FormalPara Definition

The word smegma is of Greek origin meaning soap or an ointment.

Smegma has characteristic slimy odour, composed of epithelial debris, fat, and proteins. It has mixed bacterial flora with smegum bacillus (Mycobacterium smegmatis) in 50 % of man.

FormalPara Nomenclatures

  • Smegma clitoridis: smegma in females, it collects around the clitoris and in the folds of the labia minora (Fig. 36.1).

    Fig. 36.1
    figure 1

    Smegma secretion in a female neonate

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  • Smegmaliths: Pieces of hard contaminated and retained smegma

  • Smegma Stone: Accumulated hard smegma under the prepuce (Fig. 36.2).

    Fig. 36.2
    figure 2

    Smegma collection under the perpetual orifice in a neonate

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  • Smegmoma: Perpetual smegma cyst (Fig. 36.3).

    Fig. 36.3
    figure 3

    Perpetual smegma cyst seen in the undersurface of the prepuce

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1 Smegma in History

French physician, Claude-François Lallemand (1790–1853), pronounced that smegma could provoke erections that would lead to ‘disastrous pleasures’.

American physician Roberts Bartholow (1831–1904) formulated the theory that smegma produced ‘hyperæsthesia’ of the glans.

American urologist Abraham Wolbarst (1872–1952), who updated the demonization of the foreskin and promulgated the idea that it harboured ‘carcinogenic secretions’ [1].

2 Secretion

It is secreted in both female and male mammalian genitalia.

Smegma was originally thought to be produced by sebaceous glands near the frenulum called Tyson’s glands; however, subsequent studies have failed to find such glands. Wright [2] states that smegma is produced from minute microscopic protrusions of the mucosal surface of the foreskin and that living cells constantly grow towards the surface, undergo fatty degeneration, separate off, and form smegma. Parkash et al. [3] found that smegma contains 26.6 % fats and 13.3 % proteins, which they judged to be consistent with necrotic epithelial debris. It is thought to be rich in squalene (oily material gives smegma the fishy odour), and contain prostatic and seminal secretions, desquamated epithelial cells, and the mucin content of the urethral glands of Littré. Newly produced smegma has a smooth, moist texture.

Chemically, smegma contains immunologically active compounds such as cathepsin B, lysozyme, chymotrypsin, neutrophil elastase, cytokines, and hormones such as androsterone. Lytic materials, such as lysozyme, which probably originates from the prostate and seminal vesicles, destroy bacterial cell walls and inhibit and destroy candidal species. Some state that it contains anti-bacterial enzymes such as lysozyme and hormones such as androsterone, though others dispute this [5].

According to Wright [2], little smegma is produced during childhood, although the foreskin may contain sebaceous glands. She also says that production of smegma increases from adolescence until sexual maturity when the function of smegma for lubrication assumes its full value, and from middle-age production starts to decline and in old age virtually no smegma is produced.

Øster [4] reported that the incidence of smegma increased from 1 % among 6- to 7-year-olds and 8- to 9-year-olds to 8 % among 14- to 15-year-olds and 16- to 17-year-olds (an overall incidence of 5 %) (Figs. 36.4 and 36.5).

Fig. 36.4 and 36.5
figure 4

Different distribution of smegma after retraction of the prepuce

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3 Smegma and Cancer

Although the carcinogenicity of smegma has never been demonstrated, smegma has been cited as a carcinogen by at least one article in the 1940s and 1950s, nine articles in the 1960s, four articles in the 1970s, seven articles in the 1980s, 17 articles in the 1990s Some studies have indicated a possibility that smegma may contain cancer-causing substances. They do state, however, that this link has not been proven [1].

According to the American Cancer Society it is now mainly believed that smegma itself is probably not responsible for penile cancer, but that it could potentially increase the risk of cancer by causing irritation of the penis [7]. Hence, any potential cancer-inducing property could well lie in products formed by chemical breakdown or bacterial action rather than in smegma itself [6].

4 Function

Smegma protects and lubricates the glans and inner lamella of the prepuce, facilitating erection, preputial eversion and penetration during sexual intercourse. This natural lubricant allows for prolonged intercourse and eliminates the need for artificial supplemental lubrication during normal coitus or masturbation.

5 Our Concept

Some boys may present with one or more yellowish lumps on the penis that are often diagnosed by the general practitioner as sebaceous cysts or lipoma of the penile shaft. Invariably, on outpatient assessment, these prove to be collections of retained smegma trapped by surrounding preputial adhesions (Figs. 36.6 and 36.7).

Fig. 36.6
figure 5

Smegma cyst after circumcision

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Fig. 36.7
figure 6

Multiple small smegma cysts at the edge of circumcision

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Smegma is the natural recreation of the prepuce, like other body secretions, (like ear wax). So it is not harmful by itself, unless it is complicated by other pathogens; either bacterial colonisation, virus overgrowth or combined organisms, or associated with phimosis and different forms of balanitis or balanoposthitis.

Smegma secreted during the late intrauterine period, as many neonates, and preterm may had an accumulated smegma in the 1st day of life (Fig. 36.2).

Smegma secretion and distribution had a great variations between individuals as we can see from Figs. 36.4 and 36.5, without a clear explanation.

Smegma should be cleaned frequently in uncircumcised boys by the mother during childhood, and by the boys himself latter on.

During circumcision, smegma should be cleaned and removed meticulously with saline wash, otherwise any retained small pieces will accumulate between the edges of perpetual remounts and results in different forms of cysts of smegma, which may acquire larger size and be troublesome (Figs. 36.6 and 36.7).