There are few reports of RE associated with congenital malformations of the posterior urethra. In male embryos, the paramesonephric duct undergoes degeneration and the mesonephric duct develops into the vas deferens, ejaculatory duct, and seminal vesicle. The urogenital sinus develops into the bladder, prostate, urethra, urethral gland, prostatic urethra, membranous urethra, and penile urethra. In this case, malformation of the posterior urethra may have been associated with the development of the urogenital sinus in the embryonic period. The causes of RE can be anatomical, neurogenic, or pharmacological, and ultimately impair normal anterograde ejaculation. Two distinct phases are involved in the normal physiology of ejaculation: emission and expulsion. Emission, the first stage of ejaculation, refers to deposition of the semen in the posterior urethra through the peristaltic contraction of the epididymis, vas deferens, seminal vesicles, and prostate; expulsion is defined as the transport of the semen through the urethra. Normal expulsion relies on synchronized interplay of many factors, including urinary bladder neck closure, periurethral muscle contraction, and relaxation of the external urinary sphincter. Among these factors, bladder neck contraction plays a vital role in preventing retrograde flow of semen into the bladder, and can reach a pressure of up to 500 cm H
2O [
3]. Neurogenic or myogenic factors interfering with the bladder neck contraction can lead to RE; for instance, injury of the nerves or normal anatomic structure of the bladder neck during transurethral prostatectomy is the most common cause of RE [
4]. In addition to closure of the bladder neck, other factors influencing involved expulsion also contribute greatly to anterograde flow of seminal fluid. A urethral stricture, for example, in which stenosis of the bulbous urethra can obstruct the flow of seminal fluid from the posterior urethra, can result in RE. The presence of a posterior urethral valve may also be a cause of anatomical RE [
2]. Thus, when there is weakness of bladder neck contraction or a stricture of the urethra, RE is induced by pressure that reduces the flow of seminal fluid in an anterograde direction (bladder neck contraction) and/or pressure preventing anterograde flow of the seminal fluid (urethral stricture).
In this case, malformations of the prostatic urethra, including absence of the verumontanum and the presence of cysts in the ejaculatory duct, could have affected the expulsion process. The verumontanum was replaced by a deep groove adjacent to the bladder neck, which could have affected contraction, thereby decreasing the pressure that causes seminal fluid to flow in an anterograde direction. In addition, cysts in the ejaculatory duct obstructed the anterior outlet of the prostatic urethra, and the increased pressure could have induced RE. Thus, the unusual combination of multiple malformations could have caused RE.
Several approaches have been used in the treatment of RE, including medical therapy (alpha-agonists and tricyclic antidepressants), penile vibratory stimulation, electroejaculation, and bladder neck reconstruction surgery [
5]. These methods aim at restoring the normal physiology of anterograde ejaculation. However, congenital RE resulting from an anatomical malformation is rare, and no consensus treatment regimen has been reported. Moreover, most patients with RE seek treatment because of male infertility, and urinary sperm is usually retrieved for use in artificial insemination.