|Multicystic Dysplastic Kidney (MCDK)
Multicystic dysplastic kidney (MCDK) is a kidney or kidneys with non-functioning irregular cysts of various sizes. The condition is also known as renal cystic dysplasia and Potter type II.
A major hypothesis for the development of MCDK is first trimester obstruction of the urinary tract resulting in dysplastic evolution of the kidneys with a variety of clinical and pathological manifestations.  An alternative hypothesis is the failure of the mesonephric blastema to form nephrons. 
MCDK occurs in approximately 1 in 1000 births , while the overall incidence of all prenatally determined urological anomalies is 1-2%  Among all fetal urological abnormalities, MCDK is one of the most frequent.  In a review of 102 cases of MCDK the following was noted :
A number of associations with non-renal abnormalities are reported :
Associated non-renal abnormalities, unilateral (26%)
Associated non-renal abnormalities, bilateral (67%)
Male to female ratio: 2.4:1
Chromosomal abnormalities: Increased (particularly females)
Females: more likely to have bilateral MCDK.
A wide range of anomalies are possible and may include multiple anomalies of face, fingers, lung, heart, bowels, and
genitourinary tract. 
Prenatal exposure to antiepileptic drugs (AEDs) increases the background risk overall for congenital malformations to 4 to 9% and these agents may lead to abnormal renal development and MCDK. 
Down serum screening with a value of inhibin A at ≥2 MoM is associated with fetal MCDK (OR =27.5, 95% CI: 2.8-267.7). 
In addition, Kallmann's syndrome (anosmia and hypogonadotrophic hypogonadism) is described in 2 siblings with unilateral MCDK. 
Making the correct diagnosis and obtaining post mortem studies in lethal cases is important since the recurrence risk for MCDK is approximately 3% compared to 25% for autosomal recessive polycystic kidney disease (ARPKD). 
While familial clusters of MCKD patients are observed, formal screening of relatives is not recommended. 
Other reported associations and cases reports associated with MCKD are listed below.
Abnormalities were seen in the contralateral MCDK kidney in 7 of 14 patients and in 5 of 14 patients had lethal conditions. Overall
80% of the bilateral MCDK had associated non-renal abnormalities compared to 11% of those with unilateral MCDK.  Others confirm the poor prognosis with bilateral disease, while involution, reduction or no change in renal size may be seen in cases of unilateral MCDK. 
Follow up among 53 children with unilateral MCDK demonstrated reassuring outcomes as follows over a mean follow up of 68 months :
2 with hypertension,
5 with urinary tract infection,
90% with involution of the kidney,
17% with complete involution (rate greater during first 30 months), and contralateral progressive renal hypertrophy.
In 87% of the cases, the unilateral MCDK is non-functioning and outcome is predicated upon renal and/or non-renal abnormalities. 
The detection of hydronephrosis and urinary obstruction has increased with the advent of antenatal ultrasound and the use of prophylactic antibiotics can reduce neonatal urinary infections.  The increased detection for urinary abnormalities may further improve outcomes by allowing early evaluation, follow up and treatment.
Since MCDK can be diagnosed accurately, an appropriate prognosis can be rendered. Those affected with bilateral MCDK, especially those with associated renal and/or non-renal malformations have a relatively poor prognosis and patient counseling is based upon the combination of findings. Severe dysplastic lesions with oligohydramnios and the inability to detect a normal kidney or bladder are usually lethal. 
For those with unilateral MCKD, especially those without other renal or non-renal abnormalities, the natural history is usually benign and serial follow up is warranted.  The indications for nephrectomy are reserved for complications such as MCDK size or when the kidney continues to increase in size after the second year of life. 
Other Reported Associations with MCKD
Below is a listing of other reported associations in addition to Meckel-Gruber ( renal cystic dysplasia, central nervous system malformations, polydactyly, hepatic defects, pulmonary hypoplasia due to oligohydramnios), Trisomy 13 (heart, lung defects, CNS (holoprosencephaly), growth restriction), and Trisomy 18 (growth restriction, cardiac defects, abnormal distal extremities, choroid plexus cysts, omphalocele).
Cystic accessory uterine cavity 
Caliceal diverticulum 
PAX2 (Paired box protein gene) mutations 
Seminal vesicle cyst 
Transcription factor 2 gene mutations 
VATER (vertebral defects, anal atresia, tracheo-esophageal fistula, and renal dysplasia) 
Potter sequence with penile agenesis 
Paravertebral arteriovenous fistula 
Angiotensin-converting enzyme and angiotensin type 2 receptor gene genotype 
Pentalogy of Cantrell ([defects involve the diaphragm, abdominal wall, pericardium, heart and lower sternum) 
Neonatal Bartter syndrome with polyhydramnios.
Congenital heart defects (7%) 
Chromosome 22q11 microdeletion 
Trisomy X 
Waardenburg syndrome type 1 (varying degrees of deafness, minor defects in structures arising from the neural crest, and pigmentation anomalies) 
Eur J Pediatr Surg. 2001 Aug;11(4):246-54.
Antenatal diagnosis of Multicystic Renal Dysplasia.
Ranke A, Schmitt M, Didier F, Droulle P.
Service de Chirurgie Pédiatrique B, Hôpital d'Enfants, Vandoeuvre-les-Nancy,
Multicystic Renal Dysplasia (MRD) was discovered during antenatal ultrasound
examination in 138 fetuses between 1980 and 1995. Associated malformations were
present in 66 % (42 % urological) and 22 % of the fetuses did not survive the
pregnancy or the peri-natal period .Anatomical analysis showed a wider variety of
MRD than in classical descriptions. Obstruction of the urinary tract was almost
invariable. Like the hypothesis published by Beck in 1971, our view is that, with
a very early obstruction of the urinary tract (during the first trimester), there
is a dysplastic evolution of renal tissue, while later in pregnancy the same
obstruction can induce a hydronephrosis with corticomedullary dysplasia.We advise
complete neonatal urological investigation, and surgical removal of multicystic
kidneys, to avoid multiple and inadequate evaluations of those children with a
single functioning renal unit.
Fetal Pediatr Pathol. 2008;27(6):264-73.
"Multicystic dysplastic kidney (Potter type II syndrome) and agenesis of corpus callosum (ACC) in two consecutive pregnancies: a possible teratogenic effect of electromagnetic exposure in utero".
Tonni G, Azzoni D, Ventura A, Ambrosetti F, De Felice C.
Prenatal Diagnostic Service, Division of Obstetrics and Gynecology, Guastalla
Provincial Hospital-AUSL Reggio Emilia, Reggio Emilia, Italy.
Agenesis of the corpus callosum is found in about 5 per 1,000 births and it is
due to maldevelopment or, secondary, to destructive lesions. Multicystic
dysplastic kidneys is a consequence of either developmental failure of the
mesonephric blastema to form nephrons or to early urinary obstruction due to
urethral or ureteric atresia and can be found in about 1 per 1,000 live births. A
case of fetal multicystic dysplastic kidney disease (Potter type II syndrome) and
complete agenesis of the corpus callosum demonstrated by the presence of Probst
bundles associated with colpocephaly occurring in the same mother in her two
consecutive pregnancies is reported. Data regarding possible teratogenetic effect
due to electromagnetic exposure in utero have also been investigated and raised
suspicionus as a potential risk factor. In cases of suspected second trimester
ultrasound diagnosis of agenesis of corpus callosum (ACC), the following clinical
management should be recommended: fetal karyotype; a second level scan with
differentiation between underlying conditions such as hydrocephalus and
holoprosencephaly; antenatal MRI to enhance the diagnostic accuracy of possible
associated neuronal migration (when possible); and direct demonstration of the
presence of the Probst bundles to neurohistology.
PMID: 19065324 [PubMed - indexed for MEDLINE]
Ugeskr Laeger. 2006 Jun 26;168(26-32):2544-50.
[Prenatal diagnosed hydronephrosis and other urological anomalies].
[Article in Danish]
Cortes D, Jørgensen TM, Rittig S, Thaarup J, Hansen A, Andersen KV, Thorup J,
Jørgensen C, Søgaard K, Eskild-Jensen A, Frøkiaer J, Hørlyk A, Jensen F; Danish
Society of Paediatrics, Committee of Nephrology and Urology; Department of
Paediatric Surgery, Rigshospitalet, University of Copenhagen; Danish Society of
Obstetrics and Gynaecology, Committee of Ultrasound Diagnostics; Danish Society
of Clinical Physiology and Nuclear Medicine; Department of Clinical Physiology
and Nuclear Medicine, Aarhus University Hospital, Skejby Sygehus; Department of
Radiology, Aarhus University Hospital, Skejby Sygehus; Danish Society of
Ultrasound Diagnostics; Danish Society of Radiology; Danish Society of
Nephrology; Danish Society of Urology.
H:S Rigshospitalet, Børnekirurgisk Afdeling. email@example.com
By renal ultrasound examination, urological anomalies may be demonstrated in 1-2%
of fetuses and in about 0.5% of newborns. Boys have about twice the frequency of
girls. Surgical treatment is indicated in about one fourth of these urological
anomalies. If all pregnant women in Denmark were to have fetal ultrasound
examination of the kidneys and the urinary tract, about 70 children would be born
each year with a prenatally diagnosed urological anomaly for which surgical
procedure is or will be indicated. This paper provides Danish guidelines for
prenatal diagnosis, follow-up and intervention in cases of urological anomalies
and guidelines for post-natal diagnosis, follow-up and treatment of these
anomalies, especially hydronephrosis.
PMID: 16824408 [PubMed - indexed for MEDLINE]
4 J Obstet Gynaecol Res. 1996 Dec;22(6):569-73.
A study on fetal urinary tract anomaly: antenatal ultrasonographic diagnosis and postnatal follow-up.
Kim EK, Song TB.
Department of Diagnostic Radiology, Chosun University Medical School, Kwangju,
OBJECTIVE: To evaluate the incidence, associated anomalies, and the type of
congenital urinary tract anomaly and to know the cause of congenital
METHODS: In 4.5 years, 5,442 fetuses had ultrasonography and 48 cases of fetal
urinary tract anomaly were detected. Ultrasonogram was done after delivery with
further examination as necessary.
RESULTS: The incidence of all types of anomaly was 4.3% (236/5,442) and the
incidence of urinary tract anomaly was 0.9% (48/5,442, 8.8/1,000 births) of all
babies born and 20.3% (48/236) of entire anomaly. Types of urinary tract anomaly
were as follows; hydronephrosis (37 cases), multicystic dysplastic kidney (5
cases), polycystic kidney disease (2 cases), renal agenesis (2 cases), ectopic
kidney (1 case) and hypoplastic kidney (1 case). Associated anomalies were found
in 8 cases (16.7%) among 48. Causes of hydronephrosis were ureteropelvic
obstruction in 13 cases, ureterovesical obstruction in 4 cases, vesicoureteral
reflux in 2 cases, proximal ureteral obstruction in 2 cases, and no specific
causes in 16 cases.
CONCLUSIONS: Antenatal ultrasonography is a very useful diagnostic tool in the
detection of urinary tract anomaly and a careful search for other anomalies is
indicated when urinary tract anomaly is found.
PMID: 9037946 [PubMed - indexed for MEDLINE]
5.Prenat Diagn. 1999 May;19(5):418-23.
Insights into the pathogenesis and natural history of fetuses with multicystic dysplastic kidney disease.
Lazebnik N, Bellinger MF, Ferguson JE 2nd, Hogge JS, Hogge WA.
Department of Genetics, Magee-Womens Hospital, Pittsburgh, PA 15213, USA.
To better delineate the natural history of multicystic displastic kidney disease
(MCDKD) and provide insights into the pathogenesis of this condition, we report
our experience in 102 prenatally detected cases. MCDKD is most commonly an
incidental finding on prenatal ultrasound examination. The abnormality may be
unilateral (76 per cent) or bilateral (24 per cent). In unilateral cases,
abnormality of the contralateral kidney is common (33 per cent). Associated
non-renal abnormalities occur frequently with both unilateral (26 per cent) and
bilateral (67 per cent) MCDKD, and increase the risk for an abnormal chromosome
study. Males are more likely to be affected than females with a ratio of 2.4:1,
but females are twice as likely to have bilateral MCDKD and associated non-renal
abnormalities, and four times more likely to have an abnormal chromosome study.
We suggest that the option of chromosomal analysis should be discussed with all
patients diagnosed with MCDKD in their fetus, if there is bilateral renal
involvement or if an associated non-renal abnormality is present. Unilateral
MCDKD without associated renal or non-renal abnormalities was not associated with
an abnormal chromosome study, and resulted in favourable outcomes. While
unilateral MCDKD, lack of associated anomalies, normal chromosome study and
adequate amniotic fluid are all reassuring findings, a complete neonatal urologic
work-up should be performed in all newborns. We believe the evaluation should
include voiding cystourethrography to rule out vesicoureteral reflux. Our
findings allow more precise counselling of patients regarding prognosis, and
subsequent management of the fetus found to have MCDKD.
PMID: 10360509 [PubMed - indexed for MEDLINE]
6. Hinyokika Kiyo. 1994 Nov;40(11):1009-12.
[Prenatally diagnosed bilateral multicystic dysplastic kidneys associated with
multiple anomalies: a case report].
[Article in Japanese]
Kawakita M, Arai Y, Takeuchi H, Yoshida O, Tsuruta Y, Ida K.
Department of Urology, Faculty of Medicine, Kyoto University.
A case of bilateral multicystic dysplastic kidneys with multiple anomalies is
reported. Prenatal ultrasonography showed oligohydramnios, atrial septal defect,
bilateral multicystic kidneys, omphalocele, and bowel dilatation. A male baby
died of respiratory insufficiency immediately after premature delivery. Autopsy
showed multiple anomalies of face, fingers, lung, heart, bowels, and
genitourinary tract. Seven more cases with urinary tract anomalies prenatally
detected by ultrasonography are also reported. Ultrasonography is useful to
diagnose anomalies of fetus.
PMID: 7832072 [PubMed - indexed for MEDLINE]
7. Pediatr Nephrol. 2007 Jul;22(7):1054-7. Epub 2007 Feb 20.
Unilateral multicystic dysplastic kidney in infants exposed to antiepileptic
drugs during pregnancy.
Carta M, Cimador M, Giuffrè M, Sergio M, Di Pace MR, De Grazia E, Corsello G.
UTIN e Pediatria, Università di Palermo, Palermo, Italy. firstname.lastname@example.org
Prenatal exposure to antiepileptic drugs (AEDs) increases the risk of major
congenital malformations (MCM) in the fetus. AED-related abnormalities include
heart and neural tube defects, cleft palate, and urogenital abnormalities. Among
the various congenital anomalies of the kidney and urinary tract (CAKUT),
multicystic dysplastic kidney (MCDK) disease is one of the most severe
expressions. Although prenatal ultrasound (US) examination has increased the
prenatal diagnosis of MCDK, the pathogenesis is still unclear. We report on four
cases of MCDK in infants of epileptic women treated with AEDs during pregnancy.
From October 2003 to June 2006, we observed four infants with unilateral MCDK
born to epileptic women. Three patients were considered to have typical features
of multicystic dysplastic kidney, and one infant was operated because of a cystic
pelvic mass in the absence of a kidney in the left flank. The macroscopic
appearance of this mass showed an ectopic multicystic kidney confirmed by
histological findings. All patients have been studied by US scans, voiding
cystourethrogram (VCUG), and radionuclide screening isotope imaging. The prenatal
exposure to AEDs increases the risk of major congenital malformations from the
background risk of 1-2% to 4-9%. AEDs may determine a defect in apoptosis
regulation that could lead to abnormal nephrogenesis, causing MCDK. Carbamazepine
(CBZ) and phenobarbital (PHB) during pregnancy should be used at the lowest
dosage compatible with maternal disease. The reduction, or even suspension, of
drug dosage should be achieved from the periconceptional period to the first 8
weeks of gestation to avoid any interference with organogenesis.
PMID: 17310358 [PubMed - indexed for MEDLINE]
8. Prenat Diagn. 2008 Dec;28(13):1204-8.
Down syndrome serum screening also identifies an increased risk for multicystic
dysplastic kidney, two-vessel cord, and hydrocele.
Hoffman JD, Bianchi DW, Sullivan LM, Mackinnon BL, Collins J, Malone FD, Porter
TF, Nyberg DA, Comstock CH, Bukowski R, Berkowitz RL, Gross SJ, Dugoff L, Craigo
SD, Timor-Tritsch IE, Carr SR, Wolfe HM, D'Alton ME.
Tufts Medical Center, Boston, MA 02111, USA.
OBJECTIVE: The FASTER trial compared first and second trimester screening methods
for aneuploidy. We examined relationships between maternal serum markers and
common congenital anomalies in the pediatric outcome data set of 36 837 subjects.
METHODS: We used nested case-control studies, with cases defined by the most
common anomalies in our follow-up database, and up to four controls matched by
enrollment site, maternal age and race, enrollment gestational age, and infant
gender. Serum markers were dichotomized to > or = 2 or < 0.5 multiples of the
median (MoM). Odds ratios (ORs) and 95% confidence intervals (CI) were estimated.
RESULTS: Statistically significant (p < 0.05) associations were found between
inhibin A > or = 2 MoM with fetal multicystic dysplastic kidney (MCDK) (OR =
27.5, 95% CI: 2.8-267.7) and two-vessel cord (OR = 4.22, 95% CI:1.6-10.9); hCG of
> or = 2 MoM with MCDK (OR = 19.56, 95% CI: 1.9-196.2) and hydrocele (OR = 2.48,
95% CI: 1.3-4.6); and PAPP-A > or = 2.0 MoM with hydrocele (OR = 1.88, 95%
CONCLUSION: In this large prospective study, significant associations were found
between several maternal serum markers and congenital anomalies. This suggests
potential additional benefits to screening programs that are primarily designed
to detect aneuploidy.
PMID: 19034930 [PubMed - indexed for MEDLINE]
9. Nephrol Dial Transplant. 2001 Jun;16(6):1170-5.
Multicystic dysplastic kidney and Kallmann's syndrome: a new association?
Deeb A, Robertson A, MacColl G, Bouloux PM, Gibson M, Winyard PJ, Woolf AS,
Moghal NE, Cheetham TD.
Department of Child Health, The Royal Victoria Infirmary, Newcastle-upon-Tyne NE1
BACKGROUND: Kallmann's syndrome is characterized by anosmia and hypogonadotrophic
hypogonadism. Radiographic studies of teenagers and older subjects with the
X-linked form of the syndrome have shown that up to 40% have an absent kidney
unilaterally. Although this has been attributed to renal "agenesis", a condition
in which the kidney fails to form, little is known about the appearance of the
developing urinary tract either pre- or post-natally in individuals with
METHODS: We describe two brothers who had features of Kallmann's syndrome, most
probably of the X-linked variety, who both had a major urinary-tract malformation
detected before birth.
RESULTS: The brothers were found to have unilateral multicystic dysplastic
kidneys on routine antenatal ultrasound scanning and both underwent surgical
nephrectomy of these organs post-natally. Immunohistochemical studies on the
younger sibling revealed hyperproliferative dysplastic kidney tubules which
overexpressed PAX2, a potentially oncogenic transcription factor, and BCL2, a
cell-survival factor, surrounded by metaplastic, alpha smooth-muscle
actin-positive stroma: similar patterns have been observed in patients with
non-syndromic multicystic dysplastic kidneys.
CONCLUSIONS: Our results describe a new type of urinary-tract malformation
associated with Kallmann's syndrome. However, since multicystic kidneys tend to
involute, only when more Kallmann's syndrome patients are screened in utero or in
early childhood using structural renal scans, will it be possible to establish
whether multicystic kidney disease is a bona-fide part of the syndrome.
PMID: 11390716 [PubMed - indexed for MEDLINE]
10. J Perinatol. 2008 Nov;28(11):736-42. Epub 2008 Jul 3.
Post-mortem examination of prenatally diagnosed fatal renal malformation.
Kumari N, Pradhan M, Shankar VH, Krishnani N, Phadke SR.
Department of Pathology, Sanjay Gandhi Post-Graduate Institute of Medical
Sciences, Lucknow, UP, India.
OBJECTIVE: Renal malformations can be associated with genetic syndromes and
chromosomal disorders. Fetal autopsy including histopathological examination of
kidney is important to arrive at definite diagnosis. The objective was to assess
importance of fetal autopsy and histopathology.
STUDY DESIGN: Retrospective analysis of cases with fetal renal malformations was
done. All fetuses terminated were examined with whole body radiograph, external
and internal examination and histopathological examination.
RESULT: A total of 21 cases with renal malformations were studied. Of all 3 were
of bilateral renal agenesis, 4 showed autosomal recessive polycystic kidney
disease and 13 showed features of multicystic kidney. Three of these had
hyperplasic-enlarged bladder and autopsy confirmed urorectal septum malformations
in two cases and posterior urethral valve in one case. One case had associated
malformations like encephalocele that suggested diagnosis of Meckel-Gruber
syndrome and another had associated lateral body wall defect. In five cases
kidney was hypoplastic suggestive of Potter type IIa.
CONCLUSION: Ultrasound is an effective diagnostic modality; however fetal autopsy