Preop assessment in non palpable UDT, difference between unilateral and bilateral

Quote from "ESPES Manual of Pediatric Minimally Invasive Surgery" by Ciro Esposito, François Becmeur, Henri Steyaert, Philipp Szavay -

"For preoperative evaluation and diagnosis of unilateral NPT, physical examination is all needed, and no laboratory investigation is necessary. In unilateral NPT, compensatory hypertrophy of the contralateral testis may suggest testicular absence or atrophy. Monorchidism was observed in 95% of patients with a contralateral testis 2 cc or larger in the series of Belman and Rushton [3], but this sign is not specific and does not preclude surgical exploration. In cases of bilateral NPT or unilateral NPT accompanied by anomalies of genital region such as severe hypospadias or scrotal hyperpigmentation, disorders of sex development (DSD) should be considered in differential diagnosis, and further genetic and endocrinological evaluations are needed [4]."