**2. Patients and methods**

A systematic review of the literature was performed focusing on the diverse aspects of the epidemiology, pathogenesis, diagnosis and management of acquired UDT. Data were

<sup>\*</sup> Corresponding Author

Acquired Cryptorchidism: What Should We Know? The Results of a Systematic Review 35

to explain the process of secondary ascent (excluding that for iatrogenic reasons). The first theory is based on surgical findings during orchidopexies. Atwell (Atwell JD 1985) noted the presence of a persistent processus vaginalis (PV) in 9/10 of his patients. He proposed that the acquired malposition of the testis is due to partial absorption of the PV into the parietal peritoneum, and this alteration in the distribution of the peritoneal lining of the abdominal cavity leads to traction of the spermatic cord and ascent of the testis. Clarnette et al (Clarnette et al 1977, Clarnette et al 1997) reported the presence of a fibrous structure extending with the cord structures, which on immunohistochemistry showed the characteristics of a remnant of the PV. Other studies found the presence of PV or hernia sac in 23%-76% of orchiopexies for acquired UDT (Robertson JF & Azmy AF 1988, Wright JE 1989, Meijer RW 2004, Gracia J et al 1997 , Eardley I et al 1994, Hack WW 2003b, Redman JF 2005). Based on these findings, it was suggested that the persistence of a patent PV or its remnants is responsible for tethering the testis in a static position during a period of somatic growth. However, recently Meij-De Vries et al (Meij-de Vries A et al 2010), studying the perioperative surgical findings in congenital UDTs and acquired UDTs, found that acquired UDTs are more likely to have a closed PV, and a normal insertion of the gubernaculum. The conflicts seems to be continued, after the current findings of Mirillas et al (Mirilas et al 2010) who studied the sonographic pattern of the PV in children with acquired UDTs and found that PV is patent in a manner similar to the inguinal hernia and hydrocele . They suggested that a scrotal testis could be retracted through the PV to a higher position with contraction

The second theory speculates an association between retractile testes and acquired UDTs. Agarwal et al (Agarwal PK et al 2006) reported an incidence of 32% of retractile testes which became ascending during of about 3-year follow-up period. Willie (Willye GG 1984) reported an incidence of 42% of retractile testis to become ascending. Stec et al (Stec AA et al 1987) noted an incidence of 3.2% (21 of 666 retractile testes) underwent secondary ascent and orchidopexy. They stated that the majority of retractile testes resolve without surgical intervention. Eardlay et al (Eardley I et al 1994) found that 27% of ascending testes were previously retractile. Smith et al (Smith JA et al 1989) reported an increased secondary ascent of the testes in boys with cerebral palsy, where an increased cremasteric muscle hypertonicity is noted. These findings show that about a third of ascended testes may be passing through a retractile phase through the transition from the scrotum to an extrascotal position (Hack ww et al 2003c). Natural course of acquired undescended testis in boys. *Brit J Surg*, 90, pp.728-31). The following mechanisms have been proposed to clarify the possible causes of retractile testes to become ascended: a) Smith et al (Smith JA et al 1989), speculated that cremaster muscle spasticity may be a possible cause of acquired UDT in patients with cerebral palsy. However, the proposed etiology in otherwise normal boys is not clear (Barthold JS & González R. 2003), b) The cremaster muscle is androgen sensitive and exhibits decreased activity, resulting in decreased testicular retractility, during periods of high androgen production, specifically in infancy and puberty. It has been shown, that target disruption of estrogen receptors in mice produces cremasteric hypertrophy and testicular retraction (Bartlett JE et al 2008). Theoretically, environmental chemicals that influence sex steroid production or action could exaggerate the physiological hyperactivity of the cremaster muscle in young boys and increase the risk o testicular ascent (Gray LE & Osthy 2001 ). However, reproductive hormone activity is low during mid childhood, and

of the cremaster muscle.

extracted from Medline database form inception to October 2011. A UDT was defined as a non-palpable testis inside the scrotum and for which further traction on cord traction was painful (Meij-de Vries A et al 2010). A congenital UDT was defined as a testis which had not previously descended (Meij-de Vries A et al 2010, Hack WW et al 2003b), whereas an acquired UDT was defined as an UDT in which a previous scrotal position was documented on at least one occasion (Barthold JS & González R 2003). This does not include testes identified as being cryptorchid after inguinal surgery.
