Definition: A ventrally placed urethral meatus, short of its normal terminal location.
Aetiology & risk factors
About 1 in 200 – 300 live births.
90 % isolated penile abnormalities with no other issues.
Aetiology has not been clearly defined but both placental insufficiency and disruption in the androgen cascade during development have been implicated.
Risk factors:
- 13 x risk for first degree relatives
- Low birth weight / IUGR / premature birth
- Advanced maternal age
- Maternal oestrogen/progesterone intake
- Assisted reproductive techniques
Embryological notes
Hypospadias represents an arrest in normal penile and urethral development during weeks 8 – 16.
The urethra is normally formed by the in-rolling and fusion of the urethral folds.
Fusion of the urethral folds starts proximally and continues distally – arrest of this process at any point results in the abnormal meatal position.
The terminal/glanular urethra probably has a different path of development – starting as an epithelial tag distally which involutes or undergoes retrograde ingrowth which then fuses with the penile urethra.
- Hence the different histology of the stratified squamous navicular fossa cf. transitional urethra.
- This may be why hypospadias patients have the urethral pit.
Foreskin development occurs during weeks 13 – 18, i.e. overlapping time as urethral development. Ventral fusion of the preputial folds is not completed until the urethral folds fuse – hence why failure of the fusion of the urethral folds is associated with abnormal or incomplete foreskin (dorsal hood).
Clinical features
Classic triad:
- Abnormal ventral urethral meatus, proximal to the normal terminal location
- Dorsally hooded foreskin / deficiency of ventral foreskin
- Ventral curvature (chordee)
5 – 10 % associated with undescended testis – can be as high as 50 % in proximal hypospadias.
May be associated hydroceles and inguinal hernia.
Other urinary tract abnormalities not common – no role for routine urinary tract ultrasound.
15 % asymptomatic prostatic utricle.
In patients with severe proximal hypospadias, or hypospadias with concurrent undescended testis, consider differences of sexual development (DSD)
MIP variant – megameatus with intact prepuce.
Classification
Anterior (distal) – 50 %
Middle – 30 %
Posterior (proximal) – 20 %
NB whilst typically anterior hypospadias considered most simple, be aware of possible hypoplastic skin overlying a more proximal true urethral meatus, or severe chordee which can make management still challenging.
Classify by not only the meatal location, but comment on the width/quality of the glans, the significance of chordee, the quality of urethral plate and presence of scrotal testes.
Principles of management
Goals:
- Normal urethral meatus location
- Normal voiding function (standing)
- Normal sexual activity
- Functionally straight penis
Generally surgical repair done between 6 – 18 months, before school and whilst in pads and to try avoid long term memories.
Pre-operative testosterone can enlarge the glans and penis prior to surgery. Not really used in Aust. It seems most useful in boys with small glans (14 mm width) which has been associated with higher complication rates.
Do not perform circumcision of boys with hypospadias – the foreskin can be used for reconstruction.
Consider no surgery or delaying intervention especially for distal meatus with minimal/no chordee.
Counselling parents crucial – setting expectations, could be 2 stage procedure.
Caudal nerve block useful
- Fix the curvature first
Cause may be shortened ventral skin, short urethra, or intrinsic curvature of the corpora (failure of spongiosum to develop relative to cavernosa). The cause can only really be determined intra-op with AET.
Degree of curvature may dictate a 1 vs 2 stage repair.
Majority of mild curvatures corrected with excision of the chordee connective tissue – skin and dartos.
The remainder may need dorsal plication.
If significant curvature the trend is now to use penile lengthening techniques, which mandates a 2 stage repair (6 months) before proceeding with urethroplasty portion.
- Urethroplasty or procedure of choice
Depends on:
- Meatal location
- Glans size and width
- Quality of urethral plate
- Nature of foreskin
MAGPI – meatal advancement glanuloplasty
- Suitable for distal glanular hypospadias
- Advancement technique with no incision of urethral plate
TIP – tubularised incised plate (Snodgrass)
- Modification of the Thiersch-Duplay
- Tubularisation of tissue distal to the ectopic meatus
- TIP includes midline incision of the urethral plate, increasing width available for tension free tubularisation
- Best for distal but can be modified for proximal hypospadias too (higher risk complications, other techniques preferred?)
Proximal hypospadias techniques – usually 2 step with first step curvature correction and incision of the urethral plate
- Bracka – uses graft (usually inner preputial skin, occasional buccal) as a template for urethroplasty
- STAG (staged tubularised autograft) is modification of Bracka
- Midline incision of glans and placement of graft, with tubularisation occurring at second stage 6 months later
- Byars flap
- Redundant dorsal preputial skin used
Complications:
Higher rates for proximal repairs, re-operative surgery and narrower glans < 14 mm.
- Urethrocutaneous fistula
- Glans dehiscence
- Meatal stenosis
- Urethral stricture
- Urethral diverticulum
- Recurrent curvature
- Penile torsion
- Preputial dehiscence
- BXO
- Parental or patient regret