Do the spouses sin if the wife is forced to undergo a colonoscopy performed by a male doctor due to the unavailability of a female doctor, knowing that the husband has come to hate his wife and alienate her because of this?

If a female doctor is not available to perform a medical procedure, then there is no harm in a male doctor performing it, and there is no sin upon the husband or the wife in that regard. This is based on the statement of Al-Khatib Al-Shirbini: "And know that what preceded regarding the prohibition of looking and touching is where there is no need for them. However, when there is a need, looking and touching are permissible for venesection, cupping, and treatment, even if it is in the private parts." And based on the statement of Al-Ruhaibani: "For a doctor, and whoever attends to a sick person... to look and touch as long as there is a need, even the private parts; because that is a place of need." The husband must not compel his wife or make life difficult for her because of this matter, and he must treat her kindly.