Labia majora

The labia majora are 7 to 8 cm long, 3 to 4 cm wide, and 2 to 5 cm thick; they extend between the pubis and approximately 3 cm from the anus. The subcutaneous tissue consists of loose areolar tissue that is rich in fat, and superficially, sebaceous glands. Vascularization is provided by a rich anastomosis of branches of the internal pudendal artery: posterior labial branches, branches of the pudendal artery, and branches of the perineal artery. No major vessels are found in the labia majora.

Innervation of the labia majora is from the perineal and labial branches of the perineal nerve. Lymphatic drainage is to the superficial inguinal lymph nodes.

Interlabial Sulcus

The interlabial sulci, left and right, separate the labia minora from the labia majora.

Labia Minora

The labia minora are 4 to 6 cm long and 2 to 4 cm wide; they extend off the vestibule of the clitoris, next to the prepuce of the clitoris. The subcutaneous tissue consists of firm connective tissue, erectile tissue, and elastic fibers, with no adipose tissue. The nervous and vascular fascicle underlies all of the labium. Vascularization is provided by the labial artery and vein, which run at the base of the labia and give branches to the labial crest that anastomizes superiorly with the periclitoral branches of the dorsal artery of the clitoris. ¹ Innervation is by the labial nerve, which runs with the vessels and gives terminal branches to the labial crest and the labial walls. ²

Clitoris

The clitoris, a double-arch–shaped erectile organ, is 2 to 3 cm long. The first arch is composed of three parts (three corpora cavernosa, the clitoral crura, and a footing with the suspensory ligament), whereas the second arch is composed of two bulbs (1 to 3 cm long) located in the lateral superior portion of the vagina. Arterial supply to the clitoris is provided by the deep arteries that supply the corpus cavernosum; the arteries of the bulb supply the bulb of the vestibule. The dorsal artery of the clitoris runs on the dorsum of the clitoris to the glans, where it divides into branches that supply the glans and prepuce.

The dorsal veins are the most relevant and drain into the internal pudendal veins. Innervation to the clitoris is provided by the inferior hypogastric plexus and the pudendal nerve. ³

Vagina

The length of the vagina is approximately 7.5 to 9 cm. The vaginal lumen varies in size, with some anatomic variations, and alterations resulting from vaginal delivery of a baby. The vagina is an elastic, muscular tube paved by mucosa with an underlying lamina propria of connective tissue, then a thin layer of smooth muscle, followed by the adventitia, a thin layer of dense connective tissue. The lamina propria of the mucosa contains elastic fibers as well as a dense network of blood vessels, lymphatics, and nerves. Transudate from blood vessels, combined with cervical mucus secreted by glands, provides lubrication during sexual arousal and intercourse.

The vagina is divided into four fornices: one anterior, one posterior, and two lateral. In the anterior fornix, deep to the mucosa, a thin layer of loose areolar tissue can be found in the midline that runs from the urethra and is covered by the urethral sphincter. Posteriorly, the rectovaginal space hosts the rectum muscle and the rectal fascia. In the first 4 to 6 cm, the space is thicker (2 to 5 cm) and progressively becomes thinner. The mucosa of the two lateral fornices is firmly attached to the bulbocavernosus muscle by a network of fibers The bulbocavernosus muscle is thin, 0.5 to 1.5 cm thick. Laterally, the ischiorectalis fossa hosts a fat pad that separates the pubococcygeal muscle from the ischiocavernosus muscle. Inside the fat pad run small branches of the perineal artery, and more posteriorly, of the internal pudendal artery. ⁴

The arterial supply to the vagina arises from three sources:

1. 
   

   Vaginal branches of the uterine artery for the upper vagina

   
   
2. 
   

   The vaginal arteries, branches of the hypogastric artery, to the middle vagina that penetrate the vaginal tube perpendicularly

   
   
3. 
   

   The middle hemorrhoidal and clitoral arteries that send branches to the inferior portion of the vagina

The nerve supply to the vagina is from the autonomic nervous system. Sensory fibers arise from the pudendal nerve, and pain fibers are from sacral nerve roots.

Lymphatic drainage of the vagina is generally to the internal and external iliac nodes and the superficial inguinal and perirectal nodes.

Safe Areas for Injection

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  Labia majora

  
  
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  Periclitoral area: Superficial layers around the clitoris are safe areas to inject, with care to avoid the nervous-vascular bundle running perpendicular to the clitoris

  
  
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  Lateral-anterior portion of vaginal walls

  
  
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  Inferior rectovaginal space (3 to 5 cm from the introitus)

Moderate-Risk Areas: Injections Must Be Performed With Great Care

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  Labia minora: The labial artery courses at the base of the labia; the surgeon placing fat grafts in the labia minora should be aware of this vessel and should avoid the use of small cannulas and needle.

  
  
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  Anterior vaginal wall: No fat should be placed close to the urethra, unless treatment of urinary incontinence is considered, to avoid potential perforations and urethral distortions.

  
  
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  Lateral to the bulbocavernosus muscle: The ischiorectalis fossa contains branches of the perineal and internal pudendal artery.

  
  
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  Perineal area close to the rectum: There is a risk of perforations.

High-Risk Areas

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  Major vessels can be found in the deep layers. The surgeon must avoid fat grafting where major vessels run and exercise special care injecting close to the rectum, urethra, and peritoneum.

  
  
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  Superior vaginal walls can present problems for fat grafting, as a result of the very short distance between the vaginal walls and the bladder and peritoneum; ultrasound-guided injections are recommended.

  
  
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  The superior part of the rectovaginal septum requires caution because of the thinness of the septum itself.

Volume Enhancement

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  Harvesting with 2 mm cannulas

  
  
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  Centrifugation at 3000 rpm for 2 minutes

  
  
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  Fat grafting with 1.20 mm (18-gauge) 1.60 mm (16 g) blunt cannulas