic torsion, portal hypertension, or drug induced). A common histologic diagnosis from splenomegaly in dogs and cats is extramedullary hematopoiesis.
Preoperative biopsy of the spleen is ideal if it can be safely performed. Percutaneous biopsy should be done with caution with hemangiosarcoma as it may induce life-threatening hemorrhage. Ultrasound will help determine the safety and efficacy of percutaneous biopsy and is very useful for guiding the needle to collect an appropriate sample. Fine-needle aspiration is an alternative to percutaneous biopsy of the spleen because it is simple, carries little risk, and can sometimes provide useful information. Using a 25-ga 1-inch needle on a 6 cc syringe, the spleen is isolated and held in position. As the needle penetrates the spleen, negative pressure is applied and maintained as the needle is advanced into the parenchyma. Negative pressure is discontinued and the needle slowly withdrawn. Releasing pressure prior to withdrawal minimizes the risk of blood contamination.
Splenic biopsy may be performed during an exploratory celiotomy. If the sample is to be taken from the margin, mattress sutures are placed through both surfaces of the spleen. The parenchyma is transected distal to the sutures leaving them in place to control hemorrhage. To remove a central portion, two parallel incisions are created long and deep enough to obtain a representative sample. Then, two additional incisions are made perpendicular to the original incisions creating a rectangular section of spleen to be removed. Mattress sutures are placed across the defect to control hemorrhage.
Partial splenectomy is indicated as treatment of non-neoplastic conditions as it allows for retention of normal splenic function. The vessels supplying the portion of the spleen to be removed are double ligated or clipped, and transected at the hilus. In most cases the caudal portion (free end) of the spleen is removed, as it is less likely to result in vascular compromise to the stomach. After several minutes, a line of demarcation will be visible between the viable portion of the spleen and the section that has been deprived of its blood supply. Using this line of demarcation, the splenic tissue is pinched between the thumb and forefinger milking the pulp toward the ischemic tissue. Forceps are placed along the flattened portion and the spleen is transected distal to the clamp. The cut surface along the clamp is sutured with an absorbable material in a continuous pattern. Digital pressure or a hemostatic agent can be used to control residual hemorrhage following removal of the clamp. Alternatively, mattress sutures are placed through the parietal and visceral surfaces of the spleen along the line of demarcation. The spleen is transected distal to the sutures. Automatic stapling devices, if available, are excellent for performing partial splenectomy.
Total splenectomy is performed beginning at the caudal or free end of the spleen by double ligating or clipping the vessels at the hilus of the spleen (splenic and short gastric vessels) and transecting the vessels between the ligatures. An alternative method that is faster involves ligation of the short gastric vessels and the splenic vessels distal to the pancreatic branch; however, using this technique, ischemic pancreatitis can result from inappropriate ligation of the splenic vessels.
Following splenectomy, dogs are less tolerant of experimentally induced hemorrhagic shock and do not respond as well to strenuous exercise. Sepsis following splenectomy as occurs in humans has not been reported as a complication in animals.
Indications for gastrotomy or full-thickness gastric biopsy include gastritis, foreign bodies, ulcers and inflammatory process, fungal granulomas, and neoplasia. Foreign body removal is a very common reason for performing a gastrotomy. The most common clinical signs of GI foreign body in dogs and cats include vomiting, dehydration, nausea, lethargy, and anorexia. Clinical signs are more dramatic in patients with acute gastrointestinal obstruction. These signs include severe depression and dehydration, vomiting, and abdominal pain.
Diagnosis of gastrointestinal foreign body is made based on physical examination, bloodwork, and radiography. In some cases the clinician will be able to palpate the foreign material within the stomach or the intestine. Small soft objects may be difficult to palpate as they compress easily and may go undetected. Objects in the stomach are more difficult to palpate as the stomach in located under the rib cage. Radiography may reveal a foreign object or segmental ileus and/or gaseous distention of the stomach. A gas-distended stomach is consistent with gastric outflow obstruction and is an indication for surgery as soon as possible. Contrast radiography may be performed in some cases if plain films are not diagnostic.
Treatment of gastrointestinal foreign bodies involves exploratory celiotomy and gastrotomy or enterotomy to remove the foreign body. The patient should be stabilized and rehydrated prior to surgery but surgery should be performed as soon as possible. A complete abdominal exploratory is performed and the entire GI tract is evaluated for the presence of multiple foreign bodies. The gastrotomy incision is made in a relatively avascular region of the stomach after isolating the stomach with saline moistened sponges. Stay sutures may be used to allow the surgeon to control the incision. The gastrotomy size should be large enough so that the foreign body can be easily removed without too much traction on the stomach. Take a full thickness biopsy of the stomach wall using scissors to cut a slice off of one side of the primary incision. A two-layer closure is recommended using a monofilament absorbable material on a tapered needle with the first layer that incorporates the submucosa being a continuous approximating pattern and the second layer that incorporates the serosa, muscularis, and submucosa being an inverting pattern such as a Cushing or Lembert. Thoracoabdominal (TA) auto staplers apply two rows of overlapping stainless steel staples that prevents leakage and allow for rapid resection of gastric tissue.
Indications for intestinal surgery are similar to those listed above for gastrotomy/gastric biopsy. After a complete abdominal exploratory, a decision needs to be made to obtain an intestinal biopsy, perform an enterotomy, or a resection and anastamosis. The standard subjective criteria for viable intestine are color, arterial pulsations, peristalsis, and bleeding for cut edge. If viability is questionable, resection is the sensible choice. Approximately 75-80% of the small intestines can be resected before adverse effects of short bowel syndrome are seen. The affected area should be isolated and packed off from the remaining abdominal contents. It is recommended that the enterotomy be made on the antimesenteric border of the intestine in the aborad (smaller) portion, as this is the healthier portion of bowel. The enterotomy is made longitudinally along the antimesenteric border. Single-layer direct apposition of the submucosa is preferred for rapid healing, rather than an inverting, everting, or two-layered suture pattern. A monofilament absorbable suture material on a taper needle is preferred. Alternatively, automatic intestinal stapling devices or skin staples can be used for intestinal closure. Longitudinal enterotomies are usually closed in the same orientation as the incision. The diameter of the small intestine of small dogs and cats is narrow and there are reports of intestinal stricture following routine enterotomy in these patients. In order to minimize the likelihood of postoperative stricture formation in these particular patients, the enterotomy is closed transversely, in effect widening rather than narrowing the lumen at the enterotomy.
An intestinal resection and anastamosis (IRA) involves removal of a segment of bowel and reconnecting the remaining bowel ends. The indications for this procedure include severely compromised bowel wall due to foreign bodies, intussuception, ischemia, perforation, and neoplasia. The bowel and jejunal arcades are carefully examined to select the optimal location for transection, based on bowel viability and strong pulsations of the jejunal arcade. The bowel is packed-off and luminal contents are manually expressed away from the resection site. Doyen bowel clamps or an assistant’s fingers are used to maintain luminal occlusion. The jejunal vessels leading to the terminal arcade of the segment to be resected and the terminal arcade vessels running along the mesenteric border at the level of the proposed transection are ligated with 4-0 absorbable suture material. Place crushing forceps across the bowel at an angle (approximately 30) appropriate to match luminal diameters. Luminal disparity can be addressed by differential spacing sutures, by adjusting the transection angle on the bowel ends, or by spatulation of the smaller bowel lumen. The bowel ends are sutured together using a 3-0 to 4-0 monofilament absorbable suture on a taper needle in a single-layer appositional suture pattern (simple interrupted, modified Gambee, or simple continuous). Alternatively, automated stapling devices or skin staples can be used.
Many surgeons will want to test the integrity of the enterotomy closure or anastamosis site. Warm sterile saline can be injected into the lumen until the bowel is physiologically distended. Careful inspection and gentle palpation of the suture line will reveal any leakage, and a simple interrupted suture may be placed until integrity is obtained.
Following closure of the gastrotomy or enterotomy, contaminated instruments are exchanged for sterile ones, surgeons’ gloves are changed, and the abdomen is lavaged thoroughly prior to abdominal closure. Food and water are offered 12-24 hours post-operatively. Studies have shown that enterocytes need food passage to proliferate and heal lesions. Antibiotics are administered if indicated based on the level of abdominal contamination.
Cystotomy is one of the most frequently performed surgical procedures in small animal practice. Indications for cystotomy include a variety of non-neoplastic (urolithiasis, trauma/rupture, congenital abnormalities, etc.) and neoplastic disorders. The bladder has an excellent capacity for healing and can gain 100% of its presurgical strength within 3-4 weeks after surgery. The submucosa is the surgical holding layer of the bladder. Appositional or slightly inverting suture patterns using an absorbable monofilament suture (3-0 – 4-0) on a taper needle are appropriate for bladder wall closure. It is important to avoid placement of suture material through the mucosa exposing the suture within the lumen of the bladder because it may act as a nidus for chronic infection or may become calculogenic.
Urolithiasis occurs frequently in companion animals. Clinical signs associated with urolithiasis include dysuria, hematuria and painful urination. Diagnosis is based on clinical signs, palpation of a large bladder, palpation of calculi, and radiographic or ultrasonographic evidence of calculi or crystals within the bladder. In some cases crystals are visible in voided urine. Cystotomy is indicated for removal of calculi and irrigation of the urethra. A ventral midline celiotomy is performed from the umbilicus to pubis to expose the urinary bladder. The bladder should be packed off with laparotomy sponges and one can elect to suction out the majority of the urine if the bladder is distended. Place a stay suture on the apex of the bladder for manipulation. Stay sutures can also be placed on the sides of the proposed cystotomy site to facilitate visualization. A stab incision is made into the bladder lumen on the ventral midline and the cystotomy incision is extended with Metzenbaum scissors. The bladder lumen and proximal urethra should be carefully visualized. If performing a cystotomy to remove cystic calculi, it is important to catheterize the urethra and flush it thoroughly to ensure that all calculi are removed. Culture of the bladder wall and culture and analysis of the calculi should be performed and appropriate antibiotic therapy administered. The bladder is closed in one to two layer of absorbable monofilament suture on an atraumatic needle.
The importance of continuing patient monitoring into the post-operative period should be emphasized. The level of monitoring required is dictated by the patient, the procedure performed, and the monitoring equipment and personnel available. Frequent personal observation and assessment by the clinical is as important as any monitoring equipment or laboratory values. It should be remembered that trends often provide the best information. The principles of abdominal surgery vary little from those applied during any operative procedure performed in veterinary practice. The value of careful preoperative evaluation of the patient, good surgical techniques, and the importance of operative planning and postoperative care are keys for a successful outcome.
Published on December 3, 2007.