The title of the piece is called Casting Off My Womb, which employs a play on words using a term for knitting meaning to tie off the piece so that it doesn't unravel. The title of the piece combined with the medium used to perform it (the artist and yarn) and the phrase "vagina knitting" sets up a play on words related to the role of women in society that views them as disposable goods or little more than baby factories, traditional attitudes regarding menstruation as repugnant, the female womb as the source of life, and the societal contradictions associated with the vagina and by extension women in general.
The confrontational nature of the piece is achieved by the shock value of the nude exposure of the artist and the storage of the yarn in her vagina prior to the production of the work. As the yarn is knitted into a long scarf like garment, it is suspended on coat hangers and stained with menstrual blood.
Metaphors relating to female sexuality, reproduction, abortion, the male gaze, and female control of their reproductive process work in conflict and resonate with the surrounding culture to create tension in the content of the piece. So the knitting phrase "casting (tying) off" resonates with "tying tubes" to prevent pregnancy and of course the concept of tying or binding is associated with bondage and repression. And the phrase "casting off" can also be applied to the concept of women as disposable due to infertility or aging. The "product" of the artist's vagina is suspended on coat hangers, an implement which has considerable symbolic associations with "back alley" abortions and the political and cultural repression of female control of their own reproductive process. Also, knitting is associated with the traditional knitting of baby booties by pregnant women, now suspended by coat hangers.
The result of the piece is the display of a bloody offering suspended by implements of repression of women by men. The method of execution is designed to both titillate and repulse the viewer through the nudity of the artist and the garment she creates. While the overall balance of metaphors and the tension they create in their relationship with each other is carefully crafted and the sublimation of the artist as the artwork itself validates the piece as a well crafted bit of performance art, it suffers a bit from a somewhat too obvious awareness of the market for which it is intended, evidenced by the tone of the commentary in the link provided and the somwwhat deravitive nature from the previous work of Carolee Schneeman. Also, while the overlapping metaphors work well, perhaps they work too well and become an exercise in riffing on hot button issues and metaphors without digging any deeper than their obvious connotations and contradictions. Overall, a successful piece but hardly groundbreaking.
That's my initial impression, but I'm tired now and I'm going to bed.