Hypospadias

Hypospadias, first credited to Galenus, derives from two Greek words: "hypo" (under) and "spadon" (rent).

Definition

Hypospadias is characterized by the opening of the urethra on the ventral surface of the penis, proximal to the normal site of the external urethral meatus (at the tip of the glans). This may be accompanied by a ventral curvature of the penile shaft (ventral chordee).

Characteristics

• Ventral meatus
• Ventral curvature (chordee)
• Dorsal "hood" with deficient foreskin ventrally

• 1:300 live male births
• 6000 boys each year in the US
• Genetic component:
• 8% have a father with hypospadias
• 14% have male siblings with hypospadias
• Risk for next child:
• 12% with negative family history
• 19% if cousin or uncle affected
• 26% if father or sibling affected
• More common in Caucasians (Jews and Italians)
• Higher incidence in monozygotic twins (8.5x)

• Differentiation of external genitalia into male pattern starts at 8 weeks.
• Urethralization starts proximally and advances distally (9-16 weeks).
• Coronal sulcus forms at 12 weeks.
• Glanular urethra forms at 16 weeks via endodermal cellular differentiation.
• Prepuce forms as a ridge of skin from the corona.
• Hypospadias results from failure of ventral aspect formation.
• Chordee occurs due to differential growth between normal dorsal tissue and underdeveloped ventral corporal tissue, often with fibrous tissue distal to hypospadiac meatus.

Genetic Mutations

• Testosterone-dependent sonic hedgehog
• Homeobox genes (A9, A10, A11, A13)
• FGF 10
• ATF3
• MAMLD1 (Cxorf6)

Enzyme Deficiencies

• 5α-reductase
• 3α-hydroxysteroid dehydrogenase
• 17α-hydroxylase
• 17,20-lyase

Hormones

• Extrinsic: preconceptual oestrogens and progesterones in pills, artificial reproductive techniques (ART).
• Intrinsic: steroid-secreting tumours, obesity.

Environmental Factors

• Endocrine disruptors: Bisphenol A, polyesters, vinyl.
• Vegetarian mothers: phytoestrogens especially from soy.
• Other factors: canned foods, plastics, herbicides, pesticides, birth weight (higher incidence in small for gestational age babies).

Parental Counseling and Consent

• DO NOT CIRCUMCISE
• To operate or not (cosmesis)
• To circumcise or not to (preputial flaps, grafts)
• Operative technique is subject to intraoperative findings
• May need staged repair
• Diversion or not - SPC

Goals

• Good caliber urethra with a slit-like meatus at the glans tip.
• Straight penis.
• Normal body image and self-confidence.
• Unimpaired voiding and sexual activity post-procedure.

Principles

• Timing
• Good illumination
• Magnification (loupes/microscopes)
• Atraumatic fine sutures
• Hemostasis (tourniquets, diathermy, adrenaline)
• Fine/microsurgical instruments
• Minimal trauma tissue handling

Urethroplasty Techniques

• Urethral advancement
• Tubularizing the urethral plate
• Vascularized pedicled flap
• Two-stage free flap repair
• Snodgrass’ TIP (Tubularized Incised Plate)
• Mathieu’s Flip-Flap
• Island Onlay
• Staged repair using grafts:
• Buccal mucosal graft
• Post-auricular graft
• Bladder mucosal graft

Technical Aspects/Postoperative Care

• Magnification
• Dressing (immobilization, prevention of hematoma/edema)
• Bladder spasms (oxybutynin)
• Analgesia (local penile block, caudal block)
• Diversions (stent secured to glans with open drainage into a diaper)

Factors for Technical Success

• Use of vascularized tissues
• Careful tissue handling
• Tension-free anastomosis
• Non-overlapping suture lines
• Meticulous hemostasis
• Fine suture material
• Adequate urinary diversion

• Fistula
• Wound dehiscence
• Urethrocutaneous fistula
• Meatal stenosis
• Urethral diverticulum
• Residual chordee

• Common condition.
• Genetic component exists.
• Evaluate for associated anomalies with severe proximal hypospadias.
• Rule out intersex, especially with cryptorchidism.
• Tailor repairs to the patient’s anatomy and previous repairs.