Diagnostic modalities, such as ultrasound and MRI, are nonspecific in the intra-abdominal testis, and the accuracy of these examinations was not satisfactory. The only effective diagnostic procedure is considered to be laparoscopy. However, there is a possibility of being unable to locate a testis on diagnostic laparoscopy [
6]. An accurate preoperative diagnosis is usually useful to determine the surgical approach for non-palpable testes management, particularly for high intra-abdominal cases. Kanrarci reported that identifying and locating non-palpable testes was improved by using the combination of DWI and conventional MRI, with about 90% sensitivity and accuracy [
1]. Kato et al. also reported that preoperative combined assessment using T1- and T2-weighted imaging, fat-suppressed T2-weighted imaging, and DWI enabled the identification of intra-abdominal or intra-canalicular testes preoperatively and facilitated an accurate diagnosis of non-palpable testes [
2]. They demonstrated that combined MRI assessments had an accuracy of 92.3% in the diagnosis of intra-abdominal testes; however, high intra-abdominal testes located over the pelvis, as in the present case, were not included in their reports [
2]. In the present case, we could predict the presence and location of the intra-abdominal testis, below the kidney, preoperatively by fusion view with T2-weighted and DWI images. At our center, we usually perform MRI in patients who have a non-palpable testis without contralateral testicular hypertrophy and if ultrasonography fails to demonstrate a testis, because MRI improves the accuracy of diagnosing non-palpable testis and can be useful for identifying the presence and location of a testis. However, as described in the AUA guideline, although MRI is being used more widely due to greater sensitivity and specificity, it has the problems of higher cost, low availability, and need for anesthesia [
7]. In addition, no imaging method can confirm absence of the testis with 100% accuracy [
7]. Therefore, the AUA guideline recommends surgical exploration, such as diagnostic laparoscopy (or open exploration), rather than MRI [
7]. Despite this recommendation, it would have been quite difficult to find the right testis at laparoscopy in our patient without the information obtained by MRI. Although it is hard to be dogmatic about the situations in which MRI is beneficial, examination of fusion views with T2-weighted and DWI images may be useful for preoperative localization of high intra-abdominal testes or for postoperative assessment in the rare cases where the testis cannot be identified by laparoscopy.
Previous reports demonstrated that the success rate of Fowler-Stephens orchiopexy, which was assessed by whether the testis was returned to the scrotum or the testicular size, was 69–95% [
8,
9]. A recent report suggested that the testicular blood supply after Fowler-Stephens orchiopexy was preserved in most cases [
10]; however, testicular function after Fowler-Stephens orchiopexy has not been clarified. Rosito et al. reported that ligation of the spermatic vessels during the first stage of orchiopexy for intra-abdominal testis was associated with a significant reduction of spermatogonia, although no significant changes were observed in the volumetric characteristics of the testes [
11]. Kamisawa et al. also reported, in their animal study, that Fowler-Stephens orchiopexy may not significantly contribute to the improvement of spermatogenesis [
12]. In our case, we examined the histological findings and expression pattern of the stem cell marker, UTF1, in the testicular biopsy specimen, during the second stage of a 2-stage Fowler-Stephens orchiopexy. A previous animal study demonstrated that the differentiation from gonocytes into early A spermatogonia and the stem cell activity of early A spermatogonia were disturbed during the early stage of spermatogenesis, suggesting that the loss of spermatogonial stem cell activity results in disturbances in spermatogenesis and may make fertility difficult in cryptorchidism [
13]. In our patient, although good vascularization was detected on echo color Doppler ultrasound, and median seminiferous tubule diameter and median number of spermatogonia per tubular cross section were comparable to those in inguinal undescended testis cases, the UTF1-positive Ad spermatogonia (actual stem cells) / UTF1-negative Ad spermatogonia (potential stem cells) ratio was lower than in descended testes and inguinal undescended testes. This implies that spermatogonial stem cell activity was markedly reduced, and that development of collateral vessels after the first stage of 2-stage Fowler-Stephens orchiopexy may provide enough blood to maintain testicular viability but might not be sufficient to achieve spermatogenesis, although it is unclear if the testicular findings were attributable to the intra-abdominal location of the testis or were caused by ligation of the primary testicular vessels and the 10-month collateralization period.