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Abstract

Sir, We thank Dr. Sjors Coppus for his interest in our article. The sensitivity and specificity of 3D-HyCoSy stated in the article referred to those for detection of tubal patency in our study, as stated in the abstract and results sections of the manuscript. Although the sensitivity and specificity for tubal occlusion are used in most studies, some studies did express their results in terms of tubal patency 1, 2 including the largest study evaluating the diagnostic accuracy of HyCoSy as compared to laparoscopy by Hamilton et al. 1. In fact, the same problem exists when studies comparing the diagnostic accuracy of various modalities of evaluating tubal patency. In the future, it will be ideal to standardize the data presentation method. In our study, we were unable to determine the tubal patency in 8 out of 42 (19%) tubes. In two patients (9.5% of patients), the procedure was abandoned because of excessive pain. They represented true procedure failure. The percentage was compatible with that reported (7.4%) in the literature 1. We failed to trace the remaining 4 tubes in 2 patients to the fimbrial end and hence could not draw a conclusion as to whether the tubes were patent. This represented 10.5% of all tubes that were subjected to 3D-HyCoSy assessment and was again compatible with that reported (7.4%) in the study by Hamilton et al. 1. Two early studies evaluating tubal patency with 3D-HyCoSy reported even higher failure rates (14.9% and 24%) in visualizing the entire tube 2, 3. The interpretation and calculation of the test accuracy of the inconclusive results from 3D-HyCoSy did present a problem. There is no ideal way to solve this problem, which happens in real clinical situations. We have chosen to assume those which were inconclusive as discordant with laparoscopy so as not to over-exaggerate the diagnostic accuracy of this new modality of tubal assessment at the expense of underestimating its performance. Nevertheless, we believe that one should be more stringent in the evaluation of a new diagnostic method. Underestimating is always better than overestimating its usefulness as a new diagnostic tool. Expressing the sensitivity and specificity of the HyCoSy test based on the number of Fallopian tubes studied has been used previously 1, 2, 4. Using the number of Fallopian tubes rather than patients studied as the base for calculation better reflects the usefulness of this new diagnostic tool in the study of tubal status. Even when clinical practice is concerned, unilateral tubal blockage still bears significance in deciding the treatment that should be advised. Patients should be treated with superovulation and intrauterine insemination only when both tubes are patent. Those with tubal disease including unilateral tubal blockage should be offered in vitro fertilization early. There is little controversy in the operator dependency of conventional 2D-HyCoSy as pointed out by Dr. Sjors Coppus. 3D-HyCoSy has the advantage that the images can be captured at the time of scanning and be evaluated later, so that the requirement on the technique of the operator is minimal. Although we did not evaluate the intrapersonal variability in diagnosis of tubal patency, the reproducibility can be indirectly reflected by the relatively lower percentage of tubes that could not be evaluated in our study as compared to that previously reported 2, 3. All images were analyzed by a single investigator and hence any interpersonal variation was eliminated. We admit that this study was a preliminary one and further evaluation on the diagnostic accuracy, patient acceptability, and cost-effectiveness has to be performed before it can be recommended as a standard diagnostic tool in the initial assessment of patients with subfertility.