Antenatal minimal hydronephrosis: is its follow-up an unnecessary cause of concern?

The aim of this study was to determine if follow-up of antenatally diagnosed minimal hydronephrosis (anteroposterior renal pelvis diameter <10 mm) is justified or if it is an unnecessary cause of concern for the parents involved. A case-control study, with subjects and controls selected from the Wessex Antenatally Detected Anomalies Register was performed. Information regarding antenatal and postnatal follow-up, renal tract morbidity and degree of concern was obtained from a parental questionnaire. 70 of the 115 subjects contacted (60.9 per cent) and 52 of the 81 controls (64.2 per cent) returned the questionnaire. 65 of the 70 subjects (92.9 per cent) were rescanned postnatally when 28 cases (43.1 per cent) had resolved. Coexisting ureteric and/or calyceal dilatation was evident postnatally in 12 cases and this group was significantly more likely to have underlying pathology than the group with isolated renal pelvis dilatation. Subjects were significantly more likely than controls to have a UTI. The degree of concern was significantly greater in the subject group and subject parents thought about the result significantly more often than controls. From our results we concluded that the follow-up of minimal hydronephrosis can be modified. There is no need for repeated antenatal scanning, a change that could reduce the level of parental anxiety. Postnatal follow-up is required in all patients to exclude an underlying uropathy but again this can be modified, with the majority of patients requiring only an ultrasound scan. This reduced intensity of investigation accompanied with careful explanation to the parents should help to minimize their concerns.