Rachel (not her real name), a one-month-old infant girl, had been crying incessantly. Her mum noted a “cherry-like mass” on her private parts (specifically, the perineum) upon changing her diapers, as well as the fact that Rachel had not passed urine for the last six hours.
Mum decided to bring Rachel to the hospital emergency room. She was feverish, still crying and had a big bladder.
She was seen by Dr PS, a paediatric surgeon and paediatric urologist, who suspected a prolapsed ureterocoele.
A kidney ultrasound (USG) showed that Rachel had “two” swollen left kidneys, one normal right kidney and a distended (swollen) bladder.
As Rachel’s mum had had a normal prenatal USG when she was pregnant with Rachel, she and her husband were shocked to learn that their baby had three kidneys!
Dr PS explained to them that while Rachel has a normal right kidney, the left kidney is a twin kidney, called a duplex kidney.
The cherry-like mass was a prolapsed ureterocoele. This is a ballooned-out portion of the part of the ureter that enters the bladder, which had inadvertently passed through the urethra, causing obstruction of the bladder.
Rachel had emergency surgery to decompress the prolapsed ure- terocoele (akin to puncturing a balloon so that it deflates).
Duplex (twin) kidney occurs in 0.8% of the population.
It is usually one-sided, but can occur in both kidneys in 20% of cases.
It is more common in girls.
Studies have shown that duplex kidneys have some hereditary traits. This means Rachel’s sibling has a one in nine chance of having duplex kidneys, compared with a normal risk of one in 25.
The majority of persons with duplex kidneys have no symptoms.
Those who do have symptoms usually present in childhood or infancy with a urine infection, or as in Rachel’s case, a prolapsed ureterocoele.
Duplex kidneys can be complete, that is with two kidneys and two ureters on one side (like a double- storey house with two ladders), or incomplete, with a Y-shaped ureter linking the twin kidneys.
The problems associated with symptomatic duplex kidneys are:
• Backflow of urine into the ureter (vesico-ureteric reflux, VUR) in 60%;
• Ureterocoeles in 20% (ureterocoeles are four to seven times more frequent in girls than in boys); and
• Ectopic ureter, which is a ureter that connects to something other than the bladder, for example, the bladder neck, urethra or vagina in girls.
The management of symptomatic duplex kidneys is to treat the most immediate presenting problem, i.e. the urine infection, or prolapsed ureterocoele as in Rachel’s case.
Further imaging studies should include a detailed USG of the renal system, although an MRI is sometimes needed to better visualise the anatomy of the kidneys, and a micturating-cysto urethrogram (MCU) to look for VUR.
A nuclear imaging scan is necessary to ascertain any obstruction of the duplex, which duplex kidney is obstructed, if any, and the function of each part/moiety of the duplex kidney, as well as the normal kidney.
The goals of treatment are manifold: control of the urine/kidney infection, protection and preservation of both the duplex and normal kidney function, and maintenance of urine continence.
The definitive treatment is to relieve the obstruction and remove the ureterocoele, correct the VUR, and if necessary, remove the poor or non-functioning part of the duplex kidney.
Surgery can be open, laparoscopic or robotic.
Rachel had the appropriate imaging studies, which showed a non-functioning upper pole of the left kidney, but no VUR.
She had surgery to remove the non-functioning upper part of the duplex left kidney.
She is now an active, cheerful three-year-old attending nursery class.
Rachel’s mum is planning another pregnancy, but both parents are apprehensive as they are worried similar problems may occur in their next child.
Dr PS has reassured them and helped them plan their next pregnancy.
This article is courtesy of the Malaysian Association of Paediatric Surgery. For further information, e-mail firstname.lastname@example.org. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.