The pelvic floor muscles (PFM) are two layers of muscles that wrap around the vagina and the vaginal opening. These muscles provide structural support for organs, assist with continence (bladder and bowel), contract during orgasm, and also help with stability of your core and posture. On average, the pelvic floor muscles contract 3–15 times during an orgasm. We know this because there have been studies where women have stimulated themselves to orgasm in a highly monitored setting. (I always wonder how people get funding for these kinds of studies!)
Image 3: Pelvic floor muscles. ILLUSTRATION BY LISA A. CLARK, MA, CMI.
Image 4: Female pelvic floor (sagittal view). ILLUSTRATION BY LISA A. CLARK, MA, CMI.
The superficial layer is directly beneath the skin of the vulva and is made of three muscles: ischiocavernosus, bulbospongiosus, and superficial transverse perineal. The point where the superficial transverse perineal, bulbospongiosus, and the anal sphincter come together is called the perineal body.
The deeper layer of muscles extends from the pubic bone from front to back, out to the hips, and back to the coccyx (tailbone), like a hammock. There are openings for the urethra, vagina, and rectum. This deeper layer, called the levator ani, is a made up of three muscles: the puborectalis, pubococcygeus, and the iliococcygeus.
The muscles in your pelvic floor are not typically in your conscious control—you don’t think about emptying your bladder or bowel or about having an orgasm, you just do. Once we get enough motor and sensory control, we train the bladder and bowel to work relatively independently, like a computer program that runs in the background. Evolutionarily speaking, these activities were likely off-loaded from the consciousness because if we had to be constantly aware of regulating bladder and bowel function, we would never have crawled out of the swamp!
Weakness or tearing of the pelvic floor, most commonly caused by childbirth, can contribute to incontinence (both bladder and bowel) and pelvic organ prolapse (descending of the pelvic organs and structures). If the pelvic floor becomes too tight, the resulting muscle spasm can lead to pain with sex and pelvic pain.
The vaginal mucosa
The mucosa (skin) of the vagina is about twenty-eight cell layers thick. Like the vulva, there is a layer of basal cells constantly producing new cells. Unlike in the vulva, the cells of the vagina are filled with glycogen, a storage sugar. They also have much less keratin than the vulva cells, making the surface of the vagina slightly less waterproof than the vulva. This allows a small amount of fluid to leave the bloodstream and leak between the cells of the vagina to become part of the vaginal discharge. This fluid is called transudate. The reduced waterproofing also means some substances can be absorbed from the vagina into the bloodstream.
The vaginal mucosa turns over much faster than the vulvar skin—a new layer is produced every ninety-six hours. There are several biological reasons:
• FRICTION: No matter how gentle you are with a finger, toy, tongue, or penis, friction will rub off the top layer of cells, and this needs to be repaired quickly. If heterosexual sex led to prolonged internal injury, that would dramatically affect our ability to procreate.
• NUTRITION FOR THE ECOSYSTEM: The surface layer of cells sheds approximately every four hours for a woman of reproductive age. These dead cells are filled with the storage sugar glycogen (made of thousands of glucose molecules), which feeds the bacteria that keeps the vagina healthy. Up to 3 percent of vaginal secretions are glycogen.
• CONFUSING THE BAD BACTERIA: The dead cells floating in the vagina work like a decoy. They are the first cells encountered by pathogenic (potentially harmful) bacteria. If this bacteria attaches to these free-floating cells, it gets flushed out as part of the vaginal discharge.
Image 5: Hand holding pad with discharge. ILLUSTRATION BY LISA A. CLARK, MA, CMI.
Vaginal ecosystem
The vagina typically produces 1–3 ml of discharge in twenty-four hours, but up to 4 ml has been reported as normal. For perspective, 4 ml is a completely soaked mini pad, and the image below contains a very normal amount—2 ml.
Based on my anecdotal experience, and from what I hear from colleagues around the country, more and more women erroneously believe that any vaginal discharge is abnormal. I don’t know if this is because mainstream porn frequently looks dry, women don’t talk much about their discharge, more women are removing all their pubic hair and so discharge that would normally be trapped now appears on underwear, or the fact that there are shelves of products in drugstores designed to “tame” a healthy, wet vagina.
Vaginal discharge is made of secretions from the cervix, the glands at the vaginal opening (Bartholin’s and Skene’s), various substances made by the healthy bacteria, cells that have been shed from the vaginal surface, and a small amount of transudate (fluid that leaks across from the bloodstream).
One of the most well-known bacteria in the vagina is the Lactobacillus species (spp.), often referred to as lactobacilli. These are healthy bacteria that protect the vagina. The lactobacilli produce lactic acid, which keeps the vaginal pH between 3.5 and 4.5 (acidic), making it harder for many bacteria and viruses to thrive. Lactobacilli also make proteins called bacteriocins that kill or inhibit the growth of pathogenic (harmful) bacteria—think of bacteriocins like homemade antibiotics. Lactobacilli bind to the mucosal (skin) cells in the vagina, preventing other bacteria from binding. Lactobacilli also produce hydrogen peroxide, which we used to believe had a role in vaginal defense mechanisms (that theory has fallen out of favor).
There are many different species of lactobacilli. The four main ones in terms of the vagina are L. crispatus, L. jensenii, L. iners, and L. gasseri. We are now only beginning to understand the full role of the different lactobacilli species, and so what today we think we know could change. For example, when I was in training everyone thought L. acidophilus was most common, but that was because it was one of the only types of lactobacilli that could be grown easily in a lab. With the advent of DNA technology, we have been able to get a better evaluation of the vaginal microbiome because we don’t have to coax bacteria to grow. We currently believe L. iners is the most prevalent species; 84 percent of women have this bacteria, and it dominates the vaginal microbiome for 34 percent of women. Comparatively, L. acidophilus likely has a minor role, if it even has any at all.
Each woman has one of five community states of vaginal bacteria. Four are dominated by Lactobacillus spp. (73 percent of women); the remaining 27 percent have few lactobacilli and instead have a diverse collection of other bacteria. There are many factors that go into the vaginal bacteria communities, and it is likely a complex combination of genetics and environment. White and Asian women are more likely to have lactobacilli-dominant vaginal communities, whereas approximately 40 percent of African American and Hispanic women have other, non-lactobacilli bacterial communities. The more lactobacilli, the more acidic the vaginal pH, so women who have non-lactobacilli-dominant communities may have a slightly elevated vaginal pH (in the 4.7–5.0 range).
This does not mean that those 40 percent of African American and Hispanic women have unhealthy vaginal bacteria; rather, this is a normal variant. We are only beginning to understand the vaginal microbiome, and many factors besides lactobacilli go into vaginal health.
Vaginal pH increases during menses due to the blood itself, which has a pH of 7.35. Blood also binds lactobacilli, so lactobacilli levels are reduced with bleeding. This is one explanation for why women are most susceptible to infections at the end of their menstrual periods, as they have the lowest counts of good bacteria as well as a higher pH. In addition, blood is also a good medium for bacterial growth.
SHOULD I GET MY VAGINAL MICROBIOME TESTED? There is at least one test on the market that allows you to assess some of the bacteria in your microbiome and, given the expansion