Undescended Testis (Cryptorchidism)
Summary
Undescended Testis (UDT), or Cryptorchidism, is the incomplete descent of one or both testes from the retroperitoneum to the scrotum. It is the most common genital anomaly in male neonates, affecting ~3% of term and up to 30% of preterm boys at birth. Many testes descend spontaneously by 3-6 months of age. If the testis has not descended by 6 months, spontaneous descent is unlikely. Untreated cryptorchidism carries significant risks: Impaired Fertility (due to elevated testicular temperature), Testicular Malignancy (especially Seminoma, 5-10x risk in UDT, highest in intra-abdominal testes), and Testicular Torsion. Orchidopexy (surgical fixation of the testis in the scrotum) should be performed between 6-12 months of age (and by 18 months at the latest) to optimise fertility potential and facilitate surveillance. [1,2]
Clinical Pearls
Retractile Testis is NOT Undescended: The Retractile Testis sits in the scrotum normally but is pulled up into the inguinal canal by a brisk cremasteric reflex. It can be easily manipulated DOWN into the scrotum and STAYS there momentarily. This is a normal variant and does NOT require surgery, but needs annual review as ~5-30% may become Ascending Testis.
Ascending (Acquired UDT) Testis: A testis that was previously in the scrotum but later "ascends" into the inguinal canal. Due to failure of the spermatic cord to elongate with growth. Requires orchidopexy.
Bilateral Impalpable Testes = Red Flag: This raises suspicion for a Disorder of Sex Development (DSD), particularly Congenital Adrenal Hyperplasia (CAH) in a virilised 46XX female, or anorchia. Urgent Karyotype and Endocrine review.
Cancer Risk Reduces But Persists: Orchidopexy significantly reduces testicular cancer risk (and brings the testis within reach for self-examination), but it does NOT eliminate risk entirely. Lifelong awareness is important.
Demographics
- Incidence at Birth: ~3% of Term neonates. Up to 30% of Preterm neonates (especially less than 1500g).
- Spontaneous Descent: ~70-80% of UDT descend by 3 months; most by 6 months.
- Incidence at 1 Year: ~1% of boys.
- Laterality: Right > Left (60% vs 25%). Bilateral ~15%.
- Prematurity: Major risk factor.
Risk Factors
- Prematurity / Low Birth Weight.
- Small for Gestational Age.
- Family history of cryptorchidism.
- Maternal smoking, Alcohol, Diabetes.
- Endocrine disruptors (Phthalates, etc.).
Normal Testicular Descent (2 Phases)
- Transabdominal Phase (Weeks 10-15):
- Testis descends from posterior abdominal wall (near kidney) to internal inguinal ring.
- Driven by Insulin-like Factor 3 (INSL3) from Leydig cells.
- Inguino-Scrotal Phase (Weeks 25-35):
- Testis descends through inguinal canal into scrotum, guided by the Gubernaculum.
- Driven by Androgens (Testosterone/DHT) and fetal HPA axis.
- The Processus Vaginalis (peritoneal extension) normally obliterates. If it remains patent, it predisposes to Inguinal Hernia/Hydrocele.
Arrest of Descent (Pathology)
- Hormonal Deficiency: Androgen insufficiency (Hypogonadotropic hypogonadism, Disorders of Androgen Synthesis).
- Mechanical: Gubernacular abnormality, Patent Processus Vaginalis.
- Anatomical: Ectopic position (e.g., Perineum, Femoral canal - testis goes OUTSIDE normal path).
Consequences of Undescent
- Elevated Temperature: Scrotum is 2-4°C cooler than body core, essential for spermatogenesis. Intra-abdominal testis is at body temperature -> Germinal cell damage.
- Histological Changes: Germ cell degeneration evident from 6-12 months onwards. Worsens with age.
| Condition | Key Features |
|---|---|
| Retractile Testis | Brisk cremasteric reflex. Testis can be manipulated DOWN into scrotum and STAYS momentarily. No surgery needed. Annual review. |
| Ascending Testis | Previously documented in scrotum but now impalpable or high. Needs surgery. |
| Ectopic Testis | Testis outside normal line of descent (e.g., Perineum, Femoral canal, Superficial Inguinal pouch). Needs surgery. |
| Absent Testis (Anorchia / Vanishing Testis) | Testis absent due to prenatal vascular event (Intrauterine Torsion). May have remnant nubbin. hCG stimulation test negative. |
| Disorder of Sex Development (DSD) | Especially if bilateral impalpable + ambiguous genitalia. Karyotype, Endocrine workup. |
History
Examination
Classification by Position
| Position | Description | Management |
|---|---|---|
| Intra-abdominal | Impalpable. Above internal ring. | Laparoscopy needed. |
| Inguinal (Canalicular) | Palpable in inguinal canal. Most common. | Orchidopexy. |
| Prescrotal | At superficial ring/high scrotum. | Orchidopexy. |
| Ectopic | Outside normal path. | Orchidopexy. |
Clinical Diagnosis
- Diagnosis is primarily clinical (examination). Imaging is rarely needed for palpable UDT.
When to Investigate Further (Impalpable Testis / Bilateral UDT)
- Ultrasound: Not reliable for intra-abdominal testes. May identify inguinal testis.
- MRI: Higher sensitivity for intra-abdominal testes but not routinely used.
- Laparoscopy: Gold Standard for impalpable testis. Diagnostic and therapeutic.
- Hormonal Tests (Bilateral Impalpable):
- hCG Stimulation Test: Testosterone rises if functional testicular tissue present. No rise suggests anorchia.
- AMH (Anti-Müllerian Hormone): Produced by Sertoli cells. Marker of testicular tissue.
- FSH/LH: Elevated in anorchia.
- Karyotype (Bilateral Impalpable / Ambiguous Genitalia): Rule out DSD.
Management Algorithm
UNDESCENDED TESTIS SUSPECTED
(Empty Hemiscrotum on Examination)
↓
EXAMINE IN WARM ENVIRONMENT
(Frog-leg position)
↓
TESTIS PALPABLE?
┌────────┴────────┐
YES NO (Impalpable)
↓ ↓
COMES TO BOTTOM UNILATERAL? BILATERAL?
OF SCROTUM? ↓ ↓
┌────┴────┐ LAPAROSCOPY DSD WORKUP
YES NO (Diagnostic + (Karyotype, hCG,
↓ ↓ Therapeutic) Endocrine)
RETRACTILE TRUE UDT
TESTIS (Inguinal/Ectopic)
↓ ↓
ANNUAL ORCHIDOPEXY
REVIEW at 6-12 months
(Before 18 months)
Conservative (Observation)
- Many testes descend spontaneously by 3-6 months.
- Reassure parents. Review at 6 months.
Hormonal Therapy
- hCG or GnRH Injections: Historically used to encourage descent.
- Limited Efficacy (~10-20% success) and high relapse rate.
- NOT routinely recommended in current guidelines.
Surgical Management (Orchidopexy)
- Timing: Performed between 6-12 months of age (AUA/EAU guidelines). Complete by 18 months.
- Rationale: Earlier surgery preserves fertility potential. Histological damage worsens with age.
- Palpable UDT (Inguinal):
- Standard (Inguinal) Orchidopexy: Inguinal incision. Mobilise cord. Divide Gubernaculum. Close Patent Processus Vaginalis (if present). Place testis in subdartos pouch in scrotum.
- Impalpable UDT:
- Diagnostic Laparoscopy: Identifies location (intra-abdominal, inguinal, or absent).
- If Intra-Abdominal (Viable): Laparoscopic Orchidopexy (Single-stage or Staged Fowler-Stephens if high).
- If Absent/Atrophic Nubbin: Laparoscopic removal of remnant.
Management of Ascending Testis
- Orchidopexy when identified.
Of Undescended Testis (Untreated)
- Infertility: Bilateral UDT significantly impairs fertility. Even unilateral may reduce sperm count.
- Testicular Malignancy: 5-10x increased risk (up to 40x for intra-abdominal). Seminoma is most common. Risk persists even after orchidopexy.
- Testicular Torsion: Higher risk due to abnormal anatomy.
- Inguinal Hernia: Associated with Patent Processus Vaginalis.
- Psychological Impact: Body image concerns.
Of Orchidopexy (Surgical)
- Testicular Atrophy: Risk if blood supply damaged.
- Wound Infection.
- Recurrence / Ascending Testis.
- Fertility:
- Unilateral UDT (treated early): Paternity rates near normal.
- Bilateral UDT (treated early): Fertility rates 50-65%.
- Delayed treatment: Worse outcomes.
- Malignancy: Risk reduced but not eliminated by surgery. Lifelong self-examination recommended.
Key Guidelines
| Guideline | Organisation | Key Recommendations |
|---|---|---|
| Cryptorchidism | AUA (2014) | Orchidopexy at 6-12 months. Laparoscopy for impalpable. Hormone therapy not recommended. |
| Cryptorchidism | EAU / ESPU | Similar. Emphasis on early surgery. |
| NIPE | NHS | Routine examination at birth and 6-8 weeks includes testicular palpation. |
Landmark Evidence
- Orchidopexy Timing (Kollin et al., 2006): Showed early surgery (9 months) associated with better testicular growth than late surgery (3 years).
- Cancer Risk (Wood & Elder, Pettersson): Cohort studies confirming increased malignancy risk and reduction with early surgery.
What is an Undescended Testis?
Before a baby boy is born, his testicles develop inside his tummy and then move down into the scrotum (the pouch of skin below the penis). Sometimes one or both testicles don't make it all the way down. This is called an undescended testicle.
Is it common?
Yes, it's the most common genital problem in baby boys. It happens in about 3 out of every 100 term babies, and more often in premature babies.
Why does it matter?
If a testicle stays inside the body where it's warmer, it can:
- Affect the ability to have children later in life.
- Have a slightly higher chance of developing cancer (though this is still rare).
- Be at risk of twisting (torsion).
What is the treatment?
A small operation called Orchidopexy is done between 6 and 12 months of age. The surgeon brings the testicle down into the scrotum and stitches it in place. This helps protect fertility and makes it easier to check for problems later on.
Primary Sources
- Kolon TF, et al. Evaluation and treatment of cryptorchidism: AUA guideline. J Urol. 2014.
- Radmayr C, et al. EAU Guidelines on Paediatric Urology. 2023.
Common Exam Questions
- Classification: "Retractile vs True UDT?"
- Answer: Retractile can be manipulated to bottom of scrotum and stays momentarily. True UDT cannot.
- Timing: "When should orchidopexy be done?"
- Answer: 6-12 months of age (complete by 18 months).
- Complication: "Long-term risks of untreated UDT?"
- Answer: Infertility, Testicular Malignancy (Seminoma), Torsion.
- Investigation: "Bilateral impalpable testes in newborn?"
- Answer: Urgent Karyotype and Endocrine workup (Rule out DSD / CAH).
Viva Points
- Why Early Surgery?: Explain histological damage from elevated temperature worsens with age; early orchidopexy optimises fertility.
- Laparoscopy: Gold standard for impalpable testis. Identifies location and allows single-stage or staged repair.
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.