Does the phase of the menstrual cycle really matter to anaesthesia?

The menstrual cycle is a physiological phenomenon that is accompanied by several hormonal fluctuations involving oestrogen and progesterone. Oestrogen and progesterone exert several physiological effects. There are many questions pertaining to the influence of the physiology of menstruation on anaesthesia. We attempted to find out whether the phase of the menstrual cycle can alter the physiological functions during anaesthesia, the perioperative management and outcomes. We performed a literature search in Google Scholar, PubMed and Cochrane databases for original and reviewed articles on the phases of the menstrual cycle and their relation to anaesthesia-related physiological parameters to find an answer to these questions. Many studies have shown that women, perimenstrually, may have increased pain perception, exacerbation of systemic diseases, vocal cord/peripheral oedema and post-operative nausea and vomiting (PONV). Some of the other notable findings in most studies were sleep disturbances in the luteal phase (LP), increased occurrence of PONV in the ovulatory phase and a lower requirement of intravenous sedative and anaesthetic drug requirements in the LP. We found contradictory results concerning pain perception and PONV in relation to the follicular and LPs. However, we found that literature regarding the phase of the menstrual cycle and the haemodynamic response to intubation, anaesthesia-induced hypnosis and perioperative blood loss is relatively scarce. Thus, there is a need to conduct good quality research on these topics.