Can a kidney disappear? A guide to multicystic dysplastic kidney (MCDK)

Written by: Miss Marie-Klaire Farrugia
Published:
Edited by: Cal Murphy

Pregnancy scans may occasionally suggest that one of your baby’s kidneys has not developed properly – one possible cause is a multicystic dysplastic kidney (MCDK). If a child is born with a serious problem in one kidney, how worried should we be? Expert paediatric urologist Miss Marie-Klaire Farrugia is here to explain.

What is multicystic dysplastic kidney?

Multicystic dysplastic kidney (MCDK) is a renal cystic disease which results in a non-functioning kidney on one side only; the contralateral kidney is usually normal. The affected kidney does not develop properly and consists of a bunch of cysts.  It is congenital, meaning that babies are born with the condition.

MCDK occurs in around 1 in 3640 births and is most commonly unilateral (occurring on one side of the body only, i.e. affecting one kidney, not the other). However, it can sometimes affect both. It is slightly more common in males (59%) and on the left side (53%).

 

Can a kidney disappear?

Most multicystic dysplastic kidneys simply regress on their own over time, eventually disappearing completely (involution), with the individual continuing their life with only one kidney. This is usually not a problem, with the other kidney doing the work of both. Around one third of cases involute by the second birthday; 47% at 5 years; and 59% at 10 years. However, once the condition is diagnosed, it is sensible to monitor it to ensure it is not causing any other harm to the body and that the other kidney is normal and healthy.

 

Treatment for a multicystic dysplastic kidney

While many cases of MCDK require no treatment, the condition at least requires monitoring and perhaps some management, while other cases may require intervention:

 

  1. Conservative Management

Initial management is conservative, with ultrasound follow-up to monitor involution of the MCDK and ensure good growth and hypertrophy of the other kidney.

Current guidelines advise monitoring blood pressure, urine for proteinuria, and renal function in all children with a solitary kidney (MCDK or other aetiology) in order to identify those with markers of renal injury. Hypertension (high blood pressure) should be treated medically.

MCDK has been associated with anomalies involving the genitalia, in particular congenital absence of the vas deferens (CAVD) in men, and uterus didelphys and obstructed hemi-vagina in women. Therefore, women with MCDK are recommended to have a screening pelvic ultrasound following advanced puberty. However, there is no evidence of benefit for screening in males.

The length of follow-up and indications for surgery have both diminished in recent years, due to evidence suggesting that the risk of complications of MCDK, such as Wilm’s tumour or other kidney cancer and the risk of hypertension is no higher than in the general paediatric population.

 

  1. Surgical Management

A nephrectomy may also be considered where a large palpable MCDK has failed to involute or if it enlarges. On rare occasions, an MCDK may be large enough to interfere with respiration or feeding, which is improved following nephrectomy. Another indication for nephrectomy is when other treatments have failed to cure the patient’s hypertension and no other causes have been identified apart from the MCDK.

By Miss Marie-Klaire Farrugia
Paediatric urology

Miss Marie-Klaire Farrugia is a consultant paediatric urologist based at Chelsea and Westminster Hospital and the BUPA Cromwell hospital in central London. She specialises in all areas of kidney, bladder and genital anomalies that babies are born with or develop later in childhood. In particular, she counsels pregnant mothers whose babies are prenatally-diagnosed with a kidney condition, so that the best postnatal plan can be made for the newborn.

Miss Marie-Klaire Farrugia is the clinical lead for paediatric surgery in the North West London Network, and writes guidelines and teaches in the major North West London hospitals. Her research interests include the long-term outcome of prenatally-diagnosed urological problems such as hydronephrosis and posterior urethral valves and vesicoureteric reflux. She is an experienced open, laparoscopic and robotic surgeon and performs neonatal and childhood circumcision; repair of simple and complex hypospadias including staged graft repairs; hernia and hydrocoele repairs; surgery for undescended testes; pyeloplasty; ureteric reimplantation; surgery on duplex kidneys and ureterocoeles; posterior urethral valves; nephrectomy and hemi-nephrectomy; Deflux injection for kidney reflux with urine infections; amongst others.

Miss Farrugia is an executive member of the Society for Fetal Urology and a member of the British Association of Paediatric Urologists, the European Society for Paediatric Urology, the American Association of Pediatric Urologists and the Societies for Pediatric Urology.

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