Which of the following correctly describes the relationship of the ureter to the peritoneum and its course through the pelvis?

## Peritoneal Relations and Pelvic Course of the Ureter **Key Point:** The ureter is a **retroperitoneal structure** throughout its entire course from the renal hilum to the bladder, and it crosses the pelvic brim **posterior to the gonadal vessels**. ### Peritoneal Status The ureter lies **behind the peritoneum** (retroperitoneal) and is covered by peritoneum only on its anterior surface. This is clinically important because: - Retroperitoneal pathology (e.g., retroperitoneal fibrosis, aortic aneurysm) can compress the ureter. - The ureter is NOT enclosed within the peritoneal sac. ### Course Through the Pelvic Brim As the ureter descends from the abdomen into the pelvis, it crosses the **pelvic brim** at the bifurcation of the common iliac artery. At this crossing: **High-Yield:** The ureter crosses the pelvic brim **posterior to the gonadal vessels** (testicular or ovarian vessels). The gonadal vessels descend obliquely and lie **anterior** to the ureter at the pelvic brim level. | Anatomical Relationship | Detail | | --- | --- | | Position relative to gonadal vessels | Ureter crosses **posterior** to gonadal vessels | | Position relative to iliac vessels | Ureter crosses at the bifurcation of the common iliac artery | | Peritoneal covering | Retroperitoneal | **Mnemonic:** The gonadal vessels "drape over" the ureter — gonadal vessels are anterior, ureter is posterior at the pelvic brim. ### Clinical Pearl: Sex-Specific Pelvic Relations **In females:** - The ureter passes medial to the ovary. - It then crosses under the uterine artery ("water under the bridge"). - It enters the bladder at the trigone. **In males:** - The ureter passes medial to the testicular vessels in the abdomen. - It is crossed superiorly by the vas deferens in the pelvis. - It enters the bladder posterolateral to the vas deferens. **Warning:** A common exam trap is confusing the ureter's relationship to gonadal vessels — remember the ureter crosses **posterior** (behind) the gonadal vessels at the pelvic brim, not anterior. The gonadal vessels lie anterior to the ureter as they descend toward the pelvis. [cite:Standring Gray's Anatomy 42e Ch 75; Last's Anatomy 9e]