**2. The serum level of AMH in infertile patients with endometriosis**

The relationship between endometriosis and serum AMH level is largely debated and data available in infertile women undergoing IVF are scarce. Only a limited number of studies with small study groups evaluated the impact of endometriosis on circulating AMH levels in patients with a wider range of endometriosis lesions [14, 15], most of the studies included only patients with endometrioma. The surgery for endometrioma probably affects the serum AMH level as suggested by two systematic reviews [16, 17] and represents a possible confounder of the relationship between endometrioma and AMH. It was shown that the decrease of serum AMH level after surgery was significant and persistent at 12 months in patients with endometrioma over 7 cm, with bilateral cysts and with endometriosis stage IV [18]. In turn, patients with smaller and unilateral ovarian endometrioma and stage III endometriosis had higher chances to have an only transient decline in circulating AMH [18]. However, a recent meta-analysis showed that the mere presence of

#### *The Impact of Endometriosis on Controlled Ovarian Stimulation Outcome DOI: http://dx.doi.org/10.5772/intechopen.101588*

endometrioma, without previous surgery, is associated with lower AMH levels in patients without clearly defined fertility status [19]. In this study the serum AMH level was decreased in patients with endometrioma both versus patients with non-endometriotic cysts and with healthy ovaries, suggesting a specific effect of endometriosis independent of mass effect. The dimension of the endometriotic cyst could be an important contributor to the decrease of AMH level, although the available data are limited. In the meta-analysis of Muzii et al. most of the studies included patients with mean endometrioma dimension over 6 cm, being therefore impossible to conclude smaller cysts [19]. A small study found that even endometrioma bigger than 2 cm had lower serum AMH levels in comparison with controls [20]. On the other hand, Yoon et al. failed to find any relationship of ovarian endometrioma size with serum AMH level [21]. A small study with less than 60 patients per study group showed that patients with bilateral endometrioma had lower serum AMH levels in comparison with both unilateral endometrioma and no cysts [22]. Moreover, a negative linear relationship was found between endometrioma size and serum AMH level [22]. A prospective study with 40 women per study group reported that patients with endometrioma have a progressive decline in serum AMH level at an accelerated rate in comparison with patients without endometrioma [23].

Data regarding the impact of a wider range of endometriosis lesions on serum AMH levels are limited. A cross-sectional study that evaluated women surgically explored for a benign gynecological condition irrespective of their fertility status reported a similar serum AMH level in endometriosis patients and controls [24]. Patients in this study presented with various types of endometriosis: endometrioma, deep infiltrating endometriosis and superficial lesions [24]. However, in this study, infertile patients with decreased ovarian reserve might be underrepresented since these patients are more probably referred for reproductive treatments rather than for surgery.

Several studies evaluated the relationship between endometriosis and serum AMH levels in patients with infertility. Thus, Yoo et al. found that infertile patients with endometriosis performing IVF had lower AMH in comparison with male factor infertility patients [14]. In this study, the type of the endometriosis lesions was not specified and the number of patients in the two groups was reduced (43 versus 48). Moreover, patients with and without previous surgery for endometriosis were included, without a significant difference in terms of circulating AMH in these two categories of patients. Ashrafi et al. reported that serum AMH level is decreased in patients with deep infiltrating endometriosis with or without endometrioma and infertility [25]. Another small study showed that infertile patients with endometriosis stage I and II have lower circulating AMH levels in comparison with patients with tubal infertility undergoing IVF [15]. Inal et al. found no difference in serum AMH level in infertile patients with and without endometrioma performing IVF [26]. Shebl et al. studied the serum AMH level in patients undergoing IVF and found a decreased AMH only in patients with endometriosis stage III-IV in comparison with male factor infertility, but not in patients with stage I-II endometriosis [27].
