Complete bilateral ejaculatory duct obstruction (EDO) will cause infertility; semen analysis in such cases shows azoospermia. The phenomenon is suggested to account for ≈ 5% of men with azoospermia. As ≈ 1% of infertile men present with azoospermia, two of 10 000 infertile men are expected to have EDO. This means that, e.g. in Germany, where the number of infertile men in a given birth cohort is estimated to be ≈ 50 000, this phenomenon should be observed in 10 men per year. Thus it is a rare disease. It is understandable that there are no systematic published studies on the causes, symptoms and treatment possibilities. Knowledge on these topics will be gained only by meta-analysis of reports on few patients; however, this requires that variables of the disease are cited in an evaluable manner. Thus it is regrettable that these authors  do not present, e.g. histological data, on their excised material, which would provide information on the causes.
Obviously, in such a rare disease no randomized clinical trials of treatment procedures are available. The authors recommend surgical intervention as one therapeutic possibility, which lead to an improvement in ejaculatory symptoms in their patients. However, if knowledge of the possible causes of EDO could be substantially increased the procedures for prevention and early conservative treatment might also be useful.
In terms of infertility the surgical intervention was highly effective; four of six patients, who could be followed by the authors, achieved paternity. This rate is considerably higher than that after treatment for other causes of azoospermia. In epididymal duct obstruction at most 10% of patients will benefit from therapeutic interventions, including microepididymal sperm aspiration and testicular epididymal sperm extraction in terms of paternity. Thus treating EDO appears to be satisfactory.
Patients with complete EDO are clinically impressive because of their apparent infertility, but the authors speculate that some patients might have partial EDO, and that they can be identified from clinical symptoms. Therefore they appeal to clinicians to use a systematic evaluation of ejaculatory symptoms to detect these patients. I further speculate that partial EDO may progress to complete EDO, and preventive treatment would inhibit this development. Again, increased knowledge of the causes is mandatory.