An undescended testis is one of the most frequently occurring genitourinary anomalies in the field of pediatric urology [1-4]. The incidence of undescended testes has been reported to be 0.8% of infants at 1 year of age, 3.4% to 5.5% of full-term newborns, and 9.2% to 30.0% of premature infants [5-9]. Of all undescended testes, approximately 20% are reported to be clinically impalpable [10,11]. Whereas the management of boys with palpable undescended testes is straight-forward, despite an abundance of international studies, there are no guidelines and there is considerable variability in the management of boys with impalpable testes.

Since the first report of diagnostic laparoscopy for impalpable testes in 1976, diagnostic laparoscopy has gained wide acceptance as a diagnostic procedure for identifying the exact anatomy of impalpable testes and the adnexae [12]. However, some investigators have recently reported that scrotal exploration is a potentially definitive approach for the diagnosis and management of impalpable testes [13]. Thus, we investigated the efficacy and results of diagnostic laparoscopy for the management of impalpable testes.

Between April 2000 and December 2009, 86 patients (89 testes) with impalpable, undescended testes underwent diagnostic laparoscopy. Impalpable testes were diagnosed by physical examination and ultrasonography in the outpatient department, and the diagnosis was confirmed by careful physical examination under general anesthesia before surgery. Patients with testes that were palpable under general anesthesia were excluded from this study.

All patients with impalpable, undescended testes underwent diagnostic laparoscopy before making a decision regarding surgical management. The testes were classified into the following four types on the basis of the location and viability of the testes: intraperitoneal viable testes, intraperitoneal nonviable testes (including vanished testes), extraperitoneal viable testes, and extraperitoneal nonviable testes. In every case, except for intraperitoneal nonviable testes, an exploratory inguinal incision was performed.

Clinical and follow-up data from the eligible patients were retrieved from the patients' medical records and reviewed retrospectively. Comparison of laparoscopic findings and surgical outcomes were performed by Pearson's chi-square test. All p-values were 2-sided, and data were considered statistically significant at a p<0.05.

The incidence of undescended testes is reported to be 0.8% to 1.5% in infants. Approximately 20% of undescended testes are impalpable. There are three main locations of impalpable testes: 40% of all impalpable, undescended testes are located intraperitoneally; 15% are vanished testes; and 45% have cord structures entering the internal inguinal ring [5,6]. For the assessment and diagnosis of impalpable, undescended testes, several diagnostic imaging tools, such as computed tomography or magnetic resonance imaging, cannot give us 100% reliable information about testes [12,15,16].

To diagnose undescended testes, Siemer et al recommended diagnostic laparoscopy with a sensitivity and specificity of up to 90% [17]. Ang and Forrest reported that laparoscopy for impalpable, undescended testes is of proven valuable for both diagnosis and surgical management [18]. In their study, 25.3% of impalpable testes were identified intraperitoneally and 18.9% were absent; therefore, diagnostic laparoscopy was helpful in 44.2% of impalpable testes. Thus, performing a laparoscopy can prevent unnecessary surgical exploration. Our results are consistent with these findings. In our study, there were 19 cases of intraperitoneal nonviable testes (21.3%); only 3 of 19 cases underwent inguinal exploration and 2 of 3 cases did not undergo any type of surgery. There were 18 intraperitoneal viable testes (20.2%); thus, diagnostic laparoscopy was useful for a minimum of 42.5% of cases. Because most testes were identified intraperitoneally in the patients with bilateral undescended testes, we focus more and more on the usefulness of diagnostic laparoscopy in such situations.

Recently, Snodgrass et al reported that the initial scrotal incision for a unilateral impalpable testis may be definitive management when a nubbin is identified [13]. Snodgrass et al demonstrated that laparoscopy is a reliable diagnostic tool for detection of an intraperitoneal testis, but a dilemma arises when there is no testis, and the cord structures exit the inguinal ring [13]. Thus, most patients who undergo initial laparoscopy will undergo a second inguinal incision for an orchiectomy or orchiopexy. This study suggests that scrotal exploration is a definitive procedure as a diagnostic and therapeutic tool for extraperitoneal testes and nubbins in patients with unilateral impalpable testes, but laparoscopy is only for intraperitoneal testes [19]. However, in cases of high inguinal testes, neither a scrotal nor a laparoscopic approach is definitive, necessitating a groin dissection to confirm extraperitoneal nonviable testes. Also, we acknowledge that groin dissection without any prior knowledge of a testicular location would sometimes be a tedious and challenging task without any benefit to the patient. Thus, even in cases with extraperitoneal testes, diagnostic laparoscopy clearly shows the anatomy and provides accurate visual information, which surgeons can use to make a definitive decision.

In the current study, we found that there were some discrepancies in the distribution of laparoscopic findings between unilateral and bilateral undescended testes. In cases of bilateral undescended testes, 72.3% of testes were located intraperitoneally. A previous series by Chang et al reported a higher incidence of bilaterality (25%) in patients with intraperitoneal cryptorchid testes for reasons that are not entirely clear [2]. Considering the significant role of androgens in transinguinal descent of fetal testes, our findings support the notion that bilateral cryptorchidism is more under-masculinized than unilateral cryptorchidism. The fact that greater than one-half of the patients had intraperitoneal viable testes prompts us to make every effort to find a viable testis if the laparoscopic findings suggest intraperitoneal testes.

In the current study, the success rates were 85.7% for open conventional orchiopexies and 60% for 1-stage Fowler-Stephens orchiopexies. In our center, we chose to perform open conventional orchiopexies rather than the laparoscopic approach because we believe that the key to success is a careful dissection of the vas and vessels, which would be difficult to achieve laparoscopically in a very young patient. The Fowler-Stephens orchiopexies are recommended in patients high intraperitoneal testes, defined as a distance between the testis and the internal ring >3 cm [20]. Although we prefer a 1-stage Fowler-Stephens orchiopexy due to the risk of injury to the reproductive tract, as well as the testicular vessels during the second stage of the procedure [4], a meta-analysis showed that two-stage Fowler-Stephens orchiopexy appears to carry a higher success rate than the one-stage approach (85% vs. 80%; odds ratio: 2, in favor of the two-stage procedure) [21]. Given the outcomes in the current and a previous study, we suggest consideration of two-stage Fowler-Stephens orchiopexy rather than the one-stage procedure in similar situations [4].

According to the results of our study, diagnostic laparoscopic localization and assessment of an impalpable, undescended testis was useful in a minimum of 42.5% of cases, especially for patients with bilateral undescended testes. Even though there was no statistical significance, the different success rates following orchiopexy were associated with the type of orchiopexy.