Munuaistie

Munuaistie is the Estonian term for the ureter, one of the pair of muscular tubes that transport urine from the kidneys to the urinary bladder. Each ureter begins at the renal pelvis in the kidney, descends retroperitoneally along the psoas major, crosses the pelvic brim, and enters the bladder at its posterolateral wall. The ureter-tissue penetrates the detrusor muscle of the bladder at an oblique angle, helping form a one-way mechanism to reduce backflow of urine.

Anatomically, the ureter walls consist of a mucosal lining of transitional epithelium, a muscularis layer with an inner circular and an outer longitudinal layer, and an outer adventitia. Peristaltic waves generated by smooth muscle contractions move urine steadily toward the bladder. In adults, the typical length is about 25–30 cm, though this can vary.

The ureters receive vascular supply from multiple sources along their course, including branches from the renal, gonadal, common iliac, and internal iliac arteries. Lymphatic drainage follows the arterial supply to regional nodes. Clinically, obstruction of a ureter—most commonly by stones (ureterolithiasis)—causes intermittent, severe flank or groin pain and may accompany hematuria. Other causes include strictures, tumors, inflammatory changes, and iatrogenic injury.

Diagnostics rely on imaging such as ultrasound, CT urography, or MRI. Treatments depend on the cause and may include analgesia and hydration, medical expulsive therapy for stones, ureteroscopy with stone extraction, lithotripsy, or ureteral stenting to relieve obstruction and protect kidney function.