Abnormalities of the ureteral orifice
Here a cystic dilatation (ureterocele) of the intramural part of the ureters, due to a stenosis of the ureteral orifice of the bladder, is involved.
This has to do with a backflow of urine into the kidneys, before and during miction (urination) due to a missing anti-reflux mechanism at the junction where the ureter empties into the bladder. This disorder is normally congenital, can be associated with other abnormalities (doubling, megaloureter) and is seen relatively frequently (8 time more frequent in girls).
Normally, the uretero-vesical junction functions as a sphincter and urine can only flow out through the urethra. However, the urine can also flow back to the kidneys via the ureters as a result of a change of the vesico-ureteral junction, when the intravesical pressure is elevated. This leads to frequent urinary tract infections that, by the way, should be a diagnostic hint that a vesico-ureteral reflux may be present.
Ectopia of the ureteral orifice
In this case, the ureteral orifice finds itself outside the bladder. In 80% of the cases the ectopia is associated with a doubling of the ureter. In a man, the orifice into the urethra of the ectopic ureter can lie below or into the seminal vesicle while in a woman, it can be at the level of the uterine cervix, the vagina or the vaginal vestibule.
Exstrophy of the bladder
This severe disease occurs in 1/10'000 births and mainly affects males. A median termination disorder of the abdominal wall below the navel is involved, which is caused by an absent migration of the mesoderm between the ectoderm and the cloaca during the 4th week of development. Since the musculature and connective tissue are not present, the anterior wall of the bladder (endoderm) is covered by only a thin layer of skin (ectoderm). This bilaminar wall disintegrates (as, by the way, all double-layered membranes do!) and the back wall of the bladder becomes visible.
This abnormality is associated with an (upwardly [ventrally] open urethral canal in the penile region) and a gap in the pubic bone. One also finds other abnormalities such as bilateral hernias, ectopia of the testes and an absent perforation of the anus. The surgical correction is very difficult but necessary in every instance.