Purpose: To evaluate the predictive value of a prenatal ultrasound diagnosis of clubfoot, the ability to differentiate isolated clubfoot from complex clubfoot, and establish valid recommendations for follow-up and additional investigations.

Materials and Methods: Clubfoot (CF) was diagnosed by prenatal ultrasound (US) in 85 feet in 48 fetuses at a mean gestational age of 21.6 weeks (14–35.6).

All mothers were examined prenatally in a multidisciplinary clinic for fetal abnormalities. Postnatal outcome was obtained by chart review (24) or telephone interview (24) and feet were classified as Normal (N), Positional Deformity (PD), Isolated Clubfoot (ICF) and Complex Clubfoot (CCF).

Results: At initial diagnosis, 65 feet in 38 fetuses were classified as ICF and 20 feet in 10 fetuses as CCF. Diagnosis was changed during follow-up US in 12 fetuses (25%) and final US diagnosis was N in one, ICF in 29 and CCF in 18 fetuses.

Post natal clubfoot was found in 73 feet in 40 children giving a positive predictive value (PPV) of 85%. Accuracy of specific diagnosis was significantly lower – 65% initially and 75% at final US. No post natal CCF had been undiagnosed and inaccuracies were all overdiagnoses.

24 kariotypes were performed. Three were abnormal but had additional US findings and had been classified as CCF. No abnormal kariotypes were found in fetuses diagnosed as ICF.

Conclusions:

The prenatal diagnosis of clubfoot carries a positive predictive value of 87% with lower values of ICF (76%) and CCF (69%).