Sexual arousal in females is dependent to a certain extent on the nerve endings that are present on the vulva. Arousal leads to several physical changes in the vulva.

Stages of sexual arousal in females

Arousal consists of four stages. These include:

Excitement

During this phase there is increased watery secretion that is produced to cause better lubrication. This increase in secretion is caused due to constriction of the vaginal walls and congestion and engorgement of the vaginal walls. Due to increase in pooling of blood, watery secretion seeps in and these collect in the vagina and flow out into the vulva. 

During this phase the labia majora spreads apart and flattens to expose the clitoris. The clitoris in turn increases in size. These changes may not be immediately noticeable unlike the excitation phase in males.

Plateau

During this phase the congestion of blood vessels cause swelling of the vaginal walls. This leads to decreasing the opening of the vagina to around one third of its original size. As the clitoris becomes enlarged, it starts to become erect and becomes concealed by the hood.

 

The labia minora increase considerably in thickness, approximately 2–3 times. This leads to spreading out of the labia minora and opening up of the vaginal opening.

In White Caucasian women who have never had children the color of the labia minora changes from pink to red due to blood vessel engorgement.  Among those women who have had a child before the color changes from red to dark red.

Orgasm

This is the peak in sexual arousal and this stage is marked by maximum clitoris engorgement. This engorgement leads to retraction of glans into the clitoral hood. This is thought to protect the sensitive glans during orgasm.

An orgasm is characterized by rhythmic muscle contractions of the lower part of the vagina, the uterus and the anus as well. The contractions come around once every 0.8 seconds and gradually spread out and become less intense. A typical orgasm contains 15 or more contractions depending on the intensity.

This may be accompanied by female ejaculation, causing liquid to squirt out. This is usually a clear, odourless secretion from the Skene's gland or bladder that comes out of the urethra. This is not urine and does not cause staining. Immediately after orgasm the clitoris may be so sensitive that any stimulation is uncomfortable.

Resolution

This follows an orgasm wherein the pooled blood begins to dissipate at a slower rate. The vagina returns to its normal relaxed state. The vulva returns to its normal position, size, and color.