Ejaculation: the Process and Characteristics From Start to Finish

Abstract

Purpose of review: Semen analysis serves as the initial step in the evaluation of male infertility. However, given the difficulty in interpreting abnormal findings, physicians and patients often struggle with understanding the results. In this review, we aim to review the normal physiology of ejaculation and create an accessible resource for interpreting abnormal semen volume, viscosity, liquefaction, pH, appearance, and color.

Recent findings: Emerging evidence has revealed that men with genitourinary tract infections have a greater number of seminal leukocytes, which may result in clumping of motile sperm and altered morphology. Hence, these patients may have abnormal sperm parameters secondary to their health status. Recent findings have further characterized the semen liquefaction process, suggesting that increased levels of semenogelin and decreased levels of proteases and plasminogen activators (e.g., urokinase and chymotrypsin) may be associated with the failure of semen to convert to a watery consistency.

Summary: This article creates a resource which may be referenced when abnormalities in semen analysis are encountered. We offer a comprehensive overview of normal ejaculation physiology and abnormal variants in male ejaculate volume-including aspermia, anejaculation, retrograde ejaculation, and hypo- and hyperspermia-and their potential etiologies. Additionally, we discuss several processes (infection, inflammation, and dysfunction of male sex glands) which may affect semen viscosity, liquefaction, and pH. Finally, our discussion of the potential colors of male ejaculate is meant to reduce the anxiety of both patient and provider. Through a better understanding of the process and varying characteristics of ejaculation, physicians may adequately counsel their patients on abnormal findings and concerns regarding infertility.

Keywords: Ejaculation; Male infertility; Semen analysis; Spermatozoa.