{
 "topic": "Undescended Testis",
 "slug": "undescended-testis",
 "category_id": 15594,
 "summary": "Cryptorchidism: epidemiology, evaluation distinguishing true UDT from retractile testis, red flags for disorders of sex development, and timing of orchiopexy.",
 "written_by": "claude-sonnet",
 "references": [
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 ],
 "short": [
  {
   "title": "In short",
   "content": "- Undescended testis (UDT, cryptorchidism) is the most common congenital anomaly of the male genitourinary tract, affecting roughly 1-4% of full-term boys and up to 30-45% of preterm boys.\n- About 10-25% of cases are bilateral.\n- A testosterone surge in the first two months of life (\"minipuberty\") drives spontaneous descent in up to half of affected infants; incidence falls to about 1-1.5% by 6 months of age. If the testis has not descended by 4 months, it will not descend on its own.\n- Distinguish true UDT from a retractile testis: a retractile testis can be milked into the scrotum and, after 30 seconds of holding to fatigue the cremaster muscle, stays there - a true UDT does not.\n- Bilateral non-palpable testes in a newborn should raise suspicion for a disorder of sex development, including salt-wasting congenital adrenal hyperplasia in a virilized female, which can be life-threatening.\n- The risk of an underlying disorder of sex development is about 15% when a palpable UDT accompanies mid-penile or proximal hypospadias, and about 50% when the testis is non-palpable with hypospadias.\n- Imaging (ultrasound) is not recommended to localize a non-palpable testis - it rarely changes management and should be reserved for evaluating pain or a mass.\n- Orchiopexy is recommended after 6 months of age (corrected for gestational age): inguinal or scrotal orchiopexy for palpable testes, diagnostic laparoscopy with laparoscopic orchiopexy for non-palpable testes.\n- A UDT presenting together with an inguinal hernia should be operated on at the time of diagnosis rather than waiting.\n- There is no role for hormonal therapy. Untreated UDT carries increased long-term risk of subfertility and testicular malignancy, with degenerative changes on electron microscopy detectable by 1 year of age.\n"
  }
 ],
 "long": [
  {
   "title": "Definition",
   "content": "Undescended testis (UDT), or cryptorchidism, is the absence of a testis from its normal position within the scrotum. It encompasses several distinct entities that must be told apart because their management differs: true cryptorchid/undescended testis, ectopic testis, absent (vanishing) testis, atrophic testis, retractile testis, and ascended testis (a testis documented in the scrotum as a neonate that is found higher later in childhood).\n"
  },
  {
   "title": "Epidemiology",
   "content": "UDT is the most common congenital abnormality of the male genital tract. At birth roughly 1-4.5% of full-term boys have an undescended testis, and because normal testicular descent occurs late in gestation (7-8 months), the figure is far higher in premature infants - as high as 30-45%. Bilateral involvement occurs in about 10-25% of affected boys. Descent continues after birth: up to half of congenitally undescended testes come down spontaneously in the first three months of life, and the overall prevalence falls to about 1.5% by 6 months and roughly 1% by one year, after which spontaneous descent is unlikely. There is some evidence that the incidence of cryptorchidism is rising, which has been attributed to increasing in-utero exposure to endocrine-disrupting chemicals.\n"
  },
  {
   "title": "Etiology",
   "content": "Most boys with UDT have no identifiable underlying cause. Postnatal descent is driven by a transient testosterone surge in the first two months of life (the \"minipuberty\" of infancy), which also produces noticeable penile growth; if descent has not occurred by around 4 months, the testis will remain undescended. A minority of cases have an endocrine basis, and UDT can be associated with hypopituitarism, dysmorphic syndromes, or disorders of androgen production and action. Bilateral cryptorchidism in a newborn should always raise concern for a disorder of sex development, in particular a virilized genetic female with salt-wasting 21-hydroxylase deficiency (congenital adrenal hyperplasia).\n"
  },
  {
   "title": "Clinical Features",
   "content": "Undescended testes are classified by location: abdominal (non-palpable), peeping (abdominal but can be pushed into the upper inguinal canal), inguinal, gliding (can be pushed into the scrotum but retracts immediately), and ectopic (most often a superficial inguinal pouch, rarely perineal). Most are palpable just distal to the inguinal canal near the pubic tubercle. The affected hemiscrotum is often poorly developed, with fewer rugae than the normal side. UDT is usually asymptomatic, but because the testis sits against the abdominal wall rather than moving freely, it is more vulnerable to trauma and to torsion; a boy presenting with an acutely tender groin mass and an empty ipsilateral scrotum may have torsion of an undescended testis, and an incarcerated inguinal hernia or acute hydrocele of the cord should also be considered.\n"
  },
  {
   "title": "Diagnostics",
   "content": "Diagnosis is clinical. A careful genital examination should be performed at every well-child visit in warm conditions with warm hands, since a previously descended testis can re-ascend. Inspect for scrotal asymmetry, then attempt to guide the testis along the inguinal canal into the scrotum. If it can be brought down, holding it in the scrotum for 30 seconds fatigues the cremaster muscle; a retractile testis stays down afterward, while a true UDT retracts again. Ultrasound is not recommended to localize a non-palpable testis, since it does not alter management; it should be reserved for evaluating scrotal pain or a mass. Neonates with hypospadias and an undescended testis need urgent evaluation for an underlying genetic or endocrine disorder such as congenital adrenal hyperplasia, since the risk of a disorder of sex development is about 15% with a palpable testis and midpenile/proximal hypospadias, rising to about 50% when the testis is non-palpable.\n"
  },
  {
   "title": "Differential Diagnosis",
   "content": "The key distinctions are from a retractile testis (fully descended, drawn up by an overactive cremasteric reflex, requires no treatment but close follow-up since roughly a third later become ascended and need surgery), an ascended testis, and true testicular absence/atrophy (agenesis or presumed intrauterine torsion).\n"
  },
  {
   "title": "Treatment",
   "content": "Because spontaneous descent essentially stops after 6 months, orchiopexy is recommended at that age (corrected for prematurity). Palpable testes are managed with inguinal or scrotal orchiopexy; non-palpable testes require diagnostic laparoscopy with laparoscopic orchiopexy when a testis is found. A UDT presenting with an inguinal hernia should be repaired at the time of diagnosis rather than delayed. There is no role for hormonal treatment. A testicular prosthesis can be considered for an absent or atrophic testis to address psychological impact and body image.\n"
  },
  {
   "title": "Complications",
   "content": "Uncorrected UDT is associated with increased risk of subfertility and testicular malignancy; degenerative changes are demonstrable by electron microscopy by one year of age, underpinning the recommendation for early orchiopexy.\n"
  }
 ],
 "clinical": [
  {
   "title": "Bedside Approach to the Boy with an Empty Scrotum",
   "content": "Examine in a warm room with warm hands. Inspect for scrotal asymmetry - a hypoplastic hemiscrotum suggests the testis has never descended. With the child supine or sitting, attempt to guide the testis down the inguinal canal into the scrotum. If successful, hold it in the scrotum for 30 seconds to fatigue the cremaster: a retractile testis remains down, a true undescended testis springs back up. Do not order a scrotal ultrasound to try to find a non-palpable testis - it does not change management and should be reserved for a painful or mass-like scrotum. If the testis has not descended by 6 months of age (corrected for gestational age), refer for surgery rather than waiting further, since spontaneous descent essentially does not occur after this point. A UDT found together with an inguinal hernia should go to surgery at the time of diagnosis, not be deferred to 6 months.\n"
  },
  {
   "title": "Red Flags Requiring Urgent Work-Up",
   "content": "Bilateral non-palpable testes in a newborn phenotypic male require prompt evaluation for a disorder of sex development, since the infant may be a virilized genetic female with salt-wasting congenital adrenal hyperplasia - a potentially life-threatening diagnosis. The same urgent evaluation is warranted for a neonate with hypospadias plus an undescended testis: the risk of an underlying disorder of sex development is about 15% when the testis is palpable and rises to about 50% when it is non-palpable. Separately, an acutely tender groin mass with an empty ipsilateral scrotum in a boy with a known undescended testis should prompt immediate consideration of testicular torsion (as well as incarcerated inguinal hernia or acute hydrocele of the cord) and prompt surgical evaluation.\n"
  }
 ]
}