Perineal Ultrasound: a Review in the Context of Ejaculatory Dysfunction. 
Ejaculation consists of the emission of semen from seminal vesicles and prostate, followed by expulsion.  Ejaculatory dysfunction may take several forms including premature ejaculation, delayed or anejaculation, retrograde ejaculation, and painful ejaculation.  Ejaculation is what we can see whereas orgasm is what we feel.  The presence of ejaculate does not indicate the ability to experience orgasm.  Hence, for the purpose of this work we consider orgasm and ejaculation as 2 separate neurobiological phenomena.  To review the role of advanced investigative techniques such as perineal ultrasound in the diagnosis and management of ejaculation and ejaculatory dysfunction.  We performed a PubMed search for key words individually and in combination: "ejaculation," "ejaculatory dysfunction," "delayed ejaculation," "painful ejaculation," "retrograde ejaculation," "perineal ultrasound," and "transrectal ultrasound."  We also share our local experience using perineal ultrasound in assessing ejaculation.  Perineal ultrasound can be used as an aid in the investigation of ejaculatory dysfunction.  Evaluation of ejaculatory function hinges on a detailed psychosexual history and appropriate physical examination.  Function of the ejaculatory center in the spine is androgen dependent; thus, hormonal evaluation is an important aspect of the workup.  Disorders of ejaculation and orgasm require evaluation of neuromuscular reflexes activated during sexual activity.  Dynamic ultrasonographic (US) ejaculatory-orgasmic studies allow for reproducible and detailed descriptions of the sexual response.  Transrectal ejaculatory studies are useful in uncovering reasons for lack of antegrade semen emission, especially in men with poor sperm production or after vasectomy.  Dynamic US studies contribute clinical utility in its non-invasive nature and can provide insight to the dynamic processes surrounding pelvic floor functioning in men.  Perineal US for men with delayed ejaculation or anejaculation, painful ejaculation, or retrograde ejaculation may be helpful in select cases.  Further research using this modality may help advance our understanding of ejaculatory dysfunction.  Forbes CM, Flannigan R, Paduch DA.  Perineal Ultrasound: a Review in the Context of Ejaculatory Dysfunction.  Sex Med Rev 2018;6:419-428.