Outcomes in fetuses diagnosed with megacystis: Systematic review and meta-analysis

Obstructive or non-obstructive megacystis: a prenatal dilemma

Introduction

Diagnosis of prenatal megacystis has a significant impact on the pregnancy, as it can have severe adverse effects on fetal and neonatal survival and renal and pulmonary function. The study aims to investigate the natural history of fetal megacystis, to try to differentiate in utero congenital lower urinary tract obstruction (LUTO) from non-obstructive megacystis, and, possibly, to predict postnatal outcome.

Materials and methods

A retrospective single-center observational study was conducted from July 2015 to November 2023. The inclusion criteria were a longitudinal bladder diameter (LBD) >7 mm in the first trimester or an overdistended/thickened-walled bladder failing to empty in the second and third trimesters. Close ultrasound follow-up, multidisciplinary prenatal counseling, and invasive and non-invasive genetic tests were offered. Informed consent for fetal autopsy was obtained in cases of termination of pregnancy or intrauterine fetal demise (IUFD). Following birth, neonates were followed up at the same center. Patients were stratified based on diagnosis: LUTO (G1), urogenital anomalies other than LUTO ("non-LUTO") (G2), and normal urinary tract (G3).

Results

This study included 27 fetuses, of whom 26 were males. Megacystis was diagnosed during the second and third trimesters in 92% of the fetuses. Of the 27 fetuses, 3 (11.1%) underwent an abortion, and 1 had IUFD. Twenty-three newborns were live births (85%) at a mean gestational age (GA) of 34 ± 2 weeks. Two patients (neonates) died postnatally due to severe associated malformations. Several prenatal parameters were evaluated to differentiate patients with LUTO from those with non-LUTO, including the severity of upper tract dilatation, keyhole sign, oligohydramnios, LBD, and GA at diagnosis. However, none proved predictive of the postnatal diagnosis. Similarly, none of the prenatal parameters evaluated were predictive of postnatal renal function.

Discussion

The diagnosis of megacystis in the second and third trimesters was associated with live births in up to 85% of cases, with LUTO identified as the main cause of fetal megacystis. This potentially more favorable outcome, compared to the majority reported in literature, should be taken into account in prenatal counseling. Megacystis is an often misinterpreted antennal sign that may hide a wide range of diagnoses with different prognoses, beyond an increased risk of adverse renal and respiratory outcomes.

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.

Fetal Nephrology: A Quaternary Care Center Experience

Key Points

Specialized fetal centers see a highly complex subset of patients with CAKUT with a predominance of complex or syndromic disease. The mortality rate for fetuses with complex developmental anomalies and CAKUTs or bilateral CAKUTs is high. Prenatal genetic testing was highly variable with limited diagnostic utility while focused postnatal genetic testing had much higher yield.

Background

Congenital anomalies of the kidney and urinary tract (CAKUTs) represent 15%–20% of prenatally diagnosed abnormalities. Maternal characteristics, the frequency of various forms of kidney disease including CAKUT referred for prenatal nephrology consultation, and their perinatal outcomes are less well defined.

Methods

A retrospective chart review was performed of fetal CAKUT and other forms of kidney disease referred for prenatal nephrology consults at Texas Children's Hospital Fetal Center from January 1, 2012, to December 31, 2018.

Results

Two hundred seventeen prenatal nephrology consultations were performed during the study period, representing 4.7% of total Fetal Center referrals at a mean estimated gestational age of 25.2±5.7 weeks. Maternal characteristics were as follows: The mean age was 29.3±5.6 years; 14% had advanced maternal age; 10% had a family history of CAKUT or ESKD; 5% had diabetes mellitus; and 5% of pregnancies were in vitro fertilization-assisted. Fetal characteristics were as follows: 62.7% of fetuses were male and 16% had CAKUT associated with multiple congenital anomalies. The most common prenatal diagnoses were lower urinary tract obstruction in 71 (32.7%), unilateral renal agenesis or multicystic dysplastic kidney (MCDK) in 52 (24.9%), bilateral agenesis or MCDK in 22 (10.1%), and bilateral cystic kidney disease in 19 (8.8%). Seventy-six percent of patients received genetic counseling. One hundred forty-one (64.9%) patients had some form of prenatal genetic testing with a positivity rate of 5.7%. Postnatal characteristics were as follows: 61 (28.1%) patients were seen in prenatal consultation only and no follow-up was available. Of the remaining 156 pregnancies, 136 (86.3%) were viable and delivered at a mean gestational age of 35.2±3.8 weeks. Of these, 100 (64%) survived to discharge. Additional postnatal genetic testing was obtained in 27 infants with a positivity rate of 59%.

Conclusions

Overall perinatal mortality for this cohort as a whole was high (35.8%). While prenatal genetic testing had a limited diagnostic utility, targeted postnatal genetic testing had a much higher diagnostic yield.

Megacystis Associated With an Underlying ACTA2 Variant and Diagnosis of Multisystemic Smooth Muscle Dysfunction Syndrome: A Case Report

Fetal megacystis, or an enlarged fetal bladder, is most often attributed to embryological defects, occurring early in gestation. Recent investigations have demonstrated that the underlying etiology of megacystis may be more myriad than originally thought. We present the third reported patient with megacystis due to an ACTA2 Arg179 substitution variant causing Multisystemic Smooth Muscle Dysfunction Syndrome. We also provide a description of pediatric evaluation and follow up. The growing number of cases in which this ACTA2 variant has been identified in fetal megacystis suggests that molecular sequencing is an appropriate consideration, particularly prenatally, when other features of Multisystemic Smooth Muscle Dysfunction Syndrome cannot be detected.

Fetal Megacystis in the first trimester: Comparing management and outcomes between longitudinal bladder length groups

Fetal megacystis is a sonographic sign, defined in first trimester as a longitudinal bladder length (LBD)>7 mm. Different causes may be associated with megacystis and outcomes vary with many factors. There are no international guidelines on how to manage megacystis cases, and invasive testing is controversial when no other abnormalities are found. The main objective of this study is to compare etiologies, management and outcomes of fetuses with first trimester megacystis, specifically between groups of LBD≤15 mm and >15 mm. This is a retrospective cohort study of megacystis cases managed in a Prenatal Diagnosis Center, between January 2009 and September 2020. Descriptive and bivariate analysis were performed. We studied 43 fetuses: 67.4% with LBD≤15 mm and 32.6% with LBD>15 mm. We found an association between LBD and isolated Low Urinary Tract Obstruction (LUTO) (3.4% vs 64.3%; p<0.001) and with isolated megacystis (44.8% vs 0.0%; p = 0.001). No differences were seen regarding the presence of aneuploidies (31.0% vs 14.3%; p = 0.213). Invasive testing was performed in 93.0% of cases. Overall, we report 41.9% of live births, 39.5% of pregnancy termination and 18.6% of intrauterine fetal demise. We found a higher rate of live births in fetuses with LBD≤15 mm (55.2% vs 14.3%; p = 0.011). For a mean follow-up time of 20.6 months, we report one neonatal death and one case of renal insufficiency. In conclusion, isolated LUTO is more frequent if LBD>15 mm whereas isolated megacystis is more frequently found if LBD≤15 mm. If LBD≤15 mm, live birth rates and long-term outcomes seem to be enhanced.

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%.

Fetal Abdominal Cystic Masses: Clinical Spectrum and Prenatal Ultrasound Diagnosis

OBJECTIVES

To assess the diagnostic accuracy of prenatal ultrasound in detecting intra-abdominal masses derived from different systems.

METHODS

Fetuses diagnosed with abdominal cystic masses during prenatal ultrasound were included in this study. The basic biological parameters of the fetus were measured in addition to the location of the cystic mass, the shape and size of the mass, the thickness of the cystic wall, dynamic changes, blood supply of the mass, and relationship with the surrounding organs. Whether the fetus also had other malformations was also recorded. Clinical data were followed up to 6 months after birth.

RESULTS

Between January 1, 2019 and January 1, 2021, 247 fetuses were included, most of which contained renal/adrenal cystic masses (n = 93, 37.7%), followed by hepatobiliary system (n = 48, 19.4%), gastrointestinal tract (n = 45, 18.2%), reproductive system (n = 29, 11.7%), and ureter and bladder (n = 27, 10.9%) masses, respectively. The minority were masses in other systems (n = 5, 2.0%). The overall prenatal diagnostic accuracy was 90.7%. There were significant differences in each system (χ²  = 13.0, P < .05). The most accurate type of cyst was diagnosed from renal and adrenal (96.8%) cases, followed by ureter and bladder (92.6%) cases, gastrointestinal tract (91.1%), hepatobiliary system (85.4%), and reproductive system (82.8%). Other systems (60.0%) were the least accurate type.

CONCLUSIONS

A wide variety of cystic masses can be accurately detected in the fetal abdomen, and most of these lesions can be accurately diagnosed during pregnancy.

Characteristics of fetal physiological and pathological uterine effusion observed on prenatal ultrasonography: a case report

Background

The prenatal detection rate of fetal uterine effusion is very low, and current case reports mainly focus on pathological hydrometrocolpos. We presented two cases of fetal physiological uterine effusion with different ultrasonic characteristics and compared them with one case of hydrometrocolpos with the hope of identifying strategies to reduce misdiagnosis of fetal uterine effusion.

Case presentation

This paper reports the cases of two female fetuses with abnormal pelvic echoes in the third trimester, referred to a tertiary center to be screened for suspected pelvic teratoma and cystic mass, respectively. Ultrasound consultation revealed fetal uterine effusion. The two fetuses were delivered at our hospital after a full term. Re-examining the uterus and adnexa of the neonates revealed that the uterine effusion had subsided naturally. Another female fetus had a large cystic mass in the pelvic cavity in the third trimester, and prenatal examination indicated fetal hydrometrocolpos. The fetus was delivered at our hospital after a full term. The hydrometrocolpos existed even after birth. After consultation with a neonatal surgeon and gynecologist, the newborn was diagnosed with congenital imperforate hymen with hydrometrocolpos. Hymen puncture and open drainage led to a good prognosis.

Conclusions

Prenatal ultrasonography plays an important role in diagnosing and differentiating between physiological and pathological fetal uterine effusion. It can help reduce misdiagnoses that can lead to incorrect clinical decisions.

Postnatal Management in Congenital Lower Urinary Tract Obstruction With and Without Prenatal Vesicoamniotic Shunt

Purpose: Congenital lower urinary tract obstruction (cLUTO) includes a heterogeneous group of conditions caused by a functional or mechanical outlet obstruction. Early vesicoamniotic shunting (VAS) possibly reduces the burden of renal impairment. Postpartum, pediatric urologists are confronted with neonates who have a shunt in place and a potentially impassable urethra with a narrow caliber. Early management of these patients can be challenging. Here, we would like to share the approach we have developed over time. Materials and Methods: We conducted a single-center retrospective analysis from 2016 to 2020 and included all patients diagnosed with cLUTO. Data focusing on time point and type of intervention was collected. Furthermore, patients with temporary diversion via a percutaneous VAS were selected for a more detailed review. Results: In total, 71 cases of cLUTO were identified during the study period. Within this group, 31 neonates received postnatal management and surgical intervention in our center. VAS was performed in 55% of these cases (N = 17). The postnatal treatment varied between transurethral or suprapubic catheterization and early Blocksom vesicostomy. In five infants with VAS, the urinary drainage was secured through the existing VAS by inserting a gastric tube (N = 1) or a 4.8 Fr JJ-stent (N = 4). To our knowledge, this is the first report of a stent-in-stent scheme, which can remain indwelling until the definite treatment. Conclusion: Having a secure urine drainage through a VAS allows the often premature infant to grow until definite surgery can be performed. This avoids placing a vesicostomy, which requires anesthesia.

Perinatal outcome and prognostic factors of fetal megacystis diagnosed at 11-14 week's gestation

OBJECTIVES

To evaluate aneuploidy rate, prognostic factors, and perinatal outcomes following a diagnosis of fetal megacystis at 11-14 week's gestation.

METHODS

A retrospective study of first trimester fetal megacystis from 2010 to 2020 was performed, including ultrasound finding, perinatal outcomes, pathology reports, genetic tests, and neonatal investigations.

RESULTS

A total of 98 cases of first trimester fetal megacystis was identified with an overall aneuploidy rate of 12%. There were 54% live births and 46% fetal losses including spontaneous fetal demise and elective termination. Among the 45 fetal losses, 64% had additional structural abnormalities at index ultrasound and final diagnoses were achievable in 64% cases. Among the 53 livebirths, additional ultrasound abnormalities were detected in only 1 fetus and spontaneous resolution of megacystis was detected in 96% of cases. The two cases where fetal megacystis persisted had major postnatal diagnoses: cloacal malformation and megacystis-microcolon-intestinal hypoperistalsis syndrome, respectively. Our data showed LBD ≥ 12 mm was the best individual predictor of adverse perinatal outcome and all 11 cases of lower urinary tract obstruction (LUTO) were diagnosed in fetuses with LBD ≥ 12 mm.

CONCLUSIONS

First trimester ultrasound provides important prognostic factors and isolated megacystis <12 mm is associated with a positive outcome.