Somatosensory stimulation and assisted reproduction.

To cite: Carr D. Acupunct Med 2015;33:2–6. The role of somatosensory stimulation (acupuncture and related techniques) as an adjunct to assisted reproductive technology (ART) has been hotly debated over the past decade. In the last 6 years there have been no fewer than 12 meta-analyses of 34 randomised controlled trials (table 1). Systematic and narrative reviews of the literature often report conflicting findings and opinions. Despite this controversy, subfertility remains one of the most common reasons that women consult an acupuncturist. Meta-analysis of acupuncture trials is often challenging due to methodological diversity, and this is especially true for in vitro fertilisation (IVF) due to marked differences in timing (treatment given during the follicular phase, at the time of oocyte retrieval and/or embryo transfer (ET), and/or as luteal phase support) and the variety of interventions including manual acupuncture, electroacupuncture (EA), transcutaneous electrical acupuncture point stimulation (TEAS) and laser acupuncture. Various outcome measures have been used ranging from biochemical pregnancy rate to live birth rate (LBR), depending on the duration of follow-up. LBR (‘take home baby rate’) is considered to be the ideal primary outcome measure and is clearly most important to patients. Interestingly, concordance between studies with respect to point location is relatively high. The acupuncture points targeted generally correspond anatomically to the segmental innervation of the uterus and ovaries, irrespective of whether the primary approach to point selection is traditional or neurophysiological. The paper by Shuai et al used TEAS rather than needle acupuncture and examined its efficacy and mechanisms of action in women undergoing frozen-thawed ET. TEAS significantly increased the clinical pregnancy rate (CPR) and LBR relative to a sham intervention (mock TEAS). To date there has been one other (positive) trial of TEAS in IVF and a third is currently underway. Regarding the underlying mechanism, it has been hypothesised that acupuncture-like interventions improve endometrial receptivity, based on the observations of Stener-Victorin et al and Ho et al that EA reduces impedance to flow in the uterine arteries. It is often inferred, rightly or wrongly, that enhanced uterine blood flow equals improved endometrial blood flow. In support of this assumption, acupuncture has been shown to increase endometrial thickness compared with sham acupuncture and standard care. However, Shuai et al are the first to have shown positive effects on contemporary ultrasound markers of endometrial receptivity (three-dimensional endometrial and subendometrial vascularisation index and presence of a triple-line pattern) plus HOXA10 protein expression, a novel molecular marker. Interestingly, all these studies have used serial treatments that incorporate the follicular phase of the cycle. The most recent systematic review by Shen et al only found evidence of benefit when follicular phase treatment was combined with treatment around ET, and not when timed around ETalone. It is argued that the latter approach, which typically consists of a single treatment before and one after ET (variations of the Paulus protocol), is insufficient in duration and ‘dose’ to have any major effect on endometrial receptivity and/or blood flow, and that putative effects on pregnancy rates in this context may be due to inhibition of post-transfer uterine contractions and/or reduction of patient anxiety, both of which may adversely affect pregnancy rates. 54 The efficacy of TEAS suggests that penetration of the skin or muscle is not required in order to effect endometrial receptivity and pregnancy rates, and this is supported by experiments on anaesthetised rats, wherein a measurable increase in uterine blood flow was observed during noxious pinching and innocuous brushing of the hind limb and perineum (regions innervated by the sacral segments). This Editor’s choice Scan to access more free content Editorial