a retrocaval ureter or pre - ureteric venacava is a rare anomaly which occurs in 1 per 1000 live births .
it is seen three times more often in males and is usually on the right side .
a left retrocaval ureter as such is very rare and is usually associated with situs inversus or ivc duplication .
these patients usually present in the third or fourth decades and symptoms depend on the degree of obstruction .
an 84-year - old male patient presented to us with dull , aching left flank pain of 6 months duration .
ct scan of the abdomen revealed transposed ivc to the left side and classic retrocaval ureter with proximal hydro - ureteronephrosis [ figures 13 ] .
intravenous urogram showing a sea - horse sign coronal ct image showing left retrocaval ureter with pre - caval ( arrowhead ) and post - caval ( arrow ) segments axial ct images with arrows showing ( a ) pre - caval ureter ( b ) post - caval ureter and ( c ) left renal vein
the embryogenesis of the ivc is a complex process of development involving the posterior cardinal , the subcardinal , and the supracardinal venous systems .
aberrant complexation of these veins can result into four anomalies : duplicated ivc , transposition of ivc to left , retroaortic left renal vein , and circum - aortic left renal vein . left retrocaval ureter is rare , and only eight cases have been reported in the literature so far .
left retrocaval ureter without situs and without ivc duplication is rarer with only four cases being reported in the literature .
pierro et al . reported a 0.2 to 0.5% prevalence of transposition of ivc to the left and a 0.1% prevalence of left retrocaval ureter .
 retrocaval ureter ( pre - ureteral vena cava ) is an uncommon congenital anomaly that causes ureteral obstruction by external compression . although right retrocaval ureter is a common entity , left retrocaval ureter is extremely rare . 
 a left retrocaval ureter is usually associated with situs inversus or duplicated inferior venacava ( ivc ) . 
 an isolated left retrocaval ureter with single left - sided ivc is even rarer and only four cases have been reported in the literature . 
 we present images of a case with isolated left retrocaval ureter with a single left - sided ivc without situs inversus . 
INTRODUCTION
CASE REPORT
DISCUSSION