Vesicoamniotic shunt for complete urinary tract obstruction is partially effective

The long-term outcome for children after antenatal intervention for obstructive uropathies is disappointing. We reported that renal dysplastic changes are well established 3 weeks after obstruction in a fetal lamb model. We used this model to explore renal development and bladder function after fetal intervention.

We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. A vesicostomy (female) or urethrostomy (male) were performed 21 days later. The fetuses were killed at term (145 days) and bladder volume and compliance were measured. The urinary tract was processed for histologic examination.

Twenty two fetuses were shunted. Nine were miscarried or were still-born. Thirteen survived, and 11 had a successful shunt with a small bladder (8 +/- 5 mL) compared with controls (71 +/- 19 mL) (P < .05). Shunted bladders had poor compliance. Histologically, they had thickened submucosal connective tissue with hypertrophied muscle. Histology of the renal tissue demonstrated relatively well-preserved renal architecture with reduced nephron mass (oligonephronia) in 2 lambs and multicystic dysplastic change in 3. Six (55%) had normal nephrogenesis.

In our model, shunt operations after obstructive uropathy fail to preserve bladder function. Shunting ameliorated the development of cystic dysplasia, but half of the lambs had oligonephronia or multicystic dysplastic kidney. These might develop renal failure later in life.