How is urinary obstruction due to a patent urachus in an infant diagnosed and managed?

Urinary Obstruction Due to Patent Urachus in Infants

Diagnosis

Patent urachus in infants presenting with urinary obstruction is diagnosed by voiding cystourethrography (VCUG), which is the gold standard for confirming the diagnosis and demonstrating contrast flow from the bladder through the urachal tract to the umbilicus. 1, 2

Clinical Presentation

• Neonates with patent urachus typically present with continuous urine drainage from the umbilicus starting within the first days of life. 1, 3, 4
• A giant umbilical cord cyst or enlarged umbilical cord may be detected on prenatal ultrasound and should raise suspicion for urachal anomalies. 5
• Patent urachus accounts for only 10-15% of all urachal abnormalities, making it less common than urachal sinus (49%) or urachal cyst (36%). 1, 2

Diagnostic Imaging Algorithm

For infants with suspected patent urachus based on umbilical urine drainage:

• VCUG is diagnostic in 100% of patent urachus cases and should be the first-line imaging study, demonstrating contrast flowing from the bladder through the patent tract to the umbilicus. 1, 2
• Ultrasound has limited utility for patent urachus, with studies showing it was non-diagnostic in 2 of 2 cases in one series, though it may identify the fluid-filled tract. 1, 3
• Excretory urography (intravenous pyelogram) was diagnostic in 2 of 2 cases but is now considered obsolete in pediatric urology. 1
• Sinography through the umbilical opening can confirm the diagnosis if VCUG is equivocal, though VCUG remains preferred. 1, 3

Essential Associated Evaluations

• All infants with patent urachus require complete urinary tract imaging to identify concurrent anomalies, as urachal abnormalities frequently accompany other urogenital malformations. 4
• In male infants with any urinary tract dilation on ultrasound, VCUG is mandatory to exclude posterior urethral valves, which represent a urologic emergency. 6

Management

Initial conservative management with urethral catheter drainage for 1-2 weeks should be attempted first, as spontaneous closure can occur; if the patent urachus persists on repeat VCUG, proceed to surgical excision. 2

Conservative Management Protocol

• Place a urethral catheter immediately to divert urine flow away from the urachal tract and allow potential spontaneous closure. 2
• Maintain catheter drainage for 7-14 days with continuous bladder decompression. 2
• Perform repeat VCUG after the catheterization period to document closure or persistence of the patent tract. 2
• This conservative approach has been successful in achieving spontaneous closure in documented cases, avoiding the need for surgery. 2

Surgical Management

If conservative management fails:

• Surgical excision of the entire urachal remnant with a cuff of bladder is the definitive treatment and was performed in 50% of cases in large series. 1
• Complete excision without bladder cuff was performed in the other 50% of cases, though including a bladder cuff is generally preferred to prevent recurrence. 1
• Laparoscopic excision with bladder cuff is an alternative minimally invasive approach. 1

Infection Management

• If the patent urachus presents with concurrent infection (pyocele), initiate broad-spectrum antimicrobial therapy immediately. 5
• For highly infected cases, perform drainage first followed by delayed definitive excision once infection is controlled, rather than attempting primary excision in the setting of active infection. 4
• Postoperative wound infections occur in approximately 7% of cases and should be managed with appropriate antibiotics. 1

Critical Pitfalls to Avoid

• Do not rely on prenatal ultrasound alone to exclude urachal anomalies; even when antenatal imaging shows no suspicious findings, postnatal examination of giant umbilical cords or umbilical cord cysts warrants investigation for patent urachus. 5
• Avoid attempting primary surgical excision in the presence of significant infection, as this increases morbidity; drain first, then perform delayed excision. 4
• Exercise caution during surgical excision to avoid hemorrhage from dilated umbilical arteries, which may accompany urachal remnants. 4
• Do not assume isolated patent urachus; always evaluate for concurrent urinary tract malformations, as these frequently coexist. 4