CHAPTER 10: UROGENITAL 2 Flashcards
Describe the embryology of the sexual organs
Prior to the 6th week of gestation the embryo is sexually indeterminate
Basic foetal model is female
SRY gene - present on Y-Chromosome → testes → Leydig cells (testosterone - male genitalia development) and Sertoli cells (removal of upper vagina and uterus)
If not → ovary
Virilization at 6-19 weeks gestation
After the 6th week the gonads arise from the genital ridges and differentiate into ♂+♀
The internal sexual organs form from the paramesonephric and mesonephric ducts.
The Paramesonephric duct (Müllerian duct)
- ♀ = fallopian tubes, uterus, cervix and upper vagina
- ♂ = degenerates to form the appendix testis
- Sertoli cells within the gonad secrete a testosterone analogue that acts as a Müllerian-inhibiting factor.
The mesonephric duct (Wolffian duct)
- ♂ = epididymis, ductus deferens, seminal vesicles, ejaculatory ducts
- Leydig cells secrete testosterone which stimulates development of mesonephric duct and genital tubercle.
How do the external genital organs form?
Until when are they sexually indistinct?
wk3
- cloacal membrane forms, fuses and forms genital tubercle
wk6
- cloacal membrane divides into urogenital and anal membranes
- cloacal folds divide into urethral and anal folds, with genital swellings laterally
wk 11
- o Central urethral groove
- o Urethral folds on either side of the urethral groove.
- o Labioscrotal swellings on either side of the urethral folds.
- o The genital tubercle anteriorly
- sexually indistinct up to this point
How does the male external genitalia form?
The genital tubercle elongates → penis
urethral groove grows distally down the genital tubercle, forming endoderm of the penile urethra almost to tip
Distal part of the urethra is initially formed by urethral plate (endoderm) & later replaced by ectodermal ingrowth from surface of glans penis canalising the glandular urethra and forming the external urethral meatus.
12th week → urethral folds fuse over the urethral groove, → tubed urethra from proximal-to distal.
labioscrotal swellings → scrotum, separated by scrotal septum.
7mths Testes usually descend into the scrotum
How does the female external genitalia form?
- Genital tubercle → clitoris urethral groove does not extend into the genital tubercle.
- he urethral folds do not fuse over urethral groove. Instead they form a hood over clitoris and labia minora.
- The labioscrotal swellings form the labia majora.
What is the anatomy of the penis?
- Root
- Body
- Glans
ROOT
- Bulb → corpus spongiosum
- bulbospongiosus muscle
- attaches to perineal body
- empties semen and urine
- contains urethra
- Lateral crurae (2) → corpus cavernosum
- ischiocavernosus muscle
- causes erection
- attaches to perineal memebrane
- Bulbourethral glands
What are the layers of the penis at the body?
Skin
Dartos fascia
- superficial dorsal vein
Bucks fascia
- deep dorsal vein
- dorsal artery
- dorsal nerve
Tunica albuginea
- corpus cavernosum - deep artery
- corpus spongiosum - artery to urethral bulb
What is the blood supply of the penis?
ARTERIES
- Internal iliac
- Internal pudendal
- Artery to urethral bulb
- Dorsal artery - supplies CC, skin, fascia, glans
- Deep artery (cavernosal artery - erectile)
VEINS
- deep dorsal vein → prostatic venous plexus
- venae comitantes → internal pudendal
- superficial dorsal vein → superficial external pudendal and great saphenous
What is the lymphatic drainage of the penis?
Superficial dorsal vein (skin) → superficial inguinal nodes
Glans and corpora → deep inguinal nodes → internal iliac nodes
What is the nerve supply to the penis?
Skin → posterior scrotal and dorsal br of pudendal
Glans skin → dorsal nerves
Ischiocavernosus and bulbospongiosus muscle → perineal branch of pudendal
Ejaculation → sympathetics(L1) sup&inf hypogastric plexi
Erection → parasympathetic pelvic splanchnic nerves to corpus cavernosum
What is the anatomy of the urethra?
3 parts
- prostatic
- membranous
- penile
transitional epithelium except part proximal to external meatus (stratified squamous)
external meatus → vertical split
3 constrictions
- internal meatus (bladder neck)
- prox end of navicular fossa
- external meatus
What are the fascial layers of the penis?
Colles fascia becomes Dartos and Bucks
Dartos
Bucks
Tunica albuginea (tightly binds corpus cavernosum and corpus spongiosum)
What is hypospadias?
Hypospadias is a congenital condition of the penis characterised by:
- ventral meatus
- dorsal hood = hooded prepuce
- chordee = ventral curvature
May be associated with
- paraurethral sinuses
- urethral valves
- flattened glans penis
- deficient central skin
- clefting of glans
- scrotal bipartition
What are the embryological theories of hypospadias?
- Failure of urethral folds coalesing in midline from base to tip (but what about glans?)
- Baskin (2000) urethral folds fuse → seam of epithelium → canalises by apoptosis. Similar canalisation by apoptosis of glans
- Prepuce - formed by growth of ridge of skin from corona. In hypospadias, urethral folds fail to fuse so prepuce is hooded
- Chordee - dorsal tissue grows normally, ventral urethra and associated tissues are attenuated
What is the epidemiology of hypospadias?
1 in 300 live male births
Distal - no assocs
Proximal - assoc w
- inguinal hernias (50%)
- other GU tract (25%)
- undescended testes (5% of all hypospadias, 31% of prox)
- open processus vag 9%
- upper GU tract abn 3%
- FHx - 4-10%
- IVF (4x more common)
What is the aetiology of hypospadias?
Environmental (increased oestrogens / plant oestrogens)
Androgen hyposensitivity
Genetic - father son 8%, sibling 14%
Androgen receptor deficiency
How is hypospadias classified?
- Glanular
- Coronal
- Subcoronal
- Distal penile shaft
- Mid penile shaft
- Proximal penile shaft
- Penoscrotal
- Scrotal
- Perineal
Distal = 1-4 (85%)
Proximal = 5-9 (15%)
Ant 1-3, (75%) Mid 4-6, Post 7-9
How is severity and subsequent management determined?
- meatal position
- quality of urethral plate
- glans configuration
- degree of curvature
What are the goals of treatment?
- Micturition while standing with a non turbulent stream
- Natural appearance
- Normal sexual function
- Creation of a straight penis, with even calibre neourethra terminating in a natural slit-like meatus at the apex of a naturally reconfigured glans.
- Foreskin preservation, may be requested → no long term FU studies of function
- Is correction
o Functionally necessary?
o Aesthetically feasible?
When is surgery timed?
18-36 months not good time due to Ψ morbidity of genital surgery
Antenatal screening and group education session
Assessment during 1st few wks of life → bond ω parents + make provisional plan
Early – 6-18 months
o Stage 1 – 12 months, Stage 2 – 18 months
o Single stage 12 months
o Disadv - GA risk (OK after 6 months in paed centre)
Late – 36 months +
o Out of nappies, better pt understanding and cooperation
o Disadv - Ψ genitally aware after 18 months
What impt points are assessed in H&E?
History
- direction of stream, ballooning, flow
- erection shape, size
- fhx
Examination
- foreskin - well / poor developed / absent
- glans & groove - shallow, conical / deep
- urethral plate - broad / narrow (<1cm)
- penile size - normal / reduced
- curvature - present / absent
- meatal posn
- penile torsion
- scrotum - normal / hypoplastic / bifid / transposed
What tests / investigations are there for hypospadias?
Hortons & Turner-Warwick artificial erection tests
USS if proximal
Excretory urogram / voiding cystourethrography
Urine MCS (urethral valves → infection)
Testosterone gel ?enlarge glans & penis
What is the surgical management of hypospadias when urethral plate is adequate?
Choice of op determined by quality and development of urethral plate
URETHRAL PLATE TUBULARISATION
- Glans Approximation Procedure
- Zaonz 1989
- urethral plate tubularised, for distal hyp
- Tubularised Incised Plate Procedure
- Snodgrass 1994
- midline dorsal releasing incision
- urethral plate incised (self-epithelialises), 2 lateral glans incisions, urethral plate flaps raised, tubularised and closed in 2 layers (w/o overlapping suture lines), glansplasty
- Barrier layers = spongiosum, dartos, tunica vaginalis
What surgical procedures are recommended if urethral plate is inadequate?
- Urethral Plate Augmentation (Snodgraft)
- quilted into dorsal incised defect (instead of re-epithelialisation)
- useful if glans more conical, with minimal groove and lacking external rotation of glans wings. TIP in these cases will get meatal stricture therefore graft better
- Urethral Plate Substitution (Snodgrass) 2 stage
- Bracka (1995) - more predictable outcome
- Q: does urethral plate need transecting??
- best for significant ventral chordee (because full circumferential substitution urethroplasty is needed)
- 1st stage = graft: inner prepuce, buccal mucosa (BXO) - min 15mm diameter, Nesbit procedure if needed or ventral tunica release & TV grafts
- 2nd stage 6mths - 10mm = urethra, 5mm de-epithelialised and double-breasted
What is the postop management?
Immediate
- Dorsal penile block / ring block
- Urinary diversion - 8-10 Fr children
- Ketoconazole 400mg tds to control erections (or cyproterone)
- Oxybutynin 1mg tds for bladder spasm
- Tegaderm dressing
- Double nappy
Follow- up
- monitor for stenosis, fistulae, cosmetic, urinary stream
- f/u 3/12 then 1-4yr, puberty
What other operative techniques are you aware of for hypospadias correction?
Amputation distal to meatus!
Duplay 1874 - ventral releasing preputial skin flaps & urethral reconstruction
- modified by Browne, Cecil Culp, Van der Meulen
- Duckett - transverse preputial flap tubed
- Harris - split prepuce flap
- Elder & Duckett - islanded transposition preputial flap
Mattieu 1932 - parameatal (flip) flap
- modified by Mustarde, Devine & Horton: v-shaped midline glans flap advanced into meatus
Duckett 1981 - MAGPI - meatal advancement and glansplasty (distal & mobile meatus)
Snodgrass 1994 - TIP Urethroplasty
Bracka 1995 - 2 stage inner prepuce FTSG (other donor sites buccal, bladder mucosa, skin)
Turner Warwick 1997 - Urethral dissection and advancement = BEAM Bulbar elongation and anastomotic meatoplasty
What are the complications of surgery?
EARLY
bladder spasm, infection, haematoma, wound dehiscence, oedema, erections
LATE
- fistulae
- stricture
- meatal stenosis
- UTI, residual urine
- infertility / sexual dysfunction
- hairy urethra from ventral skin flaps
- BXO balanitis xerotic obliterans (lichen sclerosis) → phimosis, stenosis → SCC (chronic)
What is epispadias and bladder exstrophy?
- Congenital defect
- anterior urethra terminates on dorsum of penis
- abnormal development of cloacal membrane
Epispadias
- ♂ - dorsal meatus, short penis, dorsal chordee, divergent corpora
- ♀ - short vagina, cleft clitoris and wide labia minora
Exstrophy - absent ant wall, eversion of bladder
- Congenital penile curvature
- Chordee
- Cryptospadias
- Peyronie’s disease
- Abnormal fixation of penile skin / Dartos fascia - Nesbit procedure: tunica albuginea plication, excision
- fibrous remnant of corpus spongiosum causing ventral penile curvature & ventral skin shortage
- Growth deficiency (not fusion defect), preserved frenulum, dorsal hooding, oblique raphe, terminal meatus, inguinal hernia
- Upward curvature, thickening & fibrosis dorsal surface of tunica albuginea extending into septum b/t corpora - 4-5th decade, assoc w Dupuytren’s
What treatment is available for penile enhancement?
- Liposuction of fat pad
- Division of suspensory ligament
- VY skin advancement from pubic area
- Dermofat onlay grafts around tunica to increase girth
- Stretching with weights
What is the management of ambiguous genitalia?
- MDT - geneticist, paeds
- Counsel parents
- Assign sex by 2yrs
Causes
- Enyzyme deficiencies
- Karyotype problems
- Congenital adrenocortical hyperplasia
- Male pseudohermaphroditism
- Mixed gonadal dysgenesis
- True hermaphroditism
46XY Androgen insensitivity, 5α reductase def, 17 α hydroxy def
46XX CAH (21 hydroxylase def)
45XO Turners Syndrome
47XXY Klinefelter’s syndrome
45XO/46XY Mixed gonadal dysgenesis
46XY ♀ SRY gene mutation
46XX ♂ SRY gene mutation
Vaginal agenesis
1 in 4000 live ♀ births
Failure of development of paramesonephric duct
Examine = vaginal dimple
USS = define kidneys, bladder and uterus, not good for vagina
IVP = exclude other UT abnormality
EUA - endoscopy and dye
Chromosome analysis
Treatment
- Pedicled Colon → mucous
- Dilatation→ Frank 1938, sequential glass or plastic moulds
- Local labial flaps Graves 1981
- SSG reconstruction → McIndoe. SSG over a mould, labia minora then oversewn and the mould left in situ for 6 months
- FTG over stent
- Flaps of labia minora
- Regional flaps such as gracilis
What indications are there for vaginal recon?
Congenital absence (Rokitansky syndrome)
Segmental (imperforate hymen, long segment atresia)
Congenital malformation → ♀ hypospadias
Surgical ablation → e.g. mid section ex for prolapse
Radionecrosis → hostile tissues
Fistulae → requires flap closure
What are the surgical options for vaginal recon?
- Preferred tissues → vagina, vulva, skin, jejunum
- Distant flaps
o Wei → bilat groin flaps
o TRAM→ pedicled through pelvis on IEA
o Bowel → but tend to get stenosis at mucocutaneous anastomosis - Vulval tissue expansion
o Appropriate tissue, no donor defect
o 2 stages
Radionecrosis
o Need to import well vascularised tissue = TRAM, Omentum, Gracilis
What are the surgical options for vaginal recon in transexuals?
Epithelium lined cavity created between prostate/urethra/seminal vesicles and rectum
Urethra cut obliquely to prevent stenosis
Techniques
- Inversion of penis, or penis and scrotum skin flaps, most common, labia from scrotum
- SSG (McIndoe) with stents
- Perineal / abdo pedicled skin flaps
- Intestinal segments
Post Op
- Regular dilatation , stent, vibrator, intercourse
What surgical options are available for neo-phalloplasty?
- Abdo tubes
- Local flaps -e.g. - abdominal and pubic
- Gracilis
- Free radial forearm - various designs, staged urethral recon and glansplasty
- Penile implant for erection - need to wrap it in Dacron to allow anchoring to pubis
- Testicular implants
What are the considerations in perineal reconstruction?
- lining
- skin
- dead space
- herniation
- anal sphincter
- stomas
What classification is there for vaginal defects?
What flaps can be used to reconstruct different defects?
Cordeiro Classification (PRS 2002)
IA Ant / lat wall → Singapore FC flap (Wee PRS 1989)
IB Post wall → VRAM (vertical skin paddle)
IIA Upper 2/3 → rolled VRAM (transverse upper abdo skin paddle)
IIB Total → bilateral gracilis
What is the blood supply of the female perineum?
Internal pudendal → perineal → posterior labial (good for perforator flaps)
What flaps are used for perineal reconstruction?
Singapore flap (Wee PRS 1989)
Lotus petal flap (Yii, Niranjan BJPS 1996)
