Cryptorchidism refers to an absence of a testis (or testes) in the scrotal sac. It may refer to an undescended testis, ectopic testis, or an atrophic or absent testis. Correct localisation of testes is essential because surgical management varies on location.
The testes develop in the abdomen and at ~21 weeks of gestation and migrate toward the inguinal canal through the deep inguinal ring. The migration is complete at ~30 weeks. The gubernaculum is the ligament which connects the testes to the scrotum. Under hormonal influence (probably testosterone), the gubernaculum contracts, and the testes descend into the scrotum. Causes/associations of undescended testes are:
- premature birth (birth occurs before full descent of testes)
- intrauterine growth restriction (IUGR)
- associations with smoking, alcohol intake during pregnancy
- androgen insensitivity syndrome
- congenital syndromes
- gestational diabetes
Ultrasound has 45% sensitivity, 78% specificity, and 88% accuracy for localisation of an undescended testis and is more accurate than clinical examination 4,5.
- lack of a testicle in the scrotal sac
- the undescended testis is homogeneously hypoechoic ovoid structure, similar to contralateral testis, with an echogenic mediastinum teste
- the ectopic testis may be high up in scrotum or within inguinal canal (39%)
- ultrasound is limited in intra-abdominal, pelvic or retroperitoneal/ectopic testes (20%)
- ultrasound is also inconclusive in evaluation of atrophic testis (41%), where it is difficult to differentiate from lymph nodes or pars infravaginalis gubernacula 1
MRI is the best cross-sectional modality to assess crypto-orchidism (replacing CT scan). It has a higher sensitivity than ultrasound (~90%) and a higher specificity (100%) 6.
Coronal T1W images can show gubernaculum testes and spermatic cord, which can be followed to locate the undescended testes. Also, ectopic pelvic or retroperitoneal location of testes can be identified. Diffusion-weighted MRI shows markedly hyperintense testes, and helps to differentiate it from surrounding structures 2.
Treatment and prognosis
Most undescended testes at birth descend in the first three months after birth
Orchiopexy is the preferred mode of management in case of viable testes high-up in scrotum or within inguinal canal / abdomen. It is performed after 1 year of age since the testes may descend without intervention.
With cryptorchidism there is 32x increased risk of developing a testicular germ cell tumour, with an incidence of 1 in 2000 (higher in bilateral cases, and in abdominal cryptorchidism) 7. The effect of surgical correction decreasing the risk of malignancy is controversial but it does allow for easier examination 7, and hopefully earlier detection.
An exaggerated cremasteric reflex can simulate cryptorchidism.
Ultrasound - testicular and scrotal
- ultrasound (introduction)
testicular and scrotal ultrasound
unilateral testicular lesion
- testicular torsion
- testicular rupture
- germ cell tumours of the testis
- sex cord / stromal tumours of the testis
- bilateral testicular lesion
- paratesticular lesions
- tubular ectasia of the rete testis
- cystadenoma of the rete testis
- testicular sarcoidosis
- testicular tuberculosis
- spermatic cord
- fibrous pseudotumour of the scrotum
- scrotal leiomyosarcoma
- testicular adrenal rest tumours (TARTs)
- tunica vaginalis testis mesothelioma
- splenogonadal fusion
- unilateral testicular lesion
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