In this sense, more does not mean better. Sometimes a child's kidney (while he is still in his mother's tummy) does not properly form a kidney. It doubles up. Most often, this kidney looks like a normal kidney, but not one, but two ureters come out of it. Less often, a child has three separate kidneys at once, similar to each other.
Some kind of kidney duplication can be found in about one in 500 people. It may seem to some that this is a profitable purchase. In fact, it is rather bad.
The fact is that two normal ureters are arranged in such a way that they pass urine into the bladder, but do not let it back in. To do this, the ureters contract in waves (like the intestine) and are stuck into the bladder in specially designated places. There are valves that keep urine from the bladder back into the ureter.
If an extra ureter leaves the kidney, there is usually no suitable place for it on the bladder. The poor have nowhere to land. It sticks into the first spot on the bladder, and this can lead to problems.
Well, this is about the same as with artisanally connected electrical wiring, nothing may happen, or it may catch on fire.
Sometimes such a misplaced ureter cannot push urine into the bladder and inflates like a balloon. The kidney also swells up and suffers from this.
Sometimes the ureter, on the contrary, is so successfully inserted into the bladder that urine flows freely back and forth. Because there is no valve. With this connection, an infection can pass from the bladder into the kidney. Well, such a ureter can also swell.
In short, there is nothing good in an extra kidney.
