Urologic Fetal Intervention: Cincinnati Fetal Center
With Dr. Greg Ryan & Dr. Pramod Reddy · hosted by Dr. Todd Ponsky & Dr. Foong Yen Lim · StayCurrentMD
Cued at 41:33 · stops at 42:18 · press play
Educational content from recorded physician discussions — not medical advice. Talk to your (or your child's) care team about your situation.
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What the experts said
Not all fetuses with urinary tract obstruction are candidates for intervention; those too healthy (normal AFI, non-obstructive dilation, unilateral UPJ) or too sick (cystic dysplasia, abnormal karyotype, multiple anomalies) should not be offered fetal surgery.
Vesicoamniotic shunts have not improved renal outcomes because the long, thin tubes do not adequately reduce bladder pressure; they provide pulmonary survivors but not renal protection.
In adult studies, bladder pressure exceeding 40 cm H₂O (29 mmHg) causes renal injury and abolishes net glomerular filtration.
Safe bladder pressures for fetal kidneys are unknown; adult thresholds are used by extrapolation.
Intravillous pressure that occludes venous flow in the placenta is approximately 23 mmHg; resting amniotic fluid pressure is 5–8 mmHg.
When a vesicoamniotic shunt is placed, the bladder often collapses and upper tracts decompress significantly, though residual hydroureteronephrosis may persist.
Fetoscopic cystoscopy must be considered experimental for LUTO until properly evaluated in a rigorous trial.
Vesicoamniotic shunt complications include migration, blockage, and (rarely) iatrogenic gastroschisis when placed at 17 weeks.
Bladder cycling enabled by fetoscopic valve ablation is physiologically important for bladder health, not for upper-tract protection.
A urethral fistula from fetoscopic laser ablation can be repaired surgically with minimal morbidity, whereas renal dysplasia cannot be reversed.
Posterior urethral valves can sometimes be ablated by blunt mechanical disruption (guidewire and catheter) rather than laser, because the valves are flimsy.
Serial bladder taps carry a risk of bladder rupture and urinary ascites, which can preclude subsequent fetoscopic intervention.
Fetoscopic procedures for LUTO can be performed under epidural anesthesia with IV sedation and local anesthetic, avoiding the deep uterine relaxation required for open fetal surgery.
Fetal anesthesia for fetoscopy includes intramuscular vecuronium, atropine, and fentanyl to prevent fetal movement and mitigate pain response.
The Cincinnati team uses a 3.3 Fr outer sheath fetoscope (1.2 mm scope) with a side port for guidewire passage during cystoscopy.
A flexible 4.9 Fr ureteroscope can be introduced through a 10 Fr sheath to improve maneuverability when accessing the fetal bladder neck and posterior urethra.
In Mark Johnson's historical studies, the third vesicocentesis provided fresher urine that correlated strongly with histologic renal damage; the first and second taps were not predictive.
Current algorithms reserve the most invasive interventions (open vesicostomy) for the worst-prognosis fetuses, which may be flawed because these patients are least likely to benefit and most likely to suffer maternal and fetal harm.
Open fetal vesicostomy predisposes the mother to shortened gestation (~10 additional weeks) and very high risk of preterm labor.
Cincinnati performed open fetal vesicostomy in six anhydramniotic fetuses; four died from preterm delivery, one has normal renal function at age 5, and one required transplant.
Greg Ryan argues there is no role for open fetal surgery in LUTO, especially in the worst-prognosis group, given the maternal and fetal risks and the experimental nature of the procedure.
Foong Yen Lim proposes that open fetal vesicostomy should be considered only in good-prognosis fetuses who fail fetoscopic intervention, not in the sickest cohort.
Better biomarkers of fetal renal function are urgently needed to guide intervention selection and predict outcomes.
In a long-term follow-up series, one-third of shunted LUTO survivors developed end-stage renal disease requiring transplant after age 5 years, despite having acceptable discharge creatinine.
Posterior urethral valve patients required transplant at median age 10–12 years; prune belly/urethral hypoplasia at ~4.5 years; urethral atresia earlier.
Progressive renal injury in shunted LUTO survivors is driven by repeated urinary tract infections, vesicoureteral reflux, and valve bladder dysfunction.
Creatinine at hospital discharge is misleading; creatinine at age 1 year is a better predictor of long-term renal function. A creatinine <1.0 mg/dL at age 1 suggests the child will not require renal replacement therapy.
Infants with LUTO triple their birth weight in the first year, revealing the true extent of renal reserve; discharge creatinine does not account for this growth.
Polyuria from fetal concentrating defects causes high bladder storage pressures, which damage the upper tracts in a vicious cycle; aggressive postnatal bladder management is required to break this cycle.
Mark Johnson's closing pearl: patient selection is the most critical factor in fetal intervention for LUTO.
Greg Ryan's closing pearl: just because a procedure can be done does not mean it should be done; honest counseling about outcomes is essential.
Fetoscopic cystoscopy altered the diagnosis in 25–33% of fetuses with suspected LUTO, according to a review by Katie Morris.
A French-Brazilian-Houston study of 111 LUTO fetuses found that only cystoscopy (not shunting) may prevent renal function impairment at 6 months of age.
In a Barcelona-Leuven series of 20 fetoscopic valve ablations, bladder size and amniotic fluid normalized in 80% of cases; among livebirths, there was no pulmonary hypoplasia and three-quarters had normal renal function.
Fetoscopic valve ablation carries a 9–10% risk of urethral fistula and a 6% risk of recurrent severe LUTO.
The Pluto trial removed bladder taps from its protocol because data suggested the most powerful effect of shunting is in poor-prognosis fetuses, and even good-prognosis fetuses have ~50% risk of bad renal function postnatally.