Multicystic dysplastic kidney

00:00 / 00:00



Multicystic dysplastic kidney

Renal system


Multicystic dysplastic kidney


0 / 9 complete

USMLE® Step 1 questions

0 / 1 complete

High Yield Notes

11 pages


Multicystic dysplastic kidney

of complete


USMLE® Step 1 style questions USMLE

of complete

A 25-year-old primigravida woman at 20 weeks of gestation comes to the obstetrician for a routine prenatal evaluation. The pregnancy has been uncomplicated, and she has been compliant with prenatal care. She takes vitamins as needed. Family and medical history are unremarkable. She did not have any prior abortions or miscarriages. Ultrasound reveals numerous cysts and no identifiable renal tissue at the location of the fetus’s right kidney. The fetus’s left kidney appears normal. Amniotic fluid index is normal. These ultrasound findings are most likely caused by which of the following?  

External References

First Aid








Multicystic dysplastic kidney p. 602, 603


Content Reviewers

Multicystic dysplastic kidney or MCDK is a congenital disease where one or both kidneys don’t form quite right, specifically causing them to not drain urine properly, which results in urine building up in the kidneys and forming multiple fluid-filled sacs called cysts.

Alright so during fetal development, first off you’ve got this structure called the mesonephric duct which is involved in development of urinary and reproductive organs, and during the 5th week of gestation, a little guy called the ureteric bud starts pushing its way into another structure called the metanephric blastema, and together, these two little embryologic structures go on to develop into a kidney.

At about the 7th week, nephrogenesis, or formation of the kidneys, starts under the influence of that ureteric bud.

By about 20 weeks, the ureteric bud has formed the ureters, the renal calyces, collecting ducts, and collecting tubules, while the metanephric blastema develops into the nephron itself, which includes the epithelial cells and the podocytes of Bowman’s capsule.

In the third trimester and throughout infancy, the kidneys continue to grow and mature.

Although not completely known, it’s thought that MCDK is a result of some sort of abnormal induction of the metanephric blastema by the ureteric bud.

This failure might be the fault of the mesonephric duct not forming right, or the ureteric bud not forming right, or both.

Regardless of the cause of failure, the ureteric bud is supposed to go on to form the ureters as well as the rest of the tubules that branch out to collect urine.

So as blood starts coming in to be filtered, and urine starts getting produced, a failure to properly develop into these urine-collecting tubules means that the urine has nowhere to go, and so it builds up in the kidneys and forms these fluid-filled cysts that are composed of abnormal connective tissue—especially cartilage—that actually replaces normal kidney tissue and decreases the kidney’s ability to function.


Multicystic dysplastic kidney (MCDK) is a congenital disorder in which the kidneys fail to develop normally and cannot drain urine properly. This causes urine to build up in the kidneys and forms multiple cysts.

MCDK is often detected during routine prenatal ultrasounds, or during early childhood with hydronephrosis and recurrent urinary tract infections of the affected kidneys.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine" McGraw Hill Education/ Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Prenatal diagnosis of fetal multicystic dysplastic kidney with two-dimensional and three-dimensional ultrasound" Ultrasound in Medicine & Biology (2002)
  6. "Clinical Aspects of Paediatric Urology" Imaging in Paediatric Urology (2003)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.