Clinical outcome of fetal uropathy. I. Predictive value of prenatal echography positive for obstructive uropathy

Revisiting the utility of prenatal ultrasound in the routine workup of first febrile UTI: A systematic review and meta-analysis of the negative predictive value of prenatal ultrasound for identification of urinary tract abnormalities after first febrile urinary tract infection in children

CONTEXT

The current EAU/ESPU and recently retired AAP pediatric UTI guidelines recommend renal bladder ultrasound after first febrile UTI in children to screen for structural abnormalities, regardless of findings on prenatal ultrasound.

OBJECTIVE

Test the hypothesis that a normal prenatal ultrasound could rule out urinary tract abnormality on post-UTI ultrasound.

DATA SOURCES

Medline, Embase, Cochrane Library.

STUDY SELECTION

Studies including pediatric patients with first febrile UTI who had both prenatal and post-UTI ultrasound.

DATA EXTRACTION

Anatomical abnormalities detected by prenatal and post-UTI ultrasound as reported per individual study criteria were extracted. Meta-analyses of 9 studies (2981 patients) were performed using a random-effects model and composite estimates of the negative predictive value (NPV) of prenatal ultrasound were calculated.

RESULTS

Overall summary NPV of prenatal ultrasound for all pediatric patients was 77%, with heterogeneity score (I2) 97.9%. Summary NPV of prenatal ultrasound for all patients under two years of age was similar at 75%, with I2 98.2% For the 4 studies to which we could apply a more stringent definition of abnormality, summary NPV was 85% and I2 97.5% for prediction of moderate post-UTI ultrasound abnormalities and summary NPV was 93% and I2 90.4% for severe abnormalities.

DISCUSSION

While we calculated an 85% NPV for a normal prenatal ultrasound to rule out significant postnatal abnormality as defined within individual studies, substantial heterogeneity amongst publications limited the precision of our estimates. This highlights the need for more rigorous investigations with attention to timing of ultrasound and the application of clinically meaningful definitions for abnormal prenatal and post-UTI studies. This may allow judicious use of prenatal ultrasound to guide clinical management for children with first febrile UTI and minimize redundant imaging with potential for false positive results. Until then, the current guidelines are justified based on the limited and heterogenous data from the currently available published studies.

CONGENITAL URINARY BLADDER OUTLET OBSTRUCTION

The term congenital ‘bladder outlet obstruction (BOO)’ describes the collection of conditions in which the normal, urethral egress of urine from the fetal bladder is impaired. The term is interchangeable with fetal ‘lower urinary tract obstruction’, as used by other authors. After considering normal urinary tract embryology, we describe the epidemiology of congenital BOO and the primary anatomical disorders associated with it. We then proceed to describe its fetal and postnatal clinical manifestations and then consider therapies and interventions which have been used to manage the condition. We not only focus on urethral and bladder disease with constitutes BOO itself, but also describe associated kidney disorders which, via chronic renal excretory failure, are important causes of morbidity. Rather than provide an exhaustive review, we emphasise studies published in the last decade, and therefore readers are referred to other reviews citing numerous earlier references.

Syndrome d’insuffisance rénale fœtale

Some anomalies of the kidney and urinary tract evolving in utero may compromise the renal function in the newborn. Early therapeutic options do exist, especially in obstructive nephropathies. The decision depends on a correct evaluation of the foetal enal function and prognosis, which is based on a range of methods: ultrasound echography, biochemical analysis of foetal urine, and, more recently, foetal serum markers such a beta-2 micro globulin. These methods are reviewed.

Fetal surgery for posterior urethral valves: long-term postnatal outcomes

OBJECTIVE

Fetal intervention for obstructive uropathy was first performed at the University of California, San Francisco in 1981. Indications for treatment were bilateral hydronephrosis with oligohydramnios. Preintervention criteria included fetal urinary electrolytes with beta-microglobulin levels, karyotyping, and detailed sonography specifically looking for renal cortical cysts. We reviewed the outcomes of children who underwent fetal intervention with specific long-term follow-up in patients who were found postnatally to have posterior urethral valves.

METHODS

A retrospective review of the University of California, San Francisco fetal surgery database was performed for patients with a prenatal diagnosis of obstructive uropathy. Medical records from 1981 to 1999 were reviewed. Long-term follow-up was documented if the cause of the urinary tract obstruction was posterior urethral valves. We collected data points, focusing on time and type of intervention, fetal urinary electrolytes, appearance of fetal kidneys, present renal function, length of follow-up, and present status of the urinary tract.

RESULTS

Forty patients were evaluated for fetal intervention; 36 fetuses underwent surgery during this time period. Postnatal confirmation of posterior urethral valves was demonstrated in 14 patients. All patients had favorable fetal urinary electrolytes. Mean gestational age at intervention was 22.5 weeks. The procedures performed included creation of cutaneous ureterostomies in 1, fetal bladder marsupialization in 2, in utero ablation of valves in 2, and placement of vesicoamniotic catheter in 9. Six deaths occurred before term delivery with premature labor and the newborns succumbing to respiratory failure. One pregnancy was terminated electively because of shunt failure and declining appearance of fetal lungs and kidney. The remaining 8 living patients had a mean follow-up of 11.6 years. Chronic renal disease with abnormal serum creatinine was present in 5 patients. Two patients have undergone renal transplantation, and 1 is awaiting organ donation. Five of the 8 living patients have had urinary diversion with vesicostomy, cutaneous ureterostomy, or augmentation cystoplasty with later reconstruction.

CONCLUSIONS

Fetal intervention for posterior urethral valves carries a considerable risk to the fetus with fetal mortality rate of 43%. The long-term outcomes indicate that intervention may not change the prognosis of renal function or be a predictor for possible urinary diversion. Despite all of these patients' having favorable urinary electrolytes, this did not seem to have any implication postnatally. When counseling families about fetal intervention, efforts should be focused on that intervention may assist in delivering the fetus to term and that the sequelae of posterior urethral valves may not be preventable. Fetal surgery for obstructive uropathy should be performed only for the carefully selected patient who has severe oligohydramnios and "normal"-appearing kidneys.

In-utero percutaneous cystoscopy in the management of fetal lower obstructive uropathy

In fetuses with lower obstructive uropathy, sonography cannot establish the cause of obstruction. We assessed whether percutaneous fetal cystoscopy could be useful in the evaluation and treatment of obstructive defects in utero. We inserted a fibreoptic endoscope through the lumen of the needle or trocar into the fetal bladder at the time of vesicocentesis or vesicoamniotic-shunt placement and looked at the the urethra, bladder neck, and ureteral orifices. Urethral vesicoamniotic shunting was considered in suitable cases; otherwise a percutaneous shunt was inserted. Fetal cystoscopy was possible in 11 of 13 patients referred. The bladder mucosa appeared haemorrhagic or oedematous in three. The ureteral orifices were seen in 9/11 fetuses, dilation was seen in five, but was only suspected in two by ultrasound. Ureteral webs were noted in two other fetuses. Two of seven fetuses underwent urethral vesicoamniotic shunting; urethral patency was achieved with urethral probing alone in one fetus. The remaining four fetuses were shunted with a standard technique. Fetal cystoscopy helps define the underlying conditions responsible for sonographic findings of lower obstructive uropathy, and allows the introduction of new treatments.

Ultrasound grading of hydronephrosis: introduction to the system used by the Society for Fetal Urology

The Society for Fetal Urology (SFU) was founded in 1988 to study the postnatal evolution of prenatally detected anomalies of the urinary tract by following those neonates whose prenatal studies have brought them to medical attention while asymptomatic. The SFU has attempted to standardize methods of performing and grading the ultrasound and radionuclide examinations in this population. A system to grade upper tract dilatation or hydronephrosis (HN) imaged by ultrasound has been developed and is being used by SFU members in 36 institutions. The appearance of the calices, renal pelvis and renal parenchyma are key in determining the grade of HN and are illustrated in this article.

Clinical outcome of fetal uropathy. II. Sensitivity of echography for prenatal detection of obstructive pathology

Among 8,579 neonates born between February 1, 1981 and March 31, 1987, and cleared by prenatal sonography for significant urinary tract abnormality 158 subsequently were hospitalized because of signs or symptoms of urinary tract disease, predominantly urinary tract infection. Evaluation of these 158 patients revealed 24 with vesicoureteral reflux, 7 with duplicated systems (2 of which showed reflux), 1 with the syndrome of Fraley, 1 with pyelectasis and 5 with mild hydronephrosis (3 secondary to reflux and 2 with diethylenetriaminepentaacetic acid renal scans considered to be nonobstructed). There was no incidence of significant obstructive uropathy that had been missed by the previous prenatal sonography and that surfaced subsequently to cause morbidity in this series. The principal disorder of the urinary tract that may fail prenatal investigation is vesicoureteral reflux.