Leakage of urine directly into the peritoneal cavity can result in urinary ascites, which is associated with a number of clinical and biochemical findings.


Potential causes of urinary ascites (see Chapter 14):

(1) bladder rupture

(2) ureter rupture

(3) rupture at the renal pelvis


Clinical findings:

(1) rapid accumulation of ascites fluid with abdominal distention

(2) oliguria (may be absent if the leakage is small or unilateral)


Serum chemistries:

(1) hyponatremia

(2) elevated serum creatinine

(3) hyperkalemia


Ascites fluid chemistries:

(1) creatinine greater than plasma or serum

(2) high BUN

(3) high potassium


The osmolality of urine is typically greater than serum. If this fluid is left in place for some time there will be a transfer of water with dilution of the original concentrations (see Herrero et al).


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