When Your Navel Leaks: the Patent Primitive Urachus

© March 6, 2008; Dan A. Gold, MD

The navel!  Some are adorned with jewelry (piercings).  Some are perhaps kept covered and forgotten.  Unless removed surgically, we all have one.  This body landmark is the remnant scar from our umbilical cord.  The cord is severed at birth and its stump soon falls away from the lower abdomen leaving the navel.  Perhaps few of us ever really think about the navel again...unless it gives trouble.  

It may simply start to itch and become irritated.  Infection and draining pus may develop.  If so, pus may collect as an abscess in the abdominal wall.  Treatment, of course involves antibiotics for the infection.  However, the real story originates deeper in the body, and at conception.

After fertilization the human embryo, now called a zygote, follows an early developmental course very similar to that which occurs in a chicken egg minus the hard shell.  There is a yolk sac with nutrients that are connected to the developing baby by a cord.  As mentioned, this umbilical cord is lost at birth, however, the remains of the yolk sac persist as a trace piece of anatomic tissue which serves no real function.  It is band-like and can be found running from the bladder up the abdominal wall to the navel (umbilicus): the primitive urachus.

In most people it is not much more than scar tissue.  However, in some, the tissue may form a passage.  It may open, i.e. become patent (pay’ -tent),  and allow the flow of urine from the bladder to the navel.  This is certainly an abnormal condition and inevitably leads to infection of the bladder, the abdominal wall, and navel.  Often the body can scar and wall off the infection, but the primitive urachus remains.  If an abscess develops, treatment can become emergent.  To effect a permanent cure, surgery is needed to obliterate the partial passageway (a sinus), or the fistula (if continuous from the bladder to the navel).

Before the operation a CT scan or ultrasound may be ordered to visualize the anatomic abnormalities.  Examination and probing at the navel may reveal the passage.  Radiologist may squirt xray dye into the passage which enables very clear xray images of the primitive urachus to be taken so the surgeon can plan the operation.

In summary, remember that fluid or intermittent infection and irritation at the navel is not a problem to be ignored.  It may be the result of embryonic structures which have persisted from earliest fetal development into adulthood.  Once this type of navel problem occurs, it is unlikely to permanently resolve itself without medical and surgical treatment.  Your doctor can help.