Epidemiology and classification

Important in the diagnosis of a woman's sexual disorder are a detailed sexual history and any objective measures which can be obtained through validated tools. Prior to the most recent classification by the DSM-5, the problems comprised four major categories, viz.

The various subtypes of sexual problems encompassed by the DSM-5 have important implications in their differential diagnosis. A clinically common presentation in women, irrespective of age, is sexual desire disorder with or without changes in the arousal response. Notwithstanding a harmonious relationship with the partner, lack of desire may impinge on the sensitivity or receptive­ness to sexual cues. Sometimes, absent or reduced sexual desire may be the cause or consequence of interpersonal factors in a relationship (7). Backed by large population data, a systematic survey confirmed the prominent role of central desire/arousal in women's sexual func­tioning. Lack of this essential psychodynamics may manifest in mood disorders and emotional cycles of anger, irritability, frustra­tion, and reduced self-esteem (4, 5, 7).

As mentioned earlier, within the DSM-5 classification, the hypoactive sexual desire disorder (HSDD) is combined with the fe­male sexual arousal disorder (FSAD) to be diagnosed as a single en­tity of female sexual interest and arousal disorder (FSIAD), which is then differentiated into lifelong versus acquired and generalized versus situational subtypes compared to normally functional con­trols. In the absence or presence of a partnered relationship, the ter­minology also includes any lack of sexual fantasies leading to marked distress or interpersonal difficulty and the incidence of which is not accounted for by any medical, drug-related (prescription or recre­ational), psychiatric (e.g. depression), or other types of sexual con­dition (7). The critical point in combining arousal disorder together with changes in desire through the revised DSM- 5 stems from an overlap and limited distinction between the two phases in the cyclic, circular response.

The desire impairment which includes HSDD is a persistent or recurrent lack or absence of sexual fantasies and interest in sexual activity. With a multitude of endogenous and extraneous factors in its causation, HSDD is often complex. Some of the predis­posing, precipitating, and maintaining influences for HSDD are low androgen level, hyperprolactinaemia, medical comorbidities, ageing, relational factors, and lifestyle factors (7). Among the coexisting medical conditions, type 2 diabetes mellitus and hyper­tension and antihypertensive medications used in the treatment have been documented with decreased sexual desire. Concurrent presence of another sexual disorder such as dyspareunia may also secondarily impair desire/arousal. The intensity of sexual desire is a function of sex steroids, which includes oestrogens in women. Therefore, the menopausal transition with attendant vulvovaginal atrophy and dyspareunia would be a factor for declining sexual interest in this age group (20). Sexual problems are a common ac­companiment of ageing per se, with a high reported incidence of loss of libido and personal distress in the elderly (2). Any psychi­atric manifestation such as depression or anxiety and medications used in their treatment are also likely to adversely affect the desire. Phobic aversion is a variant of desire disorder with a psychological basis stemming from any past sexual abuse/trauma in childhood or puberty (7).

In evidence-based studies, impaired arousal response is correl­ated with decreased pelvic blood flow and genital lubrication, which is indeed a function of the oestrogen milieu. The empirical data in­clude absence of subjective perceptions of tingling, warmth, and lubrication and objective descriptions of vaginal dryness and lack of genital sensations. In epidemiological studies, the incidence of FSAD ranged from 13% to 24%, increasing significantly with age beyond 50 years (21).

The guidelines for the diagnosis of female orgasmic disorder in­clude marked delay, diminished intensity, or complete lack of the pleasure sensation, in spite of a self-reported state of high sexual arousal/excitement. Orgasmic disorder is well recognized as a common condition with an estimated incidence and prevalence of 24-37% (22). Acquired or sudden-onset anorgasmia is often related to an organic aetiology whereas persistent psychosexual factors may predispose to a lifelong impairment (23).

Normal sexual function is compromised by any type of sexual pain disorder. Various degrees of pain are reported by sexually ac­tive women, either singly or in combination with other sexual com­plaints. The aetiopathogenic source for pain in the genitourinary syndrome of menopause (known earlier as vulvovaginal atrophy) is the underlying structural change; these include thinning of the va­ginal epithelium, decrease in the superficial and intermediate cell layers, an increase in the parabasal cell content, and a less acidic vaginal pH (24). In studies, 14-18% of women in the age range of 18-59 years presented with genital pain and/or a penetration dif­ficulty. The two main types of coital pain are distinguishable as dyspareunia, with an organic aetiology, or vaginismus, which is an involuntary retraction/contraction of the pelvic musculature during an attempted penetration (25). A non-coital type of sexual pain is reported by women with provoked vestibulodynia, with a modest prevalence of 8-12% among the vulvovaginal pain disorders. Typically, an acute pain reaction is precipitated in women with pro­voked vestibulodynia by nonsexual contacts such as gynaecological examination or tampon insertion (26). Studies show that pain dis­orders inevitably precipitate all other types of sexual problems such as impaired desire/arousal, orgasmic difficulty, and an overall re­duction in the frequency of sexual activity or sexual satisfaction.

With a few appropriate questions, the healthcare professional will be able to identify the true nature of the presenting complaint. While much of the evidence supports the role of ovarian sex steroids in the concerted promotion of sexual activity in women, orally ad­ministered oestrogens, most commonly used in hormonal contra­ceptives, have been linked to the incidence and prevalence of sexual disorders in younger women (27). The purported mechanism seems to correlate with elevated levels of SHBG, the transporter for sex hormones binding to testosterone, in view of its preferential affinity for SHBG (28). Nevertheless, the impact of hormonal contraceptives on sexual function is rather ill-defined and the extent of dysfunc­tion remains unclear. While the scientific debate still continues to ascertain whether oestrogen or androgen is the prime modulator for female sexual function, sexual impairments are commonly encoun­tered in women investigated for infertility or endometriosis. Female androgen insufficiency, included in the Princeton consensus, also denotes the existence of a clinical entity with symptoms of loss of desire or libido associated with low testosterone levels in women (8).

Within the OBGYN setting, maternal morbidity related to com­plications during pregnancy or childbirth is an overriding factor for detrimental changes in sexual health and quality of life (29); notwithstanding any attempts for sexual resumption, the resultant anatomical, physiological, and psychological implications may per­sist for variable lengths of time. Postpartum depression leading to emotional and sexual difficulties may be an important and often neglected obstetric complication in terms of addressing the couple's intimacy needs (30).

Together with ageing, the stages in the genesis of a sexual disorder in older women may not be easily deducible in view of a number of organic comorbidities impinging on psychological, interpersonal, and sociocultural factors.

Some studies also sought to decipher the association of demo­graphic characteristics, including education and income parity with the woman's sexual activity; while desire disorder was prevalent at mid- and high- income states, other forms of sexual dysfunction were also commonly identified in women from the lower socioeconomic strata or educational levels (32). Furthermore, literature evidence abounds about the association of medical comorbidity with sexual dysfunction in women across all ages (20). Coexisting lower urinary tract symptoms have been shown to interfere with the sexual func­tion to result in desire/arousal disorder, orgasmic problems, and co­ital as well as non-coital types of genital pain. Incidences of urinary incontinence during intercourse (61.9%) or orgasm (31.7%) also negatively impacted partnered sexual activity and satisfaction (4, 25). Similarly, patients with uterine fibroids or prolapse experienced sexual dissatisfaction. Higher incidences of dysfunction and sexual impairments were accounted for by survivors of gynaecological and genitourinary tumours; likewise, breast cancer is a major risk factor for multiple disorders related to desire/arousal, orgasm and sexual satisfaction (33, 34). Sexual dysfunction frequently coexists with chronic medical conditions such as coronary artery disease, thyroid problems, spinal injury, multiple sclerosis, rheumatoid arthritis, or ankylosing spondylitis (2, 4, 20). Studies variously report the clin­ical prevalence of sexual impairment in diabetic women as 25-71%. Type 2 diabetes mellitus may contribute to the evident dysfunction through sensory, autonomic neuropathy, vascular insufficiency arising from micro- or macro-angiopathy, and other associated psy­chogenic factors. Similarly, in women with type 1 diabetes, there was a significant reduction in most domains of sexual function attribut­able to disease-related metabolic and neurovascular derangements (20, 35). This highlights the importance of physical health for sat­isfactory sexual well-being and quality of living for women in any age group.