Undescended testis, called cryptorchidism, is when one or both testes fail to reach the scrotum during fetal development. Normally the testes begin in the abdomen and descend through the inguinal canal into the scrotum before birth or in early infancy. When descent is incomplete, the testis may lie in the abdomen or inguinal canal and may be nonpalpable on exam. This condition is distinct from other scrotal problems: orchitis is inflammation of the testis, often from infection; a varicocele is dilation of the pampiniform venous plexus producing a bag-of-w Worms–like feeling; and a hydrocele is fluid around the testicle causing swelling. The clinical importance lies in fertility and cancer risk, since higher temperatures and abnormal testicular environment can impair spermatogenesis and increase malignancy risk. Management typically involves orchiopexy (surgical relocation into the scrotum) if descent has not occurred by around 6 to 12 months of age, to improve fertility potential and reduce cancer risk. Some cases may descend spontaneously in the first months of life, particularly if the testis is palpable.

Simple breast cysts are fluid-filled spaces that look anechoic on ultrasound, typically round or oval with smooth, thin walls and posterior acoustic enhancement. They should have no internal echoes. An irregular shape with internal echoes, on the other hand, signals complexity—possible debris, hemorrhage, infection, or a solid component—which is not a feature of a simple cyst. So the description of an irregular shape with internal echoes does not fit a simple breast cyst.

High-risk findings on thyroid ultrasound are features that raise concern for malignancy: a nodule that is markedly hypoechoic compared with the surrounding thyroid tissue, the presence of microcalcifications, an incomplete or irregular halo, and suspicious cervical lymph nodes. Hypoechogenicity means the lesion appears darker than the adjacent thyroid tissue, which often reflects solid, potentially malignant tissue. Microcalcifications are tiny bright specks within the nodule that are highly associated with papillary thyroid carcinoma. An incomplete halo suggests the lesion isn’t fully encapsulated and may invade surrounding tissue, another warning sign. Suspicious cervical lymph nodes—enlarged and with abnormal characteristics like irregular margins or loss of the fatty hilum—point toward possible metastatic spread. In comparison, the other patterns align more with benign nodules: hyperechoic or isochoic nodules without suspicious features, a complete halo, absence of microcalcifications, and normal lymph nodes. Cystic (anechoic) nodules with a complete halo are also typically benign.

In the male pelvis, the prostate sits just in front of the rectum, so its posterior surface directly faces the rectal wall. This makes the rectum the posterior boundary of the prostate. Denonvilliers’ fascia separates these two structures, but the boundary that lies behind the prostate is the rectum. The bladder sits above the prostate, not behind it, and the urogenital diaphragm and levator ani form parts of the pelvic floor and lateral boundaries rather than the posterior face of the prostate. Clinically, this relationship explains why the posterior aspect of the prostate is accessible via a digital rectal exam and why posterior spread to the rectum is a consideration in prostate surgery.