Duplicative kidney and ureteral malformation
Duplicativekideny, refers to the normal kidney area with two kidneys and two sets of collecting system, referred to as heavy kidney, specifically refers to the extra development of that kidney (upper kidney). Clinically, it is more common in 2~5 years old, more in girls than boys, more on the left side than on the right side, and about 5% in bilateral cases.
I. Etiology and embryo
In the fourth week of embryonic life, the lower end of the middle renal tube bends toward the cloaca and protrudes toward the back of a small blind tube called ureteral bud, which grows rapidly and will form a ureter at the proximal end, and the distal end is encapsulated by a block of kidney tissue, resembling a fava bean, and develops into a renal pelvis, calyces and collecting ducts, and if the distal end of the ureteral bud branches out into two branches during this process, a duplicate renal pelvis is formed. If the branching is premature, an incomplete double ureter is formed. During the development, if another ureteral bud is issued at the lower end of the middle renal tube and rises side by side with the normal ureter, a complete double ureteral malformation occurs. And the distal primitive kidney tissue block forms two kidneys.
II. Pathology
The duplicated kidneys are one in appearance and co-located within one renal tegument. There are three types of duplicated kidney pathology: type A is the developmental type; type B is the hydronephrosis type, which resembles the changes of pediatric hydronephrosis with obstruction below, often combined with ureteral cysts; type C is the dysplasia type, which is often combined with ectopic ureteral opening. The two ureters of the duplicated kidney are in the same sheath, and the innervating vessels are one, and occasionally the two ureters do not go far down to merge into one, called Y-shaped ureters. The blood supply to both kidneys originates from one renal tip. The main blood vessel enters the lower kidney, and those who enter the upper kidney are few, and they are secondary and tertiary branches, and those who send blood vessels directly from the nephron tip into the upper kidney are rare.
Diagnosis
(A) Clinical manifestations
1, urinary tract infection: characterized by intermittent, recurrent urinary tract infection, caused by poor urinary flow in the heavy kidney and bacterial multiplication.
2, urinary dripping: due to ectopic opening, the degree of urinary dripping is proportional to the function of the upper kidney, good kidney function, heavy dripping. This kind of urinary dripping is characterized by normal urination of the child and urinary dripping in between urination.
3. Difficulty in urination: It is caused by obstruction of the urethral orifice due to a large ureteral cyst, and in a few cases, the cyst that comes out of the urethral orifice is seen during perineal examination.
4. abdominal mass: it is a heavy kidney and ureteral fluid accumulation, and after reaching a certain degree, the mass can be palpated clinically, and the mass is in the lateral abdomen and becomes cystic.
(II) Laboratory tests
1. Ultrasonography is the preferred method, and the diagnosis can be confirmed when two collecting systems are seen in the renal area, i.e., double renal pelvis images. When the duplicated ureter is dilated with a diameter greater than 1, 5 cm, ultrasound can show its course, and the ureter goes down behind the bladder and does not enter the bladder, the opening ectopic diagnosis should be thought of, and for most ureteral cysts, ultrasound can show it. The two images mentioned above can be used as an auxiliary evidence for the diagnosis of heavy kidney.
2, IVP shows double renal pelvis and double ureteral images, then the diagnosis can be confirmed, but such images are not common, accounting for only about 1/4, and most heavy kidneys do not show images. At this time, it is helpful to diagnose heavy kidney based on the change of the lower kidney image: (1) the number of calyces is less than 3, and the renal pelvis is compressed; (2) the kidney is displaced outward and downward; (3) the kidney has a transposition of the renal axis; (4) a cystic shadow is seen in the bladder. The diagnosis rate of heavy kidney is improved.
3, nuclear examination is now commonly used SPECT examination, which is highly sensitive. As long as about 5% of the heavy kidney remains functional. The drug can enter the heavy kidney, and the instrument can identify the kidney shape, size, etc.
IV. Treatment
According to the type of heavy kidney, the treatment is decided, developmental type of heavy kidney does not need treatment, when there is urinary tract infection, drugs can be controlled, B, C two types of heavy kidney, infection often occurs, drugs can not be controlled, most of the surgical treatment, surgery will be heavy kidney, repeat ureteral resection, the operation is careful not to damage the lower kidney and its ureter, reduce intraoperative bleeding common methods.
(1) finding the innervated heavy kidney vessels and cutting them off close to the renal parenchyma.
(2) Resection of the heavy kidney by blocking the renal tip with a cardiac ear clamp.
(3) Freeing the heavy kidney should be done gently to reduce renal tip tension, and the ureter of the heavy kidney is usually found first and cut off at the level of the lower pole of the kidney to fully expose the upper kidney.
Repeat ureter treatment: it should be freed close to the wall of the repeat ureter, leaving the blood flow to the lower renal ureter as much as possible to avoid damaging its blood flow, and for the thick ureter it can be freed in sections.
Treatment of ureteral cysts: cysts that are too large can be excised via the bladder, with the base retained at 0,5 cm to avoid damaging the ureteral opening of the lower kidney; for small cysts, they should be left untreated for the time being, and the repeated ureter should be cut off horizontally near the bladder for a year after, and before the ligation of the ureteral stump, a silicone tube should be placed inward to reach deeply into the cyst, and the fluid should be sucked out under negative pressure, and the cyst should be atrophied; for cysts that come out of the external urethral opening and are combined with obstruction, cyst deprogramming can be used.
V. Prognosis
The treatment effect of this malformation is relatively satisfactory, the urinary gonorrhea disappears immediately after the operation, the symptoms of urinary tract infection are quickly controlled, the child can urinate freely, and the growth and development are not affected.