Prospective Evaluation of a Prenatal Sonographic Clubfoot Classification System

Abstract

Background: The purpose of this study was to prospectively evaluate our recently described fetal sonographic classification system for prenatal diagnosis of clubfoot. Methods: Over 18 months, we prospectively enrolled consecutive pregnant patients evaluated for a prenatally diagnosed clubfoot. Prenatal sonographic scores assigned by a radiologist were compared to final clinical diagnosis and severity given by a pediatric orthopedic surgeon. Pearson's χ² test and logistic regression were used in statistical analyses on the subject level. Generalized estimating equations were used in analyses on the foot level to account for intrasubject correlation. Results: There were 50 subjects, with 26 unilateral and 24 bilateral clubfeet, according to the prenatal ultrasound (US). A total of 51 (69%) of 74 feet and 36 (72%) of 50 subjects had a postnatal diagnosis of clubfoot. The accuracy of diagnosis in cases of a severe, moderate, and mild US score was 94, 70, and 25%, respectively (p = 0.003 comparing moderate-severe vs. mild). US severity correlated with the Dimeglio classification scoring system (Spearman's correlation 0.30). Conclusion: The fetal sonographic scoring system is predictive of clinical severity after birth, and improves the ability to counsel families with a prenatal diagnosis of clubfoot.

QUESTION 2: What is the predictive value of an antenatal ultrasound showing apparently isolated talipes equinovarus?

“…Twenty-three studies (22 retrospective case series2–23 and 1 prospective observational study24) with patient data subsequent to ultrasound scans showing an apparent isolated TEV (defined as an intrauterine clubfoot deformity without other associated congenital anomalies identified) were examined. Seven were excluded as they did not adequately define the key population (fetally diagnosed isolated TEV), either because apparent isolated TEV and ‘complex’ cases were inappropriately treated as a homogeneous group3 11 13 17 18 21 or because the case-capture mechanism for the series (eg, TEV identified at birth) would not pick up all (or a representative sample of) fetally diagnosed isolated TEV, including false positives 22.…”

“…Furthermore, seven studies (four further) were excluded due to a loss to follow-up of >10%, which might lead to selection bias 6 8 11 13 18–20. Finally therefore, 12 papers2 4 5 7 9 10 12 14–16 23 24 were used in the analyses (table 1; for excluded data see online supplementary appendix). …”

“…Given that feet with positional TEV do not require treatment, they should not be considered a positive finding 14 21 26 27. The number of cases lost to follow-up in these series may contribute to an underestimation of FPR, given that these cases are more likely to be ‘normal’ or positional TEV given the relative frequency of these diagnoses, as compared with structural TEV 24 26…”

“…To calculate false positive rate, we excluded four studies not adequately discriminating between positional TEV and structural TEV,2 4 10 15 leaving eight studies,5 7 9 12 14 16 23 24 from which pooled data (283 cases of fetally diagnosed isolated TEV) yield an false positive rate of 18.0% (51/283). Only four studies provided subgroup data for isolated unilateral TEV versus isolated bilateral TEV,7 9 23 24 constituting 52 unilateral and 78 bilateral cases with associated false positive rates of 15.4% (8/52) and 14.1% (11/78), respectively.…”

“…Only four studies provided subgroup data for isolated unilateral TEV versus isolated bilateral TEV,7 9 23 24 constituting 52 unilateral and 78 bilateral cases with associated false positive rates of 15.4% (8/52) and 14.1% (11/78), respectively.…”