Hypospadias

Written by: Michael Hallahan from Peninsula Medical School,

Introduction

 

Hypospadias is a congenital abnormality of the male external genitalia, wherein the external urethral meatus is found to be abnormally proximal and ventral. Rather than the urethra emerging in the normal position, the urethral meatus may be on the shaft of the penis, the scrotum or the perineum.

 

The condition is one of the most common congenital abnormalities and occurs in around 1 in 300 births (1). Incidence is rising in some countries, including the USA where it doubled in some areas between the 1970s and 1990s (2). Whilst it has been hypothesized that this is due to increased usage of oestrogens (1), it may simply represent an increase in reporting and referral of milder, more minimal hypospadias.

 

Pathogenesis

 

The condition is thought to be caused by under-stimulation of the genital tubercle and penis by dihydrotestosterone, resulting in failed fusion of the urogenital folds. However, deficiency or abnormality of testosterone, dihydrotestosterone or 5-α reductase is not commonly found in hypospadias alone. Direct aetiology is unknown in most cases and it appears to be a multifactorial process with links made to hormonal changes, genetic susceptibility and environmental factors.

 

 

Female sex hormones have been implicated and the ever increasing use of oestrogens has been suggested as a possible cause for the recent rise in incidence. In addition it is five times more common in boys born from IVF – possibly due to the effects of materal progesterone on 5-alpha reductase (1).

 

Monozygotic twins have an 8 times increased risk of hypospadias compared to singletons (1). This may be due to in-utero competition for hCG. In some cases there also appears to be a genetic link. Of affected boys, 8% have affected fathers and 14% have affected brothers. If two family members are affected, the risk for a subsequent boy is 22% (1).

 

Presentation

 

The prominent presenting feature of hypospadias is the meatal abnormality itself. The external urethral meatus arises ventrally and proximally to the anatomical norm; either on the glans, shaft of the penis, scrotum or perineum. The site of the meatus gives rise to the three classifications of hypospadias:

 

- Distal hypospadias describes a condition where the meatus is positioned on the glans, corona or distal shaft of the penis. This accounts for 65% of presentations of hypospadias (4).

- Midshaft hypospadias, rather obviously, refers to a meatus on the midshaft of the penis, on the ventral surface. 15% of hypospadias presents like this (4).

- Proximal hypospadias is the most severe form and describes a meatus found either on the proximal shaft, the scrotum or the perineum. 20% of patients with hypospadias will fall into this category (4).

 

 

In addition to an abnormal urethral meatus, 98% of patients with hypospadias will present with a hooded prepuce; a prepuce with an incomplete or missing ventral aspect (1). Furthermore, the penis may have an abnormal ventral curvature known as chordee. This curvature, caused by the presence of a band of fibrous tissue, is present in 15% of distal cases and up to 50% of proximal cases (1). Inguinal hernias and undescended testes are also found in around 9% of cases (5). Other abnormalities of the upper urinary tract are rare in hypospadias unless accompanied by other congenital abnormalities.

 

If left untreated, hypospadias prevents patients from urinating whilst standing up due to spraying and poor control of stream. Chordee may impair sexual function and make erections painful. Ultimately this may lead to severe psychosexual problems and poor quality of life. Hypospadias is therefore almost always corrected surgically.

 

Surgical Management

 

The ultimate aims of surgical correction of hypospadias are normal urination, normal sexual function and a natural appearance. In order to achieve this, any chordee is corrected. A slit-shaped urethral meatus is then constructed at the tip of the glans. This shape provides the most natural appearance and prevents spraying of urine. Finally, where possible and desired, reconstruction of the prepuce may follow.

 

Surgery is usually undertaken before the patient can remember it, avoiding the period between 1 and 3 years when patients are deemed to be particularly uncooperative. This provides two windows, the first 12 months of life or after age 3, with individual surgeons having their own preference.

 

Since the term hypospadias covers an array of abnormalities ranging from minimal sub-coronal hypospadias to severe perineal hypospadias with significant chordee, over 300 surgical techniques have been described (6). These can be loosely categorised as either one or two stage procedures.

 

One Stage Procedure

 

The majority of hypospadias can be managed with one of the many single stage procedures. Typically, this includes distal or mid-shaft hypospadias with little or no chordee.

 

The most common techniques create a neo-urethra using the remaining urethral plate. This is a strip of urethral mucosa which extends from the ectopic, abnormal meatus to the glans groove and is essentially the unfused section of urethra. The urethral plate is incised along its lateral borders and lifted off the ventral corpora. A catheter is then inserted into the current meatus and the free urethral plate, if wide enough, can then be rolled over the catheter and sutured in the ventral aspect creating a neo-urethra. Reconstruction of the glans and shaft is then completed using a prepucial graft.

 

In cases where the urethral plate itself is not wide enough, tissue flaps or full thickness skin grafts are used to form a neo-urethra. Buccal mucosa is commonly harvested and used as a graft.

 

Diagram of One Stage Procedure

Two Stage Procedure

 

Two stage procedures are thought of as more versatile as they can repair both distal and proximal hypospadias. They may also be preferred by surgeons as only one procedure needs to be mastered. However they are commonly reserved for more proximal hypospadias or where there is significant chordee.

 

The first procedure begins with a Horton’s test to measure chordee. Full-thickness prepucial graft is then harvested and the area of the new meatus is marked on the glans. A vertical midline incision is made between the current meatus and the proposed site of the new meatus. Chordee are then dissected and a repeat Horton’s test is performed to check for a straight erection. The prepucial graft is then grafted over the split and the wound dressed.

 

 

The second stage takes place six months later to allow the prepucial graft to take. The lateral margins of this graft are incised and then rolled over a catheter, as in one stage reconstruction, and sutured to form a neo-urethra. The procedure is then completed with skin reconstruction.

 

Diagram of Two Stage Procedure

Complications

 

Early complications of surgical repair of hypospadias are similar to those of any surgical procedure and include infection, bleeding, haematoma and complications of anaesthesia amongst many others.

 

Failure of the reconstruction may occur due to infection, extravasation of urine, ischaemia, necrosis of the flap or errors of design or technique (7).

 

One of the most troublesome complications of the repair is urethral fistula. In general, the more proximal the original meatus, the greater risk. The surgeon may try to prevent fistulae by off-setting suture lines so that the skin wound does not directly overlie that of the neo-urethra. Alternatively the surgeon may apply a “waterproofing” layer such as the Dartos fascia between the sutures lines of the neo-urethra and the skin. If fistula does occur, this may be corrected or a repeat reconstruction may be required.

 

Prognosis

 

Long term prognosis of hypospadias following surgical reconstruction is generally very good, though dependent on the grade of hypospadias at birth. Modern surgical techniques can often permit normal urinary and sexual function and a give a natural appearance. The rate of dissatisfaction with penile appearance is slightly higher in those born with hypospadias when compared to controls. However, sexual experience and satisfaction is broadly similar to the rest of the population (8). Following surgical reconstruction, prevalence of long-term urinary symptoms is similar to control groups (9). Rates of dissatisfaction and reported symptoms were however more common with severe proximal hypospadias when compared with more distal hypospadias.

 

Summary

 

• Hypospadias is a congenital abnormality of the male external genitalia wherein the external urethral meatus is found to be abnormally proximal and ventral

• Rather than the urethra emerging in the normal position, the urethral meatus may be on the shaft of the penis, the scrotum or the perineum

• This is accompanied by abnormal curvature of the penis in around 15% of cases, inguinal hernias in 9% of cases and undescended testes in 9% of cases

• Hypospadias occurs in roughly 1 in 200 births

• Hypospadias is essentially failed fusion of the urethral plate during embryonic development

• Aetiology is unknown in most cases although abnormalities of testosterone and excess oestrogens have been implicated

• The abnormality is corrected surgically in either one or two stages, usually before 4 years of age

• Long term satisfaction of urinary function, sexual function and appearance is generally similar to control groups following treatment

 

References

 

1. Giele H, Cassell O. Plastic and Reconstructive Surgery. Oxford. Oxford University Press. 2008

2. Paulozzi L, Erickson D, Jackson R. Hypospadias trends in two US surveillance systems. Pediatrics; 1997; 100(5): 831-4

3.  Sadler TW. Medical Embryology. Philadelphia. Lippinccott Williams & Wilkins. 2010

4. Stone C. Evidence for Plastic Surgery. Shrewsbury. tfm Publishing. 2008

5. Khuri FJ, Hardy BE, Churchill BM. Urological anomalies associated with hypospadias. Urol Clin North Am. 1981;8:565-571

6. Baskin LS, Ebbers MB. Hypospadias: anatomy, etiology and technique. J Pediatr Surg. 2006; 41(3):463-72

7. Barbagli G, De Angelis M, Palminteri E, Lazzeri M. Failed hypospadias repair presenting in adults. Eur Urol 2006;49:887–95.

8. Moriya K, Kakizaki H, Tanaka H, Furuno T, Higashiyama H, Sano H et al. Long-Term Cosmetic and Sexual Outcome of Hypospadias Surgery: Norm Related Study in Adolescence. J Urol. 2006; 176(4 Pt 2):1889-92

9. Moriya  K, Kakizaki H, Tanaka H, Mitsui T,  Furuno T,  Kitta T et al. Long-Term Patient Reported Outcome of Urinary Symptoms After Hypospadias Surgery: Norm Related Study In Adolescents. J Urol. 2007; 178 (4): 1659-62

 

Bibliography

 

• Mathes SJ. Plastic Surgery. 2nd edition. Philadelphia. Saunders Elsevier. 2006.

• Two staged hypospadias repair (S S Thomas) [DVD]: BAPRAS

• Urethroplasty (P Mouriquaad) [DVD]: BAPRAS

• Hadidi AT, Azmy AF. Hypospadias Surgery: An Illustrated Guide. Berlin. Springer-Verlag. 2004.