Hypospadias

Hypospadias is a congenital defect that is thought to occur during the embryologic development of the urethra, between 8 and 20 weeks' gestation. The external genital structures are identical in males and females until 8 weeks, after which time the genital structures develop a masculine phenotype in males, primarily under the influence of testosterone and its byproduct, dihydrotestosterone. As the phallus grows, the open urethral groove extends from its base to the level of the corona.

The classic theory is that the urethral folds coalesce in the midline from base to tip, forming a tubularized penile urethra and median scrotal raphe. This accounts for the posterior and middle urethra. The anterior or glanular urethra is thought to develop in a proximal direction, with an ectodermal core forming at the tip of the glans penis, which canalizes to join with the more proximal urethra at the level of the corona. The higher incidence of subcoronal hypospadias supports the vulnerable final step in this theory of development.

In 2000, Baskin proposed a modification of this theory in which the urethral folds fuse to form a seam of epithelium, which is then transformed into mesenchyme and subsequently canalizes by apoptosis or programmed cell resorption.[3] Similarly, this seam theoretically also develops at the glanular level, and the endoderm differentiates to ectoderm with subsequent canalization by apoptosis.

The prepuce normally forms as a ridge of skin from the corona that grows circumferentially, fusing with the glans. Failure of fusion of the urethral folds in hypospadias impedes this process, and a dorsal hooded prepuce results. On rare occasions, a glanular cleft with intact prepuce may occur, which is termed the megameatus intact prepuce (MIP) variant.

Ventral curvature of the penis, termed chordee, is often associated with hypospadias, especially in more severe forms. This is thought to result from a growth disparity between the normal dorsal tissue of the corporal bodies and the attenuated ventral urethra and associated tissues. The abortive spongiosal tissue and fascia distal to the urethral meatus may form a tethering fibrous band that contributes to the ventral curvature. This can range from mild to very severe (90º angle). (See the image below.)

The location of the abnormal urethral meatus classifies the hypospadias. Although several different classifications have been described, most physicians use the one proposed by Barcat and modified by Duckett, which described the location of the meatus after correction of any associated chordee.[4, 5] Descriptive locations in this classification include the following:

• Anterior (glanular and subcoronal)
• Middle (distal penile, midshaft, and proximal penile)
• Posterior (penoscrotal, scrotal, and perineal)

The location is anterior in 50% of cases, middle in 20%, and posterior in 30%; the subcoronal position is the most common overall. (See the images below.)

Several etiologies for hypospadias have been suggested, including genetic, endocrine, and environmental factors.

Genetic factors

A genetic predisposition has been suggested by a fourfold increase in the incidence of hypospadias among monozygotic twins as compared with singletons. This finding may relate to the demand of two fetuses for human chorionic gonadotropin (HCG) produced by a single placenta, with an inadequate supply during critical periods of urethral development.[6]

A familial trend has been noted with hypospadias. The prevalence of hypospadias in male children of fathers with hypospadias has been reported as 8%, and 14% of brothers of children with hypospadias are also affected. The inheritance is likely polygenic.[7]

Endocrine factors

A decrease in available androgen or an inability to use available androgen appropriately may result in hypospadias. In a 1997 report by Aaronson et al, 66% of boys with mild hypospadias and 40% with severe hypospadias were found to have a defect in testicular testosterone biosynthesis.[8]

Mutations in the 5-alpha reductase enzyme, which converts testosterone (T) to the more potent dihydrotestosterone (DHT), have been associated with hypospadias. A 1999 report by Silver et al found that nearly 10% of boys with isolated hypospadias had at least one affected allele with a 5-alpha reductase mutation.[9]  Although androgen receptor deficits, quantitative or qualitative, have been shown to result in hypospadias, this is thought to be relatively uncommon, and other factors are more commonly implicated.

A higher incidence of hypospadias in winter conceptions has also been proposed. Theoretically, this may be related to the effect of daylight on pituitary function, which, in turn, affects the maternal and fetal hormonal milieu; however, other authors have not noticed this association.

A threefold increased risk of hypospadias appears to exist in males born through assisted reproductive techniques. This may reflect maternal exposure to progesterone, which is commonly administered in in-vitro fertilization (IVF) protocols. Progesterone is a substrate for 5-alpha reductase and acts as a competitive inhibitor of the T-to-DHT conversion. Other theories have suggested that an inherited testosterone deficit may be causal.[10, 11]

Other factors that contribute to infertility, such as underlying endocrinopathies or fetal endocrine abnormalities, may play a role.

Environmental factors

Endocrine disruption by environmental agents is gaining popularity as a possible etiology for hypospadias and as an explanation for its increasing incidence.

Estrogens have been implicated in abnormal penile development in many animal models. Environmental substances with significant estrogenic activity are ubiquitous in industrialized society and are ingested as pesticides on fruits and vegetables, endogenous plant estrogens, in milk from lactating pregnant dairy cows, and in pharmaceuticals such as phthalates. The association of hypospadias with increasing parity, increasing maternal age, and low birth weight noted in some studies may reflect a lifelong exposure to environmental disruptors and a possible cumulative effect.[12]

Combination theory

A growing body of evidence suggests that the development of hypospadias has a two-hit etiology involving a genetic predisposition coupled with fetal exposure to an environmental disruptor.[13, 14]

United States statistics

Hypospadias occurs in approximately 1 in every 250 male births in the United States. The incidence doubled from 1970 to 1993. Although some have suggested that this doubling actually reflects increased reporting of minor grades of hypospadias, increases in severe hypospadias were also noted. Increasing sensitivity of surveillance systems alone cannot explain this twofold increase. However, some reports linked the increased rate of hypospadias in boys born prematurely and small for gestational age and boys with low birth weight.[15, 16]

International statistics

In several countries, the incidence of hypospadias may be rising. In general, the frequency seems rather constant, at 0.26 per 1000 live births in Mexico and Scandinavia and 2.11 per 1000 live births in Hungary.[17, 18]

Race-related demographics

Historically, the incidence of hypospadias was reported to be higher in whites than in Blacks, and more common in those of Jewish and Italian descent. Subsequent assessment revealed a more balanced incidence among different race groups.[19]

With modern anesthetics, instruments, sutures, dressing materials, and antibiotics, hypospadias repair is considered generally successful. Earlier studies focused on outcome measures of cosmesis and low complication rates of urethrocutaneous fistula or dehiscence. Long-term studies on the outcomes of hypospadias with current practices have been limited. 

Although some earlier studies were discouraging, these reflected an era with poorer technical outcomes, an increased number of operations, and a lack of appreciation for the psychological morbidity associated with intervention at an older age. More severe forms of hypospadias may require long-term follow-up and multiple surgical procedures.

Hypospadias surgical complications have been described in the single digits for distal repair; however, longer follow-up, greater standardization in assessment and outcome parameters, and possibly more honest reporting have revealed complication rates approaching 50% for more proximal defects. This has given rise to renewed enthusiasm for a staged approach to these more complex forms of hypospadias, given the higher rates of success despite a second operation.[20]

Newer scoring systems designed to lend objective measures to long-term outcomes are becoming more popular.[21]  The HOPE score is a physician-assigned score shown to correlate with the severity of hypospadias; higher HOPE scores (milder hypospadias) were associated with less need for repeated operative interventions.[22, 23]

A more recent focus has been the recurrence of penile curvature after initial correction. One study found that more than 80% of those undergoing reoperation for hypospadias complications had some component of residual or recurrent curvature. These recurrences were more common after chordee excision or plication repairs than after corporal lengthening procedures.[24]

Subsequent long-term studies suggested that despite having decreased satisfaction with their genital appearance, patients who have undergone hypospadias repair are more satisfied with their sex lives in comparison with healthy control subjects.[25]

The literature has been expanding tremendously with regard to the assessment of the perception of success. In a Canadian study, more than half of the patients or parents of patients undergoing treatment of mild hypospadias had no decisional regret; however, many (40%) experienced mild regret, and a significant number (6%) experienced moderate-to-severe regret.[26] There was significant association with the desire to avoid circumcision and a high initial decisional conflict level.

Similar findings were noted in the United Kingdom, where regret was primarily associated with a small glans size, distal meatal location (mild hypospadias), and complications necessitating reoperation.[27] In this study, the level of regret was similar between those who were circumcised and those were not. This did not appear to be associated with the surgeon's experience.

Although the techniques of hypospadias repair continue to evolve, the broader future of hypospadias treatment is encouraging. Nontraditional tissue adherence techniques have been developed, including tissue glues and laser-activated soldering techniques, but have not been widely adopted.

Urethral substitutes, which may obviate the difficulties associated with severe hypospadias and poor tissue availability, are currently under investigation. These substitutes are generally acellular synthetic or natural matrices that can incorporate the patient's normal urethral cellular components.

Because most patients with hypospadias are surgically treated at a very young age, parental teaching and reassurance are very important for ensuring a satisfactory experience for the families of these patients. Early consultation with a pediatric urologist may help parents to understand the issue better, have realistic expectations, remove guilt, and provide a management plan.[28] Evidence suggests that online support groups can play an important role in how parents and patients cope with hypospadias.[29]

Obtain a thorough history and physical examination, including any history of a familial pattern of hypospadias, any past medical history or comorbidity, and a physical assessment focusing on the meatal location, glans configuration, skin coverage, and ventral curvature (chordee).

A history of parental difficulties in conceiving and treatment should also be documented; in-vitro fertilization (IVF) has been associated with a higher incidence of hypospadias.

Although the appearance of hypospadias has been identified with both antenatal fetal ultrasonography (US) and magnetic resonance imaging (MRI), the diagnosis is generally made upon examination of the newborn infant.[30]

A dorsal hood of foreskin and glanular groove are evident, but upon closer inspection, the prepuce is incomplete ventrally and the urethral meatus is noted in an abnormal proximal location. Rarely, the foreskin may be complete, and the hypospadias is revealed at the time of circumcision. If hypospadias is encountered during neonatal circumcision, after the dorsal slit has been performed, the procedure should be halted, and the patient should be referred for urologic evaluation.

Penile curvature may be readily apparent or may be discernible only during erection. Proximal hypospadias is commonly associated with a bifid scrotum and penoscrotal transposition (see the image below), in which the rugated scrotal skin begins lateral to the penis rather than in its normal posterior origin.

No laboratory tests have been found to be helpful in the evaluation and management of hypospadias. In cases where a disorder/difference of sex development (DSD) is suspected, hormonal evaluation may be needed.

Upper-urinary-tract anomalies are rarely associated with hypospadias and do not justify routine imaging in these patients unless other organ system anomalies are present. Other associated findings are more common (eg, enlarged prostatic utricle, low-grade vesicoureteral reflux [VUR]) but are of little consequence clinically unless other symptoms merit evaluation.[35]

It has been argued that prostatic utricles are an underappreciated cause of urologic morbidity and may present as penile pain with voiding, hematuria, epididymitis, and urinary tract infection (UTI) and therefore should be sought with retrograde urethrography in the setting of proximal hypospadias.[36]

In very rare instances, presence of meatal stenosis may prevent normal egress of urine and cause distal ballooning of the urethra. This may necessitate a temporizing meatoplasty to allow normal flow of urine.

The treatment for hypospadias is surgical repair. Repair is generally performed for functional and cosmetic reasons. The more proximally ectopic the position of the urethral meatus, the more likely the urinary stream is to be deflected downward, which may necessitate urination in a seated position. Any element of ventral curvature (chordee) can further deflect the urinary stream. The abnormal deflection of ejaculate may preclude effective insemination, and significant chordee can preclude vaginal insertion of the penis or can be associated with inherently painful erections.

Minor cases of hypospadias, in which the meatus is located distal to the corona on the glans, may not require surgical repair and may simply be managed with observation. It must be kept in mind, however, that although the most minor forms of hypospadias are insignificant in physiologic terms, they too may merit repair on the basis of the potential long-term psychological stress associated with having abnormal genitalia.

The goals of surgical treatment of hypospadias are as follows:

• To create a straight penis by repairing any curvature (orthoplasty)
• To create a urethra that opens at the tip of the penis (urethroplasty) with a natural slitlike configuration (meatus)
• To re-form the glans into a more natural conical configuration (glansplasty)
• To achieve cosmetically acceptable penile skin coverage
• To create a normal-appearing scrotum

The resulting penis should be suitable for future sexual intercourse, should enable the patient to void while standing, and should present an acceptable cosmetic appearance.

Timing of surgery

Before 1980, hypospadias repair was performed in children older than 3 years because of the larger size of the phallus and a technically easier procedure. As the technical aspects of hypospadias surgery progressed, the size of the phallus was no longer the limiting factor in the ideal timing of repair.

The 1996 statement by the Section on Urology of the American Academy of Pediatrics (AAP) recommended the ideal timing of repair as 6-12 months of age on the basis of anesthetic safety, genital awareness in the child and minimization of psychological morbidity, abnormal behavior, and gender identity confusion.[37]  A benefit in wound healing with earlier repair has also been perceived and may have a basis in the reduced proinflammatory cytokine production noted at younger ages.[38]  More recent concerns regarding early exposure to general anesthesia has reinvigorated this topic (see below).

Late hypospadias repair, in the pubertal and postpubertal period, is associated with complications, primarily urethrocutaneous fistula, in nearly 50% of patients.[39] Some reports cited a higher rate of complications in 5-year-old patients than in 1-year-old patients, suggesting that earlier repair is generally better.[40] Others also reported high rates of complications in adults.[41]  Subsequent reports, however, cited comparable complication rates across age groups.[42]

Some argue that hypospadias should not be repaired until the child is able to consent to the procedure himself. This position represents a dramatic shift from what has been the standard of care for decades. It must be remembered that deferring repair until the teenage years is, at this point, an unproven approach, in that there is no large scientific cohort literature assessing the psychological and social impact of withholding genital reconstruction in this population.[43, 44]

An electronic survey using Facebook identified 52 adult men with untreated hypospadias and reported worse outcomes for these men than for nonhypospadiac men.[45] Those with severe hypospadias had more adverse outcomes. Outcome measures included lower sexual health scores, worse prostatic symptom scores, more ventral penile curvature and resulting difficulty with intercourse, worse satisfaction with meatus and penile curvature, and more sitting to urinate.

In 2016, the United States Food and Drug Administration (FDA) released a Drug Safety Communication warning stating that repeated or lengthy use of general anesthetic or sedative drugs during operations or procedures in children younger than 3 years of age or in pregnant women during the final trimester may affect development of children's brains. Lengthy, in this context, was defined as longer than 3 hours. The FDA recommended that caution be exercised regarding the possible risks of delaying needed surgical or diagnostic procedures and that parents and providers carefully weigh the risks and benefits of each procedure until more information is available.

Since then, several efforts have been made to evaluate this risk objectively. One sibling-matched cohort study found no significant differences in IQ scores in later childhood between healthy children with a single anesthesia exposure before the age of 36 months and healthy siblings with no anesthesia exposure.[46]  

As of 2019, the GAS study, an international prospective randomized controlled study, had shown no cognitive differences between patients undergoing general anesthesia in infancy for inguinal hernia repair (an operation similar in duration to hypospadias surgery), and those using only regional anesthesia at 2 and 5 years of age.[47, 48]

A 2021 article by Sepulveda et al noted that such studies typically did not differentiate between the drug administration techniques employed (inhaled or intravenous) or specify whether electroencephalographic (EEG) brain monitoring was performed.[49]  

Evidence will continue to accrue, but the good-quality evidence amassed to date suggests that limited general anesthesia in infancy is safe.

These issues are important for consideration and should be included in the discussion with families before any surgical reconstruction.

Types of repair

The specific techniques for hypospadias repair are beyond the scope of this article (see Penile Hypospadias Reconstruction); however, the types of repairs can be generically grouped, and the approach to the repair is relatively standard.

The urethra may be extended by using various techniques. These techniques are generally categorized as follows:

• Primary tubularizations
• Local pedicled skin flaps
• Tissue-grafting techniques
• Meatal advancement procedures

The tubularized incised plate (TIP) repair has become the most commonly used repair for both distal and midshaft hypospadias. This technique is a primary tubularization of the urethral plate, with incision of the posterior wall of the plate, which allows it to hinge forward. This creates a lumen of greater diameter than would otherwise be possible, obviating the routine use of a flap or graft to bridge a short narrow segment of urethral plate. (See the images below.)

The TIP repair has proved adaptable to various settings, and current surveys indicate that it is the procedure of choice for most repairs by most urologists. Although it is favored by many, if the urethral plate is contributing to curvature, transection of the urethral plate to correct curvature will preclude the use of the TIP technique for complete urethral reconstruction.

Various sutures have been used in the repair of hypospadias, but polyglycolic acid–based sutures may offer the best balance of resilience when exposed to urine, without excessive time to absorption resulting in a foreign body reaction.[50]

Studies support the general concept that increasing the layers of tissue between the urethra and overlying skin coverage makes subsequent development of urethrocutaneous fistula less likely.[51] Temporary urethral stents are a common adjunct to hypospadias repair and are felt to decrease the likelihood of fistula formation. Various drainage tubes have been utilized for this purpose.[52] To stent or not to stent is an ongoing controversy, balancing the risk of irritative symptoms and urinary tract infection with the risk of urinary retention.[53]

In a retrospective-prospective observational study of 189 patients that compared 1 week of transurethral bladder catheterization after hypospadias repair with 3 weeks of catheterization, Daher et al found the longer catheterization period to be associated with better outcomes and fewer complications.[54] A subsequent meta-analysis found that duration and presence of catheter drainage may have little affect on outcome.[55]

In the setting of repeat repair after unsuccessful surgery for hypospadias when local tissues are unavailable, buccal mucosa has been used for urethral grafting. This tissue is well suited for this purpose because of its availability, characteristics that favor graft success, and resilience to a moist environment. Urethral stents are generally used for bladder drainage while healing occurs in all but the most distal hypospadias repairs.

Steps of repair

Hypospadias repair includes many steps. The penis is degloved of skin to eliminate any component of skin tethering to curvature. Commonly, an erection is induced pharmacologically or by instillation of saline solution into the corporal tissues; this allows objective assessment of curvature.[56, 57]  The ideal method for the objective assessment of the degree of penile curvature has become a controversy. Many have advocated measuring angulation with a goniometer, but more recent proposals have invovled a mobile application to correlate a photograph with defined degrees of angulation. Studies not shown any particular method to be superior to a subjective estimate or the so-called eye test.[58, 59]

Straightening of the penis (orthoplasty) is accomplished by removing any ventral tissue that limits the expansion of the corporal bodies. If this is not sufficient, milder chordee (commonly considered < 30º) can be corrected further through dorsal plication of the corporal bodies, generally in the midline to avoid injury to the nerves of the penis that course on the lateral aspect of the dorsum. This compensates for any dorsal-to-ventral corporal disproportion.

For greater degrees of chordee in which the urethral plate itself contributes to ventral curvature, the urethral plate is transected and dissected off the corporal bodies; this ultimately requires intervening urethral replacement and a staged approach. For persistent curvature, horizontal relaxing incisions in the corporal bodies, with or without grafting, may be required to straighten the penis further. A popular approach is to use the STAG (straighten and graft) or the STAC (straighten and cover) technique, in which the ventral corpora are deeply and transversely incised in tandem at the point of maximal curvature.

If the urethral plate can then be used to cover the corporotomy sites, the remaining defect is grafted, typically with prepuce or buccal mucosa (STAG technique). If the corporotomies cannot be covered with native urethral tissue, they are covered with adjacent hair-bearing skin, and the segment between urethral segments is grafted later (STAC technique). In the past, great efforts were made to cover these corporotomies with tissue such as dermis or synthetic material, but this approach has largely fallen out of favor.

It is essential to carry out an artificial erection test after attempts to correct curvature to assess the results of the procedure and ensure that the penis has been adequately straightened.[60]

If the penis is straight initially, several different approaches to creation of a tubular urethra with its opening at the tip of the glans may be undertaken. These involve tubularization or adjacent skin flap techniques. A narrow strip of urethral plate can still be reconstructed by incising the plate in the midline to allow it to expand and hinge ventrally for tubularization around a stent or catheter (the TIP technique). This latter technique also works well for repair when the penis has been straightened without transection of the urethral plate.

Repair of the glans (glansplasty) is accomplished by mobilizing the tissues ventrally to allow the edges to approximate in the midline over the tubularized urethra.

Finally, the skin is tailored and the penile shaft resurfaced. Skin deficits may be treated with local skin flap coverage from the scrotum or with tissue grafting.

The repair of penoscrotal transposition is often performed as a staged procedure because the necessary incisions may compromise the vascular pedicle to skin flaps used in the primary urethroplasty. The repair of penoscrotal transposition is usually deferred at least 6 months to allow for adequate formation of collateral blood supply.

The repair of hypospadias is generally planned as a single-stage procedure, but severe ventral penile curvature, poor skin availability, and small phallic size may be better approached in a staged manner, as described above. Generally, the curvature is corrected and tissue for later urethral reconstruction is relocated to the ventral penile shaft during the first stage; the urethroplasty and glansplasty are performed after the first stage has completely healed, usually at least 6 months later.

Adjuvant hormonal therapy

Although no corrective medical therapy for hypospadias is known, hormonal therapy has been used as an adjuvant to surgical therapy in infants with exceptionally small phallic size. Preoperative treatment with testosterone or human chorionic gonadotropin (HCG) injection has been used to promote penile growth; some have reported improvement in chordee with lessening in the severity of hypospadias. That prepubertal androgen therapy may limit normal genital growth at puberty is a concern, but this has not been confirmed clinically. Hormonal creams are typically avoided because of variable transcutaneous absorption.

One group reported preoperative parenteral testosterone administration to be beneficial in decreasing complication rates (from 13.18% to 5.45%).[61] Others, however, have reported increased postoperative complications (including fistula and dehiscence) when testosterone is used, findings that have tempered enthusiasm for this measure.[62]  A retrospective study with longer-term follow-up (18 years) suggested that the outcomes of cosmesis, penile length, body height, and complications were similar with and without testosterone supplementation.[63]

It is clear that repairs that are more proximal are associated with a greater incidence of complications.[64, 65] Older age at surgery and low surgical experience have also been associated with poorer outcomes. A study from England by Wilkinson et al found that staged repairs were associated with higher complication rates and that high-volume centers had lower complication rates.[66]

With longer follow-up, it is apparent that late complications can occur, and thus, most advocate continued evaluation through puberty.[67, 68, 69, 70]  A long-term analysis by Nguyen et al showed that the incidence of secondary surgical repair of hypospadias is underreported if follow-up is limited to less than 6 years.[71]

Immediate postoperative concerns

Local edema and blood spotting can be expected early after repair and generally do not cause a significant problem.

Postoperative bleeding rarely occurs and is usually controlled with a compressive dressing. Infrequently, reexploration may be required to evacuate a hematoma and to identify and treat the source of bleeding.

Infection is a rare complication of hypospadias repair in the modern era. Skin preparation and perioperative antibiotics are generally used. Patients are often maintained on an antibiotic course until any stents are removed, though this has not clearly been shown to be beneficial.[72]

Long-term issues

Urethrocutaneous fistulization is a major concern in hypospadias repair. The rate of fistula formation is generally less than 10% for most single-stage repairs but rises with the severity of hypospadias, approaching 40% with complex reoperative efforts. Fistulas rarely close spontaneously and are repaired by using a multilayered closure with local skin flaps 6 months after the initial repair. After repair, fistulas recur in approximately 10% of patients. (See the image below.)

Meatal stenosis, or narrowing of the urethral meatus, can occur. A urethral stent prevents any problems initially, but a fine-spraying urinary stream that is associated with straining to void may necessitate evaluation and possible surgical revision of the distal urethra.

Urethral strictures may develop as a long-term complication of hypospadias repair. These are generally repaired operatively and may require incision, excision with reanastomosis, or patching with a graft or pedicled skin flap.

Urethral diverticula may also form and are evidenced by ballooning of the urethra while voiding. A distal stricture may cause outflow obstruction and may result in a urethral diverticulum. Diverticula can form in the absence of distal obstruction and are generally associated with graft- or flap-type hypospadias repairs, which lack the subcutaneous and muscular support of native urethral tissue. The redundant urethral tissue is generally excised, and the urethra is tapered to an appropriate caliber.

Hair-bearing skin is avoided in hypospadias reconstruction but was used in the past. When incorporated into the urethra, it may be problematic and can result in urinary tract infection (UTI) or stone formation at the time of puberty. This generally requires cystoscopic depilation using a laser or cautery device or, if severe, excision of hair-bearing skin and repeat hypospadias repair.

Some surveys have suggested that milder forms of erectile dysfunction may be more common with more proximal hypospadias repairs.[73]

Consultation with a pediatric endocrinologist is indicated in cases where a child may be suspected of having a disorder/difference of sex development (DSD).