Fetal pyelectasis: comparison of postnatal renal pathology with unilateral and bilateral pyelectasis

When are amniotic fluid viral PCR studies indicated in prenatal diagnosis?

OBJECTIVE

To determine which prenatal ultrasound findings indicate the need to also obtain PCR studies for viral genome in women undergoing midtrimester amniocentesis.

METHODS

This was a retrospective observational study on women that underwent amniotic fluid karyotyping and viral PCR testing for history or ultrasound based indication. Amniotic fluid was tested for adenovirus, cytomegalovirus, respiratory syncytial virus, enterovirus, Epstein-Barr virus, and parvovirus B19 using multiplex PCR study with multiple appropriate controls. Ultrasound findings were coded as normal or abnormal with 34 categories of ultrasound abnormality stratified into 18 subgroups. Relationships between these subgroups and karyotype/PCR results were tested by Pearson chi-square method or Fisher's exact test and overall logistic regression analysis.

RESULTS

Amniotic fluid samples from 1191 patients were obtained for the study. Abnormal karyotype was detected in 5.4% of cases (64/1191), and PCR was positive in 6.5% of cases (77/1191). Abnormal fetal ultrasonographic findings were observed in 28.4% of cases (338/1191). There was an association between intrauterine growth restriction, nonimmune hydrops fetalis, hand/foot anomalies or neural tube defects (NTDs), and PCR positivity. NTDs were associated with PCR positivity in fetuses with normal karyotype and nuchal thickening, cardiac or ventral wall defects were specifically associated with aneuploidy.

CONCLUSION

Amniotic fluid viral PCR testing should be considered for fetuses with intrauterine growth restriction, nonimmune hydrops fetalis, hand/foot anomalies, or NTDs. After aneuploidy is excluded, NTDs are associated with PCR positivity.

Late second trimester assessment of pyelectasis (SERP) to predict pediatric urological outcome is improved by checking additional features

OBJECTIVE

Counseling for pyelectasis in the late 2nd trimester is usually based only upon assessing the antero-posterior (AP) width of the renal pelvis. We hypothesized that checking additional features would better predict postnatal outcome.

STUDY DESIGN

Ultrasound (<24 weeks gestational age (GA)) and newborn outcome data collected prospectively since 1986 were analyzed retrospectively. We determined if outcome predictions in kidneys with a sonographically evident renal pelvis (SERP), which had evaluation of additional features (e.g., renal and bladder lengths, presence of a dilated ureter or dilated calyces) are more accurate than those that did not have these features.

RESULTS

There were 286 fetuses studied with pediatric follow-up of an average of 6.5 years. There were 338 exams providing 459 ultrasound images with SERP. Additional features were not assessed in 183 fetuses; however 103 fetuses did have evaluation of additional features. These features were categorized as abnormal (92) or as normal (11). Fetuses with SERP and abnormal additional features required extensive urological care or died 6.1 times more often than fetuses in which additional features were not examined (p < 0.001) and 12.9 times more often when additional features were normal (p < 0.001).

CONCLUSION

Fetal kidneys with SERP (<24 weeks GA) and an abnormal additional ultrasound feature had extensive pediatric care significantly more often than when such features were not evaluated or were normal.

Ultrasonographic findings of fetal aneuploidies in the second trimester--our experiences

OBJECTIVES

The aim of this study was to determine the incidence of ultrasound findings in common fetal chromosomal defects on a relatively large series coming out from one institution. We also tried to evaluate possible clusters of ultrasound signs of major chromosomal defects.

METHODS

Of the 22,150 fetal karyotypings, 514 abnormal karyotypes (2.3%) were diagnosed prenatally between 1990 and 2004. Of them, 374 were further evaluated for abnormal ultrasound signs in this study. These represented the major chromosomal defects of Down syndrome (n = 207), trisomy 18 (n = 70), trisomy 13 (n = 28) and Turner syndrome (n = 69).

RESULTS

The incidences of major structural defects and minor anomalies were evaluated then sonographic signs with the highest incidences were established in each of the major chromosomal defects. In fetuses with trisomy 13, besides cardiac defects, the most frequently seen structural abnormalities were central nervous system anomalies and facial anomalies. In fetuses with trisomy 18 and trisomy 21, cardiac anomalies were the most common structural sonographic features, whereas the most common findings were hygroma colli and fetal hydrops in fetuses with Turner syndrome. As far as minor anomalies are concerned, increased nuchal fold was the most predictive marker of each major aneuploidy. Choroid plexus cysts were more common in trisomy 18, whereas echogenic intracardiac foci were more frequently detected in fetuses with trisomy 13 and trisomy 21.

CONCLUSION

This study may help to select the most predictive components of the genetic sonogram which may assist the counseling of women for the actual risk of the major chromosomal abnormalities.

Mild pyelectasis diagnosed by prenatal ultrasound is not a predictor of urinary tract morbidity in childhood

OBJECTIVES

To determine whether children with prenatally diagnosed mild pyelectasis have more urinary tract morbidity during childhood than children without this finding.

METHODS

Case-control study in children with pyelectasis (anteroposterior diameter of the fetal renal pelvis of 5-10 mm). A validated questionnaire was sent to the parents of 208 cases and 416 matched controls.

RESULTS

The questionnaire was returned by 146 cases and 250 controls. There was a male predominance in the case group (p = < 0.0001). There was no difference in voiding habits or in prevalence of urinary tract infections (UTI). The prevalence of UTI was high: 11.6% in cases and 10.0% in controls. The only difference was a higher prevalence of constipation in the case group (p = 0.003). Postnatally, 41 children had an ultrasound examination and 16 were referred to a paediatrician or urologist: 3 had persisting pyelectasis, 3 had a recurrent UTI and 1 required surgery (a pyeloplasty). Four of the controls were referred to a paediatrician or urologist: 3 had recurrent UTI and 1 had urinary incontinence.

CONCLUSION

Children with a mild fetal pyelectasis do not have more urinary tract morbidity during childhood than children without this finding. Therefore, there seems to be no need for additional investigation after birth.

Prenatal sonographic findings in 207 fetuses with trisomy 21

OBJECTIVE

The objective was to evaluate the contribution of second trimester ultrasound examination to the prenatal diagnosis of trisomy 21 in 207 fetuses with this aneuploidy. The type and frequency of abnormal sonographic findings were determined. Possible multiple malformation patterns, characteristic of trisomy 21 were sought.

STUDY DESIGN

Singleton fetuses that had prenatal sonography during the second trimester, then underwent cytogenetic evaluation in our institution, made up the study population. The sonographic findings of 207 fetuses with trisomy 21 were analyzed.

RESULTS

Between 1990 and 2004, fetal karyotyping was performed in 22,150 patients for different indications. An abnormal karyotype was diagnosed in 514 cases (2.3%); among them 207 fetuses with trisomy 21 were detected (40.3%). Abnormal sonography was seen in 63.8% of the cases. Structural anomalies were detected in 28.5% of the trisomy 21 fetuses, among them cardiac defects (15.9%), central nervous system anomalies (14.5%), and cystic hygromas (6.8%) were the most common. Of the minor markers, increased nuchal translucency (28%), pyelectasis (20.3%), and shorter extremities (8.7%) were common findings.

CONCLUSIONS

Appropriate diagnosis of structural anomalies, looking for relatively easily detectable minor markers and incorporating fetal echocardiography into the second trimester sonographic protocol, may increase the contribution of mid-trimester ultrasound examination to diagnosing trisomy 21.

Does the frequency of soft sonographic aneuploidy markers vary by fetal sex?

OBJECTIVE

To determine whether the frequency of soft sonographic aneuploidy markers varies by fetal sex.

METHODS

We identified all singleton fetuses with known sex undergoing genetic sonography at 17 weeks' to 21 weeks 6 days' gestation in a single perinatal center from January 1, 2000, to December 31, 2003. Markers studied were biparietal diameter/femur length, transcerebellar diameter, ear length, echogenic bowel, femur length, humerus length, absent middle fifth phalanx, nuchal fold, renal pelvis dilatation, echogenic cardiac focus, and choroid plexus cysts. Additional information extracted from the prospectively ascertained database included maternal age, referral indications, and chromosomal analyses. Multiple gestations and fetuses with structural or chromosomal abnormalities were excluded. The study received exempt review status by the Institutional Review Board. Dichotomous variables were compared by the chi(2) or Fisher exact test; continuous variables were compared by the unpaired t test.

RESULTS

In total, 4057 eligible fetuses, 2103 male and 1954 female, were examined at 18.9 +/- 0.9 weeks (mean +/- SD). Referral indications included maternal age of 35 years or older (n = 2983), abnormal second-trimester serum screen results (n = 610), soft marker on sonography (n = 583), prior aneuploid offspring (n = 24), and other (n = 125). More than 1 referral indication was possible for a given fetus. Overall, male fetuses exhibited echogenic fetal bowel (odds ratio, 1.76; 95% confidence interval [CI], 1.14-2.72; P = .009) and renal pelvis dilatation (odds ratio, 2.00; 95% CI, 1.30-3.09; P = .001) significantly more often than female fetuses. However, when fetuses were evaluated for single isolated markers, only male predominance of renal pelvis dilatation persisted (odds ratio, 2.32; 95% CI, 1.32-4.09; P = .003). No markers had increased frequency in female offspring.

CONCLUSIONS

Male fetuses exhibit a significantly increased frequency of renal pelvis dilatation compared with female fetuses. Sex-specific adjustment of sonographically derived aneuploidy risk does not appear to be indicated. However, a larger series of fetuses with trisomy 21 and pyelectasis is required to assess sex-specific risk adjustment for this marker.

Mild renal pyelectasis in the second trimester: determination of cut-off levels for postnatal referral

OBJECTIVE

To establish guidelines for postnatal referral of fetuses presenting with mild pyelectasis in the second trimester of pregnancy.

METHODS

In a retrospective study, 87 fetuses with a renal pelvis anteroposterior (RPAP) diameter of > or = 4 mm and < or = 10 mm before 28 weeks of gestation were included. All patients had a third-trimester scan and fetuses with an RPAP diameter of > or = 10 mm at that stage were referred for postnatal assessment. The family practitioner of all infants with an RPAP of < 10 mm in the third trimester was contacted for follow-up information. The RPAP diameter most predictive of renal pathology was determined with receiver-operating characteristics (ROC) curve analysis for both the first and second scans.

RESULTS

In 36 of 87 infants, 49 abnormal kidneys were diagnosed. Seven infants required surgery on eight renal tracts. The ROC curves of the first scan, second scan and differences between scans resulted in an area under the curve of 0.60, 0.87 and 0.85, respectively. The sensitivities and specificities for a cut-off level of 8, 9 and 10 mm at the second scan were 80%, 71% and 61% and 79%, 90% and 93%, respectively. At a cut-off level of 10 mm, only cases of insignificant minimal dilatation and a case of vesicoureteric reflux (VUR) requiring surgery were not detected.

CONCLUSION

After establishing a diagnosis of mild pyelectasis before 28 weeks, a second scan is mandatory to determine which infants need postnatal evaluation. A cut-off level of 8 mm has a low specificity but includes most cases of pathology. A cut-off level of 10 mm detects most significant pathology; however, VUR may not be detected.

Prenatal diagnosis and management of mild fetal pyelectasis: implications for neonatal outcome and follow-up

OBJECTIVES

To describe the natural history of pyelectasis from its detection in the second trimester to delivery, its capability to predict renal pathology and whether prenatal development of pelvic dilatation is correlated to its postnatal evolution.

STUDY DESIGN

A retrospective analysis involving 375 fetuses with a complete urological follow-up. Prenatal ultrasound was correlated with the results of postnatal investigation and frequency of postnatal surgery was established.

RESULTS

Two-hundred and eighty cases underwent at least two examinations before birth. 73.1% were male fetuses. 57.4% had a bilateral pyelectasis. Prenatal evolution of pelvic dilatation was the following:18.6% of the cases normalized, in 34.6% of the cases the dilatation reduced but did not disappear, in 30.7% it remained unchanged, while it worsened in 16.4%. One case from the first group, three cases from the second, seven cases from the third and 11 cases from the fourth needed surgical treatment. 1.9, 7.2, 18.6, 23.9% of cases respectively worsened after birth in the four groups (trend: P=0.001).

CONCLUSIONS

Prenatal diagnosis of pyelectasis improves the outcome of these children due to a surgical approach that avoids renal damage. There is a good correlation between prenatal evolution and postnatal outcome, although a postnatal follow-up is opportune in those cases that normalized before birth.

Use of genetic sonography for adjusting the risk for fetal Down syndrome

Systematic evaluation of ultrasound findings known to be associated with trisomy 21, at an appropriate gestational age, has been referred to as a genetic sonogram. A number of high-risk centers performing genetic sonography have reported detection of ultrasound abnormalities in the majority of fetuses with fetal Down syndrome. However, nonspecific markers are more commonly observed than structural abnormalities, which are detected in less than 20% of cases in a nonselected population. Also, the actual sensitivity of a genetic sonogram will depend on various factors including the markers sought, gestational age, reasons for referral, and of course the quality of the ultrasound. Appropriate use of a genetic sonogram can help to modify the risk of fetal Down syndrome by decreasing the risk when the ultrasound is normal, or increasing the risk when specific ultrasound markers are detected. The postultrasound risk can be estimated by applying specific likelihood ratios, reflecting the strength of individual markers, with the a priori risk based on maternal age alone, or combined with biochemical markers when known. We review this approach of age-adjusted ultrasound risk assessment for fetal Down syndrome and illustrate how the risk can be estimated. Individual sonographic markers are also discussed.

Prenatal diagnosis for paediatricians

In Ontario, approximately 140,000 women deliver newborn infants each year. Of these women, 60,000 to 70,000 have multiple marker screening, 10,000 undergo amniocentesis or chorion villus sampling and virtually all have at least one prenatal ultrasound. Multiple marker screening is not used in every province and territory; however, amniocentesis and prenatal ultrasound are used throughout Canada. Most paediatric patients will have been exposed to some form of prenatal diagnosis. If an abnormality is found prenatally, parents may have concerns to discuss with the paediatrician after the child is born. Likewise, if a child with a problem is born following a normal pregnancy, the parents will want to know why the problem was missed prenatally. Paediatricians should be aware of prenatal tests that have been performed to understand better their patients and their families.

Sonographic markers of fetal aneuploidy

A variety of ultrasound findings can be identified in fetuses with fetal aneuploidy. Typical findings vary with both the chromosome abnormality and gestational age at time of the ultrasound examination. Increased NT is the primary marker during the first trimester, whereas a variety of markers may be seen during the second trimester. The presence of ultrasound markers increases the risk for fetal aneuploidy, whereas a normal ultrasound reduces the risk. Optimal risk assessment includes consideration of other risk factors including maternal age, family history, and biochemical markers. It is expected that combined risks, incorporating ultrasound findings and biochemistry, will be available in the near future. How first-trimester screening is integrated with second-trimester screening remains to be determined.

Striking findings concerning the variability in the measurement of the fetal renal collecting system

OBJECTIVE

Using strict thresholds of normality, investigators have reported associations between fetal pyelectasis and aneuploidy, obstructive uropathy, postnatal pyeloplasty and vesicoureteral reflux. Although evidence continues to mount regarding the importance of fetal pyelectasis, little is known of the variability of collecting system measurements. To investigate the short-term variability and its relationship to bladder dilatation, the following study was conducted.

DESIGN

During May and June 1996, 20 mid- and late-trimester patients with varying degrees of fetal pyelectasis were recruited into this study. Each consented to undergo periodic (every 15 min for 2 h) ultrasound measurements of the fetal renal collecting systems and bladder. To account for anatomic and technical variability in measurement, we used both the sum of the transverse and anterior-posterior (AP) measurements of the collecting systems, and AP measurement alone for comparison. The variability of the collecting system measurements was assessed based upon gestational age, magnitude of pyelectasis and fetal bladder size.

RESULTS

We investigated 38 renal units in 20 patients (eight in the second trimester and 12 in the third). The mean(SE) AP diameter of all kidneys was 5.89(2.49) mm (range 15 (2-17) mm), and the sum of transverse and AP renal collecting system diameters was 13.91(5.73) mm (range 26 (4-31) mm). These data were normally distributed. When assessing the variability in individual kidneys over time, we found the mean variation (minimum to maximum) for the sum of the AP and transverse measurement to be 7.61(4.26) mm and for the AP measurement alone to be 3.80(2.49) mm. No relationship was found between variability of dilatation, magnitude of dilatation or fetal bladder size. Cyclic dilatation of the fetal bladder was observed in all cases. The mean time from maximal to minimal dilatation was 20 min (1.34 observations; range 12-30 min).

CONCLUSIONS

We found the size of the fetal renal collecting system to be highly variable over the course of a 2-h period. Seventy per cent of cases (14 of 20) had both normal (< 4 mm) and abnormal values (> or = 4 mm) during the 2-h study period. Significant caution should be used when considering the implications of renal collecting system dilatation based upon a single AP measurement.

Antenatal minimal hydronephrosis: is its follow-up an unnecessary cause of concern?

The aim of this study was to determine if follow-up of antenatally diagnosed minimal hydronephrosis (anteroposterior renal pelvis diameter <10 mm) is justified or if it is an unnecessary cause of concern for the parents involved. A case-control study, with subjects and controls selected from the Wessex Antenatally Detected Anomalies Register was performed. Information regarding antenatal and postnatal follow-up, renal tract morbidity and degree of concern was obtained from a parental questionnaire. 70 of the 115 subjects contacted (60.9 per cent) and 52 of the 81 controls (64.2 per cent) returned the questionnaire. 65 of the 70 subjects (92.9 per cent) were rescanned postnatally when 28 cases (43.1 per cent) had resolved. Coexisting ureteric and/or calyceal dilatation was evident postnatally in 12 cases and this group was significantly more likely to have underlying pathology than the group with isolated renal pelvis dilatation. Subjects were significantly more likely than controls to have a UTI. The degree of concern was significantly greater in the subject group and subject parents thought about the result significantly more often than controls. From our results we concluded that the follow-up of minimal hydronephrosis can be modified. There is no need for repeated antenatal scanning, a change that could reduce the level of parental anxiety. Postnatal follow-up is required in all patients to exclude an underlying uropathy but again this can be modified, with the majority of patients requiring only an ultrasound scan. This reduced intensity of investigation accompanied with careful explanation to the parents should help to minimize their concerns.