Thursday, October 3, 2013

The post formerly known as three things I learned: Hemoabdomen

(c) Anne Fawcett
No, Bluey isn't suffering from hemoabdomen, but I didn't want to shock everyone with a surgical picture up front. 
Before I discuss VetGirl's fantastic webinar on approach to the hemoabdomen, I need to mention that this post is one that comes with a pre-warning: there will be a surgical image of a ruptured spleen which for the uninitiated looks like a big purple fleshy organ.

This week I attended the webinar hosted by VetGirl on “Approach to the Hemoabdomen – to cut or not to cut?” by Dr Garret Pachtinger.

The hemoabdomen, or the abdomen full of blood, is most commonly an acute process, but can be a chronic presentation.  Either way these animals are in trouble and need critical intervention.

Dr Pachtinger’s presentation was beautifully logical and reassuring, and filled with pearls such as “the abdominal cavity is the most common place for clinically significant haemorrhage”. I left feeling equipped with a solid systematic approach to a presentation which can be hair-raising.

In general practice in Australia I tend to see hemoabdomen most commonly in canine patients, particularly larger dogs, though the last hemoabdomen I saw was in a cat with an avulsed kidney secondary to motor vehicle trauma.

Common signs owners report include weakness, lethargy, exercise intolerance, dyspnoea and of course a distended abdomen. The presentation is usually acute but some owners report waxing and waning signs, often associated with microbleeds of splenic masses.

On physical examination, affected dogs will have short/narrow/thready femoral pulses and pale to white gums with prolonged capillary refill time. Depending on how much abdominal effusion is present, the abdomen may not only appear distended, but have a palpable fluid wave.  Patients are often both tachycardic and tachypneic. Along with the fast heart rate, heart sounds may be diminished due to hypovolaemia. Patients often have an increased respiratory rate due to lack of oxygen delivery to the tissues.  If the blood loss is severe, decreased perfusion to the brain can lead to dysphoria. Mydriasis is a severe manifestation of decreased perfusion and often precedes cardiac arrest.

In other words the most immediate problems for these animals are hypovolaemia and decreased tissue perfusion due to blood loss. Hypovolaemic shock is differentiated from other causes of shock based on the examination findings above.  For example, animals in compensatory septic shock have injected mucous membranes, not pale or white mucous membranes and animals in cardiogenic shock tend to have a murmur and/or bronchovesicular crackles on cardiac and pulmonary auscultation.

Dr Pachtinger’s minimum database (MDB) includes a PCV, TP, BUN, and blood glucose.  The MDB is supplemented with other diagnostics including lactate, electrolyes, CBC and biochem. In patients that present with a hemoabdomen, usually both PCV and TP are low but in a peracute bleed TP drops first and the PCV may be normal.

Ultrasound (FAST) is preferred to scan the abdomen: when scanning the abdomen look at the diaphragmatic-hepatic, cystocolic, splenorenal and hepatorenal views. FAST is a more sensitive technique for detection of effusion as compared to other commonly used modalities including both radiographs and blind abdominocentesis.  With a FAST scan, you can detect an effusion of 4ml/kg, whereas you need a much larger amount of effusion, 5-25ml/kg, to detect via a blind abdominocentesis. Radiographs are less sensitive than ultrasound but can be helpful (for example screening for mets or signs of trauma like rib fractures).

If FAST is inconclusive it should be repeated once fluid resuscitation has commenced.


Dr Pachtinger covered the ins and outs of effusion analysis, including cytology and chemistry, and also talked us through techniques for FAST and four quadrant abdominocentesis.

(c) Anne Fawcett
Splenic mass in a dog prior to splenectomy. You can see where the mass has ruptured and bled. This dog made a full recovery.
Once a haemoabdomen is diagnosed, further classification is needed. The three common causes for hemoabdomen include:
  1. Coagulopathic (the most common cause being vitamin K deficiency caused by ingestion of anticoagulant rodenticides)
  2. Spontaneous (non-traumatic, e.g. a bleeding splenic mass)
  3. Traumatic (e.g. fracture or laceration of the spleen, liver, or more serious an avulsed major artery such as renal (kidney) artery)

One thing I found helpful in the discussion of anticoagulant rodenticide ingestion was that Dr Pachtinger recommends decontamination if the animal has ingested anticoagulant rat bait within six hours, then running a PT 48-72 hours later. If this is prolonged the animal should be given vitamin K for at least four weeks.  If this value is normal 48-72 hours following ingestion and decontamination, it is unlikely the patient either ingested or absorbed enough toxin to require therapy and vitamin K at that time is not needed. (REFERENCE 1 BELOW).

The most common cause of spontaneous, non-coagulopathic hemoabdomen is neoplasia (65-80% of the time). Haemangiosarcoma is the most common neoplastic cause in these cases. BUT non-malignant growths can cause hemoabdomen e.g. liver lobe torsion, splenic haematoma.

Before undertaking ultrasound, Dr Pachtinger prepares owners for one of three common ultrasound findings.

Either:
  • A solitary mass is identified. As long as chest rads are clear such patients considered better candidates for surgery as compared to a patient that has multiple masses or lesions throughout multiple organs.  With that said, a single solitary mass does not rule out malignancy and malignancy remains the most common cause of hemoabdomen.
  • Multiple masses are present – malignancy is more likely.
  • No masses or lesions are identified – this is less common but warrants further investigation once the patient is stable, such as scanning for signs of trauma, repeating the clotting test and potentially advanced imaging.

If you want to find out more about the VetGirl webinars visit http://vetgirlontherun.com/


Incidence of prolonged prothrombin time in dogs following gastrointestinal decontamination for acute anticoagulant rodenticide ingestion.

No comments:

Post a Comment

Add comments here: