Foetal Urinary Tract Obstruction
What is it?
The primary component of amniotic fluid is the urine excreted by the foetus. Since the amniotic fluid is responsible for lung development, an absence of urine not only causes kidney problems but also stunts lung development. Most commonly, these blockages are caused by a general narrowing in the urinary tract. In severe cases the increased pressure in the liver can also lead to a cyst in the liver. A blockage in a single kidney does not usually require inutero intervention. Before the surgery procedures are initiated, the foetus' kidney function must be carefully monitored. If the kidneys cannot function properly, due to too much initial damage, the results of the surgery will not be as profound because the foetus will remain unable to produce the necessary urine.
To verify the existence on a urinary tract obstruction, detection occurs during an ultrasound. An absence of amniotic fluid is a key indicator, as well as the general appearance of the kidneys. If foetal surgery is deemed appropriate for the foetus the kidney function must be analysed to measure the possible success of the procedure. This is done by inserting a needle through the mother's abdomen and into the bladder of the foetus. Urine is collected in the syringe and analyzed for electrolyte and protein levels. This urine collection and analysis is repeated twice more at twenty-four hour intervals to receive a strong and consistent set of results. If the kidneys are functioning well, foetal surgery becomes an option.
This ultrasound picture shows an elarged kidney
A cyst is visible on the kidney of this foetus
The goal of the foetal intervention is to allow the urine to exit the bladder while bypassing the blockage in the urinary tract. This allows for the re-circulation of the amniotic fluid and therefore induced lung development. Previously, open uterus surgery was required to create a diversion away from the urinary tract via a vesicostomy, but this posed many possible complications including preterm labour. Surgeons, however, have now developed a method that does not involve the opening of the uterus. A catheter is attached to a mesh stent and this is inserted, with a needle, through the abdomen and into the uterus. As the mesh stent reaches the amniotic fluid it expands, allowing for a more stable anchor into the foetus' abdomen. The stent and catheter are then placed into the foetal bladder, allowing for the urine to flow out of the bladder, through the stent, and into the amniotic fluid.
This diagram represents a basic outline
of the foetal surgery required to rectify a
foetal urinary tract infection
The Anatomy and Development of the Foetus
Medical Conditions Affecting the Foetus from initial diagnosis to treatment:
Congenital Diaphragmatic Hernia (CDH)
Congenital Cystic Adenomatoid Malformation of the Lung (CCAM)
Sacrococcygeal Teratoma (SCT)
Urinary Tract Obstruction
Radiofrequency Ablation (RFA)
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