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Understanding Causes and Concerns of Pelviectasis

Jun 13, 2024

Editors note: Original publish date: Feb 5, 2024 – Updated on June 1, 2024

During some pregnancies, a blockage may cause urine to build up in the baby’s kidneys. This causes the kidneys to swell as the urine is unable to flow from the kidneys through the ureter and the bladder.

This condition often resolves itself without treatment. However, if treatment is required, there are treatment options available. If a baby is born with pelviectasis, they may need continuous monitoring.

Hydronephrosis is a condition that occurs in adults when a kidney swells, and urine cannot be removed due to a blockage or obstruction.

Key Points

  • Pelviectasis can be detected during a prenatal ultrasound.
  • This condition occurs in roughly 1% of pregnancies.
  • Pelviectasis of the kidney in adults is called hydronephrosis (upper urinary tract dilation). In this condition, the urinary tract or the kidneys swell.

What is Pelviectasis?

Pelciectasis, also known as pyelectasis, is a condition that occurs during pregnancy in which excess urine gathers inside the baby’s kidney. The build-up of excess urine is caused by a blockage that stops the urine from flowing from the kidneys to the ureter and bladder.

What Causes Pelviectasis?

There are two main causes of pelviectasis: vesicoureteral reflux and ureteropelvic junction obstruction.

Vesicoureteral reflux

Urine normally leaves the kidneys and flows through the ureters and into the bladder. The bladder then stores the urine until it leaves the fetus’ body and joins the amniotic fluid. In some cases, a condition called vesicoureteral reflux (VUR) occurs, where urine flows backward from the bladder to the ureters and, in some cases, the kidneys.

If the urine stays in the kidneys long enough to cause swelling, it could develop into pelviectasis.

Ureteropelvic junction obstruction

Ureteropelvic junction obstruction is a condition that occurs when there is a blockage at the junction where the fetus’ ureter attaches to the kidney. This blockage causes a decreased flow of urine down the ureter and increases the fluid pressure inside the kidney.

The increased fluid pressure inside the kidney could cause pelviectasis and the decline of kidney function. Ureteropelvic junction obstruction can either develop over time secondary to injury or a change in body shape with age or be congenital (the baby is born with it). The blockage can be due to a blood vessel, scar tissue, kinking, or, in rare cases, a tumor.

Is Pelviectasis Serious?

In the majority of cases, pelviectasis doesn’t cause a significant negative impact on the baby. Most babies with pelviectasis are born healthy and continue to do well long term.

In rare cases, pelviectasis can develop into severe hydronephrosis. Hydronephrosis is a condition that develops when a kidney swells and cannot remove urine like it is supposed to. This condition can affect one or both kidneys and, over time, cause kidney damage.

Can pelviectasis be cured?

Yes, in most cases (90%), pelviectasis can go away on its own before the baby is born, and the baby will have normal kidney health and urinary function. If the swelling in the kidney does not go away on its own, further tests may be required during and after birth. A healthcare provider may conduct regular ultrasounds to ensure that the blockage doesn’t become more severe.

Most children who have pelviectasis when they are born will need to be closely monitored. A small number of babies may require surgery. The kidney health of children who require surgery needs to be monitored.

Signs and Symptoms of Pelviectasis?

Pelviectasis during pregnancy generally does not cause any noticeable symptoms. This condition is normally noticed through routine prenatal ultrasounds.

How is Pelviectasis Diagnosed?

Pelviectasis is diagnosed by a healthcare provider during a prenatal ultrasound. If the ultrasound shows pelviectasis, then additional monitoring during pregnancy will be needed.

How is Pelviectasis Treated?

In the majority of cases, pelviectasis resolves on its own without treatment. During pregnancy, a healthcare provider will monitor the condition. If required, a pediatric nephrologist or urologist will examine the baby after delivery. In some cases, a surgical procedure called a pyeloplasty is performed to remove the blockage between the ureter and the kidney.

Although uncommon, If hydronephrosis or pelviectasis becomes so severe that kidney damage during the pregnancy may occur, then fetal surgery may be recommended.

What is Pelviectasis of the Kidney in Adults?

Pelviectasis of the kidney in adults is called hydronephrosis (upper urinary tract dilation). This condition occurs when one or both kidneys swell and can’t move urine to the bladder.

Hydronephrosis can be acute (sudden) or chronic, complete or partial, one-sided or bilateral (both sides). Unilateral hydronephrosis is a condition in which only one kidney is affected. If both of the kidneys are affected, it is called bilateral hydronephrosis.

Hydronephrosis occurs in 1 in 100 adults at some stage of their life. This condition may result in the loss of kidney function or kidney failure; however, quick and effective treatment reduces the risk of developing long-term complications.


In most cases, hydronephrosis does not cause any symptoms. However, when symptoms do present, they may include:

  • Painful urination
  • Urinary tract infection (UTI)
  • Intense or sudden pain in the back, sides, or abdomen
  • Blood in the urine
  • Vomiting or nausea
  • Urinating more frequently or less than normal

The chances of developing a UTI increase when you have hydronephrosis, as urine is not able to be removed from the body. This can result in bacteria growing and multiplying in the urinary tract.


The most common cause of hydronephrosis is a blockage or obstruction in one of the parts of the urinary tract. In adults, many other conditions can cause hydronephrosis, such as:

Complications of hydronephrosis

Severe cases of hydronephrosis can cause damage to the kidneys and may lead to kidney failure. Treatment may include dialysis or a kidney transplant. However, most people recover from hydronephrosis and do not get permanent kidney damage.


Diagnosing hydronephrosis quickly is important; if left untreated, it may cause long-term kidney damage.

Hydronephrosis can be diagnosed with simple tests such as:

  • Blood tests
  • Urine tests
  • Imaging such as an ultrasound, CT scan, or an MRI
  • A physical examination

Treatment and management

The main goal of treating hydronephrosis is to remove the blockage or obstruction and restore the flow of urine from the kidney to decrease the pressure and swelling. Treatment will depend on the underlying cause. In some cases, mild cases of hydronephrosis may clear up on its own without treatment.

If hydronephrosis is sudden and severe due to a blockage, a nephrostomy tube may be placed through the skin into the kidney to drain excess urine. A ureteral stent (soft plastic tube) may also be used to hold the ureters open, allowing urine to flow into the bladder.

Panoramic Health

Panoramic Health is an integrated provider group delivering the future of kidney care. Our mission is to improve patients’ outcomes by slowing disease progression and improving their quality of life. We do this through the distinctive capabilities of our comprehensive care model, which brings together an integrated provider group with operational support, clinical support, and data & analytics at scale.

Through partnerships with practices, providers, payers, and health systems, we work to advance the usage of clinically validated best practices and cutting-edge data analytics across a continuum of reimbursement models.

*The content presented in this article is for informational use only and should not be construed as medical advice or replace the medical advice of a qualified physician.