What Is a Urachal Remnant?

This congenital abnormality might not cause any symptoms

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While a baby is growing during the first trimester of pregnancy, the organs that are needed for the baby to urinate (pee) aren’t fully formed yet. Instead, there is a channel that goes between the bladder and the belly button (navel or umbilicus). This is called the urachus. This channel normally closes up as the fetus grows.

However, when it doesn’t close fully, and the baby is born with part or all of it open, it’s called a urachal remnant. This is a rare condition and it can lead to health problems.

A urachal remnant tends to be more common in males than it is in females. This article will explain the different types of urachal remnants, how the condition may be diagnosed, and how it is treated.

toddler daughter and father
MoMo Productions / DigitalVision / Getty Images

Structure of the Urachus

As a fetus grows during pregnancy, there are many structures that change in order to accommodate the needs of the fetus to receive nutrition and to eliminate waste. One of these is the urachus, which is a tube that connects the bladder and the umbilicus.

Urine drains out through the urachus while the fetus is growing. This channel starts to close up around the 12th week of gestation. What’s left after it closes is a small cord that’s called the median umbilical ligament.

However, in rare cases, the urachus doesn’t close up in the way that it should. Either part or all of the tube remains open and it is what’s called a urachal abnormality. This is a vestigial structure, which means that it is no longer an organ that is needed or used by the body.

Urachal Abnormalities

There are four main types of urachal abnormalities:  

  • Patent (open) urachus: With this type of abnormality, the urachus is completely open. This is the most common type of urachal abnormality, accounting for what’s estimated to be approximately half of all cases, based on studies.
  • Urachal cyst: With a urachal cyst, the urachus is not connected to either the bladder or the umbilicus. It was estimated that about a third of urachal remnants are urachal cysts, but with newer imaging tests, it’s thought that this could be as high as two-thirds of all cases.
  • Urachal sinus: This type of urachal remnant is when the urachus is closed at the bladder side but is open at the umbilical side. It’s estimated that about 18% of urachal abnormalities are of this type.
  • Vesicourachal diverticulum: When this type of the abnormality occurs, the bladder side of the urachus remains open. This is the least common type, accounting for about 3% of urachal remnants.

How a Urachal Remnant Is Diagnosed

Most of the time, a urachal remnant is diagnosed in children. It’s possible, though, for a urachal abnormality to persist into adulthood without being diagnosed.

This condition might not cause any symptoms.However, there are some signs or symptoms that can prompt a physician to order tests to find out what the cause might be. This can include fluid draining from the umbilicus (naval), abdominal pain, a mass in the abdomen, or a urinary tract infection.

A urachal remnant is often found in children between the ages of 2 and 4 years. It’s estimated that about 1% of children are born with a urachal remnant. In some cases, a urachal abnormality that doesn’t cause any symptoms might only be found “incidentally.” It is discovered when there are tests done to look for another disease or condition.

Some of the tests that are done to diagnose an urachal abnormality are:

  • Ultrasonography: During this test, high-frequency sound waves are used to create an image of the internal organs. It is painless, non-invasive, and does not use radiation. This is the test that is by far the one most commonly used to diagnose a urachal abnormality.
  • Voiding cystourethrography (VCUG): This type of X-ray uses contrast to see the bladder. Contrast is put into the bladder through a catheter in the urethra. The patient will void (pee) while X-rays are taken with a fluoroscope. This test is done less often to diagnose a urachal abnormality.
  • Magnetic resonance imaging (MRI): An MRI is a test that uses magnets and radio waves to make an image of the structures in the body. For this test, a patient will lie on a motorized table which is then moved into the MRI machine. This test is used only rarely to diagnose a urachal remnant.
  • Computed tomography (CT) scan: A CT scan uses X-rays to take images of body structures. During this test, the X-ray machine is moved around the patient in order to create cross-section images of the body. This test uses radiation and is not usually used to look for a urachal abnormality.

How a Urachal Remnant is Treated

Having a urachal abnormality can lead to complications such as an increased risk of having urinary tract infections. There is also a risk of the remnant developing into a form of bladder cancer later in life. This type of cancer (urachal carcinoma) is aggressive, although it is rare. For this reason, surgery may be considered to treat a urachal remnant.

The type of surgery and associated treatment for the abnormality will depend on the type of urachal remnant, if there are any signs and symptoms or associated conditions (such as a urinary tract infection or skin infection around the naval), and the age of the patient.

An infection may need to be treated with antibiotics prior to surgery. The goal of the surgery will be to remove the urachal remnant. After the abnormality is removed, there is no risk of developing urachal carcinoma.

For older children, especially, the preferred type of surgery may be laparoscopic as opposed to open surgery. This is because the laparoscopic approach may leave less scarring because it is done through the use of a few small incisions. After the surgery, there may be a hospital stay of a few days.

Once recovered from surgery, there’s not usually a need for follow up care. Recent studies are also showing that laparoscopic surgery might be used successfully in adults as well to remove an urachal remnant.

A Word From Verywell

A urachal remnant is a rare congenital disorder (a condition that’s present at birth) which may go undiagnosed unless there are symptoms. Symptoms can be nonspecific such as abdominal pain or urinary tract infection.

In many cases, the medical team may recommend surgery to remove the remnant because of the possibility of complications and because it is associated with a rare, but aggressive form of cancer.

In most cases the anomaly can be removed and recovery is uneventful. For those that have a concern about scarring on the abdomen, laparoscopic surgery may be an option. 

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.