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Managing the acute abdomen (Part 2): surgical management (Proceedings)

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Aug 01, 2010

Acute abdomen is the acute onset of abdominal pain that requires prompt diagnosis and immediate intervention to prevent patient deterioration. The decision to operate depends on efficient diagnostic evaluation, and the timing of the surgery should be based on what will maximize survival and minimize morbidity. Each surgical acute abdomen has specific surgical techniques that require mastering. Emergency surgeons must be reasonably skilled in techniques such as gastric dilatation-volvulus correction and gastropexy, diaphragmatic hernia repair, urinary bladder repair, urinary diversion techniques, and intestinal resection and anastomosis.

Exploratory Celiotomy

A complete systematic exploratory celiotomy to detect and correct all significant abnormalities is performed as soon as the need is determined. Delaying surgery is justified only when the delay will decrease morbidity or chance of mortality. Occasionally during emergent celiotomy life-threatening problems (such as ongoing hemorrhage) will require immediate attention; systematic exploration can be performed later in the procedure. Only rarely should systematic exploration be abandoned altogether (for instance, in cases judged to be at risk of death or severe disability if not soon recovered from anesthesia).

Presurgical Preparation

Standard clipping and aseptic preparation of the abdomen from cranial to the xyphoid to caudal to the pubis should be performed with the following modifications. Clipping and prepping should extend cranially over the sternum, and liberal fields should be prepared laterally to accommodate tubes that exit beyond the incision and require anchoring sutures beyond the surgical field. Assuming that clipping does not injuriously prolong anesthesia time, the perineum and perianal areas should be clipped in preparation for postoperative hygiene.

During preparation proper patient positioning is important. In fact, improper positioning can occasionally be life-threatening. Standard positioning is dorsal recumbence with the limbs extended; however, if the patient has a large intra-abdominal mass, this positioning will allow the mass to gravitate to the dorsal abdomen where compression of the vena cava can result in decreased venous return and resultant drop in cardiac output. Patients with large intra-abdominal masses can be positioned obliquely to minimize pressure on the vena cava. Oblique positioning may be required for the surgical procedure as well; however, most cases are returned to dorsal recumbence immediately prior to surgery. Prompt entry into the abdomen is warranted in such cases so that the vena cava can be decompressed by elevating the offending organ or mass.

Time in the preparation room should also be spent instrumenting the patient for intra- and postoperative venous access and monitoring. Every surgical acute abdomen patient should have at least two venous access sites, one peripheral and one central. An indwelling urinary catheter should be placed, secured, and attached to a closed urinary collection system for intra- and postoperative monitoring of urine output.

Method of Surgical Exploration

Exploratory celiotomy should be performed in the same systematic fashion each time. Developing a habitual method of exploration will help prevent oversights. The following is the routine systematic exploration used by the author.

Exploratory celiotomy is performed in dogs and cats via ventral midline celiotomy with an incision from the xyphoid to the pubis. The skin is incised with a scalpel, and electrosurgery is used for hemostasis. Then, the subcutaneous tissue is incised off of the linea alba with Metzenbaum scissors, avoiding undermining of the skin edges. After towelling in the skin edges, the umbilicus is grasped with a thumb forceps and elevated while the linea alba is punctured with a scalpel to make an entry hole large enough to accommodate the surgeon's index finger. An index finger is inserted to palpate for intra-abdominal adhesions along the linea alba, and Mayo scissors are used to extend the linea alba incision cranially and caudally to the xyphoid and pubis, respectively. After excising the falciform ligament, a quick inspection of abdominal contents in situ is performed. At this point relief of vena caval compression, if present, is performed. Balfour abdominal retractors are placed and the systematic exploration is begun.

First, all parietal peritoneal surfaces are inspected, including the diaphragm, to observe for abnormalities such as petechiation, ecchymoses, carcinomatosis, and tears. Second, the anatomical retractors, mesoduodenum and mesocolon, are used to visualize contents of the respective "gutters". It is good to visualize and palpate the epiploic foramen during every abdominal exploration so that it can be palpated blindly, when necessary, to occlude the portal vein and hepatic artery to temporarily control hepatic hemorrhage (the Pringle maneuver). While the mesoduodenum is retracted the pancreas is inspected. After inspecting the gutters and pancreas, nongastrointestinal abdominal organs are examined. The gall bladder is inspected visually and by gentle palpation to assess the degree of turgidity; it is not necessary to "express" the gall bladder to ascertain patency. Finally, the gastrointestinal tract is inspected. Retracting the spleen caudally will facilitate exteriorization of the stomach for palpation and visual inspection of the abdominal esophagus and stomach. Evaluation of the stomach should include palpation of the pylorus. After examining the esophagus and stomach, the small intestine is examined ("running the bowel") paying particular attention to color, vascular pulsations, and presence of masses, and inspecting the mesentery for enlarged lymph nodes. The exploratory is completed by inspection of the colon and colonic lymph nodes and palpation of the pelvic canal for enlarged sublumbar lymph nodes.

Typically, close examination of suspected problem areas and obvious abnormalities is postponed until the exploration is complete. Otherwise, there is risk of missing other important abnormalities. Occasionally, one abnormal finding must be addressed before the exploration can be completed (example: an adherent mass that must be excised before underlying abdominal contents can be inspected). Upon completion of surgery the linea alba is closed with a continuous pattern using synthetic absorbable suture, the subcutaneous layer is likewise closed with a continuous pattern using synthetic absorbable suture, the skin is usually closed with staples, and tubes are anchored with friction sutures before the patient awakens.

Supplemental Surgical Techniques

During abdominal surgery the surgeon must think ahead to the postoperative convalescent period and take advantage of valuable anesthesia time. A jejunostomy tube should be placed in any animal that might vomit in the postoperative period. When deciding whether to place a jejunostomy tube the surgeon should ask himself/herself: " Why shouldn't I?" rather than "Why should I?" If vomiting does not occur and the jejunostomy tube becomes unnecessary removal is very simple. Further, if the interlocking box jejunostomy technique is used the tube can be removed as soon as it is not needed; there is no need to wait 5 to 10 days as is recommended with traditional jejunostomy tube techniques. Elective gastropexy is a reasonable technique to perform in large and giant dog breeds during surgery for acute abdomen, assuming that the additional anesthesia time is safe. The author routinely performs gastropexy as part of abdominal surgery in large and giant breed dogs because postoperative gastric dilatation-volvulus is a life-threatening and expensive complication that occasionally occurs in hospitalized patients.

Reference

Mann FA. "Acute Abdomen: Evaluation and Emergency Treatment", in Kirk's Current Veterinary Therapy XIV, Bonagura JD, ed. St. Louis, Saunders Elsevier, 2009:67-72.