Yoyo reflux -

Ans. is 'a' i.e., Duplication of ureter * Reflux of the urine from one limb of the collecting system to the other limb, rather than down towards the bladder is called yo-yo reflux (saddle reflux)* Cause: Duplication of ureters, partial duplication of ureters, duplicate renal pelvis* Another explanation of yo-yo reflux is the pressure gradient between two ureteric segments. The pressure of the lower moiety is generally higher than the upper moiety and therefore the urine generally refluxes from the lower moiety to the upper moiety* Duplication of the upper collecting system is one of the most common of renal anomalies* Complete duplication is associated with ectopic ureter, ureterocele or vesicoureteral reflux.* The incomplete duplication of the upper collecting system rarely causes urinary symptoms and usually does not carry clinically importance