Pelviureteric junction, pelvic brim and vesicoureteric junction
Mnemonic
Three constrictions, where stones lodge:
- Pelviureteric junction
- Crossing of the iliac vessels at the pelvic brim
- Vesicoureteric junction, the narrowest of the three
“Start, cross, finish.”
On a plain film the ureter runs along the tips of the lumbar transverse processes, over the sacroiliac joint, out to the ischial spine, then medially to the bladder, which is the line searched for calculi.
Pain refers by segment as the stone descends: loin (T11 to L1) at the pelviureteric junction, groin and scrotum or labium (L1 to L2) at the iliac crossing, and tip of the penis, bladder and urgency at the vesicoureteric junction, which is the basis of the classic “loin to groin” description.
Expansion
Three natural narrowings along a ureter about 25 cm long:
- Pelviureteric junction (PUJ) - where the renal pelvis becomes the ureter
- Pelvic brim - where the ureter crosses the bifurcation of the common iliac artery
- Vesicoureteric junction (VUJ) - where it passes obliquely through the bladder wall; the narrowest point
Pain radiates in a characteristic pattern reflecting the segmental innervation (T11 to L2), classically loin to groin:
- Upper ureter - flank pain
- Middle ureter - pain radiating to the iliac fossa, mimicking appendicitis
- Lower ureter - pain referred to the scrotum or labium, with urinary urgency
The oblique passage through the bladder wall also acts as a flap valve preventing reflux; failure of this mechanism in children causes vesicoureteric reflux.