What are the classifications of ureteric orifice opening locations?

Classification of Ureteric Orifice Opening Location

Normal Anatomical Position

The ureteric orifice is normally located within the boundaries of the vesical trigone, and any deviation from this position is associated with renal malformations. 1

• Orifices positioned within the normal limits of the vesical trigone indicate normal renal radiography and morphology 1
• The normal distance from bladder neck to ureteric orifice varies by gender: approximately 2.5 cm in men and 2.1 cm in women with an empty bladder 2
• With bladder filling (hydrostatic pressure of 50 cmH₂O), these distances increase to 2.9 cm in men and 2.3 cm in women 2

Anatomical Classification by Gender

Male Positioning

• In men, the ureteric orifice location remains relatively stable regardless of bladder filling 2
• The orifice maintains a consistent relationship to the bladder neck throughout bladder distention 2

Female Positioning

• In women, the ureteric orifice location changes significantly with bladder filling 2
• With an empty bladder, 66.6% of ureteric orifices are located superior to the symphysis pubis 2
• With a full bladder, 75% of orifices are positioned behind the upper border of the symphysis pubis 2
• The bladder neck in women is located at a lower level compared to men and changes markedly with bladder filling 2

Classification by Abnormal Position

Orifices located outside the normal trigonal boundaries signify accompanying renal malformations, with severity of abnormality correlating directly with the degree of positional deviation. 1

Ectopic Positions and Associated Pathology

• Abnormally positioned orifices correlate with renal hypoplasia or aplasia of nephrons, manifesting as thin kidneys and clubbed calices 1
• More severe positional abnormalities indicate dysplasia of nephrons and abnormal interstitial tissue and blood vessels 1
• The degree of orifice abnormality in location and characteristics directly correlates with the severity of ureteral and renal segment abnormalities 1

Developmental Classification

Embryological Formation

• The ureteric orifice forms during the fourth to eighth weeks of gestation from the urogenital sinus following cloaca subdivision 3
• The ureteric bud arises from the Wolffian duct and is incorporated into the developing bladder at the trigone 3
• Extensive epithelial remodeling brings the ureters to their final trigonal positions via vitamin A-induced apoptosis 3

Congenital Variations

• Ureteric duplication represents a common anatomical variation requiring special consideration 3
• Perturbation of normal developmental processes leads to clinical obstruction or urine reflux 3
• Paraureteral diverticula are associated with abnormal orifice positioning 1

Clinical Implications by Location

Lower Tract Anomaly Associations

• Abnormal orifice positions correlate with congenital urethral valves 1
• Neuropathic bladders in myelomeningocele patients show associated orifice abnormalities 1
• Paraureteral diverticula are linked to abnormal orifice characteristics and positioning 1

Surgical Relevance by Ureteral Third

• Lower third ureteral injuries involving the orifice require direct reimplantation (ureteroneocystostomy) 4
• When the distal ureter cannot reach the bladder for reimplantation, psoas hitch technique or Boari flap is necessary 4
• Resection of the distal ureter and its orifice is performed during radical nephroureterectomy due to considerable risk of tumor recurrence in this area 4