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Basics ⬇

Outline

BASICS

Definition!!navigator!!

Uroperitoneum is an accumulation of urine in the peritoneal cavity caused by rupture of the bladder or urachus, ureteral tear, or avulsion of the bladder from its urachal attachment.

Pathophysiology!!navigator!!

  • Urine has a high concentration of potassium, low concentrations of sodium and chloride, and variable concentrations of urea, creatinine, and water
  • Uroabdomen can result in urea, creatinine, and electrolytes moving across the semipermeable peritoneal membrane to equilibrate with plasma, leading to azotemia, hypochloremia, hyponatremia, and hyperkalemia
  • Creatinine is less permeable than other solutes and may remain disproportionately elevated in the abdomen
  • Pathologic abnormalities may not be apparent for several days following urine leakage
  • Hyperkalemia is the most serious of the electrolyte derangements, where profound ECG dysfunction can occur
  • Restrictive respiratory failure and colic may be observed in foals with progressive abdominal distention, and ventilation may become impaired

Systems Affected!!navigator!!

Urinary

  • Rupture of 1 or more structures of the urinary tract; bladder most common
  • Septic foci may predispose to bladder rupture

Gastrointestinal

  • Colic and ileus associated with pain and progressive abdominal distention
  • Inappetence
  • Sterile peritonitis

Cardiovascular

Hyperkalemic dysrhythmias—atrial standstill, cardiac arrest, complete third-degree atrioventricular blockade, ventricular fibrillation.

Respiratory

Tachypnea associated with progressive abdominal distention and restrictive lung expansion.

Nervous

Depression associated with hyponatremia, progressing to seizure activity.

Genetics!!navigator!!

N/A

Incidence/Prevalence!!navigator!!

Sporadic event; greatest incidence in newborn foals.

Geographic Distribution!!navigator!!

Worldwide

Signalment!!navigator!!

Breed Predilections

No known breed predilection.

Mean Age and Range

Congenital uroperitoneum tends to occur during vigorous parturition and in the immediate postpartum period. Most cases are recognized within 3–5 days of age. Acquired or secondary uroperitoneum occurs in foals from 1 to 60 days, with most cases diagnosed within the first 2 weeks of life.

Predominant Sex

  • Congenital uroperitoneum occurs more commonly in colt foals (>80%). Dorsal urinary bladder tears can occur during parturition. Colts may be predisposed owing to the relatively long urethra, high tone of the urethral sphincter, and high intravesicular pressure of a distended bladder contributing to an increased resistance to emptying
  • Congenital ureteral defects occur more commonly in fillies
  • Acquired uroperitoneum occurs equally among colts and fillies

Signs!!navigator!!

Historical Findings

  • Foals usually are born normal
  • Foals may be observed to still void some urine
  • Clinical signs are usually evident by 24–72 h of age, yet can occur as late as 3–4 weeks

Physical Examination Findings

  • Frequent attempts to urinate that may be partially successful and void a small stream. Often no urine is passed
  • Progressive inappetence, dehydration, depression, lying down
  • Progressive abdominal distention and the development of colic and/or tachypnea. Fluid ballottement may be possible
  • Ventral edema may be present
  • As electrolytes become more deranged, weakness and recumbency become a prominent feature
  • Bradycardia or tachycardia

Causes!!navigator!!

  • Congenital rupture during and/or shortly after parturition
  • Acquired urachal or bladder rupture associated with sepsis and/or local septic focus (e.g. omphalophlebitis)
  • Rarely, embryologic failure of the halves of the bladder to unite (schistocystitis) or ureteral defects can cause uroperitoneum
  • Iatrogenic rupture associated with catheters
  • Traumatic rupture

Risk Factors!!navigator!!

  • Males for congenital rupture
  • Age <4 days
  • Septicemia
  • Prematurity
  • Abdominal trauma
  • Omphalophlebitis
  • Patent urachus

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Differential Diagnosis!!navigator!!

  • Colic for various gastrointestinal reasons
  • Meconium impaction should be differentiated from ruptured bladder. Generally, foals that strain to urinate adopt a base-wide stance with ventroflexion of the back whereas foals straining to defecate often show dorsiflexion in their back

CBC/Biochemistry/Urinalysis!!navigator!!

  • Hematologic abnormalities may reflect concurrent disease such as septicemia
  • Electrolyte derangements include hyperkalemia, hyponatremia, hypochloremia. Foals receiving parenteral fluids are less likely to develop classic electrolyte changes
  • Acid–base evaluation often reveals metabolic acidosis
  • Azotemia

Other Laboratory Tests!!navigator!!

Abdominocentesis may yield copious volumes of clear yellow fluid of low cellularity with a uriniferous odor. Peritoneal fluid creatinine concentration is at least twice the serum creatinine concentration. Occasionally, calcium carbonate crystals may be present in peritoneal fluid.

Imaging!!navigator!!

Abdominal Ultrasonography

  • Increased hypoechoic fluid with abdominal viscera floating within this fluid
  • A flaccid collapsed urinary bladder may be visualized
  • Urachal examination may show the margins of a tear
  • Note that the thorax should be evaluated as pleural fluid often accumulates and detection is important when considering anesthesia for surgical repair

Abdominal Radiography

  • Loss of serosal detail of abdominal viscera
  • Standing films may show obvious fluid line
  • Positive contrast cystography using water-soluble contrast agent (e.g. 10% iohexol) should be considered to evaluate the position of a urogenital tear

Other Diagnostic Procedures!!navigator!!

ECG is indicated to assess potassium-related dysrhythmias, especially when potassium >6 mEq/L.

Pathologic Findings!!navigator!!

Presence of uroperitoneum and the structural urinary tract defect. Bladder defects tend to be dorsal. Ureteral defects lead to an accumulation of retroperitoneal urine.

Treatment ⬆ ⬇

Outline

TREATMENT

Aims!!navigator!!

  • Correct hypovolemia, electrolyte, and acid–base disturbances
  • Effective abdominal drainage
  • Correct structural defects

Appropriate Health Care!!navigator!!

  • Immediate referral to a surgical facility is recommended
  • Surgery should be performed after metabolic stabilization

Nursing Care!!navigator!!

Stabilization

  • Correction of hydration, electrolyte abnormalities, and acid–base derangements should be initiated before surgery
  • Note that, when profound hyponatremia exists, correction should be done slowly to avoid hyponatremic encephalopathy (≤1 mEq/L/h)
  • When profound metabolic acidosis exists, isotonic sodium bicarbonate solutions are indicated
  • Plasma transfusion if failure of transfer of passive immunity is evident
  • Abdominal drainage via placement of an abdominal catheter. A balloon-tip Foley catheter or peritoneal dialysis catheter is ideal and can be placed through a small (5 mm) incision under local anesthesia
  • Placement of a urinary catheter and bladder decompression should be done before surgery and may be useful for small defects in the bladder, when these may heal without surgery

Hyperkalemia

  • Isotonic saline solutions with dextrose (2.5–5%) administered IV
  • For unresponsive hyperkalemia, regular insulin can be administered with a continuous infusion of dextrose. Regular assessment of serum glucose should be performed
  • Calcium gluconate may be administered for cardioprotective effects

Activity!!navigator!!

Restricted movement is recommended before and after surgery for at least 14 days.

Diet!!navigator!!

Allow the foal to continue to nurse until shortly before surgery.

Client Education!!navigator!!

  • Clients will need to know about correct care for the abdominal incision
  • Careful observation for recurrence suggesting surgical failure

Surgical Considerations!!navigator!!

  • Emergency surgery is not indicated until the foal is medically stable
  • Before surgery, place a urethral catheter (e.g. Foley)
  • Constant ECG monitoring and acid–base assessment should be performed during surgery
  • Ventral midline celiotomy and laparoscopic techniques are described
  • Thorough inspection and assessment of structural defects should identify any necrotic/infected tissue
  • Conservative treatment is placement of urinary catheter (via urethra) for 3–5 days to allow constant drainage of bladder without surgical correction of tear. It is useful when surgical repair is not available (cost, expertise) and the defect is small

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Broad-spectrum antimicrobial coverage, especially neonates with presumed sepsis and acquired rupture, e.g. sodium penicillin (25 000–40 000 IU/kg IV every 6 h) and amikacin sulfate (25 mg/kg IV every 24 h)
  • NSAIDs may be given to control pain and inflammation related to surgery
  • Insulin (0.1–0.2 IU/kg SC or IV) may be given with dextrose infusions to help reduce the extracellular potassium concentration

Contraindications!!navigator!!

Avoid potassium-containing IV fluids or medications composed of potassium salts, e.g. potassium penicillin.

Precautions!!navigator!!

In hypovolemic patients, aminoglycosides and NSAIDs should be used with caution and at judicious dosages. Where possible, amikacin is the preferred aminoglycoside and ketoprofen is the preferred NSAID.

Possible Interactions!!navigator!!

N/A

Alternative Drugs!!navigator!!

For broad-spectrum antimicrobial coverage, third-generation cephalosporins may be used.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Serum electrolytes (especially potassium and sodium) and urea/creatinine concentrations should be performed every 2–6 h to assess response to stabilization
  • Monitoring of urine output postoperatively—should be ≥1 mL/kg/h
  • Postoperative indwelling urinary catheter use is controversial—reduces distention on the surgical site, but has a risk of ascending infection, and may lead to increased intravesical pressure if occluded

Prevention/Avoidance!!navigator!!

N/A

Possible Complications!!navigator!!

  • Significant anesthetic risk occurs where electrolyte derangements exist
  • Surgical dehiscence and re-rupture of the bladder
  • Incisional complications include infection, dehiscence, hernia, although uncommon
  • Peritonitis

Expected Course and Prognosis!!navigator!!

  • Congenital uroperitoneum associated with ruptured bladder and/or urachus carries a favorable prognosis, >80%, provided timely medical and surgical therapy is administered
  • The prognosis for rupture of the ureter carries a poorer prognosis
  • The prognosis for secondary uroperitoneum is considered less favorable, 50–60%, largely influenced by the primary disease process, such as septicemia

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Synonyms!!navigator!!

  • Uroabdomen
  • Ruptured bladder

Abbreviations!!navigator!!

NSAID = non-steroidal anti-inflammatory drug

Suggested Reading ⬆ ⬇

Bryant JE, Gaughan EM. Abdominal surgery in neonatal foals. Vet Clin North Am Equine Pract 2005;21:511–535.

Dunkel B, Palmer JE, Olson KN, et al. Uroperitoneum in 32 foals: influence of intravenous fluid therapy, infection, and sepsis. J Vet Intern Med 2005;19:889–893.

Kablack KA, Embertson RM, Bernard WV, et al. Uroperitoneum in the hospitalised equine neonate: retrospective study of 31 cases, 1988–1997. Equine Vet J 2000;32:505–508.

Author(s) ⬆

Author: Samuel D.A. Hurcombe

Consulting Editor: Margaret C. Mudge