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

https://doi.org/10.1016/j.earlhumdev.2021.105382Get rights and content

Highlights

  • Solitary renal cysts diagnosed prenatally may represent evolving renal pathology.

  • Multi-cystic dysplastic kidneys may not appear multi-cystic on initial evaluation.

  • Multi-cystic dysplastic kidneys may change in appearance on serial prenatal imaging.

  • Fetal simple renal cysts persisting postnatally rarely need intervention.

  • Fetal solitary renal cyst warrant follow-up prenatal scans and postnatal evaluation

Abstract

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.

Introduction

Solitary “simple” renal cysts detected on prenatal ultrasound scans have a reported incidence of approximately 1 in 1100 pregnancies [1]. Simple renal cysts found postnatally in childhood and in adulthood are usually asymptomatic and only require treatment when they become symptomatic or complex. We hypothesised that prenatally-detected cysts would therefore have the same outcome. The aim of our study was to elucidate the natural history of simple renal cysts detected prenatally and establish whether their postnatal outcome is really “simple”.

Section snippets

Methods

We performed a retrospective review of all antenatally-diagnosed simple renal cysts in a single tertiary referral centre (Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London) between January 2005 and December 2016. A simple renal cyst was defined as a solitary, non-septated, non-communicating cyst in an otherwise normal kidney [2]. In the United Kingdom, an anomaly scan is performed at 18–20 weeks gestation. Anomaly scans were initially performed by sonographers, and any

Results

Simple renal cysts were identified in 28 fetuses at a median gestational age of 23 (20–36) weeks (Table 1). Cysts were bilateral in 2 (7%) and unilateral in 26 fetuses (14 left-sided, 12 right-sided), giving a total of 30 cysts. Median maximum diameter was 15 (4–35) mm at initial diagnosis and 17.5 (4–100) mm across all prenatal scans. No other abnormalities were identified on initial anomaly scans.

Discussion

Our study has shown that prenatally-detected “simple” renal cysts may pose a diagnostic challenge, even when being apparent on repeat prenatal scans performed by experienced specialists. Although it is likely that the cases later diagnosed as hydronephrosis and urinomas were never cysts in the first place – it is still worth noting that what appears to be a cyst, may not in fact be one. However, the intriguing finding is that in 5 (17%) cases, the affected kidney was subsequently found to be

Conclusion

We attempt to elucidate the natural-history of prenatally-detected “simple” cysts. The outcome is not always “simple”, especially those approaching larger than 20 mm in diameter over their prenatal course. A solitary cyst in an otherwise normal kidney may in fact be a step in the evolution of a multicystic dysplastic kidney, occasionally resulting in involution of the entire kidney. At the other end of the spectrum, it may in fact be a “simple” self-resolving entity, or an asymptomatic finding

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

None declared.

References (12)

There are more references available in the full text version of this article.

Cited by (0)

View full text