Hysteroscopic Evaluation of Fallopian Tubal Patency

Introduction and scientific background:

Hysteroscopy is an important tool in the evaluation of sterility. It allows direct visualization of the uterine cavity and enables the diagnosis of numerous pathologies. Hysteroscopy shows high reliability and is considered the gold standard for intrauterine evaluation.

When performing hysteroscopy, experts often assess the patency of the tubes via the visibility of flow of the hysteroscopic fluid going through the ostia of the tubes. In the recently published study "Assessment of tubal patency: A prospective comparison of diagnostic hysteroscopy and laparoscopic chromopertubation" - it has been demonstrated that visualizing contrasting substances disperse through the ostia is a significant and meaningful metric for tubal patency.

Pre- and posthysteroscopic vaginal sonography for the evaluation of the hysteroscopic fluid in the pouch of Douglas, selective hysteroscopic pertubation of the tubes and the visibility of air bubbles traversing through the Fallopian tube ostia after an air infusion into the uterine cavity have been reported to be reliable methods for hysteroscopic tubal patency assessment. Particularly the last one, also called the "Parryscope technique", named after its inventor, seems to be highly reliable, easy to conduct and clinically relevant. The "Parryscope technique" seems to perform even better than the technique evaluating the "tubal flow".

Assessing tubal patency during hysteroscopy is highly relevant, particularly when it allows for a low cost, fast, gentle, and accurate way of gathering information that may guide clinical care. Therefore, it is important to know which of the above-mentioned techniques is the best. This prospective randomized study aims to compare the hysteroscopic assessment of the tubes via "tubal flow" and the "Parryscope technique".

Study aims:

The primary aim of this study is to evaluate the reliability of (1.) the hysteroscopic visualization of a "tubal flow" and (2.) the "Parryscope technique" as compared to the gold standard, namely laparoscopic chromopertubation.

Study hypotheses:

Null hypothesis: The hysteroscopically visualizable "tubal flow" and the "Parryscope technique" are similarly reliable in the evaluation of tubal patency.

Alternative hypothesis: The hysteroscopically visualizable "tubal flow" shows a lower sensitivity and specificity than the "Parryscope technique" for the evaluation of tubal patency.

Study design:

Prospective, randomized study.

Recruitment:

Women will be invited to participate by medical professionals at the Department of Obstetrics and Gynecology of the Medical University of Vienna using the above mentioned criteria in the course of their admission to the ward one day before surgery. Potential participants are informed about the procedure, clinical relevance and the balance of risk and benefits incurred through study participation. Patients willing to participate will express this through written affirmation (a "consent form").

Additional considerations:

1. Since in the "flow"-group air bubbles might develop spontaneously and, thus, should be assessed, conducting the "Parryscope"-technique is only possible after the evaluation of the tubal flow.
2. Reactive tubal spasms could occur especially during a prolonged hysteroscopy.
3. This is why in one particular patient only one technique should be performed.

Sample size calculation:

The calculation is based upon the following considerations:

1. Direct comparison of the two groups is not possible. Hence, separate evaluation of the two methods will be performed. Evaluating both methods in one particular patient in the course of a single intervention is impossible without a mutual interference (see: "Additional considerations" above).
2. The "flow effect" is considered the less reliable method and thus, the sample size was aligned to this method. An odds ratio of approximately 10, an alpha of 5%, a power of 80%, a general disease likelihood of 39% and a sensitivity of 66% for occluded tubes result in a total amount of 59 tubes and, accordingly, 30 patients.
3. Thus, the group for the "Parryscope"-technique should also contain 59 tubes (= 30 patients).
4. The randomization of the total 60 patients is performed as block randomization in 4 blocks via the software "R".

Statistical analysis:

Numerical data will be reported as mean and standard deviations, nominal variables as number and frequency. The McNemar Test will be used for the calculation of the reliability of the hysteroscopic assessment of the tubes. The sensitivity, specificity, positive and negative predictive values will be provided including the according 95% confidence intervals (95% CI) for both study groups (evaluated technique versus gold standard laparoscopic chromopertubation). Whether the according odds ratio is over 10 will be evaluated by the use of a binary logistic regression model. Statistical analyses were performed with the software "R". Differences were considered significant if p<0.05.

Data quality evaluation:

Extreme values will be double-checked. In addition, a random checks by two independent investigators to ensure the accuracy of the data will be conducted.