Increased risk of testis cancer in both testis (correlates with height of testis)

• 1% of undescended testes patients develop cancer 
• Historically 25-30x increased risk from baseline; likely really only 2-6x increase from normal population (which is 0.4% incidence)
• Higher risk with intra-abdominal testis (5%)
• Highest risk is with DSD
• Most common tumor is seminoma
• About 20% of UDT patients with cancer have it in the contralateral testis.
• Orchiopexy before puberty can decrease this risk by 2-6 fold (still increased from baseline)
• Main goal is to bring testicle down for easier self-examinations
• If detected after puberty, should perform orchiectomy instead

More common on the right

Natural history

• 3% incidence of cryptorchidism in newborns
• 99% of those still have cryptorchid testis at 1 year
• If it has not descended by 6 months, it will not descend later in life
• Retractile = not truly undescended, goes up and down due to cremasteric reflex. Normal testis
• Later testosterone surge in puberty makes it less retractile
• Should continue annual exams to r/o secondary ascent (happens between 7-30%)
• Ascended = was descended, then ascended. Likely abnormal gubernacular attachment causing ascension during growth. Then should be treated as undescended testicle
• If contralateral testis is normal size (not enlarged), then the testis is usually present (e.g. not absent)
• If unilateral UDT, paternity rate ~90% (similar to general population); if bilateral UDT, paternity rate 62%

If bilateral undescended - karyotype to work up DSD; CAH

• CAH  →  hyponatremia, hyperkalemia
• Defective cortisol synthesis →  increased (ACTH) →  adrenal stimulation leads to increased androgen production →  virilization in XX
• 17-hydroxyprogesterone levels to evaluate for 21-alpha-hydroxylase deficiency (most common form of CAH
• LH, FSH, testosterone, androstenedione
• If bilateral UDT and no CAH, perform Mullerian Inhibiting Substance/anti-Mullerian Hormone (MIS/aMH) testing
• aMH normally made by Sertoli cells
• If low but XY and normal external genitalia - could have 'testicular regression' or bilateral fetal testicular torsion (possibly palpating dead testes at birth), or 'persistent mullerian duct syndrome' eg defect in aMH synthesis

If also have hypospadias with UDT, consider karyotype for DSD

• Unilateral UDT: 15% DSD
• Bilateral UDT: 30% DSD
• Proximal hypospadias: 30-40% DSD

Imaging

• No great options for confirming absence of testicle (40-60% sensitivity with US/MRI)

If has not descended by 6 months, should perform orchidopexy within next year

• Optimize testicular function
• Reduce/facilitate diagnosis of testicular malignancy
• Prevent complications such as hernia (patent processus vaginalis in 70-87%) or torsion

Open inguinal orchidopexy

• Caudal block with general anesthesia
• Inguinal incision over pubic tubercle - 2.5 cm

If testis/vessels absent, open internal inguinal ring and explore retroperitoneum

• Then explore peritoneum
• If testis present, see if cord will reach - consider single, staged, or microvascular approach. 
• Ideally done between 6-9 mo so that testis can still stretch with minimal tension on vessels
• Fowler Stephen's division of testicular vessels if does not reach contralateral internal inguinal ring (testis blood supply will come from vas deferens and cremasteric collaterals)
• Single or staged (6 mo in between), unclear if atrophy rate different
• Can bypass inguinal canal directly into scrotum if cord too short - Prentiss maneuver (route under inferior epigastric and bring testicle through medial fascial hole next to pubic tubercle)
• If normal contralateral testicle and cannot reach (and post-pubertal), may perform orchiectomy. Can get frozen biopsy (eg r/o GCT) to help decision making
• If testis absent, blind-ending vessels = no testis. If vas alone or no vas/vessels, continue exploration.

Followup

• LPCH: 4-6 weeks, then 6 months (to check that has remained descended), then after puberty
• Abidari: 8d f/u, then 3 months