Undescended Testes (Cryptorchidism)
Summary
Undescended Testis (UDT) is the most common congenital anomaly of the male genitalia. It is the failure of the testis to descend from the high abdominal position (7 weeks gestation) into the scrotum (by 35 weeks). While spontaneous descent can occur in the first 3 months of life (due to the postnatal testosterone surge), it rarely occurs after 6 months. The condition requires surgical correction (Orchidopexy) to preserve fertility and facilitate cancer surveillance. [1,2]
Key Facts
- Classification:
- Palpable: Located in the groin/inguinal canal. (80%).
- Impalpable: Located in the abdomen or absent ("Vanishing testis"). (20%).
- Retractile: A normal testis that is pulled up by a hyperactive cremaster reflex but can be manipulated into the scrotum and stays there without tension.
- Why fix it?:
- Fertility: The scrotum is 2-4°C cooler than the body. Abdominal heat destroys Sertoli cells and spermatogonia by 12-18 months of age.
- Malignancy: 5-10x increased risk of testicular cancer (Seminoma). Surgery makes the testis accessible for self-examination (it does not completely negate the cancer risk).
Clinical Pearls
The Retractile Trap: Many boys referred for UDT actually have retractile testes. The Cremaster Reflex is strongest in boys aged 2-7 years. Exam Trick: If the testis shoots up the moment you let go, it is Undescended (High scrotal/gliding). If it stays down for a few moments/minutes, it is Retractile.
The "Mini-Puberty": In the first 3 months of life, LH/FSH and Testosterone surge to pubertal levels. This drives spontaneous descent. If the testis isn't down by 6 months (when this surge fades), it never will be.
Bilateral Impalpable Testes: This is a medical emergency in a newborn. You must assume this is a fully virilised female with Congenital Adrenal Hyperplasia (salt-wasting crisis) until proven otherwise. Check Karyotype and Electrolytes immediately.
Incidence
- Preterm: 30% of boys born less than 2.5kg.
- Full Term: 3-5% at birth.
- At 1 year: 1%. (Most resolve).
Risk Factors
- Prematurity.
- Low birth weight.
- Maternal smoking.
- Family history (First degree relative).
Mechanism of Descent
- Abdominal Phase (8-15 weeks): Testis moves to internal ring. Controlled by INSL3.
- Inguinal-Scrotal Phase (25-35 weeks): Gubernaculum guides testis through canal. Controlled by Androgens.
Pathology
- Failure of Gubernaculum regression.
- Abnormal HPA axis.
- Mechanical obstruction (Prune Belly Syndrome).
Signs
Technique
- Warm Room & Warm Hands: Essential to relax the cremaster.
- Position: Frog-legged (supine) or sitting cross-legged (Tailor's position).
- Milk it down: Sweep hand from Anterior Superior Iliac Spine along the inguinal canal towards the scrotum to push the testis down.
- Grasp: Use the other hand to grasp the testis once in the scrotum.
- Assessment:
- Is it palpable?
- Can it reach the bottom of the scrotum?
- Does it stay there? (Retractile vs Undescended).
Imaging
- Ultrasound: GENERALLY NOT INDICATED.
- If palpable: You don't need US.
- If impalpable: US is poor at finding abdominal testes (50% sensitivity). Diagnostic Laparoscopy is the gold standard.
- Guideline: "Don't scan, refer."
Lab (Bilateral UDT only)
- Karyotype: XX vs XY.
- 17-OHP: Rule out CAH.
- AMH & Inhibin B: Markers of testicular tissue presence (if anorchia suspected).
Management Algorithm
BOY WITH UNDESCENDED TESTIS
↓
EXAMINATION AT 6-8 WEEKS CHECK
↓
┌─────────────┼─────────────┐
PALPABLE IMPALPABLE BILATERAL
(In groin) IMPALPABLE
↓ ↓ ↓
REFER SURGERY REFER SURGERY URGENT PAEDS
(See at 3-6m) (Review now) (Endocrine workup)
↓ ↓
DESCENDED? IMPALPABLE?
(Spontaneous) ↓
↓ DIAGNOSTIC LAP
DISCHARGE (Find & Fix)
↓
STAYS HIGH?
(>6 months)
↓
ORCHIDOPEXY
(Op by 12m)
1. Conservative (0-6 months)
- Wait for spontaneous descent (common in prems).
2. Surgical (6-18 months)
- Guidelines: British Association of Paediatric Urologists (BAPU) advises surgery between 6 and 12 months. Ideally completed by 18 months max.
- Orchidopexy:
- Inguinal Approach: Mobilise cord, separate hernia sac, fix testis in scrotal pouch (Dartos pouch).
- Laparoscopy: For impalpable testes. Can lead to "Fowler-Stephens" procedure (2-stage orchidopexy).
3. Hormonal
- hCG Injections: Historically used to induce descent. Not recommended by current guidelines (low efficacy, side effects).
- Infertility: Unilateral UDT = near normal fertility. Bilateral UDT = 50% paternity rate if untreated, improves with early surgery.
- Malignancy: Risk is 5-10x general population. Seminoma is most common. Risk persists even after surgery (but self-exam is allowed).
- Torsion: 10x risk.
- Trauma: Inguinal testis is pressed against pubic bone during sports.
- Surgical Success: >95% for palpable testes.
- Cosmesis: Excellent.
- Atrophy: Rare complication of surgery (vascular injury).
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Undescended Testis | BAPU / ESPU | Surgery by 12-18 months. Do not use Ultrasound routinely. |
| Cryptorchidism | AUA (American Urological) | Refer by 6 months. |
Landmark Papers
1. Ultrasound Utility Studies
- Multiple studies confirm US has 0% impact on management. If impalpable, they need laparoscopy anyway. If palpable, they need orchidopexy. US adds cost/anxiety without value.
What is an Undescended Testicle?
Before a baby boy is born, his testicles grow inside his tummy. Normally, they drop down into the scrotum (the sack of skin) before birth. In your son's case, one hasn't completed that journey and is stuck in the groin or tummy.
Will it come down on its own?
If he is under 3 months old, it might. But after 6 months, it is very unlikely to move further on its own.
Why does he need an operation?
- Temperature: The tummy is too hot for the testicle to grow properly. It needs to be in the cooler scrotum to make sperm later in life.
- Safety: It is easier for him to check for lumps (cancer) when he is older if the testicle is in the right place.
What does the surgery involve?
It is a day-case operation. He will be asleep. We make a small cut in the groin to free the testicle and a small cut in the scrotum to stitch it in place.
Primary Sources
- British Association of Paediatric Urologists (BAPU). Management of Undescended Testis. 2011.
- Ritchey ML, et al. Management of undescended testes. AUA Guidelines. 2014.
- Tasian GE, et al. Diagnostic imaging in cryptorchidism: utility, indications, and effectiveness. J Pediatr Surg. 2011.
Common Exam Questions
- Diagnosis: "Newborn with bilateral impalpable testes?"
- Answer: Emergency. Rule out CAH (Virilised female).
- Referral: "Correct age for referral?"
- Answer: Review at 6 weeks, refer if not down by 3 months. Surgery 6-12m.
- Pathology: "Long term risk?"
- Answer: Seminoma.
- Investigations: "Role of Ultrasound?"
- Answer: None.
Viva Points
- Anorchia: "Vanishing Testis". Probably due to in-utero torsion. If laparoscopy finds blind-ending vessels, the testis is absent.
- Patent Processus Vaginalis (PPV): Almost all UDTs have an associated PPV (Hernia sac). This must be ligated during the orchidopexy.
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