Prenatal Diagnosis and Perinatal Outcomes of Congenital Megalourethra: A Multicenter Cohort Study and Systematic Review of the Literature

Open-legs axial plane: A standardized methodology and reference values for fetal genital biometry in mid-trimester ultrasound

BACKGROUND

Evaluation of the external genitalia is an important part of prenatal ultrasound. However, there is no standardized methodology that includes biometric measurements and normative data to be able to carry out this evaluation.

OBJECTIVE

To develop a standardized methodology for fetal genital biometry and obtain reference values for use in mid-trimester ultrasound.

STUDY DESIGN

A prospective cross-sectional study was used. 273 male and 253 female fetuses of normal, singleton pregnancies at 18 to 22 weeks were included. Measurements of fetal penis length, penile width and transverse scrotal diameter in male fetuses and bilabial diameter in female fetuses were performed by transabdominal ultrasound. Reference values were calculated for each gestational week.

RESULTS

Realization of the open-legs axial plane is described as a working methodology. Normative data for penile length, penile width, transverse scrotal diameter and bilabial diameter are defined, including mean, minimum and maximum values, range, and 5th, 10th, 90th and 95th percentiles.

CONCLUSIONS

We have provided a standardized methodology using the open-legs axial plane, which would integrate the main measurements. In addition with the normative data constructed from their use, we hope to be able to improve the external genitalia assessment and diagnosis of genital anomalies in mid-trimester ultrasound.

Fetoscopic urethral meatotomy in fetuses with lower urinary tract obstruction by congenital megalourethra

BACKGROUND

To describe the perinatal outcomes of fetoscopic urethral meatotomy (FUM) in fetuses with lower urinary tract obstruction (LUTO) by congenital megalourethra.

STUDY DESIGN

Between 2012 and 2020, 226 cases with LUTO were referred to our fetal surgery center in Queretaro, Mexico. We report the perinatal outcome of cases with LUTO by congenital megalourethra that were selected for FUM in an attempt to release the penile urethral obstruction.

RESULTS

Congenital megalourethra was diagnosed in 10 cases (4.4%) but only 3 cases (30%) with obstructive megalourethra and megacystis were selected for fetal surgery. Fetoscopic urethral metatotomy was successfully performed in all three cases at a median gestational age (GA) of 21.4 (18.0-26.7) weeks and with a median surgical time of 27 (12-43) min. A resolution of urethral dilatation and subsequent reduction of the penile length and normalization of both the bladder size and amniotic fluid were observed in all cases. The median GA at delivery was 35.2 (range: 30.6-38.0) weeks. There were no fetal deaths but one neonatal death (33%) secondary to renal failure and preterm delivery.

CONCLUSION

In fetuses with LUTO by congenital obstructive megalourethra, FUM is feasible and is associated with good perinatal outcomes.

[Genital abnormalities: Contextualization of a neglected area in prenatal diagnosis]

OBJECTIVE

To reflect on how the area of genital abnormalities has fallen behind in prenatal diagnosis.

METHODS

Based on the thesis that prenatal diagnosis of genital abnormalities has scarcely developed, a comparison with other areas of prenatal diagnosis and with its postnatal counterpart is presented; different explanations for this situation are examined; and a reflection is presented on ways to expand this field of knowledge.

CONCLUSIONS

Compared to other disciplines, prenatal diagnosis of genital abnormalities finds itself lagging behind in terms of diagnostic tools, management protocols and scientific literature. Potential causes include a perception of low prevalence and limited importance, or exploration challenges. Integration of current knowledge, together with the acquisition of the appropriate tools and translation to clinical medicine, would be a way to make this discipline stronger.

Sonographic measure techniques of fetal penile length

Postnatal penile length is a reliable, standardized, and widely used marker for the diagnosis of genitourinary pathology, as well as genetic and hormonal disorders. In contrast, prenatal diagnosis has not been developed equally and there is a lack of relevant literature. Our objective is to review the studies on fetal penile length, and apply findings to clinical practice. Although the most used technique is the outer penile length, there is no consensus regarding the appropriate technique for prenatal measurement. Several reports have provided reference data with high correlation. However, important issues like poor correlation with post-natal measures or presence of confounding variables are still present. Diagnosis of both a micropenis and macropenis can indicate related pathologies, and this information may benefit parental counseling and facilitate fetal management. Therefore, it is necessary to carry out prospective studies that provide reliable normative data.

Prenatal diagnosis of congenital megalourethra in the second trimester of pregnancy

Congenital megalourethra is abnormal dilation of the penile urethra due to aplasia of erectile tissue, leading to lower urinary tract obstruction. This condition should be considered when fetal penis with typical dilation is seen on prenatal scan. The dilated structure, however, can be easily missed or misinterpreted as the umbilical cord. Perinatal prognosis is poor due to direct consequences on urinary and respiratory systems, or due to severe associated anomalies. A large number of survived cases experience urinary sequelae and renal impairment. We report one case of fetal congenital megalourethra diagnosed at 17 weeks and 6 days of pregnancy.

Prenatal diagnosis and postnatal outcome of anterior urethral anomalies

OBJECTIVES

Anterior urethral anomalies (AUA) which present as anterior urethral valve, stenosis or atresia, are a rare cause for congenital urinary tract obstruction. We present our AUA prenatal diagnosis case series.

METHODS

Fetuses presenting with prenatal findings suggestive for AUA according to postnatal reported clinical and imaging signs (urinary tract dilatation, dilated bladder, enlarged edematous fetal penis, dilatation of the fetal urethra and diverticula) were followed prospectively.

RESULTS

Six fetuses were diagnosed with AUA. Diagnosis was confirmed upon examination of the neonate or the abortus. All cases presented with variable degrees of urinary tract dilatation. Four fetuses who presented with additional congenital anomalies of the kidneys and urinary tract (CAKUT) developed intra-uterine or early postnatal renal failure, while two isolated AUA cases have a normal renal outcome.

CONCLUSIONS

AUA is a rare diagnosis. However, high index of suspicion and careful sonographic assessment of the male fetal urethra in cases referred for urinary tract dilatation may enable appropriate parent counseling, optimal prenatal surveillance and timed postnatal urological intervention. As in other lower urinary tract obstructions, future renal function seems to correlate with associated CAKUT, therefore close follow up throughout pregnancy and meticulous sonographic assessment is recommended.

Prenatal diagnosis of congenital megalourethra with imperforate anus

Background

Congenital megalourethra is a rare prenatal finding while prenatal diagnosis of imperforate anus poses high challenge. This is the first prenatally ultrasound diagnosed case which had congenital megalourethra and imperforate anus. This case demonstrated the possibility of using the prenatal imaging findings to evaluate the postnatal prognostic outcomes in multi-organ anomalies.

Case

We present a case of congenital megalourethra, diagnosed prenatally at 22 weeks’ gestation, in which the penis appeared severe dilated with complete absence of the corpora spongiosa and cavernosa. This case also revealed absence of perianal muscle which was in associated with imperforate anus. Detailed prenatal ultrasonographic findings predicted the high possibility of poor outcome of the fetus in the pulmonary, renal, and sexual functions.

Conclusion

This case serves to identify not only the marked bilateral hydronephrosis features but also the striking lower urethral malformation with obstruction flow effect of the penis. Indeed we believe this is the first case report of a rare case of fetal megalourethra associated with imperforate anus at early second trimester on ultrasonography imaging.