Hawes et al. found no statistical evidence for an association between douching and trichomonas or candidiasis [25], whilst insertion of substances for drying or tightening the vagina [14] was associated with vaginal candida in univariable analyses (Figure 3).
To maintain the desired vaginal state, a range of practices are used, including intravaginal cleansing and insertion of substances [ 4].
The insertion of substances to dry and tighten the vagina appears to be common according to some studies in Southern Africa [ 30, 32, 33], notably with sex workers [ 34].
The methods used for the abortive purpose included insertion of foreign substances or injection of a liquid solution into the vaginal canal, vaginal suppository, oral tablets and strong manual compression of lower abdomen.
This initiatory death, like that of the Siberian shaman, has two specific marks not found elsewhere in combination: first, a series of operations performed on the candidate's body (opening of the abdomen, renewal of the organs, washing and drying of the bones, insertion of magical substances); second, an ascent to heaven, sometimes followed by trance journeys into the otherworld.
We considered four eligible categories of intravaginal practice: intravaginal cleansing with liquids (including douching); insertion of dry substances into the vagina; ingestion of substances intended to affect the vagina; and self-administered anatomical modifications, such as cutting at the introitus, with insertion into the cut of traditional substances that are washed away later.
For example, insertion or application of substances like herbs, pulverized rock, or commercial products to prepare the vagina for sexual intercourse can cause physical or chemical abrasions [4] that could be exacerbated during intercourse [3].
Importantly, insertion or pushing of substances such as powders, creams, herbs, tablets, sticks, stones, pulverized rock, leaves or some local and commercial products can cause physical abrasions and potentially disrupt vaginal flora, leading to bacterial vaginosis (BV) [ 7, 9] and other sexually transmitted infections including HIV [ 26, 29, 33].
Finally, as discussed above, the perceived "cleansing" properties of investigational gels, could serve to encourage gel insertion and discourage early removal or co-insertion of other substances.
In two studies reporting on insertion of herbs or unspecified substances to dry and tighten the vagina before sexual intercourse the summary unadjusted effect was 1.47 (95% CI 1.03 2.10, I2 0%) [14], [24].
Volcanic gas includes a variety of substances.
