Muller Journal of Medical Sciences and Research

: 2013  |  Volume : 4  |  Issue : 2  |  Page : 116--118

Yo-yo reflux in partial duplication of ureter: A diagnosis on the color and pulse Doppler study

Kamini Gupta, Ritu Galhotra, Kavita Saggar 
 Department of Radiodiagnosis, Dayanand Medical College and Hospital, Ludhiana, Punjab, India

Correspondence Address:
Kamini Gupta
Department of Radiodiagnosis, Dayanand Medical College and Hospital, Tagore Nagar, Ludhiana - 141 001, Punjab


The diagnosis of yo-yo reflux in patients with partial collecting system duplications is difficult. We report a case of recurrent urinary tract infections due to partial duplication of the collecting system in which yo-yo reflux is demonstrated with color and pulse wave Doppler. Our aim is to highlight the fact that radiologists and clinicians should be aware of this noninvasive, inexpensive, and easily accessible modality so as to diagnose this phenomenon more frequently in future.

How to cite this article:
Gupta K, Galhotra R, Saggar K. Yo-yo reflux in partial duplication of ureter: A diagnosis on the color and pulse Doppler study.Muller J Med Sci Res 2013;4:116-118

How to cite this URL:
Gupta K, Galhotra R, Saggar K. Yo-yo reflux in partial duplication of ureter: A diagnosis on the color and pulse Doppler study. Muller J Med Sci Res [serial online] 2013 [cited 2023 Feb 3 ];4:116-118
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A duplicated collecting system is the most common upper urinary tract anomaly, affecting nearly 15% of the population. A duplex system is one where the kidney has two pyelocaliceal systems and is associated with a single ureter or with a bifid ureter (a partial duplication) or, in the case of a complete duplication, with two ureters (double ureters) that drain separately into the urinary bladder. Partial duplication is associated with two problems: (1) ureteropelvic junction (UPJ) obstruction of the lower moiety and (2) retrograde yo-yo peristalsis of urine in the two ureters. "Yo-yo" reflux in an incompletely duplicated renal system can be demonstrated on (99m) Tc-mercaptoacetyltriglycine (MAG3) renal scintigraphy which is considered gold standard for this phenomenon. We report a case of a 32-year-old female who had partial ureteral duplication and the presence of yo-yo reflux is demonstrated with color and pulse wave Doppler.

 Case Report

A 32-year-old female patient presented with complaints of left lumbar pain and recurrent urinary tract infections. On examination, her left kidney was found to be palpable and tender. Her urine examination revealed 80-100 pus cells and 5-7 RBCs. She was referred for ultrasound examination to us. On ultrasound, her left pelvicalyceal system (PCS) was duplex with hydronephrosis of lower moiety [Figure 1]. Upper moiety was not dilated. There was duplication of upper ureters till the level just proximal to iliac bifurcation [Figure 2]. On color Doppler, there was ureteroureteral reflux/yo-yo reflux, i.e., reflux of urine from the normal caliber ureter to the dilated ureter of lower moiety. Pulse Doppler at the level of fusion of two ureters showed a high-velocity waveform corresponding to the reflux of urine into the dilated ureter above the baseline with simultaneous reduced velocity waveform below the baseline corresponding to normal distal flow of urine [Figure 3]. The diagnosis of partial duplication of ureters in the duplex left kidney with yo-yo reflux was given.{Figure 1}{Figure 2}{Figure 3}

Contrast-enhanced computed tomography (CECT) of the KUB region was done to delineate the exact anatomy. On CECT, the left kidney was found to be duplex with partial duplication of ureters till just proximal to iliac bifurcation. A small hyperdense calculus was seen in the left middle calyx [Figure 4]. Ureters were also seen to cross at the level of fourth lumbar vertebra. A single ureter was seen in the pelvis with one ureteric orifice. Subsequently the patient was operated and the presence of reflux was confirmed preoperatively.{Figure 4}


Ureteral duplication is the most common renal abnormality. In two-thirds of the cases, ureteral duplication is incomplete and ureteroureteral reflux may occur in as many as 80% of cases. Severe reflux may be associated with a loss of cortical function in the affected renal segment. [1] Partial duplication is usually diagnosed in adults and most of the cases present with hydronephrosis and recurrent UTI, as in our case.

The embryology of incomplete duplication is not well understood, but this anomaly may develop when a single ureteral bud branches before it reaches the metanephric blastema. The duplicated ureters unite at a variable distance from the kidney, and only one ureteral orifice is present on the affected side.

Ureteroureteral reflux, also known as yo-yo, saddle, or seesaw reflux, is a common but transitory phenomenon. It is less frequently observed because the few images obtained during excretory urography do not record the event. It should be suspected when there is asymmetric dilatation of ureters. Ureteroureteral reflux prevents the urinary tract from ever being completely drained and is responsible for the urinary tract infections frequently associated with partial duplication of ureters. [2]

No radiological diagnostic method that exactly shows urine refluxing from one moiety to another in incomplete duplex systems has been documented in literature. The only method that has been recently described by Chu et al. [3] was that the dynamic nature and continuous monitoring makes the radionuclide renography an ideal test for the diagnosis of yo-yo reflux. The appropriately placed regions of interests over the upper and the lower moiety of the renal duplex system give an opportunity to see changes in time activity curves of each moiety independently.

According to our best knowledge, we report the first case of real-time demonstration of yo-yo reflux with color and pulse wave Doppler ultrasound. By keeping the ultrasound probe at the site of fusion of two ureters and continuous monitoring, we could demonstrate reflux from normal caliber ureter to the dilated ureter.

The diagnosis of duplication of ureters is not difficult with routine imaging techniques; however, whenever there is asymmetric dilatation of ureters in partially duplicated system, yo-yo reflux should be suspected and Doppler ultrasound should be asked for.

The treatment in patients with partial duplication of ureters with yo-yo reflux causing hydronephrosis and recurrent UTI is surgical and should not be delayed.


We conclude that every patient with suspected yo-yo reflux should undergo a dedicated color and pulse wave Doppler scan to demonstrate this phenomenon in real time and in future Doppler can replace dynamic renal scintigraphy which is considered the ideal test for yo-yo reflux till date.


1Wu F, Snow B, Taylor A Jr. Potential pitfall of DMSA scintigraphy in patients with ureteral duplication. J Nucl Med 1986;27:1154-6.
2Fernbach SK, Feinstein KA, Spencer K, Lindstrom CA. Ureteral Duplication and Its Complications-Scientific Exhibit. Radiographics 1997;17:109-27.
3Chu WC, Chan KW, Metreweli C. Scintigraphic detection of "yo-yo" phenomenon in incomplete ureteric duplication. Pediatr Radiol 2003;33:59-61.