20) differential diagnosis of abdominal fluid accumulation

Question 1

pathophysiology of fluid accumulation

Answer 1

• Continuous filtration from the arteriole side of the capillaries
– Not visible by ultrasound/X-ray
– Absorbed by venous (and lymphatic) circulation
• Causes of pathological fluid accumulation
– Increased hydrostatic pressure in the capillaries
– Decreased oncotic pressure (hypoalbuminaemia)
– Increased permeability of the capillaries (endothel)
– Increased hydrostatic pressure in the interstitial space

Question 2

transudate differential diagnosis

Answer 2

o PLE
o PLN
o Liver cirrhosis
o Portal hypertension
• US not always diagnostic
→ PROTEIN POOR TRANSUDATE = “clear water like fluid”
– Proteinuria exclusion by urine protein measurement (UPC !!!)
– Portal hypertension ultrasound (Doppler and experience needed)
– If other two excluded and hypoalbuminaemia presents PLE is suspected

Question 3

2) EXUDATE, UROPEITONEUM, TUMORS (CELLULAR),

Answer 3

• Exudate: cause of inflammation not always visible on X-ray/US
→ Caused by: Corrugated intestines, peritonitis, pancreatitis (enteritis)
– Corrugated intestines are not always visible by US
• Uroperitoneum: Place of urinary leakage not always visible on X-ray, US
→ Caused by: Urinary bladder rapture
– Always measure creatinine from abdominal fluids
• Tumour: not always visible on X-ray/US
– Neoplastic cells/reactive mesothel cells could be mixed
– If all other causes are excluded: laparotomy

Question 4

3) HAEMORRHAGIC FLUID

Answer 4

• DD: Tumor, Trauma, Coagulopathy, Uroperitoneum, Intestinal strangulation

Question 5

4) CHYLOTHORAX, CHYLOPERITONEUM

Answer 5

• Mesenteric lymph vessel→ cisterna chyli
• Thoracic duct→ v. cava cranialis
• If thoracic duct is ligated collaterals open, obstruction does not cause chylothorax
• Th. duct rupture can cause chylothorax (sometimes spontaneously heals)
• DD: Tumours, heart failure in cat and lymphangiectasia

Question 6

A) Thoracic fluid accumulation

Answer 6

 Pleural fluid
• Dogs: pleural fluid accumulation without ascites is not likely of cardiac origin
• Cats: can be cardiac
• Types:
• Heart failure: modified transudate, chylothorax
(right sided heart failure, also in left sided heart failure in cats)
• Tumours: modified transudate, haemorrhagic fluid, exudate, chylothorax
• Infection: exudate
• Lung lobe torsion: modified transudate
• Hypoproteinaemia: transudate
• When should you search the cause of pleural fluid (also) in the abdomen?
• If the laboratory exam reveals:
– Chylothorax (rarely modified transudate)
• lymphangiectasia
– Exsudatum
• pancreatitis
• Diagnostic tools:
 Percussion
 US
 X-Ray

Question 7

B) Abdominal fluid accumulation

Answer 7

 Ascites
= Abnormal accumulation of fluid in the abdomen.
• Cats: Ascites without pleural fluid accumulation is not likely from cardiac origin
• Dogs: could be cardiac
• Types:
• Heart failure: modified transudate (right sided heart failure), rarely chylous ascites
• Tumour: modified transudate, haemorrhagic fluid, exudate
• Infection: exudate
• Thrombosis: modified transudate
• Hypoproteinaemia: transudate
• When should you search the cause of ascites (also) in the thorax?
• Congested v. cava caudalis
• Laboratory exam
– Modified transudate (rarely in chylous ascites) → NOT pure transudate
– In cases of haemorrhagic fluid, exudate
• Diagnostic tools:
 Undulation test
 US → Anechoic – particulated fluid!
• Not specific
• Differentiate from dilated bladder, obesitas
• Facilitate sampling (ascites, urine)
• Can be repeated
• E.g. after laboratory exam offluid, blood tests
• Logical approach
 X-Ray