Case of the Week #609

Vladimir Lemaire, Robert D. Stewart
UT Southwestern Medical Center, Plano, Texas, United States of America

Posting Dates: Jul 15, 2024 - Jul 30, 2024

A 28-year-old patient, G10 P1081, presented to our maternal fetal medicine unit at 23 weeks, 5 days for a fetal anatomic survey. The fetus was female with low-risk noninvasive prenatal testing. The following findings were observed.

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Answer

We present a case of bilateral multicystic dysplastic kidney disease (MCDK).

Our images demonstrate the following:

Image 1: Axial plane through the fetal lower abdomen. Both kidneys are enlarged with multiple non-communicating cysts of variable size.
Image 2: Renal vasculature demonstrated by using SlowFlow with Radiant Flow.
Image 3: The fetal bladder is not visualized.
Image 4: Four-chamber view: hypertrophic cardiomyopathy with pericardial effusion.
Image 5: Four-chamber view with color Doppler.
Image 6: Three-vessel-trachea view with color Doppler.
Image 7: Transverse plane of the fetal head at the level of the biparietal diameter (BPD).

Discussion

Multicystic dysplastic kidney disease is unilateral in approximately 75 to 80% of cases, and due to the abnormal development of the collecting system, often early obstruction (atretic ureters). Ultrasound findings include enlarged kidneys with non-communicating macrocysts of variable size within the hyperechoic parenchyma. Severe olygohydramnios is usually present and the bladder cannot be visualized.

According to Paladini et al., the risk of chromosomal anomalies reaches 15 to 18% in MCDK's bilateral form when isolated, and 25 to 28% when associated with other abnormalities. Associated nonchromosomal syndromes include: brachio-otorenal syndrome, cerebro-reno-digital syndrome, VACTERL (vertebral anomalies, anal atresia, congenital heart defect, tracheo-esophageal fistula, limb anomalies), short-rib polydactyly syndrome, and Meckel-Gruber syndrome.

Differential diagnosis for bilateral MCDK includes Meckel-Gruber syndrome and bilateral obstructive cystic dysplasia. In bilateral obstructive cystic dysplasia, the bladder is dilated with thick walls. In Meckel-Gruber syndrome, extrarenal anomalies, such as cephalocele, microcephaly, and polydactyly, are always present.

Conservative treatment after 24 weeks of gestation is recommended due to its unfavorable prognosis. Neonatal death occurs in the majority of cases due to pulmonary hypoplasia, which is a direct consequence of the severe oligohydramnios. It is crucial that an accurate and early diagnosis is reached, as it would allow a timely, safer, and less traumatic management of pregnancies affected by this condition.

Reference

Paladini, D et al. "Multicystic Dysplastic Kidney Disease". Ultrasound of Congenital Fetal Anomalies: Differential Diagnosis and Prognostic Indicators. Boca Raton, FL: CRC Press; 2014. pgs 322-323.