Ureteral obstruction

Introduction Obstruction of the ureteropelvic junction is a common urinary tract obstruction that causes hydronephrosis. Because the obstruction of the ureteropelvic junction obstructs the smooth discharge of renal pelvis into the ureter, the renal pelvis emptying disorder causes the renal system to expand. At first, the smooth muscle of the renal pelvis gradually proliferates, strengthens the peristalsis, and attempts to discharge the urine through the distal obstruction; when the increasing amount of creeping power cannot overcome the obstruction, it will lead to atrophy of the renal parenchyma and impaired renal function.

Cause

Despite in-depth research in different aspects of embryology, anatomy, and histology, the exact cause of UPJO is not yet clear. There are many causes of UPJO. The causes of UPJO can be classified into three categories by visual observation and light microscopy.

1. Intrinsic factors of the lumen: The internal factors in the lumen are mainly UPJ stenosis, valve, polyp and high ureteral opening. Among them, stenosis is a common cause of UPJ obstruction (accounting for 87.2%), mainly manifested as muscle hypertrophy and fibrous tissue hyperplasia at UPJ. The stenosis segment is generally about 2 cm long and has a section diameter of only 1 to 2 mm, often accompanied by a high ureteral opening. The UPJ valve is a congenital fold that can contain muscle. Polyps are mostly sunflower-like.

2. External factors of the lumen: The most common cause is the vagus or accessory blood vessels from the renal artery or the abdominal aorta supplying the inferior pole of the kidney, which is pressed across the UPJ and causes the ureter or renal pelvis to hang above the blood vessel. In addition, there are fiber ropes that are pressed or stuck, causing the UPJ to twist or stick.

3. Functional obstruction: manifested as dynamic dysfunction at UPJ. It is characterized by no obvious intraluminal stenosis and extraluminal compression factors in UPJ. The ureteral catheter can pass smoothly during retrograde urography, but there is obvious hydronephrosis.

an examination

Related inspection

Renal CT examination of adrenal MRI, pyelography, renal MRI, intravenous urography

1. Ultrasonic examination: The B-ultrasound examination method is simple and non-invasive, and the diagnosis is clear. It is the preferred method of examination. B-ultrasound can be used to index hydronephrosis, and the initial diagnosis of the obstruction site and the nature of the lesion are of great significance for estimating the reversibility of renal function. Doppler ultrasound reflects changes in renal blood flow through the spectrum of intra-arterial arteriovenous blood flow. Measurement of the resistance index (RI) can help identify obstructive and non-obstructive hydronephrosis. B-ultrasound is more superior in the examination of fetal urinary tract obstruction. Prenatal B-ultrasound can make an early diagnosis of congenital hydronephrosis.

2. X-ray examination: Abdominal plain film examination can understand the size of the kidney outline, and the X-ray positive stones can be clearly diagnosed. In the case of excretory urography, if the hydronephrosis or the proximal urinary tract can be developed, the obstruction site and renal function can be judged, especially the judgment of the function of the kidney. For those who do not develop IVU and are unable to perform retrograde pyelography, percutaneous nephrolithoscopic angiography can be performed [can be replaced by magnetic resonance urography (MRU)].

3. Dynamic imaging examination: The diuretic kidney map is helpful for clearing early lesions and judging whether mild hydronephrosis requires surgical treatment, especially when the bilateral hydronephrosis is light on one side and heavy on one side, and it is light on hydronephrosis. Whether the side surgery is decisive.

In recent years, the application of diuretic IVU monitored by diuretic B-ultrasound and synchronous TV video has a considerable effect on the identification of obstructive and non-obstructive hydronephrosis and diuretic kidney map.

4. Magnetic Resonance Imaging (MRI): MRI has been widely used in the diagnosis of urinary obstructive diseases in recent years. In particular, MR urography (MRU) is helpful for the location and qualitative diagnosis of obstruction, and its image is similar to urography. Because MRU does not need to use iodine-containing contrast agent and intubation technology to show urinary tract conditions, patients are safe, non-invasive, and without complications, especially when there is severe renal damage and urinary tract obstruction.

5. Renal sputum pressure test: Two catheters were placed respectively to the renal pelvis and bladder, and the contrast agent was injected through the percutaneous nephrostomy tube at a rate of 10 ml/s, and the intra-renal pressure changes during the perfusion of the contrast agent were recorded under a fluorescent screen. The pressure difference between the renal pelvis and the bladder was measured as an indicator of renal obstruction. For example, if the renal pelvic pressure is >1.37 kPa (1410 cmH2O), there is an obstruction. This method is helpful for judging whether there is obstruction in the ureteropelvic junction, but it is more complicated and traumatic, and it is less clinically applicable.

Differential diagnosis

Ureteral stenosis: refers to the ureteral lumen or the whole segment is narrower than normal due to various reasons. Although the continuity of the lumen is not interrupted, it has caused different degrees of upper urinary tract obstruction and hydronephrosis. Back pain, waist swelling and urinary, abdominal, pelvic surgery history, should suggest that the disease may be, B-ultrasound can be found in varying degrees of hydronephrosis, excretory urography and retrograde pyelography can help diagnose. If necessary, pyelography or retrograde angiography can clearly identify the location, extent, and length of the obstruction.

Ureteral cyst: is a cystic dilatation of the end of the ureter. During the embryonic development, the septum between the ureter and the urogenital sinus does not absorb and resolve, forming different degrees of stenosis of the ureteral orifice, or the fibrous structure at the end of the ureter is weak or the path between the wall is too long, and the curve is caused by the urinary flow. After the formation of a cystic dilation into the bladder. Early cases are clinically asymptomatic and are often found in the diagnosis of severe renal deformities. Symptoms are mainly urinary tract obstruction, causing repeated urinary tract infections. Due to the small opening of the cyst, persistent obstruction of the ureteral orifice can lead to ureter and hydronephrosis, loss of renal function, cystic occlusion of the bladder neck, dysuria or interruption of urinary flow, and recurrent urinary tract infection. Sometimes girls cysts can be removed from the urethra through the bladder neck and urethra, and can usually be reset by themselves.

Transurethral spinal hypertrophy: one of the clinical manifestations of bladder neck contracture. Diagnosing this disease is mainly based on the difficulty of urinating in the medical history. Therefore, the details of dysuria should be asked. When examining the body, pay attention to the presence or absence of mass in the bilateral renal area, palpation and percussion, whether the bladder is bulging. However, the diagnosis of this disease depends on bladder urethra microscopy and X-ray examination.

Deviation of the urinary catheter: One of the "triple signs" of inflammatory abdominal aortic aneurysm, which causes the ureter to shift to the heart due to inflammation and mass. Imaging studies can be diagnosed.

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