Failure of one or both testes to descend into the scrotum by 6 months of age.
Also known as: cryptorchidism, undescended testis, UDT, undescended testicle
Overview
Failure of one or both testes to reach the dependent portion of the scrotum. Classified as palpable (in the inguinal canal or high scrotal position) or non-palpable (intra-abdominal, ectopic, or absent/vanishing testis).
Epidemiology
Present in ~3% of full-term and 30% of preterm male infants; most descend spontaneously by 3-6 months. Persistent cryptorchidism affects ~1% of boys at 1 year. Higher in low birth weight, prematurity, and twins.
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Question 1ReproductiveMedium
A 9-month-old boy is brought for a well-child visit. His mother reports that his right scrotum has always looked emptier than the left. He was born at 34 weeks. In a warm, relaxed setting, the right hemiscrotum appears flat and underdeveloped, and the testis cannot be palpated in the scrotum. Gentle pressure along the inguinal canal lets the examiner feel a small testis high in the canal, but it retracts to the same position when released and cannot be coaxed into the scrotum. The left testis is normally descended. Which of the following is the most likely diagnosis?
ARetractile testis
BHeterotopic testis
CVanishing testis
DUndescended testis
Reveal answer & full explanation
Correct answer: D — Undescended testis
ARetractile testis
BHeterotopic testis
CVanishing testis
DUndescended testis✓
Why Undescended testis is correct
A palpable testis arrested high in the inguinal canal that cannot be brought into the scrotum at 9 months (>=6 months corrected age) is the classic finding of an undescended testis along the normal path of descent.
Prematurity is a key risk factor, and the empty, hypoplastic hemiscrotum with a canalicular testis fits the palpable subtype. Per AUA, refer to pediatric urology and plan orchiopexy by 18 months (ideally 6-12 months); imaging is not indicated.
Why the others are wrong
Retractile testis: a hyperactive cremasteric reflex pulls a fully descended testis up, but with warming and gentle manipulation it can be brought into the scrotum and stays there briefly. This testis cannot be coaxed down, which excludes it.
Heterotopic testis: an ectopic testis lies outside the normal path of descent (perineal, femoral, or contralateral scrotum). Here the testis is found within the inguinal canal, the normal descent route, not an abnormal location.
Vanishing testis: anorchia implies an absent, non-palpable testis with no AMH or testosterone response, confirmed surgically. This testis is palpable in the canal, so functional tissue is present.
Question 2ReproductiveMedium
A 9-month-old boy is brought to clinic because his right testis has never been felt in the scrotum. He was born at term and is otherwise growing and developing normally. On examination in a warm, relaxed setting, the left testis is in a normal scrotal position, but the right testis cannot be palpated anywhere along the inguinal canal or scrotum, and the right hemiscrotum appears underdeveloped. The remainder of the genitourinary exam is normal, and he is referred to pediatric urology. Which of the following is the most appropriate next diagnostic study?
AScrotal ultrasonography
BPelvic MRI evaluation
CDiagnostic laparoscopy
DAbdominopelvic CT scan
Reveal answer & full explanation
Correct answer: C — Diagnostic laparoscopy
AScrotal ultrasonography
BPelvic MRI evaluation
CDiagnostic laparoscopy✓
DAbdominopelvic CT scan
Why Diagnostic laparoscopy is correct
For a unilateral non-palpable undescended testis, diagnostic laparoscopy is the gold standard: it directly localizes an intra-abdominal testis or confirms its absence (vanishing testis) and lets the surgeon proceed to orchiopexy in the same setting.
The AUA cryptorchidism guideline recommends against routine imaging and directs that a non-palpable testis be evaluated surgically, because no imaging study reliably changes management.
Why the others are wrong
Scrotal ultrasonography — routine ultrasound is explicitly NOT recommended by the AUA; it has poor sensitivity and specificity for intra-abdominal testes and does not alter the decision to operate, so it only adds cost and delay.
Abdominopelvic CT scan — exposes a young child to ionizing radiation, still misses many intra-abdominal testes, and does not avoid the need for surgical exploration.
Pelvic MRI evaluation — though radiation-free, it is expensive, often requires sedation in an infant, has limited accuracy for a small intra-abdominal testis, and does not replace laparoscopy.
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Disorders of sex development (DSD) — especially if bilateral non-palpable
Pathophysiology
Testicular descent occurs in two phases: trans-abdominal (mediated by INSL3/RXFP2) and inguinoscrotal (androgen-dependent, mediated by genitofemoral nerve and CGRP). Disruption of either step results in cryptorchidism.
Clinical presentation
Symptoms
Usually asymptomatic; identified at newborn or well-child exam
Signs / physical exam
Inability to palpate the testis in the scrotum in a warm relaxed environment
Empty hemiscrotum (possibly hypoplastic)
Distinguish from retractile testis by warming the child and gentle manipulation
Differential diagnosis
Retractile testis — Hyperactive cremasteric reflex; testis can be manipulated into the scrotum and remains briefly — not cryptorchidism, no surgery needed but monitor (some become ascending testes)
Ascending testis (acquired UDT) — Previously fully descended testis later found out of the scrotum — managed similarly to congenital UDT with orchiopexy
Ectopic testis — Outside normal path of descent (perineal, femoral, contralateral scrotal); requires surgery
Anorchia / vanishing testis — Non-palpable unilateral testis; MIS and testosterone production absent on stimulation; confirmed at surgery
Diagnostic workup
Diagnostic criteria
Clinical examination — testis not present in the scrotum at >=6 months corrected age.
Anti-Mullerian hormone (AMH) and inhibin B levels can confirm presence or absence of functional testicular tissue (anorchia evaluation)
hCG stimulation test in select cases
Imaging
Routine ultrasound is NOT recommended (poor sensitivity and specificity, does not change management) per AUA
If non-palpable: diagnostic laparoscopy is the gold standard to locate or confirm absence of intra-abdominal testis
Diagnostic algorithm
flowchart TD
A[Newborn male, empty scrotum] --> B[Observe to 6 mo]
B --> C{Descended<br/>by 6 mo?}
C -->|Yes| D[Routine well-child care]
C -->|No| E[Refer to pediatric urology]
E --> F{Palpable?}
F -->|Yes| G[Inguinal orchiopexy<br/>between 6-18 mo]
F -->|No, unilateral| H[Diagnostic laparoscopy]
H -->|Intra-abdominal| I[Orchiopexy<br/>+/- Fowler-Stephens]
H -->|Absent / vanishing| J[Document, no further surgery]
F -->|No, bilateral| K[DSD workup<br/>karyotype, 17-OHP, AMH, hCG stim]
K --> H
Evaluation and management algorithm for cryptorchidism.
Treatment
First-line
Observation in first 6 months of life — most descend spontaneously
Orchiopexy between 6 and 18 months of age if testis has not descended (AUA recommends by 18 months; earlier surgery between 6-12 months may improve fertility and reduce malignancy risk)
Standard inguinal orchiopexy for palpable testis with hernia sac high ligation
Two-stage Fowler-Stephens orchiopexy for high intra-abdominal testes — first stage clipping of testicular vessels, second stage mobilization 6 months later
Hormonal therapy (hCG, GnRH) is NOT recommended by AUA — low efficacy and not durable
Post-pubertal / adult cryptorchidism
Orchiectomy generally recommended over orchiopexy after puberty due to higher malignancy risk and very low fertility potential in long-standing UDT
Bilateral post-pubertal cryptorchidism is managed individually, balancing testosterone production, fertility, and malignancy risk
Second-line / adjunct
Testicular prostheses may be offered after orchiectomy
Complications
Subfertility/infertility (greater in bilateral, intra-abdominal, and late-corrected cases)
Testicular germ cell cancer — RR ~2-8x for cryptorchid testes; orchiopexy reduces but does not eliminate risk and allows surveillance
Testicular torsion (cryptorchid testes are at increased risk)
Associated inguinal hernia (high incidence)
Psychological impact
PANCE pearls
Refer to pediatric urology by 6 months of age if testis has not descended — definitive surgery before 18 months reduces complications.
Imaging is NOT useful in cryptorchidism — diagnostic laparoscopy is the gold standard for non-palpable testes.
Bilateral non-palpable testes in a phenotypic male require urgent evaluation for disorder of sex development, including CAH (potentially virilized 46,XX female with salt-wasting crisis).
Orchiopexy reduces but does not eliminate testicular cancer risk; lifelong self-examination education is recommended.
A retractile testis is a normal variant and does not require surgery, but should be followed because a subset become ascending and require eventual repair.
References
AUA 2014 — AUA Guideline: Evaluation and Treatment of Cryptorchidism (Kolon et al., J Urol 2014)
EAU/ESPU — EAU/ESPU Guidelines on Paediatric Urology — Cryptorchidism
AAP — American Academy of Pediatrics Section on Urology resources
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