Ureteral Obstruction

Ureters can obstruct anywhere along the entire tube. When it occurs at the level where it leaves the kidney, it is called a ureteropelvic junction obstruction (UPJO). It can also occur at the level of the bladder and is called a ureterovesical junction obstruction (UVJO). When the narrowing occurs anywhere in-between, it is referred to as a ureteral stricture and described as being proximal (higher up and closer to the kidney), mid ureteral or distal (closer to the bladder).

UPJ Obstruction

A baby may be suspected of having a UPJ obstruction if hydronephrosis or dilation of the kidney is noted on prenatal ultrasounds. After the baby is born, they are often placed on antibiotic prophylaxis and will have an ultrasound and voiding cystourethrogram completed (VCUG). A nuclear medicine renal scan called a MAG 3 lasix renogram is often performed after a month. This will give further information about the function and degree of obstruction of the kidney. The degree of obstruction, relative function and ultrasound appearance are taken into account when deciding what the child needs. This can range from observation for less dilated kidneys with good function to surgery if the surgeon feels the kidney is at risk of losing function or already has diminished function.

Beyond infancy, there are a variety of presentations of UPJ obstruction. A child may have blood in the urine, noted after a very minor trauma, or a large dilated kidney is identified during evaluation of the abdomen or urinary tract for other reasons. A child may present with intermittent recurrent side pain associated with nausea and vomiting. Imaging studies are done to confirm the diagnosis, and the patient often undergoes a correction of this obstruction. The obstruction can be from various causes, including what is called an adynamic segment of the ureter, a polyp, a narrowing or stricture, kinking of the ureter or blockage from a vessel crossing over the ureter, etc.

The most common surgical technique used to treat UPJ obstruction in children is a dismembered pyeloplasty where the obstruction is cut out, and the two healthy ends of the ureter are brought together. Surgery can be done open, laparoscopically or robotically.

UVJ Obstruction

The distal or lower end of the ureter may be narrowed where it enters the bladder. This can also be diagnosed prenatally when the ureter is dilated enough to be seen on ultrasound. If so, the baby is placed on antibiotic prophylaxis and evaluated with an ultrasound and voiding cystourethrogram (VCUG). Depending on the situation, further studies with a nuclear medicine renal scan and/or MRI may be needed. Older children may present with pain, urinary tract infection or the dilation may be found incidentally.

If the patient has symptoms, experiencing recurrent infections or the kidney function is deteriorating, surgery is performed. Depending on the patient's age and the acuity of the situation, a temporary diversion may be done by a tube draining the kidney (nephrostomy tube) or by bringing the ureter to the skin (ureterostomy). These temporizing measures will be reversed when a more definitive surgery to relieve the obstruction is performed. Surgical options may include a reimplant of the ureter or involve connecting the obstructed ureter to the unobstructed ureter in the case of a duplicated collecting system. The child is followed closely with ultrasounds to ensure proper healing and relief of the obstruction.

Ureteral stricture

Ureteral strictures (narrowing) can be secondary to injury from previous instrumentation of the ureter or during surgery in the abdomen or pelvis, recurrent infections, polyps, or they can have no identifiable cause (idiopathic). The child is evaluated with an ultrasound, sometimes a VCUG, and often a nuclear medicine renal scan. Imaging to evaluate the length and degree of the narrowing, such as an MR Urogram (a special type of MRI), may also be done. In many circumstances, the patient is taken to the OR and placed under an anesthetic to get a more accurate visualization of the stricture by injecting X-ray dye backward into the ureter tube while taking periodic X-ray pictures. These images are called retrograde pyelograms.

Surgical management is dependent on the length, thickness and underlying cause of the stricture. Shorter thin strictures may be managed with a small scope with a laser or balloon dilation. Longer or thicker strictures may be managed with excising the narrow unhealthy portion and reattaching the two healthy ends of the ureter. If the gap between the ureteral ends is long, various techniques are applied to bridge that gap, including mobilizing the bladder, creating bladder flaps, mobilizing the kidney and, rarely, placing a piece of bowel in-between to replace the ureter. If the stricture lies in the more distal part of the ureter closer to the bladder, the stricture along with the remainder of the ureter into the bladder is discarded, and the ureter is reimplanted into the bladder. Stents are placed inside the ureter, and sometimes drains are left temporarily while healing occurs. Follow up usually involves removal of the stent and serial ultrasounds to ensure narrowing does not reoccur.

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