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- Review -
Hypospadias: an update
Alexander K. C. Leung1,2,William L. M. Robson3
1Department of Pediatrics, The University of Calgary,
2The Alberta Children's Hospital, and
3The Childrens' Clinic, Calgary, Alberta T2M 0H5, Canada
Hypospadias is the most common congenital anomaly of the penis. The problem usually develops sporadically
and without an obvious underlying cause. The ectopically positioned urethral meatus lies proximal to the normal site
and on the ventral aspect of the penis, and in severe cases opens onto the scrotum or perineum. The foreskin on the
ventral surface is deficient, while that on the dorsal surface is abundant, giving the appearance of a dorsal hood.
Chordee is more common in severe cases. Cryptorchidism and inguinal hernia are the most common associated
anomalies. The frequency of associated anomalies increases with the severity of hypospadias. For isolated anterior
or middle hypospadias, laboratory studies are not usually necessary. Screening for urinary tract anomalies should be
considered in patients with posterior hypospadias and in those with an anomaly of at least one additional organ system.
The ideal age for surgical repair in a healthy child is between 6 and 12 months of age. Most cases can be repaired in
a single operation and on an outpatient basis. Even patients with a less than perfect surgical result are usually able to
enjoy a satisfactory sexual life.
(Asian J Androl 2007 Jan; 1: 16_22)
Keywords: hypospadias; sporadic; cryptorchidism; inguinal hernia; renal anomaly; repair
Correspondence to: Dr. Alexander K. C. Leung, Department of Pediatrics, The University of Calgary, The Alberta Children's Hospital,
Calgary, Alberta T2M 0H5, Canada.
Received 2006-07-10 Accepted 2006-09-20
The word "hypospadias" is derived from the Greek words
hypo, which means below, and spadon, which means
rent or hole. Hypospadias is the most common congenital anomaly of the penis . The condition is characterized by
a urethral meatus that is ectopically located proximal to the normal location
and on the ventral aspect of the penis. In
severe cases, the urethral meatus opens onto the scrotum or perineum.
At approximately 6 weeks of gestation, the genital tubercle develops anterior to the urogenital sinus. The
urogenital membrane is flanked on each side by the outer genital swellings and the inner urethral folds .
Virilization of the male external genitalia occurs during the second month of gestation under the influence of testosterone synthesized by the
fetal testes . Placental human chorionic gonadotropin stimulates Leydig cells of the fetal testes to produce testosterone.
Testosterone is converted to the more potent dihydrotestosterone by the enzyme
5a_reductase type II. For dihydrotestosterone to be effective, the hormone must bind
to androgen receptors in the genital tissues . One of
the first signs of virilization is an increase in
the distance between the anus and the genital structures, followed by
elongation of the phallus, formation of the penile urethra,
and development of the prepuce . The penile urethra
forms as a result of the fusion of the medial edges of the
endodermal urethral folds . The fusion of
endodermal urethral folds proceeds from proximal to distal and
is usually completed by the end of the first trimester .
The ectodermal edges of the urethral folds then fuse over
the urethra to form the prepuce . It was formerly
considered that the glandular urethra formed as an
ectodermal ingrowth of tissue that invaginated
through the glans to meet the proximal urethra . However, recent
evidence suggests that urothelium has the capability to
differentiate into a stratified squamous epithelium, such
that the entire male urethra can be formed by the fusion
of the urethral folds . Failure of fusion of the
endodermal urethral folds leads to hypospadias.
The incidence of hypospadias has been estimated to
be 0.4 to 8.2 per 1 000 live male births [7, 8]. The wide
variation is likely because of geographic, environmental
or genetic differences and different methods in data
collection [7, 9]. The condition is more common in
Caucasians, least common in Hispanics, and
intermediate among African-Americans . There has been an
overall increase in incidence of hypospadias both in
Europe and North America [6, 7, 9]. Data from published
studies in these jurisdictions suggest that the incidence
of hypospadias doubled between the 1970s and the 1990s
[6, 7, 9]. Data from the USA includes reports
from the Metropolitan Atlanta Congenital Defects Program
(MACDP) and the nationwide Birth Defects Monitoring
Program (BDMP) . The incidence of hypospadias measured by the BDMP increased from 20.2 per 10 000
live births in 1970 to 39.7 per 10 000 live births in 1993
. The increase is unlikely to be attributable to increased
access to medical care, improved recognition, or better
reporting since the MACDP data showed that the rate of
severe cases increased while the ratio of mild to severe
cases decreased . The rising rates might be a result
of the increased incidence of premature infants with low
birthweight, or to fetal exposure to progestins or to
compounds with estrogenic or anti-androgenic activity .
No increase in the incidence of hypospadias has been
noted in less-developed countries .
The etiology is multifactorial. In the majority of cases
the hypospadias develops as a sporadic problem and
without an obvious underlying cause. In general, the more
severe the hypospadias, the more likely an underlying
cause can be identified . Albers et
al.  evaluated 33 patients with severe
penoscrotal, scrotal, or perineal hypospadias with a range of diagnostic techniques that
included clinical assessment, ultrasonography, karyotyping,
endocrine evaluation, and molecular genetic analysis of
the androgen receptor gene and the 5a-reductase gene.
Notwithstanding such an extensive evaluation, the cause
was determined in only 12 (36%) patients. Boehmer
et al.  evaluated 63 unselected cases of severe
hypospadias with clinical and molecular biological techniques
and identified the cause in only 20 (32%) patients.
Defects in testosterone production by the testes and
adrenal glands, failure of conversion of testosterone to
dihydrotestosterone, deficient numbers of androgen
receptors in the penis, or reduced binding of dihydrotestosterone
to the androgen receptors could all result in hypospadias
. Several studies have shown subnormal testosterone
response to human chorionic gonadotropin in some boys
with hypospadias [12, 13]. Although the majority of boys
with hypospadias have normal testosterone levels, this does
not necessarily imply normal androgen production
Although the use of an oral contraceptive does not
lead to hypospadias , maternal exposure during early
pregnancy to other estrogenic compounds or to progestins
might increase the risk of hypospadias [14, 15].
Environmental substances that contain estrogenic activity are
common and include pesticides on fruits and vegetables,
milk from lactating dairy cows, some plants, and pharmaceuticals. Klip
et al.  conducted a survey of the 8 934 sons of a Dutch cohort of 16 284 women
(response rate 67%) who were diagnosed with a fertility
problem. Of the 205 boys born to mothers exposed to
diethylstilbestrol during pregnancy, four had hypospadias.
Only eight cases of hypospadias were reported in the
remaining 8 729 children (odds ratio [OR]: 21.3; 95%
confidence interval [CI]: 6.5_70.1). Pons et
al.  analyzed the computerized files of 17 633 boys of
mothers some of whom were exposed to diethylstilbestrol
in utero. Three (1.2%) of the 240 boys with maternal
exposure to diethylstilbestrol had hypospadias. Only 44
(0.5%) cases of hypospadias were found in the
remaining 17 393 boys (OR: 4.99; 95% CI: 1.2_16.8). These
findings confirm an increased risk of hypospadias in the
sons of women exposed to diethylstilbestrol during
pregnancy . Several authors suggest that a maternal
vegetarian diet, which contains higher amounts of phytoestrogens, might result in an increase in the
incidence of hypospadias [17, 18]. Of 7 928 boys born to
mothers who took part in the Avon Longitudinal Study
of Pregnancy and Childhood (ALSPAC), 51 cases of hypospadias were identified . The study showed a
weak association between hypospadias and maternal consumption of a vegetarian diet high in soya products.
Other authors did not find such as association [19, 20].
An association between maternal progestin intake and
hypospadias has been noted in several studies [21, 22].
The National Birth Defects Prevention Study analyzed
502 boys diagnosed with severe hypospadias and 1286
control boys without hypospadias . Forty-two case
mothers (8.4%) and 31 control mothers (2.4%) reported
progestin intake during the period from 4 weeks before
conception through 14 weeks after conception (OR:
3.7; 95% CI: 2.3_6.0). There is evidence that activating
transcription factor 3 (ATF3) responds to estrogenic or
anti-androgenic activity and might play a role in the
development of hypospadias [23, 24]. Liu et
al.  examined the expression of ATF3 in penile skin tissue
obtained from 28 children with hypospadias and in 20 normal tissue
samples obtained during elective circumcision.
Eighty-six percent of the samples from patients with
hypospadias were immunohistochemi-cally positive for ATF3,
compared with 13% of normal tissue samples .
Seventy-five percent of samples from patients with
hypospadias were positive when tested by in situ
hybridization, compared with 1% of circumcision samples. The study
indicates that ATF3 is upregulated in the penile skin
tissues of boys with hypospadias and suggests a role of
ATF3 in the pathogenesis of hypospadias .
Maternal exposure to anti-epileptic drugs such as
valproic acid might increase the risk of hypospadias .
Maternal exposure to xenoandrogens such as DDT (metabolite p,p'-DDE), vinclozolin, and diethylhexyl
phthalate has been shown to cause hypospadias in animal
studies [27, 28]. Data on human studies, however, are
lacking. A higher incidence of hypospadias has been found
in boys conceived by intra-cytoplasmic sperm injection
(ISCI) or in vitro fertilization (IVF) [29, 30]. However,
when controlled for other factors such as maternal age,
parity, multiple or singleton birth, and paternal subfertility,
the increased risk was not statistically significant [15,
31]. Several studies have shown that maternal smoking
is not associated with an increased risk of
hypospadias [14, 18].
Intrauterine growth retardation and low birthweight
are risk factors for hypospadias [32, 33]. The risk
increases with decreasing birthweight and is independent
of gestational age . Gatti et al.  found that
hypospadias is 10 times more common in
small-for-gestational-age infants compared with normal infants.
There is an increased incidence of hypospadias in
both monozygotic and dizygotic twins . Roberts
et al.  noted that monozygotic male twins had an
8.5-fold increase in hypospadias, compared with singleton
live male births. Fredell et al.  found that in 16 of 18
monozygotic pairs discordant for hypospadias, the twin
with the lower birthweight had hypospadias. The mean
difference in birthweight was 498 grams. The authors
suggested that in the presence of two fetuses, there might
be a relative placental insufficiency to one of the fetuses
and less than adequate human chorionic gonadotropin to
meet the demands of both pairs of male gonads .
The birthweight of a non-twin sibling without
hypospadias is significantly higher than that of the proband with
Some authors suggest that advanced maternal age
and primiparity are risk factors [6, 37]. Other authors
did not find this association .
A high familial incidence of hypospadias
is observed and a polygenic predisposition is likely [7, 39]. In a
series of 1 314 cases of hypospadias reported by Leung
et al. , 71 (5.4%) cases had at least one other affected
relative. The risk of recurrence of hypospadias in a
second male sibling is 12% to 14% . About 7% to 9%
of the fathers of boys with hypospadias also have
hypospadias [2, 41]. If the father and the child are both
affected, the risk of recurrence for a second sibling is
increased to 26% [40, 42]. In general, the risk that a
second male sibling will be born with hypospadias
increases with the severity of hypospadias in the index
child . A dominant gene inheritance might be
responsible for a small number of cases of hypospadias. Lowry
et al.  reported two kindreds with familial
hypospadias of different severity that affected members of at
least two generations. Page  reported six instances
of hypospadias in three or more generations and
suggested a dominant Mendelian characteristic in these cases.
Frydman et al.  reported a large consanguineous
Bedouin family that included eight members with
various degrees of hypospadias. These authors postulated
that an autosomal recessive inheritance might account
for a subgroup of familial hypospadias.
Hypospadias has been found in various chromosomal
aberrations, such as 4p-,
18q-, paracentric inversion of chromosome 14, and the Klinefelter syndromes [1, 46].
Hypospadias can be associated with genetic
syndromes such as Smith-Lemli-Opitz, hypertelorism, hypospadias
(BBB), hand-foot-genital, Reifenstein, Wolf-Hirschhorn,
Denys-Drash, Silver-Russell, and G [1, 2, 46].
Hypospadias is a frequent finding with ambiguous genitalia of
various causes such as hermaphroditism and mixed
5 Clinical manifestations
The urethral meatus is ectopically located on the
ventral aspect of the penis and proximal to the normal site,
and might open onto the scrotum or perineum. The meatal
position can be classified as anterior or distal (glandular,
coronal, subcoronal), middle (midpenile), or posterior or
proximal (posterior penile, penoscrotal, scrotal, perineal)
. The subcoronal position is the most
common. Proximal cases are considered severe. Approximately
60% to 65% of cases are distal, 20% to 30% midpenile, and
10% to 15% proximal . In severe cases, the scrotum might
appear bifid . The proximally displaced urethral meatus
is often stenotic in appearance. Micropenis is uncommon
except with severe cases associated with chordee .
Characteristically, the foreskin on the ventral
surface is thin or absent while the foreskin on the dorsal
surface is abundant and has the appearance of a dorsal
hood . In the rare megameatus intact prepuce (MIP)
variant, the foreskin is normally developed and the
urethral meatus has the appearance of a fish-mouth. In
some cases, a blind-ending pit on the glans simulates a
normal meatus and the only clue to hypospadias is a
deficient ventral foreskin.
Chordee, derived from the Latin word
chorda, which means string, refers to the ventral curvature of the penis.
Chordee is caused by atrophy of the corpus spongiosum,
fibrosis of the tunica albuginea and fascia over the tunica,
tightness of the ventral skin and Buck's fascia, tethering
of the penile shaft skin onto the underlying structures, or
tethering of the urethral plate onto the corpora cavernosa
[1, 47]. Chordee becomes more apparent and might only
be noticeable with penile erection [1, 2]. The extent of
chordee can be demonstrated by compression of the
corpora cavernosa in the perineum, which causes the penile
shaft to become engorged. With additional compression
at the base of the penis, an erection can be
elicited . Chordee is more commonly associated with cases of
proximal hypospadias. Chordee is best assessed
intra-operatively with an artificial erection test (Gittes test).
The clinical presentation varies with severity of the
disorder. Children with hypospadias and a narrow
meatus may have a weak urinary stream that is deflected
downwards and splayed. A normal stream might be present in those children with mild hypospadias who have
a urethral meatus located on the glans. Affected children
might not be able to void while standing. Uncorrected,
erections might be painful in those children with chordee,
and sexual intercourse might not be possible in severe
cases. Fertility might be otherwise affected as the
abnormal deflection of the ejaculate might preclude
6 Associated anomalies
Cryptorchidism and inguinal hernia are the most
common anomalies associated with hypospadias [34, 49, 50].
Approximately 8% to 10% of boys with hypospadias have
cryptorchidism and 9% to 15% have an associated inguinal hernia . Clinicians should suspect the
possibility of an intersex condition if a child with hypospadias
also has cryptorchidism and one or both gonads are
impalpable. Enlargement of the utriculus masculinus is
present in approximately 11% of children with posterior
hypospadias [6, 51]. Urinary tract anomalies such as
ureteropelvic junction obstruction, vesicoureteric reflux,
pelvic or horseshoe kidney, crossed renal ectopia, and
renal agenesis occur in 1% and 5% of cases with
isolated anterior and posterior hypospadias, respectively [6,
49]. When anomalies coexist in one, two, or three other
organ systems, the incidence of an associated renal
anomaly increases to 7%, 13% and 37%, respectively
[49, 52]. There is a direct, almost linear relationship
between the severity of hypospadias and the frequency
of an associated anomaly . Anterior and middle
hypospadias are most often present as an isolated anomaly.
7 Diagnostic evaluation
Laboratory studies are not usually indicated for
isolated anterior or middle hypospadias. Screening for a
urinary tract anomaly by renal ultrasonography should
be considered in patients with posterior hypospadias and
in those with an anomaly of at least one additional organ
system. Karyotyping should be performed in patients
with cryptorchidism or ambiguous genitalia [2, 8]. Other
tests that should be considered include serum electrolytes,
17-hydroxyprogesterone, testosterone, luteinizing hormone, follicle-stimulating hormone, and sex
hormone-binding globulin, ultrasonography of the abdomen,
human chorionic gonadotropin stimulation tests, and
molecular genetic analysis of the androgen receptor gene
and the 5a reductase gene [8, 42]. The ordering of
endocrine tests should be directed by the history, physical
examination, and abnormal laboratory findings. In
patients with associated micropenis, a pituitary evaluation
followed by a trial of testosterone therapy should be
The goals of hypospadias surgery are to create a
straight penis that is adequate for sexual intercourse, to
reposition the urethral meatus to the penile tip to allow
the patient to void while standing, to create a neourethra
of adequate and uniform caliber, to construct a normal
looking penis, and to accomplish the foregoing with as
few complications as possible . Surgical correction
should also be considered in patients with a distal
hypospadias and minimal deformity as the psychological
benefit can be substantial . The ideal age for surgical repair
in a healthy child is approximately 6 to 12 months of age
[53, 54]. The advantages of early surgery include easier
after care, which includes better restraint for hygienic
purposes and less likelihood of urinary catheter dislodgement, less separation anxiety, less need
for analgesia, less postoperative emotional disturbance, and
better parent-infant bonding [5, 53, 55]. After 6 months
of age, the anesthetic risk is no greater than when the
child is older . Mureau et al.  found that boys
who had surgical correction of hypospadias at an early
age had fewer sexual inhibitions compared with boys
who had surgical correction at a later age.
Penile size is usually not a limiting factor for early
surgical correction . If micropenis poses as a
problem or if there is insufficient foreskin for repair,
preoperative treatment with exogenous testosterone might improve
the outcome [5, 54]. This can be achieved by the
administration of testosterone enanthate, 20 to 25 mg
intramuscularly, 3 and 6 weeks prior to surgery, or
topical dihydrotestosterone cream applied daily for 1 month
prior to surgery [6, 54]. For patients who still have an
extremely small phallus at 6 months of age, a shift in the
timing of repair to an older post-conceptional age may
Many procedures have been designed for the repair
of hypospadias and no single procedure is suitable for all
cases. Most cases of hypospadias can be repaired in a
single operation. The most common procedures include
the meatal advancement-glanuloplasty (MAGPI), glans
approximation procedure (GAP), and tubularization
following incision of the urethral plate (TIP) [29, 57, 58].
A two-stage repair might be required for more severe
forms of penoscrotal or perineal hypospadias [2, 59].
Complete excision of the chordee tissue is essential in
patients with severe hypospadias and chordee.
Suprapubic urinary diversion is not necessary when repairing
hypospadias, no matter how severe the abnormality or
how complex the repair is. Surgery should only be
performed by a pediatric urologist or a surgeon with special
and extensive expertise in hypospadias repair. In
patients with hypospadias, circumcision is contraindicated
as the foreskin might be needed for urethroplasty or to
provide penile shaft skin coverage . It is interesting
to note that in MAGPI and TIP, the foreskin is not used
in hypospadias repairs. With successful surgery, the
appearance should be that of a normal circumcised penis
and the cosmetic outcome is generally good.
Early complications of hypospadias repair include
bleeding, hematoma, wound infection, wound dehiscence,
necrosis of the shaft skin, urinary tract infection, and
urinary retention [2, 60]. Late complications include
urethrocutaneous fistula, meatal stenosis, recurrent or
persistent chordee, urethral stricture, balanitis xerotica
obliterans, urethrocele and urethral diverticulum [47, 61].
The rate of fistula formation is less than 10% for
one-stage repairs in anterior hypospadias, and increases with
the severity of the case. The rate of complications
depends on the severity of the hypospadias, age at surgical
correction, availability of adequate tissue for reconstruction,
experience and skill of the surgeon, and whether there
are previous failed attempts [60, 61]. Complications might
be minimized by selecting the appropriate procedure,
careful handling of tissues, optical magnification and the
use of stents, and use of fine, absorbable material .
In experienced hands, complication rates for distal,
midshaft, and proximal repairs are < 5%, 5% to 10%,
and 15%, respectively .
Children with hypospadias have normal onset of
puberty . Most patients with hypospadias have normal
testicular and androgen end-organ functions . Sexual
function should be normal after successful hypospadias
repair. Fertility should not be affected unless the patient
has an associated anomaly such as cryptorchidism, a
chromosomal abnormality, or a varicocele [1, 64]. Most
patients, including those with a less than perfect result
from hypospadias repair, are able to enjoy a satisfactory
sexual life .
Hypospadias is the most common congenital anomaly
of the penis. Identifiable causes implicate a deficiency in
androgenic stimulation of fetal genital tissue, or
conversely, exposure to excess estrogen or progestin
containing compounds in utero. There is evidence that
ATF3 responds to estrogenic or anti-androgenic activity
and might play a role in the pathogenesis. A high familial
incidence of hypospadias is observed and a polygenic
predisposition is likely. In most cases, however, a cause
cannot be identified. The ideal age for surgical repair in a
healthy child is between 6 and 12 months of age. Most
cases can be repaired in a single operation and on an
outpatient basis. With modern surgical techniques and
in the hands of an experienced pediatric urologist or
surgeon, the functional and cosmetic results are usually
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