Prenatal Identification and Confirmation of Jacobsen Syndrome: A Series of Four Cases.

Jacobsen syndrome (JBS) is a rare contiguous gene disorder caused by partial deletion of the distal part of the long arm of chromosome 11. Only a few prenatal cases of JBS have been reported, and data on prenatal ultrasonographic findings are relatively scarce. We analysed four cases of JBS diagnosed prenatally in our centre. All four cases received ultrasound examination in the second trimester. Cardiac defects and intrauterine growth retardation (IUGR) were present in three cases. Ventriculomegaly, shortened femur length and pyelectasis were found in two cases. According to the literature, IUGR, pyelectasis and ventriculomegaly are common prenatal phenotypes of JBS. In addition, cardiac defects, trigonocephaly and shortened femur are also found. Our presentation of these cases provides more ultrasonic information for the prenatal diagnosis of this rare disease. Key Words: Ultrasound, Prenatal diagnosis, Jacobsen syndrome, Chromosomal abnormalities, Fetal malformation.

Prenatal diagnosis of a 1.651-Mb 19q13.42-q13.43 microdeletion in a fetus with micrognathia and bilateral pyelectasis on prenatal ultrasound.

OBJECTIVE: We present prenatal diagnosis of a de novo 1.651-Mb 19q13.42-q13.43 microdeletion in a fetus with micrognathia and bilateral pyelectasis on prenatal ultrasound. CASE REPORT: A 32-year-old woman underwent amniocentesis at 28 weeks of gestation because of fetal micrognathia and bilateral pyelectasis on prenatal ultrasound. Amniocentesis revealed a karyotype of 46,XX. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr 19q13.42q13.43 (55,028,722-56,680,564) × 1.0 [GRCh37 (hg19)] or a 1.651-Mb microdeletion encompassing 44 Online Mendelian Inheritance in Man (OMIM) genes including NLRP7, GP6, TNNT1, TNNI3 and DNAAF3. The parents did not have such a deletion and decided to continue the pregnancy. At 37 weeks of gestation, a 2560-g female baby was delivered by cesarean section because of oligohydramnios and decreased fetal movements. The baby manifested cleft palate, micrognathia and retrognathia at birth. She was doing well at age three months. Her body weight was 5.3 Kg (15th-25th centile), and body length was 59.2 cm (25th-50th centile). Renal sonogram showed bilateral mild pelvic dilation. She manifested no psychomotor retardation and no other internal organ abnormalities during pediatric follow-ups. CONCLUSION: A 19q13.42-q13.43 microdeletion can be associated with micrognathia, retrognathia, cleft palate and bilateral pyelectasis at birth.

Moderate and severe fetal pyelectasis: Correlation between prenatal aspects and postnatal outcome.

BACKGROUND: Renal pelvic dilatation (RPD) is a frequent finding in fetal ultrasound. The aim of the study is to correlate the prenatally detected moderate and severe pyelectasis with the postnatal outcome. METHODS: A retrospective analysis involving 90 cases of prenatally detected moderate and severe RPD referred to our prenatal diagnosis centre with 18 months of urological follow-up. Prenatal ultrasound was correlated with postnatal renal function, assessed by plasmatic creatinine and/or renal scintigraphy performed before surgery. RESULTS: Cases were divided between two groups according to postnatal management: group A including 35 newborns (38.9%) that needed surgical treatment and group B with 55 patients (61.1%) who were managed conservatively. The group A presented higher median RPD (18 mm, IQR 12-25 mm) compared to the group B (11 mm, IQR 10-14 mm). The most common anomaly detected within group A was pelvi-ureteric junction (PUI) obstruction (43%). Within group B 32 cases (58%) showed spontaneous resolution of hydronephrosis during postnatal follow up. In case of moderate pyelectasis the risk of postnatal surgery was 25% and raised to 60% for severe RPD. In our study, 29 newborns showed pathologic scintigraphies: 25 required surgery while 4 did not find indication for surgery due to ipsilateral renal function irreversible damage. 6 patients had high creatinine level (>0.6 mg/dl). 35 cases out of 90 (39%) developed monolateral irreversible renal function impairment. CONCLUSION: Moderate and severe RPD are often correlated with postnatal renal damage, therefore a close multidisciplinary follow-up is required. Prenatal scanning is highly predictive of postnatal outcome and can address properly the prenatal counseling.

Prenatal natural history of isolated fetal mild bilateral pyelectasis.

OBJECTIVE: To analyze the prenatal outcomes in a cohort of fetuses with mild bilateral pyelectasis and determine whether performing serial ultrasounds is a good follow-up strategy. METHODS: A prospective longitudinal study was conducted on 62 fetuses with mild bilateral pyelectasis. Fetal mild bilateral pyelectasis was considered when the renal pelvis measured (in millimeters) ≥5.0 to 10.0, ≥7.0 to 10.0, and ≥10.0 to 15 at ≤23 weeks 6 days, 24 to 31 weeks 6 days, and ≥32 weeks, respectively, with no uretero-calyceal dilatation. Ultrasounds were performed every 3 weeks to assess whether the mild bilateral pyelectasis regressed, remained unchanged (Group 1) or progressed (Group 2). RESULTS: Group 1 consisted of 53 fetuses (85.4%), and progression was observed in 9 cases (Group 2, 14.6%). The initial renal pelvis diameter was significantly larger in fetuses with progression (p=0.028). Statistically significant differences in the renal pelvis diameter were also found at weeks 31 and 35 for both kidneys (p<0.05). The cases requiring intrauterine procedures or early delivery were not observed. CONCLUSION: Fetal mild bilateral pyelectasis with no calyceal dilatation is a benign condition that can be managed in the postnatal period. The initial renal pelvis diameter and the diameter in week 31 or 35 were valuable parameters for identifying cases that would eventually need specific postnatal procedures.

Prenatal natural history of isolated fetal mild bilateral pyelectasis

OBJECTIVE: To analyze the prenatal outcomes in a cohort of fetuses with mild bilateral pyelectasis and determine whether performing serial ultrasounds is a good follow-up strategy. METHODS: A prospective longitudinal study was conducted on 62 fetuses with mild bilateral pyelectasis. Fetal mild bilateral pyelectasis was considered when the renal pelvis measured (in millimeters) ≥5.0 to 10.0, ≥7.0 to 10.0, and ≥10.0 to 15 at ≤23 weeks 6 days, 24 to 31 weeks 6 days, and ≥32 weeks, respectively, with no uretero-calyceal dilatation. Ultrasounds were performed every 3 weeks to assess whether the mild bilateral pyelectasis regressed, remained unchanged (Group 1) or progressed (Group 2). RESULTS: Group 1 consisted of 53 fetuses (85.4%), and progression was observed in 9 cases (Group 2, 14.6%). The initial renal pelvis diameter was significantly larger in fetuses with progression (p=0.028). Statistically significant differences in the renal pelvis diameter were also found at weeks 31 and 35 for both kidneys (p<0.05). The cases requiring intrauterine procedures or early delivery were not observed. CONCLUSION: Fetal mild bilateral pyelectasis with no calyceal dilatation is a benign condition that can be managed in the postnatal period. The initial renal pelvis diameter and the diameter in week 31 or 35 were valuable parameters for identifying cases that would eventually need specific postnatal procedures.

The Impact of Gestational Age at Delivery on Urologic Outcomes for the Fetus with Hydronephrosis.

OBJECTIVE: Compare short-term urologic outcomes with delivery timing in fetuses with severe hydronephrosis. METHODS: An ultrasound database was queried for severe hydronephrosis. Cases were categorized into late preterm/early term (36 0/7 - 38 6/7 weeks) and full term (39 0/7 weeks or greater) groups. Baseline characteristics were compared using standard statistical methods. Spearman's correlation analysis was performed for grade and severity of hydronephrosis on first postnatal ultrasound with gestational age at delivery. RESULTS: Of 589 cases, 79 (33 late preterm/early term, 46 full term) met criteria. Baseline characteristics were similar between groups. Spearman's correlation coefficients (rs) indicated that increased postnatal Society for Fetal Urology grade, rs= -0.26 (95% CI [-.48, -.002]), and severity of hydronephrosis, rs= -0.39 (95% CI [-.59, -.14]), both correlated with earlier delivery. CONCLUSION: Late preterm/early term delivery resulted in worse short-term postnatal renal outcomes. Unless otherwise indicated, delivery for fetal hydronephrosis should be deferred until 39 weeks.

Ultrasound screening: Status of markers and efficacy of screening for structural abnormalities.

Aneuploidy is a major cause of perinatal morbidity and mortality and can have a significant impact on expecting parents and their families. With early screening and diagnosis it is important to be able to educate parents regarding the potential impact of the diagnosis. This knowledge allows parents the opportunity to consider management options early in the pregnancy, permitting more time to mentally and emotionally prepare both for the course of the pregnancy, and after the birth of the child should the pregnancy continue. Prenatal screening provides pregnant women a non-invasive risk assessment for the most common aneuploidies. Those who are considered "high-risk" then have the option for additional diagnostic (invasive) testing. Prior to the 1980s, prenatal screening consisted of risk assessment through maternal age; however, with the advent of maternal serum biochemical analysis and ultrasound, the field of prenatal screening developed significantly. As biochemical and sonographic advances continued into the 1990s, the emphasis shifted to risk assessment in the first trimester, with the combination of maternal serum analytes and sonographic evaluation of the nuchal translucency.(1) Within the last decade, the introduction of non-invasive screening (NIPT/S) has shown great impact on the expansion and evolving practice of prenatal screening. Although in many places the standard for prenatal testing continues to include maternal serum analytes and sonographic evaluation, the role of each marker alone and in combination remains important. In the era of increasingly available screening tests, especially with NIPT/(NIPS), this article attempts to review the current role of ultrasound in prenatal care and elucidate the role of ultrasound markers in prenatal screening.

Comparison of conventional versus three-dimensional ultrasound in fetal renal pelvis measurement and their potential prediction of neonatal uropathies.

OBJECTIVE: To establish a threshold value for fetal renal pelvis dilatation measured by automatic volume calculation (SonoAVC) in the third trimester of pregnancy to predict neonatal uropathies, and to compare these results with conventional antero-posterior (AP) measurement, fetal kidney 3D volume and renal parenchymal thickness. METHODS: In a prospective cohort study, 125 fetuses with renal pelvis AP diameter of ≥5 mm both at 20 weeks of gestation and in the third trimester, underwent an additional 3D volume measurement of the fetal kidney in the third trimester. Receiver operating characteristic (ROC) curves for establishing threshold values for fetal renal pelvis volume, AP measurement, fetal kidney volume and renal parenchymal thickness to predict neonatal uropathies were analyzed. Also, sensitivity, specificity, area under the curve (AUC) and likelihood ratios were calculated. RESULTS: A cut-off point of 1.58 cm³ was identified in the third trimester of pregnancy (AUC 0.865 (95% CI 0.789-0.940), sensitivity 76.3%, specificity 87.4%, LR+ 6.06, LR- 0.27) for measurements with SonoAVC. A cut-off value of 11.5 mm was established in the third trimester of pregnancy (AUC 0.828 (95% CI 0.737-0.918), sensitivity 71.1%, specificity 85.1%, LR+ 4.77, LR- 0.34) for the conventional AP measurement. A cut-off point for fetal kidney volume was calculated at 13.29 cm³ (AUC 0.769 (95% CI 0.657-0.881), sensitivity 71%, specificity 66%, LR+ 2.09, LR- 0.44). For renal parenchymal thickness, a cut-off point of 8.4 mm was established (AUC 0.216 (95% CI 0.117-0.315), sensitivity 31.6%, specificity 32.6%, LR+ 0.47, LR- 2.10). CONCLUSION: This study demonstrates that 3D fetal renal pelvis volume measurements and AP measurements both have a good and comparable diagnostic performance, fetal renal volume a fair accuracy and renal parenchymal thickness a poor accuracy in predicting postnatal renal outcome.

Sonographic depiction of fetal ureters.

AIMS: Classic literature states that the fetal ureter should not be visible unless dilated. Our main objective was to produce an effective, reproducible method for fetal ureter depiction during an anatomic survey. Our secondary objectives were to record the frequency of visible ureters among normal fetuses and among fetuses with mild pyelectasis and also to determine the diameter of the sonographically demonstrated ureter. SUBJECTS AND METHODS: One hundred twenty consecutive fetuses undergoing a second trimester scan were enrolled in the study. Ninety-nine anatomically normal fetuses and 21 fetuses with isolated mild pyelectasis (antero-posterior renal pelvis diameter of ≥4 mm and <7 mm) were subjected to a detailed anatomical survey. One hundred twenty fetuses were analyzed bilaterally. RESULTS: A total of 154 (64.2%) ureters were depicted. In the first group 123 (62.1%) ureters, in the second group 31 (73.8%) ureters were depicted (p = 0.06). The diameters of the ureters ranged from 0.4 to 2.7 mm. The majority (n = 80) (52%) were visualized at both proximal and distal segments. CONCLUSIONS: Our study demonstrates that the ureter can be demonstrated in normal fetuses and in fetuses with mild pyelectasis. Ureteral depiction is likely to be composed of normal transient passage of urine associated with peristalsis and is not always a pathological finding.

Controversial ultrasound findings in mid trimester pregnancy. Evidence based approach.

Mid trimester fetal anatomy scan is a fundamental part of routine antenatal care. Some U/S soft markers or controversial U/S signs are seen during the scan and create some confusion regarding their relation to fetal chromosomal abnormalities. Example of these signs: echogenic focus in the heart, echogenic bowel, renal pyelectasis, ventriculomegaly, polydactely, club foot, choroid plexus cyst, single umbilical artery. We are presenting an evidence based approach from the literature for management of these controversial U/S signs.

Assessment of in-utero venlafaxine induced, ROS-mediated, apoptotic neurodegeneration in fetal neocortex and neurobehavioral sequelae in rat offspring.

Venlafaxine (VEN), a serotonin and noradrenaline reuptake inhibitor is being used as a drug of choice for treating clinical depression even during pregnancy. It is an important therapeutic option in the treatment of perinatal depression, but the effects of VEN on fetus and the newborn are uncertain. Therefore, present study was undertaken to investigate the safety of in-utero exposure to VEN in terms of developmental neurotoxicity and neurodegenerative potential by using prenatal rat model. The selected doses of VEN (25, 40 and 50mg/kg) were administered to pregnant rats from GD 5 to 19 through oral gavage. The fetal brains were dissected and processed for histopathological measurements of neocortical thickness that showed significant reduction. Considering vulnerability of immature brain to free radical injury, VEN exposed neocortices were tested for reactive oxygen species (ROS) levels which were significantly increased. As ROS play important role in the initiation of apoptotic mechanisms, we explored for in situ detection of apoptosis by confocal microscopy that showed enhanced apoptosis including chromatin condensation which was further reconfirmed by electron microscopy. Substantially increased levels of pro-apoptotic protein Bax and decreased levels of anti-apoptotic protein Bcl2 as shown by western blotting also supported the increased neuro-apoptotic degeneration. For further correlation of these findings, prenatally VEN exposed young-adult rat offspring were assessed for open field exploratory behavior that showed increased anxiety-like and stereotypic responses indicating disturbed neurobehavioral pattern. The study concludes that prenatal VEN exposure may primarily enhance ROS generation that plays a key role in regulating release of proapoptotic factors from mitochondria and thereby enhancing apoptotic neurodegeneration that affect proliferation, migration and differentiation of cells, resulting in neuronal deficits manifested as long term neurobehavioral impairments.

Influence of second-trimester ultrasound markers for Down syndrome in pregnant women of advanced maternal age.

The objective of the present study was to evaluate the influence of second-trimester ultrasound markers on the incidence of Down syndrome among pregnant women of advanced maternal age. This was a retrospective cohort study on 889 singleton pregnancies between the 14th and 30th weeks, with maternal age ≥ 35 years, which would undergo genetic amniocentesis. The second-trimester ultrasound assessed the following markers: increased nuchal fold thickness, cardiac hyperechogenic focus, mild ventriculomegaly, choroid plexus cysts, uni- or bilateral renal pyelectasis, intestinal hyperechogenicity, single umbilical artery, short femur and humerus length, hand/foot alterations, structural fetal malformation, and congenital heart disease. To investigate differences between the groups with and without markers, nonparametric tests consisting of the chi-square test or Fisher's exact test were used. Moreover, odds ratios with their respective 95% confidence intervals were calculated. Out of the 889 pregnant women, 131 (17.3%) presented markers and 758 (82.7%) did not present markers on the second-trimester ultrasound. Increased nuchal fold (P < 0.001) and structural malformation (P < 0.001) were the markers most associated with Down syndrome. The presence of one marker increased the relative risk 10.5-fold, while the presence of two or more markers increased the risk 13.5-fold. The presence of markers on the second-trimester ultrasound, especially thickened nuchal fold and structural malformation, increased the risk of Down syndrome among pregnant women with advanced maternal age.

Second trimester ultrasound markers of fetal aneuploidy.

Although it is widely accepted that the best time to screen for chromosomal abnormalities is the first trimester, ultrasound evaluation of the fetus in the second trimester has also been shown to be useful for this purpose. A multitude of markers of varying strength has been developed over the past 30 years. In addition, the optimal time to diagnose fetal anomalies with confidence is also the mid second trimester. Therefore, performance of obstetrical ultrasound at this point in gestation continues to be an important component of prenatal care.

Second-trimester fetal genetic ultrasonography to detect chromosomal abnormalities

Genetic ultrasonography refers to the evaluation of risk of chromosomal abnormalities via various soft sonographic markers. Although the maternal serum test is the primary screening method for chromosomal abnormalities, genetic ultrasonography is also widely used and can help increase detection rates. To date, many soft markers, including choroid plexus cysts, echogenic intracardiac foci, mild ventriculomegaly, nuchal fold thickening, echogenic bowel, mild pyelectasis, short femur and humerus length, and absent or hypoplastic nasal bone, have been reported. An aberrant right subclavian artery was the most novel soft marker introduced. Because these soft markers involve diverse relative risks of chromosomal abnormalities, it is difficult to apply them to clinical practice. To optimize the efficacy of genetic ultrasonography, it is important to understand the precise relative risks of chromosomal abnormalities innumerous soft markers and integrate these risks with each other and the results of maternal serum screening.

Post-natal ultrasound morpho-dynamic evaluation of mild fetal hydronephrosis: a new management.

BACKGROUND: Fetal hydronephrosis is the most common anomaly detected on antenatal ultrasound examination, affecting 1-5% pregnancies. AIM: A new management in mild antenatal renal pelvis dilatation (ARPD), using a technique based on both morphological and dynamical evaluation. MATERIALS AND METHODS: Prospective study conducted during a 36-months period in 180 consecutive newborns referred as having mild ARPD. Examinations consisted in a morphological ultra-sound (US) scan evaluating antero-posterior diameter, renal parenchyma, ureteral evidence and pelvis morphology and, subsequently, a dynamic evaluation to analyze any change of the urinary tract during bladder voiding. All children were evaluated both at 3rd day and 1 month after birth. They were divided among those with negative examinations and those with at least one positive scan, trying to discriminate within the latter, children suspected for transient pyelectasis from those suspected for organic pathology. RESULTS: 108 patients had normal US findings both at birth and at 1 month. The remaining 72 babies had at least one abnormal US examination: 54 were suspected for transient pyelectasis, while 18 suspected for organic pathology. At the end of the study, 61 babies (33.9%) had final diagnosis of transient pyelectasis and 11 cases (6.1%) of organic pathology. At one month the dynamic pattern of US findings had the highest negative predictive value, while renal parenchyma evaluation has the highest accuracy. CONCLUSIONS: a dynamic US approach allowed to better select among infants suspected for transient pyelectasis from those suspected for organic pathology, avoiding unnecessary and invasive examinations in healthy babies.

Isolated fetal pyelectasis and the risk of Down syndrome: a meta-analysis.

OBJECTIVES: We performed a meta-analysis to examine the performance of second-trimester (14-24 weeks' gestation) isolated fetal pyelectasis as a marker for trisomy 21 and to calculate its associated weighted pooled likelihood ratios. METHODS: PubMed, Ovid MEDLINE and Cochrane databases were searched using the terms 'pyelectasis' and 'pelviectasis'. Studies were included if fetuses with isolated pyelectasis were reported separately from fetuses with other soft markers of aneuploidy and/or structural anomalies and if knowledge of the fetal karyotype was unknown at the time of ultrasound examination. RESULTS: Individual study statistics were pooled as weighted positive and negative likelihood ratios with 95% CIs, using a random-effects model. Ten observational studies were included (2148 cases of isolated pyelectasis). Isolated fetal pyelectasis was defined in seven out of 10 studies as a renal pelvis anteroposterior diameter of ≥ 4 mm. Isolated fetal pyelectasis was associated with pooled positive and negative likelihood ratios of 2.78 (95% CI, 1.75-4.43) and 0.99 (95% CI, 0.98-1.00), respectively. CONCLUSIONS: The detection of isolated fetal pyelectasis on mid-trimester ultrasound is associated with an increased likelihood of trisomy 21. If the finding of isolated fetal pyelectasis is used to adjust the trisomy 21 risk from maternal serum screening tests, a positive likelihood ratio of 2.78 should be used in the calculation.

Prenatal anteroposterior pelvic diameter cutoffs for postnatal referral for isolated pyelectasis and hydronephrosis: more is not always better.

PURPOSE: Congenital hydronephrosis and isolated pyelectasis are frequently diagnosed by prenatal ultrasound. About 80% of cases resolve spontaneously in early childhood. Currently there is no agreed on protocol for prenatal followup. Most clinicians use a renal pelvis anteroposterior diameter of greater than 4 mm as a threshold for identifying isolated pyelectasis and hydronephrosis at 33 weeks of gestation or anteroposterior diameter greater than 7 mm at 40 weeks of gestation. We sought to determine a fetal renal pelvis diameter cutoff at 20 and 30 weeks of gestation that would be able to predict significant nephron uropathy requiring surgery. MATERIALS AND METHODS: Our protocol included 2 prenatal ultrasounds at 20 and 30 weeks of gestation and 3 postnatal ultrasounds at ages 1, 6 and 12 months. Between January 2009 and December 2011 we evaluated 149 prenatal cases (130 males, 19 females) of isolated pyelectasis and 41 cases (28 males, 13 females) of hydronephrosis with a renal pelvis anteroposterior diameter of greater than 4 mm at 20 weeks of gestation. RESULTS: For isolated pyelectasis we identified cutoffs of 6 mm at 20 weeks of gestation (100% sensitivity, 84.3% specificity) and 10 mm at 30 weeks of gestation (100% sensitivity, 91.9% specificity). For hydronephrosis we identified cutoffs of 10 mm at 20 weeks of gestation (100% sensitivity, 86.1% specificity) and 12 mm at 30 weeks of gestation (100% sensitivity, 66.7% specificity). CONCLUSIONS: Using these thresholds, we could avoid a significant number of followup ultrasounds in the prenatal and postnatal periods, as well as invasive postnatal tests (ie voiding cystourethrography and mercaptoacetyltriglycine scintigraphy) without missing even a single case of obstructive nephropathy requiring surgery.

Outcome of isolated fetal renal pyelectasis diagnosed during midtrimester screening ultrasound and cut-off value to predict a persistent or progressive pyelectasis in utero.

AIM: To define a better cut-off value of the renal pelvis anteroposterior diameter (RPAPD) to predict persistent or progressive pyelectasis during pregnancy. METHODS: We retrospectively reviewed 8873 women whose fetal RPAPD was measured. Midtrimester pyelectasis was defined as a RPAPD of ≥4 mm. Persistent/progressive pyelectasis was defined as a RPAPD of ≥10 mm before delivery. A RPAPD cut-off value to predict a persistent/progressive pyelectasis was determined by receiver operating characteristic curve analysis. RESULTS: Among 249 isolated cases of pyelectasis, persistent/progressive pyelectasis was found in 6.9% before delivery. The midtrimester RPAPD cut-off value that best predicted persistent/progressive pyelectasis before delivery was ≥6 mm with sensitivity, specificity, positive and negative predictive values of 64.3%, 88.7%, 30.0%, and 97.1%, respectively. CONCLUSIONS: Although most cases of midtrimester fetal pyelectasis regress to normal during pregnancy, those with a RPAPD of ≥6 mm in the midtrimester are at higher risk for persistent or progressive pyelectasis.

Natural history of fetal renal pyelectasis.

OBJECTIVE: To follow the natural progression of fetal renal pyelectasis detected in the mid second trimester ultrasound in an unselected obstetric population. STUDY DESIGN: Single-centered, retrospective study that included all level II ultrasounds done from Jan 2008 to Dec 2009. The initial level II ultrasound was done in the mid second trimester. The renal pyelectasis detected on the antenatal ultrasound (AUS) was classified as mild (5-7 mm), moderate (7.1-9 mm), or severe (>9.1 mm). Postnatal outcomes were classified as "Resolved", "Improving", or "Worsened". RESULTS: Ninety-eight cases of fetal renal pyelectasis were detected. Sixteen patients were excluded. Of the remaining 82 cases of fetal pyelectasis, 32 (39%) were mild, 21 (25.6%) moderate, and 29 (35.4%) severe. In 74 (90.2%) infants, pyelectasis resolved, remained stable, or improved in the postnatal ultrasound. In eight (9.8%) infants, pyelectasis worsened. CONCLUSION: Totally, 90.2% of pyelectasis detected on AUS resolved spontaneously, remained stable or improved. The magnitude of fetal renal pyelectasis did not correlate with postnatal outcome. All fetal renal pyelectasis ≥ 5 mm detected on the mid second trimester ultrasound should be followed antenatally. Those fetuses with persistent pyelectasis should be evaluated after birth and followed until resolution of pyelectasis or until a diagnosis is obtained.