The diagnosis of bladder outlet obstruction (BOO) in women has become a challenge for functional urology. Up to date, the lack of one definition worldly accepted resulted in the creation of many definitions with different cut-offs. 

The objective of this study is to compare six different definitions of BOO and evaluate the interobserver agreement in a group of 4 residents of general urology and one graduated urologist.

After institutional approval, we invited all residents and attendings of urology service to a theoretical-practical workshop where we explained to them the interpretation of the pressure flow urodynamic studies and taught six different definitions of BOO; Farrar, Chassagne, Lemack, Defreitas, Blaivas y Groutz, Solomon-Greenwell. After that we invited one resident of every year and one graduated urologist, with prior consentient of the participants, we applied a test where they had to evaluate 30 urodynamic studies (UDS) and classified them in obstructed or unobstructed according to 6 different definitions learned in the previous workshop. Finally, we asked them to choose the easiest, the hardest and the fastest definitions based on their personal feelings.

Interobserver agreement of all 5 participants was assessed by kappa statistical analysis, the cut-offs values for this analysis were: <0 no agreement; 0.01-0.2 slight agreement; 0.21-040 fair agreement; 0.41-0.60 moderate agreement; 0.61-0.80 substantial agreement; 0.81-1.0 almost perfect agreement. We classified the type of mistakes the participants made; error of interpretation of urodynamic studies and miscalculation in the criteria. P values were considered significant at <0.05.

Urodynamic Studies of a total of 30 women were reviewed of these we excluded 2 because they did not meet de quality control.
We obtained substantial agreement for Farrar, Chassagne, Defreitas and Blaivas-Groutz definitions, we obtained fair agreement for Lemack and Solomon-Greenwell definitions. Table 1.
From a total of 840 responses we found 120 errors, we classified the type of mistakes the participants made; error of interpretation of urodynamic studies (45.8%) and miscalculation in the formula (54.1%). Table 2 demonstrates the type of mistakes for every participant.
Finally, 100% of the participants chose the Solomon-Greenwell as the most difficult definition, for the easiest 40% chose Defreitas; 40 %, Farrar 40% and Chassagne 20%. For the fastest they chose 40% Defreitas; 40 %, Farrar and 20% Blaivas and Groutz.

This study proved less interobserver variability and highest agreement between Chassagne, Defreitas and Farrar definitions. These definitions also shown less mistakes and were considered fast and easy when applying the diagnostic criteria. Solomon-Greenwell was reported as the most difficult and had more errors in miscalculation may be because it implies a complex formula. The study also shown less error rate as the year of residency increased, this can be explained by their experience in the rotation of urodynamics department. The result of the graduated urologist may be explained because its main practice is not related with functional urology

Chassagne, Defreitas and Farrar definitions proved substantial interobserver agreement. Solomon-Greenwell and Lemack were the definitions where the highest number of pitfalls were seen also the lowest level of agreement.