Equis ISSN 2398-2977

Urachus: patent

Synonym(s): Urachal fistula

Contributor(s): Jonathan Pycock, Wendy E Vaala

Introduction

  • Cause: congenital and acquired forms of failure of the urachus to occlude at the umbilicus.
  • Acquired types may be associated with systemic debilitation and/or umbilical infection.
  • Signs: Presents within first 2 weeks of life with moist umbilicus and leakage of urine from the patent urachus.
  • In acquired forms may be severe systemic signs in compromised neonatal foal.
  • Diagnosis: history, signs.
  • Treatment: is usually medical with antibiotic therapy, local umbilical cleaning/skin protection, possibly cautery, primary problem care and surgical resection of the umbilical remnants with persistent cases.
  • Prognosis: guarded in systemically ill foals.

Pathogenesis

Etiology

  • Congenital or acquired.

Pathophysiology

Congenital urachus syndrome
  • Urachus never closes at birth.
  • Unknown etiology possibly due to distention from cord torsionin uteroor during delivery leading to tension of the umbilicus, dilation of the urachus and preventing occlusion.
    Acquired urachus syndrome
  • Re-opens post-partum as the dried umbilical stump falls off.
  • Associated with umbilical infection/inflammation or excessive use of concentrated iodine dip resulting in premature sloughing of umbilical stump.
  • Excessive wetness or trauma to the umbilical stump in the recumbent foal.
  • Prolonged recumbency in debilitated foal.
  • Poor/inexperienced cord ligation or severance. Ligature, if not removed may result in premature sloughing of stump.
  • Any cause of increased intra-abdominal pressure, eg meconium retention   Rectum: meconium impaction  (tenesmus, dysuria etc).
  • Urine leakage   →   persistent irritation and potential source of infection.
  • Congenital forms are present at birth.

Timecourse

  • Acquired forms develop in the first 2 weeks of life.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

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