What is PUV?

This may be quite a long post...

It was quickly confirmed that Posterior Urethral Valve was the diagnosis, so what does PUV mean?   Well to understand the pathology of the urinary tract it is probably easiest to first go through normal urinary anatomy (it helps to look at the figure at the top of the page).

Normal:
Fetal kidneys (which make urine after birth) are responsible for making the amniotic fluid in the womb.  The kidneys send the fluid down the ureters into the bladder, and then the bladder sends the fluid out through the urethra (penis).  The amniotic fluid surrounds the fetus and allows for fetal support, but also stimulates lung development by swallowing  (yes, the baby essentially swallows his own pee!).  At birth the kidneys obviously become responsible for removal of waste products and fluid regulation.

PUV:
Basically an abnormal tissue formation is acting like a one-way valve in the baby's urethra, which is causing the obstruction. This leads to several consequences, but it can basically be divided into two broad catagories: everything that happens anatomically distal (after) the obstruction and everything that happens anatomically proximal (before) the obstruction.

Distal problems:
The major problem is oligohydraminos, which is a 5 dollar word to describe low amniotic fluid.  The obstruction prevents amniotic fluid from escaping the urethra so immediately the baby is much more compressed while in the uterus.  This causes minor/major phyiscal abnormalities that include club feet, smushed up facies and even dislocated shoulders.  If you can imagine being covered in shrink wrap without the ability to maneuver to change positions, that is what Owen was going through, and he was in the same position for at least 20 weeks of the pregnancy. 

With all that said, Owen luckily only has some slight leg malformations.  They tend to curve in and his feet  (especially his toes) interlock monkey style, but physical therapy is already meeting with him 3 times a week to help straighten everything out.   The major problem with oligohydraminos is lung hypoplasia, or underdevelopment of the lungs (remember, swallowing amniotic fluid stimulates lung development).  This is by far, the most severe consequence of PUV and is the major reason PUV babies do not survive upon birth. If surgical intervention had not been performed on Owen there is good reason to believe he would not have survived the first few hours of birth and it is because of this lung issue.



Proximal problems:
Since the fluid can't get out the urethra, the fluid and pressure has to go somewhere, so everything abnormally moves back up to where it originated.  Beginning with the bladder, fluid fills up to a point where the bladder becomes much larger than average size.  The bladder is made out of muscle and just like any muscle that is stressed (bicep, heart, etc), the muscle compensates by getting larger (AKA hypertrophy).  So the bladder wall is thickened which may lead to more long term (but not emergent) issues like inability to urinate without the aid of catheter or leaking periodically throughout the day.  The bladder problems may be life long but we really won't know for a few years.  Moving further back, the ureters are dilated which compromises the drainage of the kidneys into the bladder. One of Owen's surgeries during his first week of life actully worked to relieve pressure off his ureters to see if they will work again.  Finally the kidneys are the final resting place for the pressure and fluid leading to a condition caused hydronephrosis. This basically means the kidneys are much larger than they should be due to such a high accumulation of fluid.  This results in kidney damage, and if left unrelieved long enough, end stage renal disease/kidney failure.  Unfortunately, it appears that although Owen avoided the dreadly lung hypoplasia , he couldn't escape the damage inflicted to both his kidneys.  As this point, the only true curative treatment for Owen's kidneys is a physical transplant, which we will described more later.

Overall PUV is something that randomly occurs in about 1/8000 live births. It happens in males only and the severity flucuates depending on the case.  Clinically, symptoms may range anywhere from never being diagnosed due to being asymptomatic, to death within a few hours after birth due to inadequate lungs.  Obviously, Owen is on the more severe end, but we thank God everyday for the lungs he is more than blessed to have!