Description
The Normal Vulva
The vulva is a complex organ, due to its embryologic derivation from the three germ layers belonging to the embryonic disc:
●● ectoderm (squamous epithelium);
●● mesoderm (connective epithelium);
●● endoderm (vulval vestibule).
This embryological derivation is responsible for the different variants in morphology that occur during the development of the vulva.
A correct and thorough knowledge of the ‘normal’ vulva is vital for several reasons. Firstly, it is important in order to recognize some of the normal anatomical variants in order to differentiate them from pathological features. This will prevent unnecessary excision and treatment of normal areas. Secondly, it leads to a more specific and logical approach in treating vulval disorders. In some conditions, the normal anatomy of the vulva is altered and this can give diagnostic clues.
It is important to note that the ‘normal’ vulva modifies itself during a woman’s lifetime, depending on age, obstetrical and gynaecological history.
Normal vulval anatomy
The vulva may be considered as the combination of the mucosal, cutaneous, muscular and connective tissue structures that compose the lower part of the female genital tract. The peculiarity of this localization means that the vulva is in close association with urological structures (urethra and bladder), gynaecological structures (vagina), and intestinal structures (rectum and anus).
The borders of the vulva are: mons pubis anteriorly, perineal body posteriorly, genital crural folds laterally and hymen medially (Figure 1.1). In this triangular‐shaped region, with naked‐eye examination, five distinct structures clearly appear: the labia majora, the clitoris, the vestibule, the labia minora and the hymen (Figure 1.2 a, b).
There is usually a limited description of the internal structures of the vulva in gynaecological and dermatological textbooks. These structures reach the plane of the perineal fascia (or urogenital membrane) under the skin. A knowledge of the anatomy of these structures and planes then encompasses the clitoral body, the minor vestibular bulbs and glands, the urethral opening and the paraurethral glands, which are all part of the vulva. A good understanding of the anatomy, together with its embryological development, allows a comprehensive approach to vulval morphology and correct surgical dissection if required.