before birth, but should be followed by serial ultrasound. All single-sided lesions, even those where the kidney is destroyed (dysplasia), can be successfully managed after birth. Fetuses with mild partial obstruction to both kidneys who do not have cysts in their kidneys or abnormal urine electrolytes and maintain their amniotic fluid volume can also be successfully managed after birth. It is important to follow these fetuses with serial ultrasound to make sure they maintain enough amniotic fluid volume for lung development and do not develop signs of kidney damage.
This is a good time to plan the time, type, and place of delivery. Although most babies will require some surgery after birth, it is usually not urgent. Most babies will not require intensive care and can be evaluated in the nursery or even later after they have left the hospital. However, fetuses with urinary tract obstruction that develop very dilated kidneys and have any degree of oligohydramnios and any risk of small lungs should be delivered in a specialized center with an intensive care nursery.
In cases where the urinary obstruction affects both kidneys and there is low or absent amniotic fluid, a careful and thorough evaluation is necessary because fetal intervention may be an option.
For more information about our guidelines for fetal intervention for urinary obstruction you can download our pdf brochure for urinary obstruction fetal intervention.
Prior to fetal intervention, it is essential to determine that the kidneys have not suffered damage that would make normal function impossible. There are two ways that kidneys can be assessed. The first is by ultrasound evaluation. The radiologist can determine on an ultrasound whether or not the kidney tissue looks normal. The presence of cysts or echogenic (bright white) tissue is usually not a favorable sign.
The second method of determining kidney function in a fetus is by taking a sample of fetal urine and analyzing the electrolytes and protein levels. This procedure is done exactly like an amniocentesis. A needle is placed through the mother’s abdomen and into the fetus’s bladder. A fetal urine sample is taken, the fetal bladder is completely drained of urine, and the urine sample is sent for testing. Determination of normal karyotype (chromosomes) can also be done on this urine sample of the fetus. This procedure should be repeated in 24 to 48 hours and the fetal urine should again be sent for electrolytes and protein. It may be necessary to take a third urine sample in another 24-48 hours. A fetal urine sample is taken three times in order to get the most accurate assessment of kidney function, as the first sample has been in the bladder for a long time and may not give the best information. The second sample may be urine which had been in the kidneys for a prolonged period of time and drained into the bladder after the first bladder tap. The results of the analysis on the third sample enable the medical team to give the most accurate prognosis and recommendations for treatment. Only fetuses with bilateral (both kidneys) urinary obstruction and evidence of good kidney function by ultrasound and electrolyte and protein levels are candidates for fetal intervention.
Fetuses with bilateral obstructions (usually males with posterior urethral valves) who lose amniotic fluid volume and develop signs of renal compromise before 24 weeks, require intensive management before and after birth.
The most severe cases have evidence of progressive renal failure. The kidneys show cysts or increased “brightness” (echogenicity), urine electrolytes are abnormal, and amniotic fluid may decrease or disappear. These fetuses may require decompression, relief of the obstruction, before birth.
The goal of fetal intervention is to allow the urine to get past the obstruction and exit the fetus into the amniotic fluid. Restoring the normal flow of urine into the amniotic fluid will allow the lungs to grow and the kidneys to develop. Fetal intervention for urinary obstruction has improved dramatically over the past 25 years. The first fetal intervention for urinary obstruction involved open fetal surgery (an incision in the uterus to expose the fetus) and placement of a vesicostomy. A vesicostomy is an opening in the lower fetal abdomen that directly goes into the fetal bladder. The urine is able to exit the fetus through this opening and drain into the amniotic fluid. This method of treatment was successful, but the women who underwent this procedure experienced preterm labor from the incision made in the uterus. Then, a less invasive means of intervention was developed. This involved the placement of a specially designed tube, the Harrison Catheter, into the fetal bladder. The procedure is similar to an amniocentesis. A small hollow needle is placed through the mother’s abdomen into the fetal bladder, using the sonogram for visualization. One end of the tube is in the fetal bladder and the other end in the amniotic fluid. Urine escapes the fetal bladder through the tube. The problem with these catheters is that they can become plugged or dislodged, sometimes requiring repeated procedures. This technique has proven effect and has been used thousands of times around the world with good success. However, it is difficult to keep these little tubes in place and functioning for extended periods of time.
More recently, we have developed a technique (FETENDO fetal surgery) to directly relieve the obstruction at the bladder outlet by putting a very small (3-mm) fetoscope directly into the fetal bladder and disrupting the valves, opening the obstruction. This can now be done through a very small scope placed through a nick in the mother’s skin rather than through open surgery. Relieving fetal urinary tract obstruction has proven very effective in restoring amniotic fluid volume and allowing the fetal lungs to grow. It is not yet proven that relieving the obstruction before birth will always preserve renal function and prevent long-term renal failure.
We recommend that after consulting with your primary physician, your newborn be started on Amoxicillin, an antibiotic, immediately after birth. This will prevent any infection of the urinary tract. No testing is recommended until the baby is one month of age and the kidney function has matured. At this time, we would recommend a renal (kidney) ultrasound and a Diuretic Renal Scan, and an appointment with a surgeon for consultation. Both of these tests will help evaluate the anatomy and function of the kidneys.
On occasion, the surgeon will request a third test, called a “Voiding Cystourethrogram” or VCUG, to examine the urinary system for reflux (or back up) of urine from the bladder into the kidneys. Based on the results of these studies, the surgeon will be able to identify the specific renal abnormality, assess the health of the kidney(s), and make recommendations for the treatment of your baby’s condition. The recommendations for treatment range from periodic testing to operation intervention.
Baby Sarah Elizabeth has a very successful recovery from an SCT which is removed while she is still a fetus.