- Kidney Outflow Stenosis (Uretero-pelvic Junction stenosis-UP Stenosis)
Blood coming to the kidney is filtered and waste materials are converted into urine and this urine is transferred to the kidney. It is sent to the urinary bladder from the pool in the middle part through the urinary duct (ureter) (renal pelvis). Stenosis at the junction of the pool and the duct is called renal outlet stenosis - UP stenosis. It is the most common congenital defect of the kidney. Inadequate muscle development at the junction is often blamed. However, external factors that put pressure on the junction (such as abnormal vascular structures) may also be the cause. As a result, the kidney swells and enlarges because the urine, which must be sent downwards from the kidney to the urinary bladder through the duct, cannot be discharged easily.
- Symptoms, Findings and Diagnosis
While routine pregnancy monitoring is being done in the womb, it may be noticed that the baby's kidney is enlarged in control ultrasonography. This finding, which can be noticed more easily especially in the last 3 months, has become the most frequently diagnosed condition of renal outflow stenosis today. Of course, there are other diseases such as urinary reflux that cause swelling of the fetal kidney. However, in postnatal examinations performed in babies with enlarged kidneys, taking into account other possibilities, the most common disorder is renal outflow stenosis.
In children that are not noticed before birth, urinary tract infections accompanied by high fever in infancy, bleeding in the urine, and abdominal swelling. Renal outflow stenosis may be suspected. In older ages, abdominal pain, flank pain and frequently recurring urinary tract infections may occur. The risk of kidney stone formation is increased in these patients due to the presence of urine that cannot be easily excreted in the kidney.
In cases of doubt, the first radiological evaluation to be performed is kidney ultrasonography. Depending on the severity of the outlet stenosis, a result of mild, moderate or severe dilatation (hydronephrosis) may be obtained. To understand the severity of stenosis more objectively and to decide what to do in treatment. Renal scintigraphy is required. With the help of images obtained during the passage of a substance administered through the vein through the kidney, information can be obtained about the severity of stenosis, if any, and the function of the kidney.
In cases where there is suspicion of external pressure on the renal outlet (such as vascular compression)
Strong>, Magnetic Resonance Imaging may be useful when the presence of other congenital defects (such as horseshoe kidney) is suspected.
- Treatment
Follow-up can be done in cases of mild or moderate stenosis. Especially if diagnosed in the neonatal period, there is an expectation of improvement in the stenotic area with growth and development. For those to be followed, ultrasonography and scintigraphy are planned to be performed at intervals depending on the severity of the stenosis. Surgical correction is recommended in cases where there is severe renal enlargement and swelling at the time of initial diagnosis, in cases where excretion from the kidney into the canal is extremely prolonged on scintigraphy, and in cases where there is a serious decrease in kidney function. The main purpose of surgery is to widen the kidney outlet and duct junction (pyeloplasty) and to eliminate external pressure, if any. This surgery can be performed by open, laparoscopic or robot-assisted laparoscopic methods. There is another alternative, which is to enter through the urinary tract only with endoscopy and open the narrow section from the inside, but this method is not suitable for every patient.
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