Obstructive Genitourinary Defect
Obstructive genitourinary defects are congenital narrowing or absence of urinary tract structures at any level of the system. These conditions are the most common congenital defect of any organ system. The severity of the problems for the child depends on the degree and level of the obstruction. There are a number of kinds of obstructions, depending on the location and severity. For example, the most common type of obstruction is at the uteropelvic junction (UPJ), an obstruction that occurs between the ureter and the kidney at the place they join. Urine does not easily pass through the ureter and consequently it backs up through the renal system. The second most common obstruction is where the ureter enters the back wall of the bladder, the ureterovesicular junction (UVJ). UVJ obstruction, which usually involves only one kidney, will result in backflow and enlargement of the ureter (called megaureter).
Any type of urinary tract obstruction will interfere with normal fetal development, and the degree of damage depends on the severity of the obstruction. The spectrum of fetal injury depends on the type, degree and duration of the obstruction. In unborn babies with high-grade obstruction, urine output is decreased, leading to lack of amniotic fluid (called oligohydramnios). The lungs also will not develop properly due to the lack of amniotic fluid. In fetuses with posterior urethral valve obstruction, the most common cause of fetal obstructive uropathy, nearly 30% will develop renal failure by childhood.
A far less serious kind of obstruction in the urinary system is called phimosis, which is congenital or acquired (inflammatory) constriction of the foreskin, which then cannot be retracted. Paraphimosis is a term describing inability of the foreskin to be retracted.
Finally, another obstruction affects the valves between the urethra and the bladder, which can also be a site of obstruction (posterior urethral valves). Obstruction of urine flow between the bladder and the urethra may be severe and may lead to bladder malfunction, pressure build-up in the renal system, and kidney damage.
This group of common birth defect occurs in around 1 in 350 babies, and the prevalence appears to be modestly increasing. If the obstruction is in both kidneys (bilateral UPJ) the outlook is poor because hydronephrosis in typically severe. These conditions do run in families, indicating some degree of genetic cause, though the actual cause is unknown.
Common Associated Conditions
Symptoms include recurrent urinary tract infections and may also include impaired growth. Hydronephrosis, which is kidney damage, is a frequent result of an obstruction in the urinary system.
Short-term Treatment and Outcomes
Obstructive defects of the renal pelvis (within the kidney itself) can sometimes be detected on ultrasounds during pregnancy. Once the baby is born, renal ultrasound is needed to confirm the extent of the obstruction. It is important to correct this problem by relieving the obstruction as soon as possible to maximize normal kidney function. The blockage in the urinary drainage system is surgically corrected. Back-flow of urine in the system is diagnosed using a test called a voiding cystourethrography (VCUG). A scope can also be inserted into the urethra and into the bladder and ureters.
Phimosis or paraphimosis is easily corrected with circumcision. When either condition is present, the result of surgery is excellent.
Long-term Treatment and Outcomes
Long-term follow-up with a urologist and/or nephrologist (if there is kidney damage) will be very important so that any complications can be detected promptly and treated. High blood pressure is always a concern with any urinary tract disorder, and that can affect many body systems as well as do ongoing damage to the kidneys.
Any obstruction in the renal system will cause urinary stasis that may result in impaired renal function (hydronephrosis), infection and calculus formation (kidney stones, also called renal calculi).
Sexual disability or infertility can result, especially in males. Possible complications of surgery include infection and trauma to structures of the urinary system.
Implications for Children's Development
Children may have multiple surgeries and invasive tests that can be uncomfortable and frightening. Their fears and anxieties must be acknowledged and they need family and professional support. Their growth needs to be monitored regularly since the kidneys produce chemicals that stimulate growth and this can be affected if the kidneys are damaged.
Children should be taught simple information about their condition and treatment, using terms that they can understand. Books and dolls can help children understand how their bodies work. They should be encouraged to ask questions about their bodies and the treatments and tests. Children do not need a great deal of detailed information but rather they require reassurance and explanations that are tailored to their age and understanding.
They need to be helped to understand that blood tests and uncomfortable procedures are necessary to help them feel better, even though they experience temporary pain or discomfort. Play therapy can assist young children to express their fears and feelings and can reveal misunderstandings they may have about their condition or treatment. Reliable information and support resources for parents is available online.
- National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC)