Pediatric – Multicystic Dysplastic Kidney
What is Multicystic Dysplastic Kidney?
A multicystic dysplastic kidney is a congenital (birth) condition which affects the fetus’ kidney. In this, the healthy kidney is replaced by many cysts of varying sizes and there is little or no functioning in such kidneys.
It has been found as a major reason for abnormal abdominal masses and is easier to detect with prenatal ultrasound which is done before the birth of the child.
A significant portion of multicystic kidneys develop on the left hand side. At times, this condition is also seen on both sides but this is highly dangerous as well-developed kidneys are responsible for production of vital amniotic fluid which is important for ideal development of the lungs. In many cases, this condition is not a cause for great concern as even a single functioning kidney is sufficient to provide normal level of amniotic fluid in the body.
This condition is seen to affect male and female fetus equally but Caucasian children are known to more prone to this.
Sonography is the ideally advised diagnostic test for this condition. If the condition is seen in the fetal stage, post-childbirth tests are necessary to determine whether the condition is multicystic dysplastic kidney (MCDK) or hydronephrosis. In case MCDK is suspected in a newborn a sonogram is normally advised before being discharged from the hospital. In case the child is also suffering from relative dehydration or lowered kidney function the sonogram should still be carried out at the earliest.
In case the newborn child exhibits noticeable symptoms (including palpable abdominal mass, abdominal pain, incontinence and repetitive UTI (urinary tract infection) sonography is usually the first diagnostic test. This test allows the doctor to determine whether other types of urinary tract anomalies are also present, or if there is intra-abdominal or retroperitoneal malignancies.
Multicystic dysplastic kidney can also be detected with other imaging diagnostic tests however sonography is believed to more fast and accurate. Additionally it is an easier test and does not pose discomfort to the newborn.
Radionuclide imaging can then be used to make better distinction between MCDK (hydronephrosis type) and another type of obstruction in the kidney. This test gives additional information about the level of functioning remaining in the affected kidney and is also better than IVP (intravenous pyelography) for children. Both technetium-99m (99m Tc) mercaptoacetyltriglycine (MAG-3) and 99m Tc dimercaptosuccinic acid (DMSA) studies can demonstrate lack of function in the affected kidney, but MAG-3 studies can also provide information regarding drainage in an obstructed hydronephrotic kidney.
Voiding cystourethrography (VCUG) is advised for patients with MCDK to check the urinary tract for VUR and other abnormalities. Although a small number of patients are afflicted with this disorder, VUR may lead to reflux nepthropathy in the contralateral solitary kidney, hence it is important to undergo a VCUG in order to detect potentially harmful (bit correctible) reason for the damage to the kidney.
The initial method of treatment for this condition today remains constant surveillance to determine the level of functioning left in the affected kidney. This has become easier with advanced non-invasive imaging tests. As most of these conditions tend to regress on their own this is the most popular form of treatment for this condition. The National Multicystic Kidney Registry, a national database that monitors this condition, also reveals that the risk of this malignancy developing within a multicystic dysplastic kidney is very low.
Since 1975, there have been only about 9 case reported of this condition. Hypertension is also a considerably lower risk in such children (only 4 out of 508 according to the Registry). Presently, most pediatric urologists recommend active monitoring through regularly scheduled ultrasound exams until the condition is seen regressing or are not detected anymore through ultrasound.
In some cases where there is no natural improvement seen by monitoring, the doctor may advise complete removal of the affected kidney (Nephrectomy) which is normally performed using minimally invasive surgical procedure (laparoscopic) or another similar procedure.
Medical conditions perceived to be associated with MCDK
Hypertension (high blood pressure)
Chronic renal insufficiency/End-stage renal disease
Urinary tract infection (UTI)