What is infravesical obstruction (LUTO)?
Infravesical obstruction (synonym: obstructive uropathy: LUTO - Lower Urinary Tract Obstruction) is diagnosed by ultrasound as urethral narrowing (stenosis) or posterior urethral valve.
How is the diagnosis made?
The diagnosis is made by ultrasound. The fetus is found to have a severely filled urinary bladder, congested kidneys, and quite often oligo- or anhydramnios.
What is the prognosis of the child with this diagnosis?
Pronounced LUTO leads to bilateral marked hydronephrosis and renal insufficiency already in the womb (in utero). In pronounced cases, there is decreased excretion (diuresis) and consequent oligo- or anhydramnios, leading to underdevelopment of the fetal lungs (pulmonary hypoplasia). The chances of survival are questionable at this stage.
What tests are performed?
To better assess renal function, biochemical analysis of fetal urine (including electrolytes and beta-2-microglobin) is performed by selective puncture of the urinary bladder. The puncture is often combined with human genetic analysis.
How is the stent implantation performed?
Suprapubic stent implantation is performed during ultrasound examination under sterile conditions.
Local anesthesia is applied through the abdominal wall beforehand. Before stent insertion, amniotic fluid infusion is performed in case of anhydramnios to allow stent implantation. Puncture of the fetal urinary bladder is performed with a 1.2 mm diameter puncture needle.
Decompression of the obstructed urinary tract leads to normalization of the amniotic fluid volume and consequent regression of pulmonary hypoplasia.
When can stent implantation be performed in LUTO?
Stent implantion is performed from 16+0 SSW.
What are the complications?
The complication rate is very low with experienced fetal surgeons.
The most common complications are shunt dislocation after a few weeks or months (20-50%) and premature rupture of membranes.
Other complications such as hemorrhage, injury, or infection are rare (<1%).
In case of stent dislocation, reimplantation is offered if necessary.
After stent insertion, an ultrasound check is performed. This will check the following:
- Stent position
- Fetal heart rate (Doppler)
- Amount of amniotic fluid
- Exclusion of a complication
