Fetal Megacystis: Associated Structural Abnormalities and Obstetric Outcomes.

Purpose: We evaluated the obstetrical outcomes, ultrasonographic characteristics, and final diagnosis in pregnancies with fetal megacystis (FM). Methods: We evaluated the obstetrical outcomes and associated structural abnormalities of fetuses with FM detected between FM between 2000 and 2021. Results: 17 FM were diagnosed, 16 had follow up. 16 were early megacystis. 14/16 (87.5%) of pregnancies were terminated, 1/16 (6.25%) resulted in intrauterine death, and 1/16 (6.25%) survived. FM was associated with 13 other abnormal sonographic findings in 12/16 (75%) pregnancies. The most common associated ultrasound abnormality was umbilical cord cyst in 3/16 (18.75%). Recognized etiologies included posterior urethral valves (2), trisomy 18 (2), trisomy 13 (1), Prune Belly syndrome (1), and Megacystis-Microcolon-Hypoperistalsis syndrome (1). Conclusion: Most FM are detected in the 2nd trimester, most are electively terminated, are associated with other ultrasonic abnormalities in 75%, most commonly umbilical cord cyst, and have an identifiable cause in 44%.

Z-scores of fetal bladder size for antenatal differential diagnosis between posterior urethral valves and urethral atresia.

OBJECTIVE: To construct reference values for fetal urinary bladder distension in pregnancy and use Z-scores as a diagnostic tool to differentiate posterior urethral valves (PUV) from urethral atresia (UA). METHODS: This was a prospective cross-sectional study in healthy singleton pregnancies aimed at constructing nomograms of fetal urinary bladder diameter and volume between 15 and 35 weeks' gestation. Z-scores of longitudinal bladder diameter (LBD) were calculated and validated in a cohort of fetuses with megacystis with ascertained postnatal or postmortem diagnosis, collected from a retrospective, multicenter study. Correlations between anatomopathological findings, based on medical examination of the infant or postmortem examination, and fetal megacystis were established. The accuracy of the Z-scores was evaluated by receiver-operating-characteristics (ROC)-curve analysis. RESULTS: Nomograms of fetal urinary bladder diameter and volume were produced from three-dimensional ultrasound volumes in 225 pregnant women between 15 and 35 weeks of gestation. A total of 1238 urinary bladder measurements were obtained. Z-scores, derived from the fetal nomograms, were calculated in 106 cases with suspected lower urinary tract obstruction (LUTO), including 76 (72%) cases with PUV, 22 (21%) cases with UA, four (4%) cases with urethral stenosis and four (4%) cases with megacystis-microcolon-intestinal hypoperistalsis syndrome. Fetuses with PUV showed a significantly lower LBD Z-score compared to those with UA (3.95 vs 8.83, P < 0.01). On ROC-curve analysis, we identified 5.2 as the optimal Z-score cut-off to differentiate fetuses with PUV from the rest of the study population (area under the curve, 0.84 (95% CI, 0.748-0.936); P < 0.01; sensitivity, 74%; specificity, 86%). CONCLUSIONS: Z-scores of LBD can distinguish reliably fetuses with LUTO caused by PUV from those with other subtypes of LUTO, with an optimal cut-off of 5.2. This information should be useful for prenatal counseling and management of LUTO. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Fetal megacystis: a lot more than LUTO.

OBJECTIVE: Fetal megacystis presents a challenge in terms of counseling and management because of its varied etiology and evolution. The aim of this study was to present a comprehensive overview of the underlying etiologies and structural anomalies associated with fetal megacystis. METHODS: This was a retrospective multicenter study of cases referred to the fetal medicine unit of one of the eight academic hospitals in The Netherlands with a diagnosis of fetal megacystis. For each case, data on and measurements of fetal urinary tract and associated structural anomalies were collected. All available postmortem examinations and postnatal investigations were reviewed in order to establish the final diagnosis. In the first trimester, fetal megacystis was defined as longitudinal bladder diameter (LBD) ≥ 7 mm, and in the second and third trimesters as an enlarged bladder failing to empty during an extended ultrasound examination lasting at least 40 min. RESULTS: Of the 541 pregnancies with fetal megacystis, it was isolated (or solely accompanied by other signs of lower urinary tract obstruction (LUTO)) in 360 (67%) cases and associated with other abnormal ultrasound findings in 181 (33%) cases. The most common associated ultrasound anomaly was an increased nuchal translucency thickness (22%), followed by single umbilical artery (10%) and cardiac defect (10%). A final diagnosis was established in 418 cases, including 222 (53%) cases with isolated LUTO and 60 (14%) infants with normal micturition or minor isolated urological anomalies. In the remaining 136 (33%) cases, concomitant developmental or chromosomal abnormality or genetic syndrome was diagnosed. Overall, 40 chromosomal abnormalities were diagnosed, including trisomy 18 (n = 24), trisomy 21 (n = 5), Turner syndrome (n = 5), trisomy 13 (n = 3) and 22q11 deletion (n = 3). Thirty-two cases presented with anorectal malformations involving the anus, rectum and urogenital tract. In cases with confirmed urethral and anal atresia, megacystis occurred early in pregnancy and the bladder appeared severely distended (the LBD (in mm) was equal to or greater than twice the gestational age (in weeks)). Fetal macrosomia was detected in six cases and an overgrowth syndrome was detected in four cases, comprising two infants with Beckwith-Wiedemann syndrome and two with Sotos syndrome. Megacystis-microcolon-intestinal hypoperistalsis syndrome was diagnosed in five (1%) cases and prenatally suspected only in one case. CONCLUSIONS: Although the main cause of fetal megacystis is LUTO, an enlarged fetal bladder can also be present as a concomitant finding of miscellaneous genetic syndromes, developmental disturbances and chromosomal abnormalities. We provide an overview of the structural anomalies and congenital disorders associated with fetal megacystis and propose a practical guide for the differential diagnosis of genetic syndromes and chromosomal and developmental abnormalities in pregnancies presenting with fetal megacystis, focusing on the morphological examination of the fetus. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Fetal megacystis: Institutional experience and outcomes.

BACKGROUND: Fetal megacystis is a sonographic feature that may be indicative of several underlying pathologies. Despite advances in diagnosis and management, the overall prognosis of affected fetuses remains poor and about 50% of such pregnancies are terminated. AIMS: To define the frequency, management, survival and renal outcomes of fetal megacystis over nine years at Wellington Hospital, New Zealand. MATERIALS AND METHODS: A nine-year retrospective review of fetuses with an antenatal diagnosis of megacystis was undertaken. RESULTS: Sixteen cases were identified (nine live births, five terminations and two perinatal deaths). This gives an observed frequency of one per 940 fetuses scanned. Two-thirds of the live births have survived and been followed for a mean of 5.3 years. None have required renal dialysis or transplantation to date. CONCLUSIONS: The current series contributes to our knowledge of fetal megacystis and helps to inform antenatal counselling. Improved prognostic criteria are urgently required to accurately differentiate between fetuses with favourable versus poor outcomes.

Prognosis of Isolated First-Trimester Fetal Megacystis with Spontaneous Resolution.

OBJECTIVE: Fetal megacystis has a poor prognosis. During the first trimester, it is frequently associated with chromosomal abnormalities or multiple malformations, but can also be isolated and resolve spontaneously. In this study, our main objective was to determine the fetal and pediatric prognosis in this particular situation. METHODS: This was a retrospective multicenter study. We describe the cases referred to our fetal medicine centers and also cases previously reported in the international literature. RESULTS: Five cases were referred to our fetal medicine centers. After spontaneous resolution of megacystis, close ultrasound follow-up revealed urinary tract abnormalities in all cases. These abnormalities were all transient. After birth, 1 of the children developed a mild ureteropelvic junction obstruction. Pediatric follow-up was normal for the other children. Our 5 cases plus 79 in the literature mean that 84 cases of isolated first-trimester fetal megacystis with spontaneous resolution have been reported to date. The risk of chromosomal abnormality was 2.4% (2/84) and pediatric follow-up was normal in 96.4% of cases (81/84). CONCLUSION: Even when isolated first-trimester fetal megacystis resolves spontaneously, fetal karyotype analysis and close prenatal ultrasound follow-up should be performed. When there is no chromosomal abnormality, the renal pediatric prognosis seems to be good.

Early vesico-amniotic shunting - does it change the prognosis in fetal lower urinary tract obstruction diagnosed in the first trimester?

OBJECTIVES: The aim of the study was to assess the outcome of vesico-amniotic shunting performed before 16 weeks of pregnancy in fetuses with severe megacystis diagnosed in the first trimester of pregnancy. MATERIAL AND METHODS: Between January 2008 and October 2012 severe megacystis with the bladder length > 15 mm was diagnosed in 17 fetuses. The procedure of early vesico-amniotic shunting (VAS) was offered to 8 patients with presumably isolated LUTO. The procedure of VAS was performed in 6 fetuses. Before the intervention one or two procedures of vesicocentesis and urine analysis were performed. RESULTS: In all treated cases shunts provided urinary tract decompression. All babies were born prematurely, 2 of them died due to premaurity, 3 of them survived and have normal renal function at the age of 5-6 years. In 4/5 children accompanying malformations were later diagnosed, in 1 born prematurely neonate necropsy was not performed. CONCLUSIONS: Our results suggest that early vesico-amniotic shunting in fetal LUTO is feasible and may potentially prevent not only pulmonary hypoplasia but also renal insufficiency. However, the rationale of the procedure needs further investigation due to a high risk of long-term morbidity and co-existing malformations in children Before offering the therapy detailed counseling of the parents about the possible pros and cons of the therapy is necessary.

Chromosomal abnormalities associated with fetal megacystis.

Fetal megacystis has been reported to be associated with chromosomal abnormalities, megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS), obstructive uropathy, prune belly syndrome, cloacal anomalies, limb-body wall complex, amniotic band syndrome, anorectal malformations, VACTERL association (vertebral anomalies, anal atresia, cardiac malformations, tracheo-esophageal fistula, renal anomalies and limb abnormalities) and fetal overgrowth syndrome such as Bechwith-Wiedemann syndrome and Sotos syndrome. This review provides an overview of chromosomal abnormalities associated with fetal megacystis which is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal megacystis.

Syndromic and single gene disorders associated with fetal megacystis (I): Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS).

Fetal megacystis has been reported to be associated with chromosomal abnormalities, megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS), obstructive uropathy, prune belly syndrome, cloacal anomalies, limb-body wall complex, amniotic band syndrome, anorectal malformations, VACTERL association (vertebral anomalies, anal atresia, cardiac malformations, tracheo-esophageal fistula, renal anomalies and limb abnormalities) and fetal overgrowth syndrome such as Bechwith-Wiedemann syndrome and Sotos syndrome. This review provides an overview of syndromic and single gene disorders associated with fetal megacystis which is useful for genetic counseling at prenatal diagnosis of fetal megacystis.

Antenatal Determinants of Postnatal Renal Function in Fetal Megacystis: A Systematic Review.

Introduction: To evaluate the clinical usefulness of demographic data, fetal imaging findings and urinary analytes were used for predicting poor postnatal renal function in children with congenital megacystis. Materials and methods: A systematic review was conducted in MEDLINE's electronic database from inception to December 2023 using various combinations of keywords such as "luto" [All Fields] OR "lower urinary tract obstruction" [All Fields] OR "urethral valves" [All Fields] OR "megacystis" [All Fields] OR "urethral atresia" [All Fields] OR "megalourethra" [All Fields] AND "prenatal ultrasound" [All Fields] OR "maternal ultrasound" [All Fields] OR "ob-stetric ultrasound" [All Fields] OR "anhydramnios" [All Fields] OR "oligohydramnios" [All Fields] OR "renal echogenicity" [All Fields] OR "biomarkers" [All Fields] OR "fetal urine" [All Fields] OR "amniotic fluid" [All Fields] OR "beta2 microglobulin" [All Fields] OR "osmolarity" [All Fields] OR "proteome" [All Fields] AND "outcomes" [All Fields] OR "prognosis" [All Fields] OR "staging" [All Fields] OR "prognostic factors" [All Fields] OR "predictors" [All Fields] OR "renal function" [All Fields] OR "kidney function" [All Fields] OR "renal failure" [All Fields]. Two reviewers independently selected the articles in which the accuracy of prenatal imaging findings and fetal urinary analytes were evaluated to predict postnatal renal function. Results: Out of the 727 articles analyzed, 20 met the selection criteria, including 1049 fetuses. Regarding fetal imaging findings, the predictive value of the amniotic fluid was investigated by 15 articles, the renal appearance by 11, bladder findings by 4, and ureteral dilatation by 2. The postnatal renal function showed a statistically significant relationship with the occurrence of oligo- or anhydramnion in four studies, with an abnormal echogenic/cystic renal cortical appearance in three studies. Single articles proved the statistical prognostic value of the amniotic fluid index, the renal parenchymal area, the apparent diffusion coefficient (ADC) measured on fetal diffusion-weighted MRI, and the lower urinary tract obstruction (LUTO) stage (based on bladder volume at referral and gestational age at the appearance of oligo- or anhydramnios). Regarding the predictive value of fetal urinary analytes, sodium and ß2-microglobulin were the two most common urinary analytes investigated (n = 10 articles), followed by calcium (n = 6), chloride (n = 5), urinary osmolarity (n = 4), and total protein (n = 3). Phosphorus, glucose, creatinine, and urea were analyzed by two articles, and ammonium, potassium, N-Acetyl-l3-D-glucosaminidase, and microalbumin were investigated by one article. The majority of the studies (n = 8) failed to prove the prognostic value of fetal urinary analytes. However, two studies showed that a favorable urinary biochemistry profile (made up of sodium < 100 mg/dL; calcium < 8 mg/dL; osmolality < 200 mOsm/L; ß2-microglobulin < 4 mg/L; total protein < 20 mg/dL) could predict good postnatal renal outcomes with statistical significance and urinary levels of ß2-microglobulin were significantly higher in fetuses that developed an impaired renal function in childhood (10.9 ± 5.0 mg/L vs. 1.3 ± 0.2 mg/L, p-value < 0.05). Conclusions: Several demographic data, fetal imaging parameters, and urinary analytes have been shown to play a role in reliably triaging fetuses with megacystis for the risk of adverse postnatal renal outcomes. We believe that this systematic review can help clinicians for counseling parents on the prognoses of their infants and identifying the selected cases eligible for antenatal intervention.

Fetal Therapy for Renal Anhydramnios.

The most severe forms of congenital anomalies of the kidney and urinary tract present in fetal life with early pregnancy renal anhydramnios and are considered lethal due to pulmonary hypoplasia without fetal therapy. Due to the high rate of additional structural anomalies, genetic abnormalities, and associated syndromes, detailed anatomic survey and genetic testing are imperative when stratifying which pregnancies are appropriate for fetal intervention. Restoring amniotic fluid around the fetus is the principal goal of prenatal treatment. The ongoing multi-center Renal Anhydramnios Fetal Therapy (RAFT) trial is assessing the safety and efficacy of serial amnioinfusions to prevent pulmonary hypoplasia so that the underlying renal disease can be addressed.

Fetal megacystis: A systematic review.

Fetal megacystis is variably defined and understood. The literature on fetal megacystis was systematically reviewed, focusing on prenatal diagnosis, associations and outcomes. This yielded a total of 18 primary references and eight secondary references. Fetal megacystis has an estimated first-trimester prevalence of between 1:330 and 1:1670, with a male to female ratio of 8:1. In the first trimester, megacystis is most commonly defined as a longitudinal bladder dimension of ≥7 mm. Later in pregnancy, a sagittal dimension (in mm) greater than gestational age (in weeks) + 12 is often accepted. Megacystis can be associated with a thickened bladder wall, which has been objectively defined as >3 mm. Oligohydramnios is present in approximately half of all cases. The most common underlying diagnosis is posterior urethral valves (57%), followed by urethral atresia/stenosis (7%), prune belly syndrome (4%), megacystis-microcolon-intestinal-hypoperistalsis syndrome (MMIHS) (1%), and cloacal anomalies (0.7%). Karyotype anomalies are found in 15%, and include trisomy 18, trisomy 13 and trisomy 21. Ultrasound imaging alone is often insufficient to enable a definitive diagnosis, although it may indicate that a specific diagnosis is more likely. Overall, about 50% of reported fetuses with megacystis are terminated, but this proportion varies considerably between countries and over time. Prognostic stratification is evolving, with the most important factors being oligohydramnios, gestational age at diagnosis, degree of bladder enlargement, renal hyperechogenicity, karyotype, and sex. CONCLUSIONS: This review demonstrated some consensus on the ultrasound criteria for defining fetal megacystis, and illustrated the spectrum of pathologies and their relative frequencies that can cause this condition. It also underlined important associated karyotype anomalies. To progress understanding of the natural history of enlarged fetal bladders, more accurate diagnostics are required, and risk stratification needs to be refined to facilitate prenatal counseling.

Prenatal detection of megacystis: not always an adverse prognostic factor. Experience in 25 consecutive cases in a tertiary referral center, with complete neonatal outcome and follow-up.

INTRODUCTION: Megacystis is a condition of abnormal enlarged fetal bladder for gestational age, which is usually associated with urological malformations that may constitute a life-threatening condition for the baby. OBJECTIVE: The purpose of this study was to assess the prognostic and etiological criteria of fetal megacystis and to describe the neonatal outcome in a large series collected in a single tertiary center. STUDY DESIGN: A retrospective observational study was conducted between 2008 and 2012. We reviewed all consecutive cases of fetal megacystis diagnosed during routine ultrasound (US) screening. The following data were collected and analyzed: maternal age, gestational age at diagnosis, prenatal ultrasonographic details of the urinary system, extra-urinary ultrasonographic anomalies, fetal karyotype, pregnancy outcome, postnatal diagnosis, and medical/surgical follow-up. RESULTS: Of the 25 fetuses included in this study, 76% were males. The mean gestational age (GA) at diagnosis was 23.1 ± 7.5 weeks (range 12-34), among them only four (16%) were diagnosed during the first trimester. Associated urological malformations were detected in 92% (n = 23) of the cases, while other malformations were detected in 36% (n = 9). Oligohydramnios or anyhydramnios were observed in 52% (n = 13) of the cases. Twelve (48%) fetuses were considered as having poor prognosis for renal function. Vesicocentesis with or without vesico-amniotic infusion were performed in 28% (n = 7) of the cases. Pregnancy outcome was surprisingly good, with only one case of prenatal death and survival rate of 96% (n = 24) of liveborn babies. Posterior urethral valve (PUV) (n = 9, 36%) was the most common etiology of the fetal megacystis, followed by persistent urogenital sinus (n = 2, 8%), Prune belly syndrome (n = 2, 8%) and bilateral vescico-ureteral reflux (VUR) (n = 2, 8%). Surgical or endoscopic procedures were performed in 75% (n = 18) of the cases. Six (24%) newborns presented with moderate/severe respiratory distress that requested invasive assisted ventilation. Three cases (n = 3, 12%) of perinatal death were observed due to severe impaired renal function. After a median follow-up of 29 months renal function was good in 79% (n = 19) of the cases. CONCLUSIONS: Fetal megacystis may underline a wide range of associated pathologies with the highest prevalence of urinary malformation. Optimal counseling of the involved parents requires a multidisciplinary approach to allow the best management during the pregnancy and the perinatal period. Despite the high risk of renal failure, lung hypoplasia, and severe associated anomalies, the outcome of fetuses with megacystis could be improved thanks to an appropriate perinatal diagnosis and neonatal management.