Abdominal Trauma: A Diagnostic and Therapeutic Dilemma


Wayne E. Wingfield, DVM Diplomate, ACVECC, ACVS Department of Clinical Sciences College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins, CO 80523





Table of Contents

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Introduction

The occurrence of abdominal injuries is unknown in dogs. There are many etiologies associated with this injury. Abdominal injuries are often occult. Most injuries are caused by blunt trauma inducing lacerations of the liver and/or spleen, urological trauma, infarcted bowel, or reproductive organ damage during pregnancy. Penetrating injuries from gunshot, impalement injuries, and bite wounds are more obvious. Gunshot wounds represent the most frequent penetrating abdominal injury. The wounding potential of missiles is related both to velocity and mass of the bullet. This is most easily understood when recalling tissue injury is directly proportional to the kinetic energy delivered and kinetic energy is proportional to the mass of the missile but more importantly, to the square of its velocity. High velocity missiles produce cavitation within the abdomen which is sufficiently energetic to disrupt hollow organs, break bones and spread contamination.

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Diagnosis of Abdominal Trauma

Physical examination findings and diagnostic studies are required in deciding which abdomen should be surgically explored following penetrating injury. This decision is generally based upon signs of peritoneal penetration, unexplained shock, ileus, organ evisceration, free gas on radiographic examination or evidence of bacteria or plant debris following abdominocentesis or peritoneal lavage. Blunt abdominal trauma cases are challenging diagnostic problems because the clinical manifestations may be delayed for hours or days.

With blunt abdominal trauma, the physical examination is the most informative portion of the diagnostic evaluation and should be as complete as time and the patient's condition permit. Increasing abdominal size can be an important clue for intra-abdominal injury. Consequently, measurements of the abdominal girth at the umbilical level should be made soon after admission. This baseline measurement can be used to measure subsequent significant changes. In human adults, each inch increase in girth may represent 500 to 1000 ml of blood.1 Abdominal rigidity and tenderness are important clinical signs of peritoneal irritation by blood or intestinal contents.

A four quadrant abdominocentesis is one means for confirming blunt abdominal injury. From the fluid obtained, a packed cell volume, total solids, cytology, and a blood urea nitrogen sample are submitted. If the packed cell volume of centesis fluid exceeds the peripheral packed cell volume, very likely there is either a splenic, hepatic or renal parenchymal laceration. Additionally, it is probably a good idea to submit some of the intra-abdominal blood for analysis of total bilirubin. With major biliary tree or common bile duct injury , the clinical signs of icterus are often delayed 4 to 6 weeks. If the abdominal fluid bilirubin is significantly greater than peripheral bilirubin, then surgical exploratory will be required to close the lacerated organ. This surgery is not considered an emergency procedure.

With urological injury, the packed cell volume of the abdomi- nal fluid will be lower than the peripheral packed cell volume due to hemodilution with urine. Previously, creatinine was recommended for confirmation of free urine in the abdominal cavity.2 More recently, the finding that blood urea nitrogen levels and urea nitrogen levels in abdominal fluid are also elevated in acute urological trauma.3,4 Currently, the Azostix is used to assess the presence of urea nitrogen in abdominocentesis fluid. This allows the practicing veterinarian to confirm urological trauma more readily.

Diagnostic peritoneal irrigation is useful in the diagnosis of abdominal injuries where the four-quadrant tap was unfruitful and the patient continues to be unstable in spite of your shock therapy. The animal is placed in a lateral recumbency and 2 needles are placed in the abdominal cavity. Warmed crystalloid solution is infused into the peritoneal cavity until fluid is dripping from the second needle. Generally it will require 10 - 20 ml/kg of crystalloid before the second needle becomes productive. A sample is collected and placed in an EDTA tube for analysis.

Use of peritoneal lavage for diagnosis of abdominal injury is advocated by some.5,6 Ideally, a peritoneal dialysis catheter should be employed. If no blood, bile, urine or intestinal fluid can be aspirated, the abdominal fluid is irrigated with 250 to 1000 ml of warmed saline. If feasible, the patient is moved from side to side to assure the saline reaches all areas of the abdominal cavity. The fluid is then allowed to drain via gravity.

There is some controversy concerning what constitutes a positive test for blood. One subjective criterion has been the ability to read newsprint through IV tubing containing the fluid. Others feel that a quantitative red blood cell count of 100,000/mm3 or a white blood cell count of 500/mm3 is positive for significant abdominal hemorrhage. Measurement of amylase in lavage fluid is costly and is of insignificant value in assessment of pancreatic or intestinal trauma.7 Disseminated intravascular coagulopathy (DIC) is often over-diagnosed in trauma patients. Most of the coagula- tion deficiencies seen are due to dilution by crystalloids or use of commercially available colloidal solutions like dextran or hetastarch.

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Treatment of Abdominal Trauma

In the dog or cat, the treatment for hemoabdomen is to approach these patients as conservatively as possible. In fact, it is very unusual to require surgery for a splenic or hepatic laceration. These species are very tolerant of this sort of injury as witnessed by the numerous animals submitted to necropsy with a healed splenic and/or hepatic capsule, yet no history of prior surgery for the injury incurred years previously. A recent study in dogs has shown the benefit of abdominal compression in conjunction with intensive fluid therapy for survival of abdominal hemorrhage.8 Caution should be employed in applying an excessively tight bandage when thoracic injuries are also present.

Emergency management of intraperitoneal rupture of the bladder, urethra, and/or ureters involves drainage of the abdominal fluid via an indwelling Foley catheter until the patient is sufficiently stable to undergo anesthesia and surgical repair. Prior to surgery, contrast studies of the kidneys, ureter, and bladder should be performed to assess the severity of injury using an excretory urogram. Additionally, if there is evidence of lower urinary tract injury, positive contrast urethrography and cystography are advocated.

Should plant debris or significant numbers of mixed bacteria be found with centesis of the abdominal fluid, a ruptured viscus is likely and exploratory surgery is indicated. All patients with penetrating abdominal wounds require a surgical exploratory as soon as possible.

It is very important to provide adequate tissue perfusion and restoration of needed clotting factors through fresh whole blood and/or plasma transfusion in conjunction with your aggressive use of crystalloids and occasional use of either hypertonic saline or colloids (dextrans or hetastarch).

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Conclusions

The following summary recommendations for traumatized patients are highlighted:

1) Trauma frequently affects multiple organ systems.

2) An organized, systematic approach should be undertaken for each patient. This approach begins with an assessment of the respiratory, cardiovascular, and neurological system and concludes with fracture/luxation management and diagnosis of abdominal injuries.

3) An aggressive diagnostic and therapeutic approach is taken towards each of the involved systems.

4) Overtreatment of some complications can be just as hazardous as undertreatment. This is especially true of respiratory trauma and/or intra-abdominal hemorrhage.

5) Constant monitoring and reassessment of the patient's status are mandatory.

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References

1.Wilson RF: Trauma, in Shoemaker WC, Thompson WL, Holbrook PR (eds): Textbook of Critical Care. Philadelphia, WB Saunders 1984, pp 877-914.

2.Burrows CF, Bovee KC: Metabolic changes due to experimentally induced rupture of the canine urinary bladder. 35:1083-1088, 1974.

3.Shaw PM, Kim KH, Ramirez-Schon G, et al. Elevated blood urea nitrogen: An aid to the diagnosis of intraperitoneal rupture of the bladder. J Urol 122:741-743, 1979.

4.Rubin MJ, Blahd WH, Stanisic TH, et al: Diagnosis of intraperitoneal extravasation of urine by peritoneal lavage. Ann Emer Med 14:433-437, 1985.

5.Crowe DT, Crane SW: Diagnostic abdominal paracentesis and lavage in the evaluation of abdominal injuries in dogs and cats: Clinical and experimental investigations. J Am Vet Med Assoc 168:700-708, 1976.

6.Powell DC, Bivens BA, Bell RM: Diagnostic peritoneal lavage. Surg Gynecol Obstet 155:257-264, 1982.

7.Alyono D, Perry JF, Jr: Value of quantitative cell count and amylase activity of peritoneal lavage fluid. J Trauma 21:345- 348, 1981.

8.McAnulty JF, Smith GK: Circumferential external counterpressure by abdominal wrapping and its effect on simulated intra-abdominal hemorrhage. Vet Surg 15:270-274, 1986.

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Blunt Abdominal Trauma

Notice the diffuse abdominal bruising present on this dog's abdomen.

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Etiology of Abdominal Injuries

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Penetrating Abdominal Injury Due to Gunshot

Gunshot Wound to the Abdomen

Closeup of the Gunshot Wound

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Needle Abdominocentesis

A 20-gauge needle is inserted into the peritoneal cavity. If fluid exudes from the needle hub, this fluid is collected for cytology, packed cell volume, and culture.

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Packed Cell Volumes Taken Via Centesis

Notice the packed cell volume from the centesis fluid exceeds the packed cell volume taken from the peripheral vein.

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Azostix Used to Assess Urea Nitrogen

Notice the dark green color of the Azostix indicating a positive test for urine.

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Bile Removed Via Abdominocentesis Following Abdominal Trauma

Notice the bile-colored appearance of the fluid in the syringe.

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Positive Contrast Study of Urological Trauma

Notice the urethra has been severed from it's attachment to the bladder.

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Contrast Studies of a Ruptured Urethra

A fractured pelvis in the male dog is commonly associated with urethral injury in the dog.

Positive Contrast Urethragram

Notice the ruptured urethra adjacent to the fractured pelvis.

Positive Contrast Urethragram

Positive contrast study showing a ruptured bladder with contrast material leaking into the abdomen.

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Abdominal Compression Bandage in Trauma

A snug bandage is placed around the abdomen of the dog with abdominal hemorrhage secondary to trauma.

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Revised April 14, 1998