Pre- and Postnatal Resolution and Postnatal Outcome of Prenatally-Diagnosed Simple Renal Cysts
Stavros Loukogeorgakis, PhD1, Elisabetta Sanna, MD2, Iris Derwig, MD2, Gauri Paramasivan, MD2, Christoph C. Lees, MD1, Marie-Klaire Farrugia, FRCSEd(Paed.Surg)1.
1Chelsea & Westminster Hospital, London, United Kingdom, 2Queen Charlotte's and Chelsea Hospital, London, United Kingdom.
Pre- and postnatal resolution and postnatal outcome of prenatally-diagnosed simple renal cysts
The significance of prenatally-diagnosed simple renal cysts is not well-established. The aim of our study was to 1. establish the rate of in-utero and postnatal resolution, and 2. determine the postnatal outcome of cysts which have not involuted spontaneously.
We retrospectively reviewed all simple renal cysts diagnosed in-utero between January 2005 and December 2016 in a single center for fetal care, using our ultrasound database (Astraia Obstetrics, Astraia Software Gmbh, Munich Germany). The diagnosis of a simple renal cyst was based on the presence of a solitary, non-septated cyst with well defined borders, and no communication between the cavity of the cyst and the renal pelvis in an otherwise normal-appearing kidney. The gestational age (GA), location and size of the renal cyst at diagnosis were recorded. Fetuses were monitored at regular intervals during pregnancy in order to determine the antenatal course of the cyst. Fetuses with persistent renal cysts were delivered locally, and were followed-up postnatally at hospitals belonging to the North West London Paediatrc Surgical Network. Following audit registration and ethical approval, we reviewed postnatal scans and patient records (paper and electronic) at each center.
Renal cysts were indentified antenatally in 31 fetuses at a median GA of 23 weeks (20-36 weeks). Cysts were unilateral in 28 fetuses (28/31: 90.4%), with the right kidney affected in 14 (14/31: 45.2%) and the left in 14 (14/31: 45.2%). Bilateral renal cysts were found in 3 fetuses (3/31: 9.6%). Median maximum diameter of cysts was 15 (4-35) mm at the time of diagnosis. A median of 2 follow-up antenatal scans (0-9 scans) were perfomed to monitor cyst progression. Antenatal cyst resolution was observed in 4 fetuses (4/31: 12.9%), and the diagnosis was modified in subsequent in utero imaging in 5 patients (5/31: 16.1%; hydronephrosis in 3 fetuses, adrenal mass in 1 fetus, and echogenic kidney in 1 fetus). Fetuses with resolved cysts or revised diagnoses were excluded from subsequent analysis; postnatal follow-up data was available for all (22) of the remaining patients. Postnatal ultrasound was normal
in 8 infants (8/22: 36.4%), consistent with cyst resolution. The diagnosis of a simple renal cyst was confirmed in postnatally in only 3 patients (3/22: 13.7%); these were followed up for a median 51 months (range: 39-60 months) and were managed conservatively due to the lack of symptoms. In the remaining 11 patients the postnatal diagnosis was different (11/22: 50%; multicystic dysplastic kidney/MCDK in 3 patients, duplex kidney with dilated upper moiety in 3 patients, adrenal cystic mass in 3 patients and unilateral atrophic kidney/renal agenesis in 2 patients).
Our study is helpful when counselling patients with prenatally-diagnosed simple cysts: overall, 38.7% resolve spontaneously, either pre- or postnatally, whereas 9.7% remain stable and are monitored postnatally. In the remaining 51.6% subsequet scans may reveal other findings including MCDK/echogenic kidneys with subsequent involution; dilated duplex systems or adrenal pathology.
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