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Lower Urinary Tract Obstruction
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Educational content from recorded physician discussions — not medical advice. Always talk to your child's care team about your child's situation.
Content of this collection
There is no good data that allows prediction of renal injury at gestational ages of 26 or 28 weeks using the established electrolyte cutoffs. — Mark, Overview of Prenatal Diagnosis: Cincinnati Fetal Center · 27:51
Overview of Prenatal Diagnosis: Cincinnati Fetal Center
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Dr. Mark P. Johnson, research chair in fetal therapy, discusses an overview of prenatal diagnosis of fetal lower urinary tract obstruction. Dr. Johnson describes the most common causes of lower urinary tract obstructions, progressive oligoh
video40:34 · Nov 2018
Prenatal diagnosis of fetal lower urinary tract obstruction: Fetal...
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Dr. Mark P. Johnson, research chair in fetal therapy, discusses an overview of prenatal diagnosis of fetal lower urinary tract obstruction. Dr. Johnson describes the most common causes of lower urinary tract obstructions, progressive oligoh
video40:14 · Jan 2019
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. — Pramod Reddy, Urologic Fetal Intervention: Cincinnati Fetal Center · 2:04
Urologic Fetal Intervention: Cincinnati Fetal Center
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Dr. Pramod Reddy, Division of Pediatric Urology, discusses fetal cystoscopy. Dr. Reddy discusses fetal intervention and risks, urinary tract obstructions, open intervention versus fetoscopic intervention, the risks of shunt usage for renal
video1:01:40 · Nov 2018
Fetal urological aspect: Fetal Genitourinary Disease 2015
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Dr. Pramod Reddy discusses fetal cystoscopy, includingfetal intervention and risks, urinary tract obstructions, open intervention versus fetoscopic intervention, the risks of shunt usage for renal functions, normal fetal fluid pressure rang
video59:23 · Jan 2019
Expert statements from the recordings in this collection.
Urologic Fetal Intervention: Cincinnati Fetal Center
In adult studies, bladder pressure exceeding 40 cm H₂O (29 mmHg) causes renal injury and abolishes net glomerular filtration.
Pramod Reddy4:49
Safe bladder pressures for fetal kidneys are unknown; adult thresholds are used by extrapolation.
Pramod Reddy5:13
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.
Pramod Reddy4:00
Intravillous pressure that occludes venous flow in the placenta is approximately 23 mmHg; resting amniotic fluid pressure is 5–8 mmHg.
Todd Ponsky5:43
When a vesicoamniotic shunt is placed, the bladder often collapses and upper tracts decompress significantly, though residual hydroureteronephrosis may persist.
Greg Tiao7:38
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.
Vesicoamniotic shunt complications include migration, blockage, and (rarely) iatrogenic gastroschisis when placed at 17 weeks.
Greg Tiao14:06
The Cincinnati team uses a 3.3 Fr outer sheath fetoscope (1.2 mm scope) with a side port for guidewire passage during cystoscopy.
Foong Yen Lim30:01
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.
Pramod Reddy30:18
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.
Foong Yen Lim24:13
Fetal anesthesia for fetoscopy includes intramuscular vecuronium, atropine, and fentanyl to prevent fetal movement and mitigate pain response.
Todd Ponsky24:57
Serial bladder taps carry a risk of bladder rupture and urinary ascites, which can preclude subsequent fetoscopic intervention.
Foong Yen Lim22:42
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.
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.
Greg Tiao34:57
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.
Greg Tiao49:58
Posterior urethral valve patients required transplant at median age 10–12 years; prune belly/urethral hypoplasia at ~4.5 years; urethral atresia earlier.
Greg Tiao51:24
Progressive renal injury in shunted LUTO survivors is driven by repeated urinary tract infections, vesicoureteral reflux, and valve bladder dysfunction.
Greg Tiao52:13
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.
Pramod Reddy56:52
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.
Pramod Reddy56:52
Bladder cycling enabled by fetoscopic valve ablation is physiologically important for bladder health, not for upper-tract protection.
Pramod Reddy16:39
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.
Pramod Reddy18:30
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.
Pramod Reddy41:33
Open fetal vesicostomy predisposes the mother to shortened gestation (~10 additional weeks) and very high risk of preterm labor.
Pramod Reddy41:06
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.
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.