Patent Urachus

What the urachus is

Before birth, the bladder is connected to the umbilical cord by a tube called the urachus. It normally closes and shrinks into a fibrous cord (the median umbilical ligament) by the end of pregnancy. When it stays partly or completely open, a urachal anomaly results.

Types of urachal anomalies

Causes and associated conditions

The cause is failure of normal closure during development. A patent urachus is sometimes linked to a blockage of urine flow from the bladder, such as posterior urethral valves in boys, which keeps pressure high and the channel open. Doctors check for these problems.

Symptoms

• a persistently wet or irregular belly button
• clear, yellowish fluid leaking from the navel, especially when the baby cries, strains or urinates
• a slow-healing umbilical cord stump
• swelling or redness around the navel
• urine-smelling discharge
• urinary tract infections

If infected, there may be pus, redness, fever and irritability.

Diagnosis

• examination of the navel
• testing the fluid for urine (creatinine or urea)
• ultrasound: shows a tubular structure from the bladder to the belly button
• voiding cystourethrogram (VCUG): dye in the bladder may show the connection and checks for urethral blockage
• fistulogram: dye injected through the navel opening in some cases
• CT or MRI occasionally in older children or adults

Other causes of a wet or discharging navel in newborns, such as an umbilical granuloma, an umbilical hernia, an omphalomesenteric (vitelline) duct remnant connected to the bowel, and omphalitis, are considered.

Treatment

• treating infection first, with antibiotics if needed
• surgical removal (excision) of the entire urachus and a small cuff of the bladder dome, usually by keyhole surgery or a small incision below the navel
• treating any blockage of urine flow, such as urethral valves

In some very young infants with a small patent urachus and no other problems, doctors may wait briefly to see if it closes on its own, since some close spontaneously in the first months.

Complications

Without treatment, patent urachus can cause:

• recurrent infections and abscesses
• skin irritation around the navel
• urinary tract infections
• stones in the channel

In adults, urachal remnants carry a very small risk of a rare cancer (urachal adenocarcinoma), one reason surgeons remove the whole remnant.

Outlook

After surgery, most children recover quickly, with a hospital stay of 1 to 2 days, and have no long-term problems.

Frequently asked questions

What is a patent urachus?

A patent urachus is an open channel between the bladder and the belly button that normally closes before birth. Urine can leak through it, making the belly button wet. It is a rare birth difference usually found in newborns.

What are the signs of a patent urachus?

The main sign is clear fluid leaking from the belly button, often more when the baby cries or strains, and a navel that stays wet or does not heal after the cord falls off. Infection can cause redness, pus, swelling and fever.

How is a patent urachus diagnosed?

Doctors use an ultrasound to show the channel between the bladder and navel. Testing the fluid can confirm it is urine. A bladder X-ray with dye (VCUG) may show the connection and check for blockages in urine flow.

How is a patent urachus treated?

It is usually treated with surgery to remove the urachus and close the bladder, often by keyhole surgery. Any infection is treated first, and any blockage of urine flow is also addressed. Most children recover fully.

Can a patent urachus close on its own?

Sometimes, in the first months of life, a small patent urachus closes on its own, especially once any urine flow blockage is treated. Many, however, persist or cause infections and need surgical removal.