<s>[INST] context: IVP in ureterocele usually shows a round filling defect, sometimes large, in the bladder corresponding to the ureterocele, and characteristic finding of duplication of the collecting system (ureteroceles are nearly always associated with ureteral duplication)
Ureterocele :

Is a cystic dilatation of the terminal ureter, and is obstructive because of a pinpoint ureteral orifice.
It is more common in females
Affected children often are discovered by prenatal sonography or during an investigation of UTI (IVP)
Treatment : o transurethral incision of ureterocele : effectively relieves the obstruction but it may result in V.U.R. necessitating ureteral reimplantation later, or
' open excision of ureterocele and reimplantation 'as primary management'. About other options
An isolated VUR or Duplication of ureter do not explain the filing defect in the bladder.
Sacrococcygeal Teratoma :
The most common presentation here is with an abnormal, obvious protruding mass from the sacral area. Out of the 4 varieties known, only Type IV which contributes 9.8 % ie entirely pre-sacral and not visible externally (90.8% tumors are visible externally).
Bladder and Rectum may be displaced anteriorly but a filling defect is not characteristic as in ureterocele.
Ureters may be partially obstructed resulting in hydro-ureter and hydronephrosis. [/INST] question: A 6 year old girl presents with Recurrent E.coli infection in urine. Ultrasound of abdomen shows Hydroureter and Hydronephrosis. Micturating cysto – urethrogram shows filling defect in urinary bladder. The likely diagnosis is – | options: A: Sacrococcygeal Teratoma B: Vesicoureteric Reflux – grade II C: Duplication of Ureter D: Ureterocele | answer: D </s>