KEY NOTES CHAPTER 7: THE TRUNK AND UROGENITAL SYSTEM - Hypospadias.

Question 0

Apart from the 3 characteristic abnormalities, what other findings may be present?

Answer 0

∘ Flattened glans penis
∘ Downward glans tilt
∘ Deviation of the midline penile raphe
∘ Scrotal encroachment onto the penile shaft
∘ Midline scrotal cleft
∘ Penoscrotal transposition.

Question 1

What is hypospadias?

Answer 1

A congenital condition characterised by:

1. Abnormally proximal urethral meatus on the ventral aspect of the penis or scrotum.
2. Hooded, ventrally deficient, prepuce (foreskin).
3. Ventral curvature of the penis (chordee).

Question 2

What is ‘Megameatus intact prepuce’ (MIP)?

Answer 2

MIP = variant of hypospadias.

∘ normal foreskin that conceals a glanular or distal shaft hypospadias.

Question 3

What is the epidemiology of hypospadias?

Answer 3

• 1 in 300 live male births.
• Increased risk of hypospadias in:
  ∘ +ve FHx (4-10%)
  ∘ IVF
  ∘ Placental insufficiency - low birth weight, preterm, maternal obesity, diabetes, hypertension.
• 10% associated with inguinal hernias.
• 20% of hypospadias associated with other GU abnormalities:
  ∘ cryptorchidism: 3% of distal, 10% proximal.
  ∘ asymptomatic paraurethral sinuses, urethral valves, enlarged prostatic utricle.

Question 4

What is the aetiology?

Answer 4

• in most cases is unknown.
• Presuming hypospadias is a form of developmental arrest, these factors are implicated:
∘ Defects of testosterone synthesis
∘ Androgen receptor deficiency
∘ Mutations in FGF8 and FGFR2 genes
∘ Increased levels of exogenous (environmental) oestrogens.

Question 5

How is hypospadias classified?

Answer 5

Duckett’s classification (position of urethral meatus).

Distal (85%)
1 Glanular
2 Subcoronal
3 Distal penile
4 Midshaft

Proximal 
5 Proximal penile
6 Penoscrotal
7 Scrotal
8 Perineal.

Question 6

How do the internal organs develop?

Answer 6

Internal organs
• Embryo is sexually indeterminate until week 6.
• 6th week: gonads arise from genital ridges and differentiate into their male and female forms, in response to arrival of primordial germ cells from yolk sac.
• Internal sex organs form from the mesonephric and paramesonephric ducts:

Question 7

What does the mesonephric ducts form?

Answer 7

• Aka Wolffian duct.
• Forms majority of male internal sex organs.

• The sex-determining region of the Y chromosome (SRY) induces:
- genital ridge cells to
differentiate into Sertoli cells which secrete Müllerian-inhibiting factor which causes paramesonephric ducts to regress (8th-10th weeks).
- genital ridge mesenchyme to differentiate into Leydig cells which secrete testosterone and stimulates development of:
∘ Mesonephric ducts
∘ Genital tubercle.

• In males, mesonephric ducts give rise to 'SEED':
∘ Seminal vesicles
∘ Epididymis
∘ Ejaculatory ducts
∘ Ductus (vas) deferens.

(Paramesonephric ducts degenerate into appendix testis and prostatic
utricle).

Question 8

What does the paramesonephric ducts form?

Answer 8

• Aka Müllerian duct.

• In females, paramesonephric ducts persist and develop into:
∘ Fallopian tubes
∘ Uterus
∘ Cervix
∘ Upper vagina.
- The lower vagina is initially occluded by the vaginal plate.
- This elongates during 3rd-5th months and subsequently canalises to form inferior vaginal lumen.

(Without Y chromosome and SRY, Sertoli cells, Müllerian-inhibiting factor, Leydig cells and androgen production are not formed and mesonephric ducts degenerate).

Question 9

How do the external organs develop?

Answer 9

• Before 11th week, external genitalia are sexually indistinct.
• At 11th week, the external genitalia consist of:
∘ Central urethral groove (endoderm)
∘ Urethral folds either side of the urethral groove
∘ Labioscrotal swellings either side of the urethral folds
∘ Genital tubercle anteriorly.

• Male or female differentiation depends upon androgen receptor signalling.

Question 10

How does the male external genitalia develop?

Answer 10

• Genital tubercle forms the penis.
• Urethral groove grows distally down genital tubercle (but not to tip of penis).
• Distal glanular urethra is formed by ectodermal ingrowth from the glans penis, evidenced by stratified squamous epithelium in fossa navicularis.
• Urethral folds fuse (proximal-to-distal) over urethral groove, forming a tubed urethra.

• Embryonic penis initially exhibits a ventral curvature.
∘ Chordee may therefore be due to arrest of penis development at this stage.

• Labioscrotal swellings fuse to form the scrotum.
• Testes descend into scrotum, with aid of the gubernaculum, around 7th month.

Question 11

How does the female external genitalia develop?

Answer 11

• Genital tubercle forms the clitoris.
• Urethral groove does not extend into genital tubercle.
• Urethral folds do not fuse over urethral groove. Instead, they form:
∘ Labia minora
∘ Prepuce of the clitoris.

• Labioscrotal swellings become labia majora.

Question 12

Describe the anatomy of the penis.

Answer 12

Root
Body
Glans

Question 13

What does the root of the penis consist of?

Answer 13

1. Bulb of the penis centrally.
   - Continues as corpus spongiosum in the body.
   - Penetrated by the spongy urethra and paired bulbourethral arteries.
2. Crura (each side of the bulb).
   - Continues as corpus cavernosum in the body.
   - Attached to ischiopubic rami.
   - The deep arteries of the penis enter each crus to run in corpora cavernosa.
3. Bulbospongiosus and ischiocavernosus muscles.

Question 14

What does the body of the penis consist of?

Answer 14

∘ Two adjacent corpora cavernosa (dorsal).
∘ Single corpus spongiosum (ventral), containing spongy urethra.
• These three cylinders of tissue are enclosed by tunica albuginea -> deep fascia of penis (Buck’s fascia)
∘ Paired dorsal arteries of the penis, a dorsal vein and dorsal nerves are contained within
Buck’s fascia.
• Subcutaneous connective tissue contains abundant smooth muscle fibres (dartos fascia - continuous with Colles’ fascia of perineum).

Question 15

What does the glans consist of?

Answer 15

• Distal part of corpus spongiosum expands to form the conical glans penis.
• Corona: prominent proximal margin of glans.
• External urethral meatus is slit-shaped.

Question 16

How is the urethra divided anatomically?

Answer 16

1 Prostatic urethra
2 Membranous urethra
- Passes through deep perineal pouch.
- Pierces perineal membrane to become penile urethra.
3 Penile urethra
- aka spongy urethra (within corpus spongiosum).

Question 17

Draw a cross-section of the penis.

Answer 17

.

Question 18

How do you assess a child with hypospadias?

Answer 18

History
Antenatal history (placental insufficiency) , prematurity, low birth weight.
?IVF
FHx
PMH

Witness erections - chordee?
Direction and flow of urinary stream.

Examination

• Penis size
• Urethral meatus
• Foreskin (complete / incomplete, hooded) non-retractile is normal
• Testicles
• Inguinal hernia

Question 19

When are investigations indicated?

Answer 19

Most distal hypospadias, investigations are not indicated.

Proximal hypospadias, cryptorchidism should have:

• Pelvic ultrasound (internal genitalia)
• Karyotype analysis
• Serum electrolytes (screen for congenital adrenal hyperplasia).

Syndromic hypospadias cases may be associated with developmental delay, abnormal facies, anorectal and scrotal malformations.

Question 20

What are the aims of surgery?

Answer 20

∘ A normal aesthetic appearance, including a slit-like terminal meatus
∘ Normal erection and sexual function
∘ Normal urinary stream.

Question 21

Discuss the timing of surgery.

Answer 21

Controversial
∘ North America ~6 and 12 months.
∘ Europe ~12 and 18 months.

Psychological considerations
• 18-36 months has been labelled as ‘difficult period’ for hospitalisation (based on outdated practices when parents couldn’t stay with children).
• Some evidence surgery between 3 and 5 years increases anxiety for physical injury.
• Other evidence shows no difference in quality-of-life assessment related to patient age at operation.

Technical considerations
• Patients with small penis / glans, proximal hypospadias are technically more difficult.
• Delaying surgery may be indicated.

Question 22

…

Answer 22

• Urethral catheters extend into the bladder (can cause bladder spasm).
• Urethral stents do not extend beyond the external sphincter of the bladder (more easily dislodged).
• Incidence of dysuria, urinary retention and urinary extravasation is higher without diversion.

Question 23

How can urethroplasty techniques be broadly classified?

Answer 23

1 Urethral plate tubularisation.
2 Urethral plate augmentation with skin flaps.
3 Urethral plate substitution with grafts.

• Any ventral curvature is addressed before completing the urethroplasty.

Question 24

What may ventral chordee be due to?

Answer 24

Ventral curvature may be due to: - true chordee - deficient ventral skin and soft tissue tethering.

Question 25

How is chordee corrected?

Answer 25

• Degloving of penile skin. ∘ Apparent curvature may improve or completely resolve. • Severity is assessed by inducing an artificial erection - Horton's test: 1 Place a Jakes catheter (tourniquet) around base of penis. 2 Inject sterile saline into one corpus cavernosum. * If there is no chordee, urethroplasty is done. * If ventral curvature persists, i.e. true chordee, the following can be done: Ventral curvature <30∘ • Nesbit procedure: midline dorsal plication of tunica albuginea with 4-0 or 5-0 permanent sutures placed opposite the area of greatest bending, with/ without excision of an ellipse of tunica. Ventral curvature >30∘ • Ventral lengthening procedure. - Transverse incision through the urethral plate + skin grafts or local flaps. - Incision of tunica albuginea.

Question 26

What are the common types of urethroplasty procedures for distal hypospadias?

Answer 26

``` Tubularised incised plate (TIP). Meatal advancement and glanuloplasty incorporated (MAGPI). Mathieu flip-flap. Urethral advancement and Onlay preputial flaps. ```

Question 27

How did TIP repair develop and describe the steps.

Answer 27

∘ Simple tubularisation first described by Thiersch (1869) and Duplay (1880). ∘ Urethral plate incision described by Rich et al. (1989). ∘ Snodgrass (1994) combined these techniques. A. Horizontal line leaving Furlit cuff- deglove penis and correct chordee. Midline longitudinal incision (if necessary) through urethral plate which widens, converts a flat surface into a deep groove to form a slit-like meatus (incision re-epithelialises). B-C. Lateral edges of urethral plate are incised into corpus spongiosum and glans, to allow the edges to be brought over 6Fr stent to form a tube. D. Tube is sutured (2 layers 7/0 PDS), 3mm proximal to end of urethral plate to create an oval meatus and minimise stenosis. E. A dartos flap 'waterproofing' layer is raised from prepuce (Snodgrass originally described buttonholing technique) or shaft to cover suture line. F-G. Glans wings are sutured together over dartos flap (5/0 VR subepithelial stitches) to fashion an aesthetic glans. Skin sutured with 6/0 rapide +/- foreskin recon or circumcision.

Question 28

What is MAGPI repair?

Answer 28

Meatal advancement and glanuloplasty (Duckett 1981). Suitable for very distal and mobile meatus with no chordee. 1. Longitudinal incision made between meatus and its intended position. 2. The longitudinal incision is sutured transversely, in Heineke-Mikulicz fashion. 3. Advancement of the glans bilaterally around the urethra.

Question 29

What is the perimeatal-based flap technique?

Answer 29

• Described by Mathieu. • Also known as the 'flip-flap'. 1. Distally-based skin flap is designed with base just proximal to meatus. 2. Flap is flipped to create superficial part of circumference of urethra and sutured to edges of urethral plate to form a tubed urethra. 3. The glans is approximated around the neourethra.

Question 30

What is BEAM (urethral advancement) and who described it?

Answer 30

Bulbar elongation and anastomotic meatoplasty (Turner-Warwick 1997) • Involves circumferential dissection and advancement of distal urethra. • Extreme mobilisation of urethra to bulb can gain 2.5 cm of urethral length in children. • Requires a separate perineal incision to fully mobilise bulbar urethra and avoid tension on advancement to the level of the normal meatus.

Question 31

What is the onlay preputial flap?

Answer 31

• Superficial part of urethral circumference is reconstructed with patch of skin from inner aspect of prepuce. • Useful for midshaft hypospadias. 1. Flap is pedicled on subcutaneous tissue, transposed around penile shaft and sutured to edges of urethral plate to form a tubed urethra. 2. The pedicle, consisting of dartos fascia, can be used as a waterproofing layer.

Question 32

For proximal hypospadias, what are the surgical options?

Answer 32

• Depends on whether urethral plate is intact following release of chordee. ``` • If the urethral plate is preserved: ∘ TIP ∘ Onlay preputial flap. • If the urethral plate is transected or excised: ∘ Tubularised preputial flap ∘ Two-stage repair. ```

Question 33

What precautions are taken for TIP repairs in proximal hypospadias?

Answer 33

1. Beware not to create two strips when incising a completely mobilised urethral plate. 2. Divergent corpus spongiosum is sutured over neourethra. 3. Tunica vaginalis flap (off testis) or dartos flap used for waterproofing.

Question 34

Describe the tubularised preputial flap.

Answer 34

- similar to onlay preputial flap, but flap is longer and wider.

Question 35

When is 2-stage repair considered?

Answer 35

∘ Scrotal or perineal hypospadias ∘ Severe ventral curvature ∘ Small penis. Principles of two-stage repair: 1. Correction of ventral curvature, by division / excision of urethral plate. 2. Widening urethral plate by incising it longitudinally. 3. Resurfacing incised raw area with tissue to be used for neourethra formation at second stage. - Full-thickness graft from inner prepuce / buccal mucosa (described by Cloutier (1962), popularised by Bracka). - Alternatively, use a vascularised preputial flap, (described by Bretteville). 4. Second stage is usually performed 4-6 months later, depending on tissue quality - resurfaced area is incised 10-15mm wide U shape, to allow tubularisation.

Question 36

What are the complication rates of hypospadias surgery?

Answer 36

``` Depends on technique, proximal / distal, surgeon's experience. Quoted complication rates: ∘ Distal TIP 10% ∘ Proximal TIP 20% ∘ Preputial flap 25% ∘ Two-stage repairs 15% ```

Question 37

What are the early and late complications?

Answer 37

``` Early complications • Bladder spasm • Haematoma • Wound dehiscence • Oedema • Erections (suppressed with cyproterone acetate, an anti-androgen or ketoconazole). ``` Late complications • Fistula • Urethral stenosis (technical error, ischaemia or BXO). Most commonly at proximal anastomosis site. • Diverticulum (due to distal obstruction or turbulent urinary flow). Presents as ballooning of neourethra during voiding & post-void dribbling. • Persistent urinary tract infections (with hair-bearing FTSG urethral reconstructions).

Question 38

What is BXO? How is it treated?

Answer 38

* Aka lichen sclerosus et atrophicus. * Premalignant lesion, associated with SCC. * May present with late development of meatal stenosis or neourethral stricture. * Characteristic white appearance. • Treatment: Radical excision of affected skin and mucosal graft reconstruction (buccal or bladder). • Topical treatment (steroid or tacrolimus) may not be appropriate in hypospadias because urethra and glans likely to be involved.