Female external genitalia on fetal magnetic resonance imaging

Imaging in fetal genital anomalies

Genital anomalies are a heterogeneous group of congenital pathologies that have become increasingly relevant since the Chicago Consensus of 2005. Their postnatal diagnosis has developed significantly in the last two decades, while prenatal diagnosis seems to be underdeveloped, with few protocols available, fragmented scientific literature, and low diagnostic rates. This review aims to examine the current status of this subspecialty from the perspective of prenatal imaging. Indications for the evaluation of fetal genitalia can be divided into medical and non-medical reasons. Medical reasons include sex-linked disorders, detection of other anomalies, relevant family history, or multiple pregnancy. Non-medical reasons include parental request for sex disclosure. Disclosure of fetal sex may be associated with ethical, legal, and medical issues. The main imaging technology used is 2D ultrasound, although there are other complementary techniques such as 3D, MRI, or Color Doppler. Regarding working methodology, several authors have drawn attention to the lack of standardized protocols and guidelines. Most guidelines tend to limit their recommendations to study indications and ethical issues. Technical proposals, measurements, or working methods have not yet been standardized. Fetal sex determination is usually divided into early and late gestation. Early gestation is based on the sagittal sign. Late gestation is based on direct visualization. There are several measurements to describe male and female genitalia, such as penile length, bilabial diameter, or scrotal diameter. Prenatal diagnosis of genital pathologies presents some particularities such as the wide spectrum of phenotypes, the high frequency of associated deformities, or the time of diagnosis. Some of the most frequent pathologies are ambiguous genitalia, fetal sex discordance, hypospadias, micropenis, clitoromegaly, ovarian cysts, hydro(metro)colpos, and cloacal anomalies. Higher-quality studies and direction from scientific societies through the implementation of clinical guidelines are needed.

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.

[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.

Assessment of clitoral anatomy in human fetuses

PURPOSE

To determine fetal clitoral dimensions in antenatal period and to provide a contribution to external genital morphology determination in premature infants.

METHODS

Thirty-one formalin fixed female fetuses aged between 18 and 40 weeks (17 fetuses aged 21.53 ± 1.88 weeks in the second trimester and 14 fetuses aged 31.00 ± 4.90 weeks in the third trimester) were evaluated. 20 (64.5%) fetuses were between 3 and 97% percentile range and within normal limits. Clitoris appearance (completely covered by labium majus/partially showing/prominent), length and width of clitoris, labium minus length, length, and width of labium majus were assessed.

RESULTS

Clitoris length during the second trimester was 4.84 ± 1.09 mm, whereas it was 5.43 ± 1.07 in the third trimester. Clitoris width was as 3.35 ± 0.88 mm in the second trimester and as 4.55 ± 0.96 mm in the third trimester. A statistically significant increase was seen in width of clitoris, length, and width of labium majus and length of labium minus with gestational age in the second and third trimesters (p < 0.05). No significant difference was found between the second and third trimesters in terms of clitoris length (p = 0.146). A homogenous spread in clitoris appearance was obtained between the second and third trimesters without any significant difference (p = 0.912). In addition, fetus percentiles showed a homogenous spread without any significant differences between completely covered, partially covered and prominent groups (p = 0.452).

CONCLUSION

The anatomical data can be beneficial to the development of fetal radiological screening procedures in females and also in morphological assessment criteria in premature infants, effectively assisting in diagnosing anomalies during the early term.

Appearance of external genital organs and types of hymen in Turkish female foetal cadavers

The present study's purpose was to determine the size and morphometric development of the female external genital organs on foetal cadavers. Dimensions of labia majora, labia minora and clitoris, bilabial diameter, vertical and horizontal diameters of hymenal opening, distance between the external urethral orifice and hymenal opening, distance between the clitoris and external urethral orifice and anogenital distance were measured. The hymenal types were determined. Mean values of parameters according to gestational weeks, months and trimesters were calculated. Imperforate hymen were determined in the first trimester. Twenty-eight foetuses with annular hymen, 25 foetuses with imperforate hymen, and 1 foetus with septated hymen were determined in the second trimester. Twenty-four foetuses with annular hymen, 3 foetuses with imperforate hymen, 1 foetus with fimbriated hymen, and 1 foetus with hymenal tag were determined in the third trimester. All foetuses in the full term were determined with annular hymen.

Evaluation and management of disorders of sex development: multidisciplinary approach to a complex diagnosis

Various disorders of sex development (DSD) result in abnormal development of genitalia, which may be recognized at prenatal ultrasonography, immediately after birth, or later in life. Current methods for diagnosing DSD include a thorough physical examination, laboratory tests to determine hormone levels and identify chromosomal abnormalities, and radiologic imaging of the genitourinary tract and adjacent organs. Because of the complex nature of DSD, the participation of a multidisciplinary team is required to address the patient's medical needs as well as any psychosocial issues that the patient or the family may encounter after the diagnosis. The first step in the management of DSD is sex assignment, which is based on factors such as the genotype; the presence, location, and appearance of reproductive organs; the potential for fertility; and the cultural background and beliefs of the patient's family. The primary goal of sex assignment is to achieve the greatest possible consistency between the patient's assigned sex and his or her gender identity. Once the sex is assigned, the next step in management might be surgery, hormone therapy, or no intervention at all. Patients with ovotesticular DSD and gonadal dysgenesis may require a gonadectomy, followed by reconstructive surgery. Some patients may need hormone replacement therapy during puberty. An understanding of the immediacy of families' need for sex assignment and clinicians' need for reliable diagnostic imaging results will help radiologists participate effectively in the prenatal and postnatal assessment of patients with DSD.

Prenatal management of disorders of sex development

Disorders of sex development (DSD) rarely present prenatally but, as they are very complex conditions, management should be directed by highly specialised medical teams to allow consideration of all aspects of diagnosis, treatment and ethical issues. In this brief review, we present an overview of the prenatal presentation and management of DSD, including the sonographic appearance of normal genitalia and methods of determining genetic sex, the prenatal management of pregnancies with the unexpected finding of genital ambiguity on prenatal ultrasound and a review of the prenatal management of pregnancies at high risk of DSD. As this is a rapidly developing field, management options will change over time, making the involvement of clinical geneticists, paediatric endocrinologists and urologists, as well as fetal medicine specialists, essential in the care of these complex pregnancies. The reader should also bear in mind that local social, ethical and legal aspects may also influence management.