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Urology

Center for Antenatal Urology

The Division of Pediatric Urology at Morgan Stanley Children's Hospital is an integral part of the Maternal/Fetal Medicine Center. A large number of abnormal findings seen on sonograms during pregnancy are related to urology. Our staff works closely with specialists from the fields of Obstetrics, Neonatology, Pediatric Anesthesiology, as well as all pediatric surgical sub-specialties. This collaboration is invaluable to the management of any finding during pregnancy and also allows for a seamless transition from pregnancy to delivery to care of the infant.

Our pediatric urologists are highly experienced in treating the following prenatal urologic conditions, including:

• Hydronephrosis
• Ureteropelvic junction (UPJ) obstruction
• Reflux
• Ureterovesical junction obstruction (UVJ)
• Ureterocele
• Ectopic ureter
• Posterior urethral valves
• Prune belly syndrome
• Multicystic dysplastic kidney

Hydronephrosis
Hydronephrosis is a term that describes extra fluid in the kidneys and/or ureters. It can sometimes be called "large kidneys" or "swollen kidneys." Hydronephrosis can be seen in a variety of conditions listed below. However, the majority of children diagnosed with hydronephrosis during pregnancy will have the hydronephrosis resolve within the first few years of life. Nevertheless, it is critical for an experienced pediatric urologist to make the distinction between the child with non-threatening hydronephrosis and the child whose hydronephrosis needs further management.

Ureteropelvic junction (UPJ) obstruction
Each of the two kidneys produces urine, which drips into a funnel-like structure called the renal pelvis. The urine travels from the pelvis into the ureter, a hollow tube (approximately the size of a piece of spaghetti) on its way to the bladder. The point where the ureter and pelvis meet is called the ureteropelvic junction (UPJ). When a blockage exists in the urinary system, this is its most common location. There are several causes of a UPJ obstruction. Some children have a ureter that is very narrow or strictured at the UPJ. Others have a ureter that inserts too high on the renal pelvis causing a kinking of the ureter. Still others have an extra blood vessel that goes to the lower pole of the kidney; in this situation, the ureter drapes over this vessel -- almost like a pair of pants draped over a hanger.

But the most common cause of UPJ obstruction is poor peristalsis. Peristalsis is the rhythmic propulsions of material similar to the way the intestines push food forward. In UPJ obstructions, urine often backs up in the kidney because the ureter at the UPJ lacks enough muscle fibers to push the urine forward. If surgery is necessary, removal of that lazy section or narrowed section of ureter will reestablish normal flow.

During pregnancy, the size of the renal pelvis is measured. The larger the pelvis, the more likely it is that a UPJ obstruction exists. However, if at term the renal pelvis is equal to or less than 10 mm, the chance of a significant obstruction requiring surgery is quite low.

Tests after the baby is born include repeat ultrasounds; possibly a voiding cystourethrogram (VCUG) to rule out reflux; and MAG-3 lasix washout renal scans to assess the kidney function and drainage. MAG-3 is an agent injected in a vein that travels to the kidney where it normally is quickly excreted. In an obstructed kidney, its drainage from the kidney is delayed. Some children may further require an intravenous pyelogram (IVP) or magnetic resonance imaging (MRI).

Most cases of hydronephrosis can be observed and they will gradually resolve over the first two to three years of life. However, if the hydronephrosis is pronounced and there is an obstruction at the UPJ, the obstructing segment will be surgically removed. This can be done typically via an incision in the flank or via robotic surgery. This procedure is called a pyeloplasty. The success rate for this procedure is approximately 95 percent.

Vesicoureteral Reflux
Urine normally travels from the kidney to the bladder in one direction like cars on a one-way street. Reflux is the retrograde, or backwards, flow of urine from the bladder into the ureter and kidney. Approximately 20 percent of children with hydronephrosis will have reflux. A voiding cystourethrogram (VCUG) test establishes the diagnosis of reflux. The VCUG involves placing a small catheter into the bladder via the urethra. The bladder is then filled with a dye material (contrast) and the bladder is inspected with quick X-ray snapshots (fluoroscopy) to see if the dye stays in the bladder during filling and voiding or if it escapes to the kidney.

When reflux is present, it is graded 1 through 5. Most children who have reflux have grades 1 through 3 and most of these resolve in the first few years of life.

The main goal of treatment is prevention of urinary tract infection (UTI). UTI combined with reflux can cause kidney infections (pyelonephritis) and possibly even kidney damage. If reflux requires surgical treatment, the options include ureteral reimplantation or cystoscopic injection of a material into the ureteral orifice. The success rate of ureteral reimplantation is in the range of 98 percent in most cases. The ureter is brought further into the bladder. This allows the ureter to become compressed during bladder filling, which prevents reflux. Success for the bladder injections can range from 50 to 85 percent with the more severe grades of reflux having the lower rates of success.

Ureterovesical junction obstruction (UVJ)
If there is a blockage where the ureter enters the bladder, it is called a UVJ obstruction. The ureter can get quite large and is called a megaureter. However, not all dilated ureters are obstructed and the hydronephrosis from UVJ obstruction will often improve with time. The same tests used for diagnosing UPJ obstruction, namely MAG-3 lasix washout renal scan, IVP, and MRI, can be used to diagnose UVJ obstruction. If a UVJ obstruction exists, it is often due to a segment of poorly peristalsing ureter near the bladder. In addition to removing the obstructed segment, the ureter needs to be tapered or narrowed to fit properly into the bladder.

Ureterocele
A ureterocele is a cyst-like enlargement of the ureter in the bladder. It is typically found when there are two ureters draining a kidney. When a ureterocele is present, it is associated with the upper ureter. It causes obstruction of varying degrees in the upper portion of the kidney and has varying levels of function. The ureterocele rarely can block the bladder outlet and prevent urine from exiting the fetal bladder. The ureterocele is also associated with reflux in nearly half of all cases.

The choices for treatment of a ureterocele are numerous and need to be individualized to each child, depending on the presence of reflux, function of the kidney's upper pole, size of the ureterocele, and degree of hydroneprhosis. Treatment options include cystoscopy and puncture of the ureterocele; upper pole nephrectomy; resection of the ureterocele and ureteral reimplantation; connecting the upper pole ureter to the lower pole ureter; and observation. Some of these procedures are appropriate for the newborn and some are best done at an older age.

Ectopic ureter
An ectopic ureter is one that drains somewhere other than the bladder. Like ureteroceles, ectopic ureters are usually associated with kidneys that have two ureters and involves the upper pole ureter. These ureters can be quite dilated. In girls, ectopic ureters cause continuous incontinence. As with ureteroceles, the evaluation of ectopic ureters requires a combination of postnatal ultrasounds, VCUG, nuclear renal scan, and MRI. If no function is seen in the upper pole of the kidney, an upper pole nephrectomy is performed. If function is seen, the ectopic ureter (along with the lower pole ureter) is reimplanted into the bladder. Another option is connecting the upper pole ureter to the non-obstructed lower pole ureter.

Posterior urethral valves
Posterior urethral valves (PUV) can be the most severe urologic condition seen in the fetus. The valves are abnormal leaflets at the beginning of the urethra and can partially or completely block the flow of urine out of the bladder. PUV can cause from mild to moderate to severe hydronephrosis in one or both kidneys. The hydronephrosis can be so pronounced that there is the chance of significant renal damage. Other times, one kidney can bear the brunt of most of the hydronephrosis and the other kidney is spared and will function normally. Fortunately, in most cases both kidneys have reasonable function.

Of great significance with PUV is the amount of amniotic fluid around the fetus. This fluid is composed almost totally of urine that leaves the fetal bladder. Without this fluid, the fetal chest is compressed and the lungs do not develop properly. Uncommonly, a fetus is found to have PUV, severe hydronephrosis, and oligohydramnios (reduced amount of amniotic fluid). It is in this concerning, although unusual, situation that a fetal procedure is considered. The procedure most often performed is placement of a stent, or tube, that drains urine from the obstructed urinary bladder into the amniotic space. This has the dual benefit of relieving the pressure on the bladder and kidney and also restoring the amniotic fluid to a normal volume. The stent is introduced via needle and a wire similar to the way an angioplasty stent might be delivered to a heart artery.

After delivery, in all cases of PUV a sonogram of the kidneys and bladder and a VCUG is obtained. A urethral catheter is inserted to drain the bladder. The child is monitored closely and lab tests are drawn to measure the kidney function. Shortly after the baby is born cystoscopy is performed, whereby a telescope is used to look inside the urethra and burn away the urethral valves. It is especially important a child with PUV be delivered and cared for in a medical center that has all of the pediatric specialties (i.e. Anesthesia, Neonatology/ICU, Pediatric Urology, Pediatric Nephrology, etc.) necessary to take care of this condition. The child may need no future procedures whatsoever or possibly other procedures based on the presence of reflux and kidney function.

Prune belly syndrome
Prune belly syndrome (PBS) is rare and is classically described as a male child with three main findings: a wrinkled abdominal wall due to insufficient abdominal wall muscles; testes found in the abdomen; and abnormalities of the urinary tract. It is the last finding that can be seen on the obstetrical ultrasound and alert the physician to the diagnosis of PBS. The obstetrical ultrasound may show evidence of an enlarged prostatic urethra, an enlarged bladder and hydronephrosis. These urinary tract findings can look like posterior urethral valves. At times the obstetrical ultrasound may demonstrate bilateral undescended testes. A small group of PBS patients may have an obstruction in the middle of the urethra (megalourethra). Oligohydramnios (deficiency in amniotic fluid) can be present and can lead to poor lung development.

Since many other anomalies can be associated with PBS, it is again critically important for the child to be in a major pediatric center with specialists from Anesthesia, Neonatology/ICU, Pediatric Urology, Pediatric Nephrology, Cardiology and Pulmonology available. Even prior to the urologist's evaluation, the child must be examined for possible abnormalities in the heart, lungs and bones.

The baby is then evaluated with an ultrasound. The ureters are often more severely dilated than the kidneys. Nevertheless, the kidneys can be so hydronephrotic and function so poorly as to ultimately require dialysis. But the majority of PBS patients do not require dialysis. A VCUG will assess for reflux which is quite prevalent in PBS.

Treatment options are debated as to how aggressively to tailor the enlarged bladder, but there is general agreement that the baby will need surgical procedures to bring the testes into the scrotum; to correct the ureteral reflux; and to reconstruct the abdominal wall. None of these procedures are necessary immediately after birth.

Multicystic dysplastic kidney (MCDK)
Multicystic dysplastic kidney (MCDK) describes a kidney that has been replaced by cysts. This should not be confused with polycystic kidney disease (PCKD) in which both kidneys are ultimately replaced by cysts and kidney function progressively deteriorates. In MCDK, the other kidney usually functions well and the child is able to lead a perfectly normal life (with perhaps some minor limits on high-speed activities, i.e. skiing etc).

During pregnancy, the ultrasound is quite reliable in distinguishing the MCDK from hydronephrosis. After birth a sonogram will confirm the MCDK. In cases where the diagnosis is in doubt, a nuclear renal scan is obtained. A VCUG is performed to rule out the possibility of reflux.

There is debate as to whether a MCDK requires removal and how often sonograms need to be repeated, but studies have shown that many MCDKs will shrink with time. Even if the MCDK needs to be removed, it is rarely required in the newborn period.