Inflammation of the duplicated renal collecting system and ureter with severe hydrouretronephrosis

A 61-year-old man presented with fever, elevated inflammatory markers and bacteriuria. After five days of antibiotic therapy, the inflammatory markers were still elevated; furthermore, the patient reported loss of appetite, bloating and pain in the left lower abdomen. Physical examination revealed tenderness and a palpable mass in the left lower abdomen.

Abdominal CT with contrast showed distorted anatomy of upper pole of the left kidney with distinctly dilated renal collecting system, megacalyces, dilated renal pelvis and megaureter (Fig. 1a).

The diffusely dilated upper ureter extended from the upper renal moiety firstly to the right part of the abdomen and then followed its twisted course downwards into the pelvis, where it ectopically inserted into the prostatic urethra (Fig. 1b). The wall of abdominal part of ureter was thickened and the lumen was distended up to 11 centimetres. The distal part of ureter was twisted and dilated up to 2 centimetres.

However, the lower pole of the left kidney was normal (Fig. 1a), with normal parenchyma density and normally wide separate ureter inserting to the bladder (Fig. 1b).

These radiographic findings were consistent with obstruction and inflammation of the duplicated renal collecting system and ureter resulting in severe hydroureteronephrosis.

The right kidney is normal in size, shape, and position.

Background

Duplicated renal collecting system is one of the most common congenital urinary tract abnormalities, with incidence between 0,7 % and 4 %. It is defined by incomplete fusion of the upper and lower pole of the kidney, which creates two separate drainage systems – ureters –  from the kidney, each having its own ureteral orifice. [1,2]

The duplication anomaly occurs during the embryological development of urogenital organs when two ureteric buds arise from a single mesonephric duct and fuse with metanephros as the kidney precursor. [3] The relationship between the upper and lower pole ureters is described by the Weigert-Meyer rule, which states that the lower renal moiety ureter implants in orthopic position earlier and more superolateral into the bladder. Whereas the upper renal moiety ureter insert ectopically anywhere between the normal lower renal pole ureter and the nearby pelvic organs. [4,5]

Clinical Perspective

Most patients with duplicated system remain asymptomatic. An altered anatomy is usually discovered prenatally or among pediatric patients. However, it can be also diagnosed in adulthood, incidentally or when complications (such as obstruction, infection or vesicoureteral reflux) occur. Typical symptoms include hematuria, abdominal pain, urinary incontinence, and recurrent urinary tract infections. Furthermore, hydroureteronephrosis can be severe enough to cause flank pain or even a palpable mass, such as in our case. [1, 2]

Imaging Perspective

Ultrasonography is an initial imaging modality to detect major abnormalities and complications, such as hydronephrosis or ureterocele. Key ultrasonographic findings include asymmetrical renal length, abnormal parenchymal contour and asymmetrically dilated pelvicalyceal of upper and lower renal pole. [1]
Contrast-enhanced abdominal computer tomography provides more detailed information about an abnormal renal tract anatomy. General CT findings include dual collecting system, duplicated ureter and its ectopic insertion (to prostatic urethra in males or vaginal vault in females), and obstruction of the upper pole moiety with evidence of associated hydronephrosis. [1,2]

Outcome

Management is based on clinical manifestation, effect on kidney function and age. Conservative treatment is recommended for adults with less symptoms, whereas surgical approach is considered when the symptoms interfere quality of life. [1] In our case, the diagnosis of urinary infection was made with urinalysis, urine culture and purulent fluid culture obtained during percutaneous nephrostomy. The patient was successfully treated with intravenous antibiotic therapy with ertapenem.

Teaching points: Duplicated renal collecting system is a common radiological finding but is infrequently newly diagnosed in adulthood. Although most of the patients remain asymptomatic, it should be considered in patients with recurrent urinary infections or hydroureteronephrosis.

Written informed patient consent for publication has been obtained.