Sonographic landmarks to differentiate "false labor" and "early true labor" as a possible new application of ultrasound in labor ward.

OBJECTIVE: To evaluate discrimination of clinical parameters and ultrasound examination to differentiate "false labor" and "true labor".

METHODS: In a prospective study during a period of 6 months, a total of 178 patients in term (37-41 weeks) consulting our obstetric unit for uterine contraction, were enrolled. Patients were examined separately by a midwife and a resident and separated into "true labor group" and "false labor group". The clinical characteristics of true versus false labor patients were compared. ROC curves were developed to determine an optimal cervical length and uterocervical angle for prediction of true labor.

RESULTS: The prevalence of real labor was 57.3%. Patients who were in true labor had more painful and more frequent contractions. The "true labor" group had shorter cervical length and larger uterocervical angle. The optimal CL cut-off was 1.4mm with a specificity of 73% (RR 4.3, sensibility 63%, PPV 14%, NPV 95%). The optimal UCA cut off was 123° (RR 6.7, sensitivity 50%, specificity of 83%, PPV 10%, NPV 96%). The best performance was demonstrated by combined testing, yielding LHR+ that rich 13.

CONCLUSION: In this study, we reported a new application of ultrasound to identify false labor and avoid unnecessary hospitalization with obstetric and adverse economic impacts.