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Hypospadias

Hypospadias with blunt end due to a dorsal hood over the glans
Normally tapering male penis

Findings:

A bulbous end to the penis is identified. This was seen throughout the examination and is characteristic of hypospadias. The normal male penis is seen in comparison.

Discussion:

Identification of fetal sex has always been of paramount interest to expectant parents. While in the past it was mainly of psychological benefit more recently knowledge of the fetal sex has assumed importance in adequately counseling parents with suspected x-linked disorders and as an aid in determining zygosity in twin gestations. The use of sonography to assess fetal sex has achieved accuracy rates of > 90%. Prediction rates for male gender in some series have been reported to be as high as 100%. It is of interest that while a number of malformations are known to affect the genitalia, few have been reported sonographically. In a study designed to assess expectations of detecting abnormalities, it was concluded by most participants in the study, that malformations of the genitalia would virtually never be seen, unless specifically sought during a routine examination. Abnormalities of the genital tract are important to recognize not only because of the isolated abnormality but the potential association with other malformations, chromosomal abnormalities and syndromes.

Early in embryological development the male and female genitalia appear virtually identical. The determination of gender is based upon hormonal stimulation. Female genital structures form in the absence of testicular hormones. Normal male development requires that appropriate hormonal stimulation by androgens begin by approximately eight menstrual weeks. It is between 14 and 16 weeks of gestation that the normal penile urethra forms. Hypospadias is thought by some to be due to failure of fusion of the urethral groove secondary to either testosterone deficiency or end organ insensitivity to testosterone. After 20 weeks gestation external genital structures are determined and fixed.

Hypospadias is a relatively common abnormality with a reported prevalence between 0.2 and 4.1 per 1000 live births. It is more common in whites than in Blacks and more common in Italians and Jews.The prevalence of hypospadias in monozygotic tiwns is 8.5 fold higher than in singletons.The urethral meatus is abnormally positioned in this condition, opening proximally and ventrally to its normal position. The classification of hypospadias is often based upon the location of the urethral meatus. Anterior meatal openings in approxmately 50%, midshaft meatus in 30% and posterior meatal opening in the remaining 20%. The sonographic findings and an excellent review of the subject were described by Sides et al. and Devesa et al. The sonographic findings of hypospadias are: anomalous distal morphology of the penis (it loses its pointed end, which becomes blunter or straighter, in the form of a squashed cone) , small lateral folds seen as longitudinal echogenic lines (dermal remains of the prepuce), small penis, ventral incurving (chordee) due to a fibrous band along the normal span of the spongy body and anomalous urinary stream (due to an anomalous opening of the urethra on the ventral surface of the penis. It should be remebered however that abnormal penile angulation can occur in the absence of hypospadias. More recently, Meizner et al described the "tulip sign" which was seen in six of their patients with severe hypospadias. This sign represents the severe curvature of the penis in association with penoscrotal transposition of a bifid scrotum. As the authors state, this may be difficult to distinguish from normal female anatomy.

As was mentioned above, while hypospadias may occur in isolation, it may be seen with other urogenital or non-urogenital abnormalites. Associated abnormalities of the genitourinary tract may be seen in as many as 40% of patients with hypospadias and include: vesiocureteral reflux, cryptorchidism and inguinal hernia. Hypospadias may also be part of a variety of syndromes such as the Opitz syndrome and its variants.

Syndromes Frequently Manifesting Hypospadias

Opitz syndrome (BBB syndrome)

Opitz-Frias syndrome (G syndrome)

Smith-Lemli-Opitz syndrome

Nager syndrome

Aniridia-Wilms tumor association

Fetal trimethadione syndrome

Fraser syndrome

Rapp-Hodgkin ectodermal dysplasia syndrome

Rieger syndrome

Schinzel-Giedion syndrome

Triploidy syndrome

4p-syndrome

13q-syndrome

From: Sides D, Goldstein RB, Baskin L, Kleiner BC. Prenatal diagnosis of hypospadias J Ultrasound Med 15:741-746, 1996

References:

Sides D, Goldstein RB, Baskin L, Kleiner BC. Prenatal diagnosis of hypospadias J Ultrasound Med 15:741-746, 1996

Benacerraf BR, Saltzman DH, Mandell J. Sonographic diagnosis of abnormal fetal genitalia. J Ultrasound Med 8:613-617, 1989

Cooper C, Mahony BS, Bowie JD, Pope II. Prenatal ultrasound diagnosis of ambiguous genitalia. J Ultrasound Med 4:433-436, 1985

Birnholz JC. Determination of fetal sex. N Engl J Med 309:942, 1983

Emerson DS, Felker RE, Brown DL. The sagittal sign: an early second trimester sonographic indicator of fetal gender. J Ultrasound Med 8:293-297, 1989

Mandell J, Bromley B, Peters CA et al. Prenatal sonographic detection of genital malformations. J Urol 153:1994

Baskin LS, Duckett JW. Hypospadias In Gillenwater J (Ed): Adult and Pediatric Urology, 2nd Ed, CV Mosby, St Louis, 1995

Devesa R, Munoz A, Torrents M, Comas C, Carrera J. Prenatal Diagnosis of Isolated Hypospadias Prenatal Diagnosis 18:779-788, 1998

Meizner I, Mashiach R, Shalev J et al. The 'tulip sign': a sonographic clue for in-utero diagnosis of severe hypospadias. Ultrasound Obstet Gynecol 19:250-253, 2002

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Peter W. Callen, M.D.
Professor of Radiology, Obstetrics, Gynecology and Reproductive Science
University of California Medical Center, San Francisco, California