Predictors of poor neonatal outcomes in prenatally diagnosed multicystic dysplastic kidney disease

Long-term Outcomes, Including Fetal and Neonatal Prognosis, of Renal Oligohydramnios: A Retrospective Study over 22 Years

OBJECTIVE

To assess the long-term outcome of renal oligohydramnios and risk factors for fetal, neonatal, and postneonatal death.

STUDY DESIGN

This retrospective cohort study included fetuses with prenatally detected renal oligohydramnios between 2002 and 2023. Patients who were lost to follow-up were excluded. Fetal, neonatal, and long-term outcomes were evaluated, and their risk factors were analyzed.

RESULTS

Of 131 fetuses with renal oligohydramnios, 46 (35%) underwent a termination of pregnancy, 11 (8%) had an intrauterine fetal death, 26 (20%) had a neonatal death, nine (7%) had a postneonatal death, and 39 (30%) survived. Logistic regression analyses showed that an earlier gestational age at onset (odds ratio 1.16, 95% confidence interval (CI) 1.01-1.37) was significantly associated with intrauterine fetal death; anhydramnios (odds ratio 12.7, 95% CI 1.52-106.7) was significantly associated with neonatal death as a prenatal factor. Although neonatal survival rates for bilateral renal agenesis, bilateral multicystic dysplastic kidney (MCDK), and unilateral MCDK with contralateral renal agenesis were lower than for other kidney diseases, one case of bilateral renal agenesis and two of bilateral MCDK survived with fetal intervention. Kaplan-Meier overall survival rates were 57%, 55%, and 51% for 1, 3, and 5 years, respectively. In the Cox proportional hazards model, birth weight <2000 g (hazard ratio 7.33, 95% CI 1.48-36.1) and gastrointestinal comorbidity (hazard ratio 4.37, 95% CI 1.03-18.5) were significant risk factors for postneonatal death.

CONCLUSION

Long-term survival following renal oligohydramnios is a feasible goal and its appropriate risk assessment is important.

Fetal Therapy for Renal Anhydramnios

The most severe forms of congenital anomalies of the kidney and urinary tract present in fetal life with early pregnancy renal anhydramnios and are considered lethal due to pulmonary hypoplasia without fetal therapy. Due to the high rate of additional structural anomalies, genetic abnormalities, and associated syndromes, detailed anatomic survey and genetic testing are imperative when stratifying which pregnancies are appropriate for fetal intervention. Restoring amniotic fluid around the fetus is the principal goal of prenatal treatment. The ongoing multi-center Renal Anhydramnios Fetal Therapy (RAFT) trial is assessing the safety and efficacy of serial amnioinfusions to prevent pulmonary hypoplasia so that the underlying renal disease can be addressed.

Sonographic Detection of Multicystic Dysplastic Kidneys

Multicystic dysplastic kidney (MCDK) is a common nonhereditary cystic dysplasia that can be detected antenatally. This disorder commonly manifests in utero and presents unilaterally; however, this patient’s case demonstrates bilateral MCDKs. The use of sonography is essential in diagnosing this disorder both antenatally and following birth. Bilateral MCDKs present as large anechoic cysts overtaking renal parenchyma and halting all normal renal physiologic functions. This case study demonstrates the importance of early detection, the progression of this disorder, as well as the large part sonographic imaging plays in visualizing the MCDK.

Multicystic Dysplastic Kidney: Prenatal Compensatory Renal Growth Pattern

OBJECTIVES

To assess the prenatal growth pattern of the normal kidney contralateral to a multicystic dysplastic kidney (MCDK).

METHODS

A retrospective study was conducted in a single referral center over 4 years. Cases diagnosed prenatally as MCDK and confirmed postnatally constituted the study group. For creation of nomograms, only isolated cases of MCDK were included.

RESULTS

Sixty-one fetuses had a diagnosis of an MCDK during the study period. After exclusion of cases with associated malformations, 47 fetuses remained, providing 94 measurements for creation of nomograms. The growth pattern of the normal kidney contralateral to an MCDK was linear throughout gestation (percentile = 20.01 + 1.5 gestational age; linear R²  = 0.753; r = 0.868) and was significantly higher during the third trimester (29-38 weeks' gestation) compared to the second trimester (22-28 weeks' gestation; P < .001). A comparison of the growth pattern of the normal kidney contralateral to the MCDK to the growth pattern of a solitary kidney revealed a significant higher compensatory trend during the third trimester (P < .0001). The mean kidney lengths at 22 and 38 weeks' gestation correlated with the 52nd and 88th and with the 84th and 90th percentiles for the normal kidney contralateral to the MCDK and a solitary kidney, respectively.

CONCLUSIONS

According to our study, the normal kidney contralateral to an MCDK has a unique growth pattern during intrauterine life, with dominant growth during the third trimester. The exact mechanism for this pattern, in comparison to early renal hypertrophy shown in solitary kidneys, is currently not clear. These data provide relevant information for the multidisciplinary prenatal counseling of future parents regarding the future renal outcome.

Postnatal outcome of prenatally-detected "simple" renal cysts: Are they really simple?

BACKGROUND

The majority of simple renal cysts diagnosed postnatally are asymptomatic and rarely require treatment unless they become symptomatic or complex. We hypothesised that prenatally-detected simple renal cysts would have a similar harmless outcome.

AIMS

To establish the natural history and postnatal outcome of prenatally-diagnosed simple renal cysts.

STUDY DESIGN

Single-centre retrospective case-series review (12-year period).

SUBJECTS

All patients with prenatally-diagnosed simple renal cysts (defined as a solitary, non-septated, non-communicating cyst in an otherwise normal kidney).

OUTCOME MEASURES

Prenatal and postnatal changes to cyst size, persistence, resolution or modification of diagnosis. Data is presented as the proportion of patients or median (range).

RESULTS

30 cysts were detected (2 bilateral, 26 unilateral) in 28 fetuses (median gestational age of 23 [20-36] weeks). Median maximum diameter was 15 (4-35) mm at initial diagnosis and 17.5 (4-100) mm across all prenatal scans. On follow-up scans diagnosis was modified in 16 (53%) to: multicystic dysplastic kidney (MCDK), dilated duplex kidney, hydronephrosis, urinoma, renal agenesis and adrenal mass. 12 (40%) cysts resolved. 2 (7%) asymptomatic cysts persisted at one year postnatally. Cyst maximum diameter in the modified diagnosis group (21.5 [10-100] mm) was significantly larger than the simple cyst group (12 [4-20] mm) (P = 0.03).

CONCLUSIONS

Our study revealed the challenges of prenatal ultrasound imaging, with modified diagnoses in over half the cases. Kidneys with solitary cysts could evolve into multicystic kidneys or involute completely, which suggests a true alteration in morphology rather than sonographic error. Persistent simple cysts in an otherwise normal kidney, however, resolved spontaneously or remained asymptomatic. Prenatally-detected simple cysts should be monitored with serial imaging.

Fetal interventions for congenital renal anomalies

Congenital abnormalities of the kidney and urinary tract (CAKUT) represent 20% of prenatally diagnosed congenital abnormalities. Although the majority of these abnormalities do not require intervention either pre or postnatally, there is a subset of patients whose disease is so severe that it may warrant intervention prior to delivery to prevent morbidity and mortality. These cases consist of patients with moderate lower urinary tract obstruction (LUTO) in which vesicocentesis, shunting or cystoscopy are options and patients with early pregnancy renal anhydramnios (EPRA) in whom amnioinfusion therapy may be an option. The main causes of EPRA are congenital bilateral renal agenesis (CoBRA), cystic kidney disease (CKD) and severe LUTO. Untreated, EPRA is universally fatal secondary to anhydramnios induced pulmonary hypoplasia. The evidence regarding therapy for LUTO is limited and the stopped early PLUTO (Percutaneous Shunting in Lower Urinary Tract Obstruction) trial was unable to provide definitive answers about patient selection. Evidence for EPRA therapy is also scant. Serial amnioinfusions have shown promise in cases of EPRA due to CoBRA or renal failure and this treatment modality forms the basis of the ongoing NIH funded RAFT (Renal Anhydramnios Fetal Therapy) trial. At present, there is consensus that treatment for EPRA should only occur in the setting of a clinical trial.

Ultrasound Imaging of Renal Cysts in Children

Renal cysts can be focal or diffuse and unilateral or bilateral. In childhood, most renal cysts are due to hereditary diseases rather than simple cysts or acquired cystic diseases, unlike adults. Inherited cystic diseases can be ciliopathies due to a primary ciliary defect (as in polycystic kidney diseases and nephronophthisis). Acquired causes include obstructive cystic dysplasia, dyselectrolytemia, and acquired cysts in renal replacement therapy. The final diagnosis requires a multispecialty approach, including radiology, pathology, and genetics. Imaging is a very important component in treating patients with cystic renal diseases. This article discusses the ultrasound findings of cystic renal diseases in children, along with a brief discussion of other imaging modalities and a suggested ultrasound reporting format.

Etiology and management of early pregnancy renal anhydramnios: Is there a place for serial amnioinfusions?

Early pregnancy renal anhydramios (EPRA) comprises congenital renal disease that results in fetal anhydramnios by 22 weeks of gestation. It occurs in over 1 in 2000 pregnancies and affects 1500 families in the US annually. EPRA was historically considered universally fatal due to associated pulmonary hypoplasia and neonatal respiratory failure. There are several etiologies of fetal renal failure that result in EPRA including bilateral renal agenesis, cystic kidney disease, and lower urinary tract obstruction. Appropriate sonographic evaluation is required to arrive at the appropriate urogenital diagnosis and to identify additional anomalies that allude to a specific genetic diagnosis. Genetic evaluation variably includes karyotype, microarray, targeted gene testing, panels, or whole exome sequencing depending on presentation. Patients receiving a fetal diagnosis of EPRA should be offered management options of pregnancy termination or perinatal palliative care, with the option of serial amnioinfusion therapy offered on a research basis. Preliminary data from case reports demonstrate an association between serial amnioinfusion therapy and short-term postnatal survival of EPRA, with excellent respiratory function in the neonatal period. A multicenter trial, the renal anhydramnios fetal therapy (RAFT) trial, is underway. We sought to review the initial diagnosis ultrasound findings, genetic etiologies, and current management options for EPRA.

"Watch and Wait" Strategy for Multicystic Dysplastic Kidney (MCDK): Status Survey of Perceptions, Attitudes, and Treatment Selection in Chinese Pediatric Urologists and Pediatric Surgeons

To investigate the perceptions, attitudes, and treatment selection of Chinese pediatric urologists and pediatric surgeons regarding a "watch and wait" strategy for multicystic dysplastic kidney (MCDK). We used a cross-sectional survey in this study. We sent the questionnaire to pediatric urologists and pediatric surgeons to capture their views via the "Questionnaire Star" online survey platform between November and December 2019. The questionnaire contained the basic information and surgical experiences of the respondent, respondents' awareness regarding the counseling of prenatally-diagnosed MCDK and the treatment of MCDK, and respondents' knowledge regarding the imaging modalities, frequency, and duration of follow-up. Of the 200 questionnaires we sent, we received 151 responses. Of those 151 complete responses, most respondents were women (n = 104, 68.9%), pediatric urologists (n = 78, 51.6%), and practicing with at least 5 years of surgical experience (n = 112, 74.2%); 11.9% reported >20 years' experience. Eighty-two surgeons (54.3%) provided positive counseling for prenatally-diagnosed MCDK. Ninety-nine surgeons (65.6%) advocated conservative management for MCDK, and only 14.8% of respondents suggested limiting the use of radiographic evaluation for MCDK. Surgeons working in academic teaching facilities and those from East China were more likely to select a "watch and wait" strategy. Chinese pediatric urologists and pediatric surgeons have inadequate knowledge of the "watch and wait" strategy for MCDK. An expert consensus on the strategy of "watch and wait" for MCDK in China is urgently needed to promote the application of this non-surgical treatment mode in clinical practice. A larger sample size is required to fully identify the current opinion of Chinese pediatric urologists and pediatric surgeons regarding the management of MCDK.

Amnioinfusions to Treat Early Onset Anhydramnios Caused by Renal Anomalies: Background and Rationale for the Renal Anhydramnios Fetal Therapy Trial

Anhydramnios caused by early anuria is thought to be universally fatal due to pulmonary hypoplasia. Bilateral renal agenesis and early fetal renal failure leading to anhydramnios constitute early pregnancy renal anhydramnios (EPRA). There have been successful reports of amnioinfusions to promote lung growth in the setting of EPRA. Some of these successfully treated EPRA fetuses have survived the neonatal period, undergone successful dialysis, and subsequently received a kidney transplant. Conversely, there are no reports of untreated EPRA survivors. This early success of amnioinfusions to treat EPRA justifies a rigorous prospective trial. The objective of this study is to provide a review of what is known about fetal therapy for EPRA and describe the Renal Anhydramnios Fetal Therapy trial. We review the epidemiology, pathophysiology, and genetics of EPRA. Furthermore, we have performed systematic review of case reports of treated EPRA. We describe the ethical framework, logistical challenges, and rationale for the current single center (NCT03101891) and planned multicenter trial.

Magnetic resonance imaging for evaluation of foetal multicystic dysplastic kidney

We sought to evaluate the diagnostic value of foetal magnetic resonance imaging (MRI) for multicystic dysplastic kidney (MCDK) disease. We retrospectively identified 55 foetuses with MCDK diagnosed (51 unilateral; 4 bilateral) by foetal MRI. We analysed the anatomical findings by prenatal MRI and compared them with the prenatal ultrasound (US) and postnatal findings. Additional diagnostic information added by MRI was recorded. The gestational age of the 55 foetuses ranged from 22 to 35 weeks (mean, 26.5 ± 3.6 weeks). The age of the pregnant women ranged from 23 to 40 years (mean, 31 ± 4.2 years). All 55 cases were performed at 1.5 T magnetic resonance unit. MRI sequences, including steady-state free precession (SSFP), single-shot fast spin echo (SSFSE), T₁-weighted imaging (T₁WI), and diffusion weighted imaging (DWI) sequences. Follow-up was obtained for 53 cases (2 cases of autopsy, 51 cases of postnatal imaging or surgery confirmed). Among the 51 unilateral cases, 16 cases were associated with other urinary tract anomalies, 3 cases with extra-renal anomalies, and the remaining 32 cases without associated anomalies. 2 of 16 cases with contralateral renal agenesis were with oligohydramnios and pulmonary hypoplasia. 2 of 4 bilateral MCDK presented with oligohydramnios and pulmonary hypoplasia. 52 of 53 cases were correctly diagnosed by MRI compared with the final diagnoses; 40 of 53 (75.5%) cases were correctly diagnosed by prenatal ultrasound. Both prenatal ultrasound and MRI failed to correctly diagnose one case bilateral MCDK, and MRI correctly changed the ultrasound diagnosis in 12 cases. Foetal MRI can add additional diagnostic information to prenatal US in the assessment of MCDK, even change the prenatal counselling and decisions.