Knowledge of pertinent normal lower genital tract anatomy is also useful when identifying vaginal and vulvar cysts [3]. The vagina, an empty tubular structure with a lumen that is held in place by its surrounding muscular and connective tissue support structures, sits between the bladder and rectum. The most proximal aspect of the vagina, the vaginal apex, heads posteriorly toward the ischial spines. Normal vaginal length is generally between 7 and 10 cm. In the absence of prior total hysterectomy, the cervix is present at the vaginal apex. The outer portion of the cervix (the ectocervix) is made of nonkeratinized stratified squamous cells and the inner portion and canal of the cervix (the endocervix) is comprised of simple columnar cells. Where these two different cell types meet is termed the transformation zone. The vaginal walls consist of three layers. The first layer in direct communication with the vaginal lumen is the vaginal epithelium (also referred to as “mucosa” despite an absence of glands) that is made of nonkeratinized stratified squamous epithelium. Deep to the mucosa is the muscularis that contains smooth muscle, collagen, and elastin. The deepest layer is the adventitia that is made of collagen and elastin connective tissue. The muscularis and adventitia together are referred to as the fibromuscular layer, and is commonly referred to as the pubovesicocervical fascia anterior to the vagina or the rectovaginal fascia posterior to the vagina. On the lateral aspects of the vagina, the adventitia extends out to the pelvic walls and contains fat, lymphatics, and neurovasculature.

Blood is supplied to the vagina from the descending cervical branch of the uterine artery and branches of the internal iliac artery including the vaginal, middle rectal, and internal pudendal arteries. Lymphatic drainage of the upper two-thirds of the vagina is to the obturator nodes as well as the external and internal iliac nodes, while the lower third of the vagina drains to the inguinal nodes [4]. Portions of the inferior hypogastric plexus are responsible for sympathetic innervation of the vagina [5].

The urethra, which averages 3 cm in length, rests on and is supported by an endopelvic fascial layer and the anterior vaginal wall [6, 7]. It is comprised of four layers: mucosa, submucosa, internal urethral sphincter made of smooth muscle, and striated external urethral sphincter made of skeletal muscle. The inner surface of the proximal urethra is lined by transitional epithelium while the distal urethra is lined by stratified squamous epithelium [8]. This epithelium is continuous with bladder epithelium proximally and with that of the vaginal vestibule distally. Paraurethral glands open into the urethral lumen within this layer in the dorsal or vaginal side of the distal urethra [9]. The most pronounced of these paraurethral glands are the Skene glands that can be visible on the inner surface of the external urethral meatus. Blood supply to the urethra comes from the internal pudendal, vaginal, and inferior vesical arteries, while nerve supply comes from the pudendal nerve for somatic control and portions of the inferior hypogastric plexus for autonomic control [10]. The lymphatics of the distal third of the urethra drain into the superficial or deep inguinal nodes, whereas the proximal two-thirds drain into the external iliac, internal iliac, and obturator nodes.

The vulva is the term for the female external genitalia and includes the mons pubis, labia majora, labia minora, clitoris, vestibule, vestibular bulbs, vestibular glands, Bartholin (greater vestibular) glands, Skene (paraurethral) glands, external urethral meatus, and vaginal orifice. The skin over the mons pubis and labia majora has hair and a fatty subcutaneous layer. The obliterated processus vaginalis, or canal of Nuck, and the round ligament exit the inguinal canal and terminate within the fat or skin of the labia majora. The skin over the labia minora does not have hair and its subcutaneous tissue is devoid of fat.

The vaginal vestibule is an area in between the labia minora. The specific boundaries include the clitoris anteriorly, the fourchette posteriorly, the Hart line laterally, and the hymen medially. Distal to the Hart line the exposed tissue is a keratinized stratified squamous epithelium, while proximally it is nonkeratinized stratified squamous epithelium. The vestibule also contains the urethral, vestibular, Bartholin, and Skene gland openings.

The Bartholin glands are the female equivalent of the male bulbourethral, or Cowper, glands. One gland is situated at 5 O’clock while the other rests at the 7 O’clock position and each gland possesses a duct that opens into the vaginal vestibule. The inner surfaces of these glands are lined by columnar cells that secrete mucus to provide lubrication [11].

A history and physical exam is the starting point of any vaginal or vulvar cyst workup. Specific symptoms to address in the patient’s history of present illness include the presence or absence of vaginal or vulvar pain, dyspareunia, urethral versus vaginal discharge, spotting, post-void dribbling, leakage of urine, dysuria, incomplete voiding, or palpable mass. The patient should be questioned regarding recent vaginal trauma or placement of foreign body into the vagina. Pertinent aspects in the history include age, known congenital urogenital tract anomalies, obstetrical history including vaginal trauma and repair, sexual activity, recurrent urinary tract infections, prior vaginal surgery, and history of pelvic radiation therapy. Gynecological history including menstrual cycles, prior vaginal infections, endometriosis, fibroids, and exposure to diethylstilbestrol (DES) in utero may be specifically applicable to the patient’s presenting condition.

A targeted physical examination should include bimanual and speculum exams. A pelvic organ prolapse assessment to rule out prolapse as a cause for vaginal bulge symptomatology should be completed. Special attention should be taken to palpation of the anterior vaginal wall; a compressible bulge and discharge per urethra should raise suspicion for urethral diverticulum. Vaginal discharge should be evaluated. Masses such as cystic-appearing bulges should be examined with special attention taken to note the size, location, and tenderness of the cyst.