Normal gonadal descent
1. The undifferentiated sex cords remain near the kidney until around week 7, where under the influence of SRY they begin to form testes
- Held in place here by the gubernaculum caudally and the cranial suspensory ligament
2. Trans-abdominal migration
- During 10 – 15th week the testis migrates towards the deep ring
- Mediated by Mullerian inhibiting substance (MIS) and androgens, and insulin like growth factor 3
- Regression of the cranial suspensory ligament
- Swelling and enlargement of gubernaculum
3. Inguinoscrotal descent
- Formation of peritoneal diverticulum (processus vaginalis)
- Shortening of the gubernaculum, plus increased intra-abdominal pressure
- Appears to be mediated by testosterone/androgens
Other theories behind descent – calcitonin gene related peptide from genitofemoral nerve
Aetiology
Multifactorial – disrupted endocrine regulation, gene defects (insulin like GF-3) and/or mechanical with inability to increase intra-abdominal pressure (Prune-Belly, gastroschisis, diaphragmatic hernia)
Epidemiology
About 3 % of newborns undescended testis.
1 % remain undescended at 3 months, with little change to 1 year old.
2nd peak incidence of detection around 5 years old.
Up to 30 % in premature babies.
Bilateral in about 20 %.
80 – 85 % isolated with no other issues.
Right more commonly undescended.
Risk factors:
- Prematurity
- Low birth weight
- Family history
- Maternal obesity and diabetes
Classification
Undescended testis / cryptorchidism – absence of testis in normal scrotal position
Vanishing testis – present initially in development but lost as a result of vascular accident or torsion
Retractile testis – able to be milked down into the scrotum and remains there
Gliding testis – able to be milked down but with difficulty or pain and immediately ascends when traction removed
Ectopic testis – outside the path of normal descent (perineum, lateral to scrotum, thigh, contra-lateral).
Ascending testis – initially in scrotum but then ascends – cord doesn’t grow at same as child – 10 % of retractile testis become ascending testis
Clinically important to distinguish between palpable (80 %) and impalpable (20 %), and truly undescended vs retractile.
Location
Variable rates depending on study and population analysed.
Palpable testis locations:
- Within inguinal canal (canalicular)
- Pre-scrotal
- ‘Peeping’ within inguinal canal at deep ring
- ‘Superficial inguinal pouch’ (80 %) between Scarpa’s and external oblique fascia, adjacent to external superficial ring (technically outside descent path but not considered ectopic)
Non palpable testis locations:
- 40 % intra-abdominal
- 30 % vanished – blind ending vas and vessels before deep ring
- 20 % vanished – blind ended vas and vessels within canal
- 10 % inguinal but not palpable
Ultrasound and MRI can be unreliable for impalpable testis with false positives and negatives – hence laparoscopy first line investigation.
Pathophysiology
Histological changes within first few years of life – defective transformation of gonocytes and loss of germ cells.
- Neonatal gonocytes transform to type A spermatogonia during first 12 months
Defective transformation / abnormal development most apparent from 2 years of age onwards
In testis which remain undescended – progression to complete loss of germ cells – minimal seminiferous tubules and azoospermia.
Carcinoma in situ develops in up to 25 % of intra-abdominal testis which remain there into adult life.
Histological changes probably a combination of:
- Temperature related damage
- Pituitary gonadal dysfunction
- Underlying dysplasia as part of testicular dysgenesis
Congenitally maldescended testes almost always associated with patent processus vaginalis.
The goal of treating cryptorchidism is to reverse or prevent abnormal germ cell development to avoid:
- Impaired fertility if left alone
- Much higher malignancy risk if left alone (can surveil better, orchidopexy reduces RR 5 -> 2)
- Higher rates of torsion and missed torsion
- Psychosocial effect in later life / cosmesis
Clinical assessment
History:
- (corrected) age of child / antenatal history
- Other co-morbidities, issues, syndromes, previous (inguinal) surgery
- Has the testis ever been in the scrotum? (at birth, warm baths)
Examination:
- Frog leg in warm environment with warm hands, on repeated occasions
- Bimanual technique
- ?Palpable testis along line of descent, or in ectopic position
- Hypospadias, hernia, other evidence of under virilisation
- Development of scrotum
- Contralateral testis – if large (> 2 mL) suggests hyperplasia / other testis may be vanished
Investigations
- No real role for ultrasound or MRI
- Exception is bilateral impalpable testis, in which case considering DSD
- Laparoscopy and EUA standard for impalpable testis
- Karyotyping and further investigation as per DSD if concerns re: bilateral impalpable
Management
If undescended testis at 3 months, unlikely to descend, and recommended for orchidopexy.
Retractile testes should be surveilled (10 – 12 % chance of acquired cryptorchidism / ascending)
If testis in base of scrotum at 3 months, no follow up required.
Hormonal treatment – course of LH or HCG – not really used in Aust (AUA guidelines = do not use).
Palpable testis:
Single stage orchidopexy aiming at around 12 – 18 months (ideal balance between preventing pathological change, and safety of anaesthesia)
Day case.
Scrotal approach (Bianchi) – can’t ligate patent processus vaginalis at same time.
Inguinal + scrotal:
- Aim to bring the testis to a tension free scrotal position without damage to the vas or vessels
- Delicate dissection of vas and vessels
- High ligation of patent processus vaginalis to allow length
- Manoeuvres if needed for length – sweep off peritoneum at deep ring, Prentiss manoeuvre (division of inferior epigastrics)
- Transverse scrotal incision, creation of dartos pouch and an anchoring lower suture
- Finger dissection via canal into scrotum, and passing testis down.
Impalpable testis:
Consider re-examining the child another day if behavioural.
No role for imaging.
Book for EUA +/- laparoscopy +/- inguinal orchidopexy at 6 – 18 months (Australian trend is 12 – 18 months) to determine location with plans to proceed depending on findings – intra-abdominal (40 %), vanished with blind end in abdomen (30 %), vanished with blind end in canal (20 %), inguinal (10 %)
EUA – ?actually palpable, ?compensatory contralateral hypertrophy.
Laparoscopy – head down. Looking for a visible testis, vessels/vas entering the ring.
If in inguinal canal – may be able to proceed with one stage standard inguinal orchidopexy.
If in abdomen consider Fowler-Stephens 2-stage repair (unless excellent vessel length – test is if can move the testis to the contralateral deep ring)
If blind ending in abdomen – no further treatment needed (likely intravaginal torsion) – case over. Most Australians don’t fix the contralateral side.
- If dysmorphic testis – remove
Fowler-Stephens two stage repair is based on the principle that the issue in an intra-abdominal testis is the length of the testicular vessels do not allow tension free movement to scrotal position (not the vas length):
Testicular vessels are divided, and then 6 months allows the artery to the vas collaterals to become more robust and then mobilisation is done.
Preserve as much peri-vasal tissue as possible during first stage.
Retractile testis
- Testis can be seen in normal position in scrotum, often at birth or after warm bath
- Able to be milked down with gentle traction
- Normal size
- Does not immediately retract or spring back when milked down
Retractile testes are safe to observe on a 6 to 12 month basis.
If still retractile at 5 – 10 years, surgery can be offered especially if uncomfortable, gliding, or any suggestion of ascending testis (acquired cryptorchidism – approx. 12 %)
Complications of orchidopexy
- Testicular atrophy about 5 %
- Injury to the vas about 1 – 2 %
- Failure / retraction – more likely the more proximal to initial testis – 8 – 25 %
- Post operative oedema, haematoma, infection.
Follow up after orchidopexy – consider seeing child again at puberty to discuss self examination and malignant risk.
Bilateral UDT
Single side at a time, and fix the better side first. Consider DSD etc.
Post pubertal / adult cryptorchidism
- Issues – fertility, cancer risk, hormonal.
- Options – orchidectomy, orchidopexy, or surveillance.
- If normal contra-lateral testis, and fertility not desired, and any atrophy – orchidectomy safest.
- If wanting fertility, small other testis – can offer orchidopexy with caveats.
- May be safe to leave alone in a 60 year old (or alternatively remove).