ureter

The ureter is a muscular tube that transports urine from the renal pelvis of each kidney to the urinary bladder. In adults, it is about 25–30 cm long and 3–4 mm in diameter. It runs retroperitoneally along the psoas major, descends to cross the pelvic brim at the bifurcation of the common iliac arteries, and enters the bladder at the posterolateral angle of the trigone through the ureterovesical junction.

The wall of the ureter consists of mucosa (transitional epithelium), a submucosa, a muscular layer with an inner longitudinal and an outer circular layer (often described as a peristaltic muscular coat), and an outer adventitia. Peristaltic waves propel urine from the kidney toward the bladder, aided by stretch and autonomic input.

Blood supply along the ureter is segmental: proximal segments receive branches from the renal arteries; mid and distal segments emerge from branches of the renal, gonadal, common iliac, and internal iliac arteries. Venous drainage parallels the arterial supply to the renal and iliac veins. Lymphatic drainage follows the arterial supply to the lateral aortic (lumbar) and iliac nodes. Innervation is autonomic, with inputs from the renal, aorticorenal, and hypogastric plexuses; pain is typically referred to the flank, groin, or testicular/ovarian region.

Clinical relevance includes obstruction (e.g., ureteral stones, strictures, or tumors) causing hydronephrosis or hydroureter and acute renal colic. Ureteral injuries may occur during pelvic surgery. Management can involve stenting (double-J stent), nephrostomy, or surgical repair. Congenital anomalies include duplex collecting systems, ureterocele, and UPJ obstruction. Imaging modalities include ultrasound and CT urography.