What is the anatomy and function of the female ureter?

Anatomy and Function of the Female Ureter

The female ureter is a tubular structure that transports urine from the kidney to the bladder, with a rich segmental blood supply from multiple arterial sources that must be preserved during surgical interventions to prevent ischemic complications.

Anatomical Structure

Location and Course

• The ureter is a muscular tube approximately 25-30 cm in length
• It extends from the renal pelvis to the bladder
• The female ureter has a shorter course in the pelvis compared to males
• The course can be divided into three segments:
  • Proximal/upper third: From renal pelvis to pelvic brim
  • Middle third: Crosses over the iliac vessels at the pelvic brim
  • Distal/lower third: Courses through the pelvis to enter the bladder

Dimensions

• Average internal diameter: 3-5 mm in adults 1
• Diameter increases progressively with age:
  • Infancy: approximately 3.2 mm
  • Adolescence (>16 years): approximately 5.0 mm
• The mid-ureteral segment typically has the widest diameter, followed by the distal third, then the proximal third 1

Blood Supply

• The ureter receives blood from multiple arterial sources along its course 2:
  • Upper third: Branches from renal artery and gonadal artery
  • Middle third: Branches from aorta and common iliac artery
  • Lower third: Branches from internal iliac artery
• This segmental vascular network forms longitudinal anastomoses within the adventitia and muscular layers
• Preservation of this blood supply is critical during surgical interventions to prevent ischemic complications 2

Histological Structure

• Three layers:
  • Inner mucosal layer (transitional epithelium)
  • Middle muscular layer (smooth muscle arranged in spiral, longitudinal, and circular patterns)
  • Outer adventitial layer (connective tissue)

Functional Aspects

Physiological Function

• Primary function: Transport urine from kidney to bladder through peristaltic contractions
• Peristalsis is initiated at the pacemaker cells in the proximal ureter
• Contractions are regulated by:
  • Autonomic nervous system (sympathetic and parasympathetic)
  • Non-adrenergic, non-cholinergic (NANC) neurotransmitters 3

Neuropharmacological Control

• Sympathetic control:
  • Alpha-adrenoceptors: Increase contraction amplitude
  • Beta-adrenoceptors: Promote relaxation
• Parasympathetic control:
  • Muscarinic receptors: Increase contraction amplitude
• Other important mediators 3:
  • Purinergic system (ATP): Important for sensory/motor functions
  • Nitric oxide (NO): Major inhibitory neurotransmitter causing relaxation
  • Prostaglandins: PGF2α causes contraction, PGE1/E2 promotes relaxation

Clinical Significance

Anatomical Variations and Congenital Anomalies

• Complete duplication (two separate ureters from a single kidney)
• Incomplete duplication (bifid ureter)
• Ectopic ureter (abnormal insertion into locations other than the bladder trigone)
• These anomalies increase risk of urinary tract infections and other complications 4

Surgical Considerations

• During surgical repair of ureteral injuries, minimal mobilization is essential to preserve blood supply 2
• Different repair techniques based on location of injury:
  • Upper/middle third: Ureteroureterostomy with minimal mobilization
  • Lower third: Ureteroneocystostomy (reimplantation)
• Stent placement is strongly recommended in all ureteral repairs 2

Gender Differences

• Female ureters are generally shorter in the pelvic segment compared to males
• After age 9, the average widest internal ureteral diameter is slightly larger in males compared to females 1
• In females, the ureter has a close anatomical relationship with reproductive organs, particularly at the pelvic brim where it passes under the ovarian vessels and near the uterine artery

Pathological Considerations

Trauma

• Pelvic fractures can lead to ureteral injuries, particularly in the distal portion 5
• Iatrogenic injuries during gynecological procedures are more common in females due to the proximity to reproductive organs

Obstruction

• The female ureter is susceptible to external compression from gynecological conditions (fibroids, ovarian masses, pregnancy)
• Obstruction can lead to hydronephrosis and potential kidney damage if not addressed

Diagnostic Approaches

• Contrast-enhanced CT with delayed urographic phase is the gold standard for evaluating ureteral anatomy and injuries 5
• Ultrasound can assess for hydronephrosis but has limitations for direct ureteral visualization
• MR urography provides detailed anatomical information without radiation exposure 1

Understanding the complex anatomy and blood supply of the female ureter is essential for appropriate surgical management and preservation of renal function when addressing ureteral pathology.