Uterine Sounding: Is There a Difference between Blind and Hysteroscopically Directed Measurements?

Study objective: To evaluate the accuracy of traditional blind uterine sounding in measuring uterine cavity length (UCL), compared with measurement by hysteroscopic guidance.

Design: A cross-sectional descriptive study (Canadian Task Force classification III).

Setting: Academic multispecialty medical center.

Patients: Fifty-eight women undergoing elective hysteroscopic procedures.

Intervention: UCL measurement.

Measurements: UCL measurements were obtained by the traditional blind sounding technique and by hysteroscopically directed measurement. Hysteroscopic measurements were assumed to represent true uterine cavity length. Differences between the 2 measurements were calculated to analyze error and bias.

Results: Mean UCL for blind sounding and hysteroscopically directed measurements were 80.81 mm and 86.55 mm, respectively. The magnitude of error between measurements was >10 mm in 36.2% of cases, with underestimation of true UCL in 55.17% of cases.

Conclusion: True UCL is underestimated by blind sounding, and the frequency, magnitude, and direction of error may be greater than are clinically acceptable.