Hemoabdomen: False negative paracentesis taps can be common

Q. Could you provide a brief review of hemoabdomen and its diagnosis/management in dogs and cats?

A. Bleeding into the abdomen of dogs and cats is usually a critical emergency. The likelihood of death associated with bleeding into the abdomen, however, depends largely on the rate and duration of hemorrhage. Those that bleed slowly may never get into any trouble; those with profuse hemorrhage often arrive as an emergency or "dead on arrival".

The following article describes the current diagnosis and management of severe hemoabdomen - Gfeller RW: An Intensivist's Approach to Hemoabdomen. Proc 20th Annual Forum ACVIM 20:14-16, 2002.

Hemoabdomen can be considered as traumatic and non-traumatic. Traumatic hemoabdomen is caused by blunt or penetrating trauma to the abdomen that results in direct injury to abdominal organs. The most common source of blunt trauma resulting in hemoabdomen is motor vehicle accidents that result in injury to the spleen, liver or kidneys. Bite wounds that penetrate the abdominal wall or projectile injuries are examples of penetrating trauma likely to cause hemoabdomen.

Non-traumatic hemoabdomen can be caused by ruptured masses, anticoagulant rodenticide intoxication and coagulopathy.

The initial step in diagnosis is determining if, in fact, a hemoabdomen exists. Animals presenting after obvious abdominal trauma that have pale mucous membranes, tachycardia, weak thready pulses, a distended abdomen with an obvious fluid wave, and are positive for blood when paracentesis is performed are straightforward. These animals need to be handled quickly.

Does it exist?

Diagnosis of hemoabdomen or hemoperitoneum is more difficult in the animal that has mild abdominal hemorrhage or is afflicted with a slowly leaking ruptured abdominal tumor. It is said that 40 ml of fluid per kg of body weight must be present in the abdomen before abdominal distention is detected.

Four-quadrant abdominal paracentesis has been recommended. A positive paracentesis of blood that does not clot is diagnostic of a hemoabdomen; however, false negative "taps" are common. A sample obtained from paracentesis that clots likely indicates rapid and ongoing hemorrhage or there has been a needle perforation of a vessel or organ. If there is any doubt, the procedure should be repeated.

The sample obtained from paracentesis should then be examined cytologically. If there is an absence of platelets and phagocytized erythrocytes are seen in leukocytes, the sample is consistent with a hemorrhagic effusion.

If platelets are present, the sample may be fresh blood taken from an organ or vessel within the abdomen or may indicate rapid and ongoing hemorrhage.

Ultrasound examination aids in the diagnosis of hemoabdomen. The probe can quickly and non-invasively determine if fluid is present. Once fluid is located with the ultrasound, it can be sampled using a syringe and needle. Further, the ultrasound can be used to examine the echogenicity of the liver, spleen and other abdominal structures. Abnormal visceral echogenicity may indicate neoplasia.

Ultrasound aid

Diagnostic peritoneal lavage (DPL) is safe and rapid, and a very sensitive indicator of abdominal hemorrhage. Briefly, a commercial DPL catheter or a large bore over-the-needle catheter (with multiple fenestrations added using aseptic technique) is inserted into the surgically prepared abdomen.

The site of insertion is immediately caudal to and right of the umbilicus. Warm, sterile crystalloid fluid (up to 20 ml/kg) is infused through the positioned catheter. Distribute the fluid by gently rocking the animal back and forth a few times (if safe to do so); then aspirate a few milliliters of the intra-abdominal fluid from the catheter. If the hematocrit of this fluid is greater than 5 percent, or if you cannot read newspaper print through it, there has been a significant abdominal bleed.

Another important question that must be answered after hemoabdomen is confirmed is whether or not the hemorrhage is ongoing.

Is hemorrhage ongoing?

If hemorrhage is not controlled, the case may rapidly become surgical. Packed cell volume and total protein measurements in peripheral blood are not useful in determining whether or not there is ongoing hemorrhage.

If hemorrhage is ongoing, the hematocrit and total protein will decrease, but it may take several hours before fluid shifts from the interstitial fluids causes enough reduction to raise suspicion. Decreasing blood pressure, increasing pallor of the mucous membranes, serial circumferential measurements of the abdomen indicate the abdomen is enlarging, and an increasing heart rate are physical indicators of ongoing abdominal hemorrhage that is significant.

The DPL is quite useful in answering this question early. Serial samples are obtained from the DPL catheter every 4 to 5 minutes and spun in the hematocrit centrifuge. A steady increase in the hematocrit of fluid recovered indicates ongoing hemorrhage.

Beware of the animal that presents in lateral recumbency with pale mucous membranes, tachycardia, weak-to-nonexistent pulses or bounding pulses, oxygen needed and a notably distended abdomen with a fluid wave. Also beware of the animal that presents with mild signs of shock and no obvious abdominal distension.

Beware

As shock is treated with fluid therapy, the mucous membranes become paler, the shock worsens, and the abdomen begins to distend.

Either of these animals may die if the bleeding is not controlled rapidly and definitively. This often means that surgery is indicated now!

Procedurally, immediate activity could go something like this (recognize that several things are happening at once, not necessarily in the order written):

Emergency measures

• Oxygen should be supplied to the animal by flow-by, face mask, oxygen collar or any other means available. The oxygen cage is not acceptable as many other procedures must be done simultaneously.

• An intravenous catheter is placed in a peripheral or central vein in the forelegs or neck.

• An activated clotting time test is performed.

• Blood pressure determinations are done.

• Low-volume resuscitation using oxyglobin (Biopure Corp., Cambridge, Mass.) infusion is begun through an intravenous catheter. A rapid gravity flow is used initially.

At the first sign of improvement (usually after infusion of 2-5 ml/kg) or when systolic pressure is >60 mm Hg, the infusion rate is slowed to 10 ml/kg per hour or less, and the animal intensively monitored. If the animal is noted to be deteriorating, the infusion rate is increased as needed. Simultaneous crystalloid infusion is indicated at two to three times maintenance rates. The animal is prepared for immediate surgery.

If oxyglobin is unavailable and the animal's blood type is known and a source of suitable fresh whole blood is readily available, a blood transfusion may be started.

The animal may not be able to wait for typing, cross-matching, thawing, warming or obtaining fresh blood, so if it is not readily available, synthetic colloids (such as dextran 70, oxypolygelatin or hetastarch) should be administered. Enough colloid should be administered to raise the systolic blood pressure to greater than 60 mm Hg. Systolic pressures of >100 mm Hg are to be avoided.

If a systolic pressure of at least 60 mm Hg cannot be achieved with colloids, an additional intravenous catheter is placed and crystalloid fluids are administered by rapid bolus. Fluid therapy hemodilutes the animal's blood, which reduces blood viscosity and dilutes clotting factors. Hemodilution and increased blood pressure may worsen the severity of hemorrhage.

The animal is prepared for immediate surgery. Anesthetic induction in the face of shock and hypotension is risky, but the animal will die without it. Anesthetic agents that are known to promote hypotension (such as propofol) should be avoided. The anesthetized animal is supported with positive pressure ventilation.

If a systolic pressure of at least 60 mm Hg cannot be achieved with fluid administration or if there is no pulse palpable in the femoral arteries, an emergency thoracotomy is performed and the aorta cross-clamped with a tourniquet or suitable vascular clamp. Note the time of aortic occlusion. Occlusion times of >10 minutes must be avoided. Proceed immediately to exploratory laparotomy.

If the systolic pressure can be maintained or if there is a palpable pulse in the femoral artery, the animal is prepared for exploratory laparotomy.

Procedurally, the midline is opened between the xiphoid and the umbilicus just enough to allow the surgeon to get a hand into the abdomen. The hand is advanced along the left abdominal wall, moved cranially and medially to locate the aorta and renal artery. The hand is then moved cranially identifying the right renal artery, then the cranial mesenteric artery and finally the celiac artery.

At the level of the celiac artery, the surgeon applies enough digital pressure to occlude these vessels. This procedure has been documented to prevent the devastating and often fatal hypotension that results when the tamponade effect of the abdominal distension is relieved.

A suction tip is advanced into the abdomen and the blood is collected into a sterile container for possible autotransfusion. Certainly asepsis is desirable, but even if it cannot be maintained, the blood should not be discarded. In cases where there is no other alternative, autotransfusion of contaminated blood can be lifesaving.

The abdomen is opened to the pubis and packing material is liberally stuffed into the abdomen. Suitable materials include laparotomy sponges, gauze or even towels. Packing the abdomen provides a tamponade effect that helps control hypotension induced by venous dilatation. Packing will often control venous hemorrhage as well. When the packing is in place, the aortic occlusion can be removed.

If the animal is hemorrhaging rapidly in spite of occlusion of the aorta at the level of the celiac artery, a Pringle maneuver should be attempted.

The hepatic artery, the portal vein and the common bile duct are occluded using digital pressure or a tourniquet. Simultaneously, the cranial mesenteric artery is occluded to prevent portal hypertension. This maneuver should be held for 10 minutes. After 10 minutes, the portal occlusion must be released for at least one minute every 10 minutes.

If the source of hemorrhage is found and can be repaired, the repair is accomplished, ancillary procedures are done (j-tube insertion for example) if the animal's condition permits and the abdomen closed.

If the source of the hemorrhage is not readily identified or cannot be readily repaired, the packing is left in the abdomen and the abdomen is closed temporarily using towel clamps, surgical staples, sutures or even safety pins.

The animal can be treated with blood, fluids or whatever is appropriate, and then the abdomen re-explored in 24 to 48 hours when the animal is more stable.