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:
- 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.
- 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.