Hypospadias: Causes, Diagnosis and Treatment
Review literature: (Mouriquand et al, 1995) (Baskin, 2000)
Definition of Hypospadia
Hypospadia is a common congenital disease of the penis with an abnormal ventral opening of the meatus of the urethra. Hypospadia are often associated with a ventral curvature of the penis (chordee) and/or a deficient ventral prepuce (foreskin) with a dorsal "hood". The classification of hypospadias depends on the position of the urethral meatus:
- Penile (distal-middle-proximal)
Epidemiology of Hypospadias
1–8/1000 births. Distal hypospadias are more often. The incidence of hypospadias is increasing (see etiology).
Risk Factors for Hypospadias
Family history: about 7% of patients with hypospadia have children with hypospadia; and 14% of male siblings of the index patient with hypospadia.
Further risk factors: increased maternal age, low birth weight, in-vitro fertilization.
Causes (Etiology) of Hypospadias
Embryology of the Male Urethra:
The urethra emerges from the urethral folds, which fuse ventrally under the influence of androgens. The fusion begins proximally in the 11th week of gestation and proceeds distally. The fusion involves endodermal and ectodermal tissue. The androgen effect is mediated by the 5α-reductase.
In hypospadias, malformations concern the endodermal and ectodermal tissue. An example of an ectodermal abnormality is the deficient ventral foreskin with a dorsal "hood". Endodermal abnormalities include the position of the meatus, a deficient urethra distal to the meatus and chordee formation (urethral plate).
An absolute (low concentration) or relative (decreased sensitivity of the target tissue) androgen deficiency is a major cause for the development of hypospadias. Many enzyme deficiencies which cause hypospadias are known, such as 5α-reductase deficiency or defects of the androgen receptor. In 10–70% of severe proximal hypospadias, an enzyme deficiency or hormonal disease affecting the androgens can be found.
Hypospadias have a multifactorial etiology involving several known genes (polygenic disease). This can be concluded from the family history and twin studies. In addition to the known enzyme defects (see above), most genes involved in the etiology of hypospadias are still unknown.
A variety of substances with estrogenic activity contaminates the environment and is enriched through the food chain. Substances with estrogenic activity are insecticides, natural estrogens from plants and chemicals from the plastics industry. The impact on wildlife is well documented: thin egg shells in birds or penis malformations in alligators. The worldwide increase in hypospadias in humans is also attributed to these environmental factors.
Penis Curvature in Hypospadias:
The chordee (urethral plate) has previously been considered the cause for ventral penile curvature in hypospadias. This is now questioned by many studies. Penile curvature is now considered a part of normal penile development. In addition, the conservation and utilization of the urethral plate is essential for hypospadia operations popularized by Snodgrass. In the majority of cases, the curvature of the penis can be corrected using the technique of Nesbit.
Signs and Symptoms
Hypospadias are usually asymptomatic. Distal hypospadias without curvature do not cause any functional limitations and are "only" a cosmetic problem due to the expectations of parents and patient [fig. asymptomatic hypospadia of an adult]. Proximal hypospadias can disturb the control of the urine stream; an accompanying curvature can hinder sexual intercourse.
Associated congenital disorders:
Cryptorchidism or disorders of sex development in 7%, inguinal hernia in 12%, mental retardation (6%) and malformations of the heart (5%), musculoskeletal system (3%), anal canal (1%).
Diagnostic work-up of Hypospadias
In addition to a careful physical examination (position of the meatus, open processus vaginalis, cryptorchidism, signs of DSD), ultrasound imaging of the urinary organs is necessary. If anomalies are identified, an intravenous urography or micturition cystourethrogram may be necessary.
Investigations in Scrotal and Perineal Hypospadias:
The risk of disorders of sex development is increased in proximal hypospadias, the following evaluations are necessary:
- Family history
- Hormone analysis (Testosterone)
- Fibroblast culture with evaluation of androgen receptors and 5α-reductase enzyme activity.
- Pelvic ultrasound imaging, MRI and/or retrograde genitography
- Micturition cystourethrogram
Treatment of Hypospadias
Principals of Hypospadia Surgery
For a full discussion of the surgical principles of hypospadia operations please see Chapter Urologic Surgery/General principles of hypospadia operations.
Assessment and management of penile curvature is done after artificial erection of the penis. In the majority of cases, the curvature of the penis can be corrected using the technique of Nesbit. In severe cases, grafting of the tunica albuginea helps in straighting the penis. Resection of the chordee is only rarely performed. For tubularized incised plate (TIP) urethroplasty, conservation of the urethral plate is mandatory.
Urethroplasty is reconstruction of the missing distal urethra. The below described surgical techniques differ primarily in the technique of urethroplasty: application of flaps, incision of the urethral plate or free oral mucosa transplants.
A second layer of tissue covers the neourethra and prevents the formation of fistulas. Most often, a pedicled subcutaneous (dartos) flap is raised from preputial, penile or scrotal skin.
Meatoplasty and glanuloplasty:
Reconstruction of the meatus and the glans to achieve meatus at the tip of the penis with a vertical slit.
Skin coverage of the penile shaft is achieved with various techniques (e.g. transfer of penile skin).
MAGPI Hypospadia Operation:
MAGPI is Meatal advancement and glanuloplasty (Duckett, 1981b). The MAGPI-technique is only suitable for distal hypospadias. Technique and complications see Chapter Urologic Surgery/MAGPI-technique for hypospadia repair.
Tubularized incised plate (TIP) Urethroplasty
TIP urethroplasty is suitable for distal and proximal penile hypospadias (Snodgrass, 1994). The TIP urethroplasty is considered technically simple and has a low complication rate, the cosmetic result of the glans and the meatus is good. Furthermore, the TIP urethroplasty is an useful option for re-operations with preserved urethral plate. The urethral plate is not removed but deeply and longitudinally incised. After mobilization and tubularization, the urethral plate is closed around a catheter. A ventral curvature is corrected using the Nesbit technique. For a description in detail, please see Chapter Urologic Surgery/Tubularized incised plate (TIP) urethroplasty.
Mathieu Hypospadia Repair
The Mathieu hypospadia repair is a good option for distal penile hypospadias (Mathieu, 1932). An rectangle of skin over the proximal urethra is raised and folded distally. To avoid a horizontal meatus, a modification of the original technique with V-incision of the flap exists (MAVIS = Mathieu and V incision sutured). Technique and complications see Chapter Urologic Surgery/Mathieu hypospadia repair. The most common complications are unfavorable meatal cosmetics, skin flap necrosis with fistula or stricture of the urethral meatus.
Island Flaps Hypospadia Repair
Island flap hypospadia repair is suitable for distal and middle penile hypospadias (Duckett, 1981a). The island flap is raised from the prepuce: the pedicled flap consists of the inner leaf of the prepuce with Tunica dartos. The flap is rotated around the penis and used in onlay technique with a preserved urethral plate. If a resection of a chordee has been necessary, a tubular island flap is necessary. Technique and complications see Chapter Urologic Surgery/Island flaps hypospadia surgery.
Two-stage Hypospadia Repair
Indications for a two-stage hypospadia repair are severe proximal hypospadias and situations after failed hypospadia surgery. Technique and complications see Chapter Urologic Surgery/Two-stage hypospadia repair.
Hypospadia Repair with a Free Oral Mucosa Graft
Indications for the use of a free oral mucosa graft are situations after failed hypospadias surgery.
Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Baskin 2000 BASKIN, L. S.:
- Hypospadias and urethral development.
In: J Urol
163 (2000), Nr. 3, S. 951–6
Duckett 1981a DUCKETT, J. W.:
- The island flap technique for hypospadias repair.
In: Urol Clin North Am
8 (1981), Nr. 3, S. 503–11
Duckett 1981b DUCKETT, J. W.:
- MAGPI (meatoplasty and glanuloplasty): a procedure for subcoronal
In: Urol Clin North Am
8 (1981), Nr. 3, S. 513–9
Mathieu 1932 MATHIEU, P.:
- Traitement en un temps de l’hypospadias balanique ou juxtabalanique.
In: J Chir
39 (1932), S. 481?486
Mouriquand u.a. 1995 MOURIQUAND, P. D. ;
PERSAD, R. ; SHARMA, S.:
- Hypospadias repair: current principles and procedures.
In: Br J Urol
76 Suppl 3 (1995), S. 9–22
Snodgrass 1994 SNODGRASS, W.:
- Tubularized, incised plate urethroplasty for distal hypospadias.
In: J Urol
151 (1994), Nr. 2, S. 464–5