Abstract

OBJECTIVES: To establish the diagnostic accuracy of obstetric ultrasound at a tertiary fetal medicine centre in the prenatal detection of unilateral and bilateral MCDK in fetuses where this condition was suspected; and to undertake a systematic review of the literature on this topic. METHODS: Retrospective observational study of all cases with an antenatal diagnosis of either unilateral or bilateral MCDK referred to a regional tertiary fetal medicine unit between 1997 and 2015. Postnatal diagnosis was confirmed by postnatal ultrasound reports or postmortem examination. The accuracy for prenatal ultrasound in the diagnosis of MCDK was calculated. We also performed a review of the literature using a systematic search strategy, regarding the prenatal diagnosis and diagnostic accuracy of MCDK. RESULTS: We included 144 women in the analysis; 37 (25.7%) opted for pregnancy termination (due to unilateral MCDK with additional abnormalities, bilateral suspected MCDK or severe obstructive uropathy). In 126 women all pre- and postnatal data were available, including 104 livebirths; 19 who opted for TOP and where PM was available; and 3 that had an intrauterine fetal death. Two infants died shortly after birth, (due to known bilateral MCDK and known cranial vault defect). The overall number of postnatally confirmed MCDK was 100: of these 98 were diagnosed prenatally (true positive), while 2 were thought to be hydronephrosis prenatally (false negative) and the diagnosis of MCDK was made after birth. In 9 cases the initial antenatal diagnosis of suspected MCDK was revised, either later in pregnancy (n = 2) or postnatally (n = 7). The overall diagnostic accuracy of MCDK reported in the existing literature was found to range from 53.3 to 100%. MCDK was isolated in the majority of cases, while in 29% of cases was found to be associated with other renal and extra-renal fetal abnormalities. CONCLUSIONS: Our study suggests that the diagnostic accuracy for the use of antenatal ultrasound to detect postnatal MCDK was about 91% and can therefore be used to guide antenatal counselling. However, prenatal or postnatal revision of the diagnosis occurs in about 7% of cases and parents should be counselled appropriately.