Ultrasound Markers in Fetal Hydronephrosis to Predict Postnatal Surgery

Abstract

Purpose Parents confronted with the finding of antenatal hydronephrosis (ANH) are particularly interested in whether their baby will need postnatal surgery. The objective of this study was to predict ANH requiring surgery on the basis of the fetal anteroposterior renal pelvic diameter (APRPD) and the Society for Fetal Urology (SFU) grading system.

Materials and Methods The medical records of 179 patients with the finding of ANH were reviewed retrospectively. ANH was graded according to the SFU grading system. Prenatal ultrasound examinations were correlated to postnatal outcome, which was divided into three groups: prenatal resolution, conservative management and surgical treatment.

Results 58 (32.4 %) cases were classified as prenatal resolution, 89 (49.7 %) babies were assigned to the conservative outcome group and 32 (17.9 %) patients needed surgical repair. Postnatal surgery was best predicted in the second trimester (area under the receiver operating characteristics curve: 0.839) by an APRPD cut-off of 8.3 mm (sensitivity: 77.8 %; specificity: 85.7 %; PPV of 53.9 %, NPV of 94.7 %). The combination of the parameters “progression of SFU grade” and SFU grade 3 or 4 achieved a sensitivity of 84.4 % and a specificity of 80.3 % for the prediction of surgery.

Conclusion Second-trimester APRPD is a useful parameter for predicting the risk for postnatal surgery. The SFU grade should be assessed in every prenatal ultrasound examination as some further risk estimates can be made based on its dynamics over time.

Zusammenfassung

Ziel Wenn Eltern mit der pränatalen Diagnose einer antenatalen Hydronephrose (ANH) konfrontiert werden, sind sie vor allem daran interessiert, ob ihr Baby postnatal eine Operation benötigen wird. Ziel dieser Studie war es, die Notwendigkeit einer Operation bei ANH anhand des fetalen anteroposterioren (AP) Nierenbeckendurchmessers und dem Grading System der Society for Fetal Urology (SFU) vorher zu sagen.

Material und Methoden Die Krankengeschichten von 179 Patienten mit der Diagnose einer ANH wurden retrospektiv analysiert. Die ANH wurde nach dem SFU Grading System eingeteilt. Die pränatalen Untersuchungen wurden mit dem postnatalen Outcome korreliert, welche in drei Gruppen eingeteilt wurden: pränatale Resolution, konservatives Management und operative Behandlung.

Ergebnisse 58 (32,4 %) Fälle wurden als pränatale Resolution klassifiziert, 89 (49,7 %) Babies wurden in die konservative Outcome Gruppe eingeordnet und 32 (17,9 %) Patienten brauchten eine chirurgische Intervention. Die Notwendigkeit einer Operation wurde am besten im zweiten Trimenon (area under the receiver operating characteristics curve: 0,839) mit einem cut-off von 8,3 mm im AP Durchmesser des Nierenbeckens (Sensitivität: 77,8 %; Spezifität: 85,7 %; PPV von 53,9 %, NPV von 94,7 %) vorhergesagt. Die Kombination der Parameter „Progression im SFU Grad“ und SFU Grad 3 oder 4 erreichten eine Sensitivität von 84,4 % und eine Spezifität von 80,3 % für die Vorhersage einer Operation.

Schlussfolgerung Zweittrimester Ultraschall ist ein nützlicher Parameter für die Vorhersage einer Operation bei ANH. Der SFU Grad sollte bei jeder pränatalen Verlaufsuntersuchung evaluiert werden, da eine Risikoeinschätzung anhand der Dynamik gemacht werden kann.

Key words

fetal hydronephrosis - postnatal surgery - prenatal diagnosis - renal pelvic dilation - anteroposterior renal pelvic diameter

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