Previous testicular position in boys referred for an undescended testis: further explanation of the late orchidopexy enigma?

Authors


W.W.M. Hack, MD, PhD, Medical Centre Alkmaar, Department of Paediatrics, Wilhelminalaan 12, 1815 JD Alkmaar, the Netherlands.
e-mail: w.hack@mca.nl

Abstract

OBJECTIVE

To investigate the significance of the acquired undescended testis (UDT), which is differentiated into congenital and acquired forms, by assessing the previous testicular position in affected boys.

PATIENTS AND METHODS

The study comprised 261 boys who had been referred for a non-scrotal testis to the outpatient clinic during an 8-year period (1993–2000). There was a bimodal distribution of age, with peaks at 2.0 and 10.0 years. In each boy with UDT the previous testicular position was ascertained.

RESULTS

On referral, 340 testes were not in the scrotum (182 uni- and 79 bilateral). Of the 340 testes, 82 (24%) in 61 boys were diagnosed as retractile, whereas the remaining 258 in 221 boys were undescended. The previous testicular position was known in 208 of 221 boys (94%), with 244 UDTs. In 65 of these 244 (26.6%) the testis had never been scrotal (congenital UDT); in 179 (73.4%) a previous intrascrotal position was recorded in early childhood (acquired UDT) at least once, in 149 (61%) at least twice and in 117 (48%) at least three times. The mean age at referral for congenital UDT was 2.1 years and for acquired UDT was 8.4 years.

CONCLUSIONS

These results show that acquired UDT is frequent, and occurs at about three times the rate of congenital UDT. Because these boys are referred for treatment later in childhood, the acquired UDT probably accounts for the high rate of (late) orchidopexy.

INTRODUCTION

The undescended testis (UDT) is a common genital abnormality in prepubertal boys. Although retained testes are present in 0.8–1.1% of boys by 1 year old [1–3], orchidopexy rates are substantially higher, at 2.6–3.4%[4,5]. Furthermore, despite recommendations for orchidopexy as early as 1 year old, most are undertaken later in childhood [6,7]. At present, the UDT is classified into congenital and acquired forms, the latter also including high scrotal forms [8]. To investigate the significance of the phenomenon of acquired UDT we assessed the previous testicular position in boys referred for a non-scrotal testis.

PATIENTS AND METHODS

The study included 261 boys who were referred for a non-scrotal testis to the outpatient clinic during an 8-year period (1993–2000). As shown in Fig. 1, the distribution of age was bimodal, with peaks at 2.0 and 10.0 years. A UDT was defined either as a testis which could not be manipulated into the scrotum or one which could be ‘milked’ downwards through the scrotal entrance high into the scrotum, but after release immediately retracted to the groin (high scrotal testis). Further traction on cord structures is painful. In contrast, a retractile testis can be brought down into the scrotum and does not retract when released until the cremasteric reflex is evoked; in this case, traction on cord structures is not painful.

Figure 1.

The age at referral of 261 boys with a non-scrotal testis. There is a bimodal distribution for age with peaks at 2 and 10 years old (mean 6.6 years, sd 4.13).

In each boy the testes were examined while they were supine and with crossed legs, using a two-handed technique, palpating the scrotum and inguinal region. If palpable, the testis was manipulated downwards by gentle manoeuvres from the groin region into the lowest position along the pathway of normal testicular descent. This lowest position was used to classify each testis. In each boy with UDT, the previous testicular position was ascertained from records at the Youth Health Care Institutions.

RESULTS

On referral, 182 boys had a unilateral (81 left- and 101 right-sided) and 79 had bilateral non-scrotal testes, giving 340 in all. In 82 of these testes (24%) in 61 boys, the testicle was classified as retractile; in the remaining 258 (221 boys), the testicle was diagnosed as undescended. In 208 of these 221 boys with 244 UDT, the previous testicular position was known; as shown in Fig. 2, in 65 (26.6%) the testis had never been scrotal and in 179 (73.4%) it was previously scrotal at least once, in 149 (61%) at least twice and in 117 (48%) at least three times.

Figure 2.

The previous testicular position in 244 UDTs; in 65 the testis had never been scrotal, whereas in the remaining 179 a scrotal position was documented at least once in 179, at least twice in 149, and at least three times in 117.

From the physical examination and previous testicular position the diagnosis at referral (mean age 7.1 years, range 0–16) was as follows: 258 testes were classified as undescended; in 13 boys with 14 UDT there were no data on previous testicular position but in the remaining 244 the diagnosis was congenital UDT in 65 (26.6%) and acquired UDT in 179 (73.4%). The mean (sd, range) age at referral was 1.9 (2.3, 0–14) and 8.5 (3.4, 0–16) years for congenital and acquired UDT, respectively.

DISCUSSION

These results show that in 74% of boys referred for UDT the testis was acquired, with a mean age at referral for congenital UDT of 2.3 years, and for acquired UDT of 8.5 years. Acquired UDT describes the condition in which a testicle is in a normal scrotal position in early childhood but becomes truly undescended later [8–11]. If the testis can still be made to enter high into the scrotum, but after release immediately retracts to the groin, the condition is termed high scrotal testis (or ‘gliding testis’[12]). If the testis can no longer be pushed into the scrotum the condition is termed ‘ascending testis’.

To diagnose acquired UDT correctly reliable information on the previous testicular position is essential. In the Netherlands, a national register of testicular position was introduced in 1986, after a consensus development conference on the ‘non-scrotal testis’[13]. Amongst other factors, this resulted in the accurate documentation of testicular position in the early years of life in each boy during health-centre visits. The underlying pathogenesis of acquired UDT remains unclear, although partial absorption of the processus vaginalis into the parietal peritoneum, failure of the spermatic cord to elongate in proportion to body growth, persistence of a fibrous remnant of the processus vaginalis [14] and ectopic gubernaculum tethering the testicle as the boy grows are possible causal factors. Acquired UDT secondary to groin surgery is termed a ‘trapped testis’.

At present, the orchidopexy rate is substantially higher than the rate of UDT [4,5,15,16] and despite recommendations for early orchidopexy at 1 year old [17], over 60–80% of all operations are undertaken at 7–12 years old [15,18]. For example, in the Netherlands, the annual number of operations for UDT between 1986 and 2000 was 4217 (Table 1). However, the expected annual number, according to the prevalence of UDT of 1%, would be 800–1000. Furthermore, 86% of the operations (50 765/59 045) were in boys older than 2 years.

Table 1. The number of orchidopexies for undescended testis by age at operation per year, within the Netherlands (1986–1989 and 1991–2000; data from Prismant, Institute for Healthcare Management, Utrecht, the Netherlands)
YearAge, years
01–23–45–67–89–1011–1213–1415–16Total
  • *

    no reliable data available.

1986  35  421  627  767  961  1025  752  244    87  4 919
1987  26  444  607  620  917  976  692  227    89  4 598
1988  20  407  577  532  806  937  614  239    66  4 198
1989  26  474  549  512  733  903  689  204    81  4 171
1990*
1991  25  491  571  528  698  923  737  218    66  4 257
1992  33  534  562  473  627  891  698  263    92  4 173
1993  22  556  538  548  794  927  855  328    73  4 641
1994  27  622  564  596  700  992  889  362    99  4 851
1995  22  616  474  444  631  795  733  346    99  4 160
1996  41  627  485  457  587  762  717  336  134  4 146
1997  16  625  448  446  564  726  716  305  106  3 952
1998  31  670  397  369  507  725  609  322  127  3 757
1999  17  666  409  370  496  715  546  245    99  3 563
2000  29  757  433  393  485  614  546  257  145  3 659
Total37079107241705595061191197933896136359 045

In recent years evidence has been accumulating that late orchidopexy might be accounted for by acquired UDT [19–23]; several studies found that 40–70% of those undergoing orchidopexy had previously descended testes [24]. In addition, most boys undergo surgery when much older than usually recommended. Our recent report of 707 orchidopexies for UDT in 565 patients from 1986 to 1999 showed that > 80% of the testes had previously been in a normal scrotal position [25]. Furthermore, 91% of the boys were ≥ 3 years old at operation.

Although the high rate of late orchidopexy was initially explained by surgery in boys with a retractile testis after an error in the physical examination [5,26], or by late recognition of congenital UDT [18,21], there is considerable doubt about this supposition. Several reasons must be considered: (i) it is unlikely that a faulty or poor examination occurs on such a large scale to account for so many operations; (ii) the peak age for late orchidopexy is 9–11 years, suggesting acquired UDT [20,23,27], with a retractile testis being most common in boys aged 5–6 years [28]; (iii) in the Netherlands, the introduction of the national register of testes at birth, aiming to prevent orchidopexy for retractile forms [13], did not reduce the orchidopexy rate, which remains at three to four times the rate of UDT; and (iv), despite an increase in the peak age for early orchidopexy, probably as a result of educational programmes, there remains a peak age in the older group, suggesting acquired UDT [20]. Finally, the results of the present study show that boys with an acquired UDT are referred for treatment about three times more often than boys with congenital UDT. These values and the bimodal distribution for age at referral correspond very closely with the early and late orchidopexy rates.

In summary, these results confirm, as others have noted [10,14], that acquired UDT is more important in boys referred for a non-scrotal testis than is generally recognized. Because they present later in childhood these testes may explain the discrepancy between the 1% incidence of (congenital) UDT and the 2–3% orchidopexy rate. Furthermore, they explain why significantly many orchidopexies occur later in childhood. The question remains as to whether orchidopexy is indicated for acquired UDT, to preserve and improve spermatogenesis in adulthood. Recent evidence suggest that many acquired UDTs will descend spontaneously at puberty, with testicular volumes appropriate for age [29].

Abbreviations
UDT

undescended testis.

Ancillary