In women with endometriosis anti-Müllerian hormone levels are decreased only in those with previous endometrioma surgery.

STUDY QUESTION

Are anti-Müllerian hormone (AMH) levels lower in women with endometriosis, notably those with endometriomas (OMAs) and deep infiltrating lesions, compared with controls without endometriosis?

SUMMARY ANSWER

Endometriosis and OMAs per se do not result in lower AMH levels. AMH levels are decreased in women with previous OMA surgery independently of the presence of current OMAs.

WHAT IS KNOWN ALREADY

The impact of endometriosis and OMAs per se on the ovarian reserve is controversial. Most previous studies have been conducted in infertile women. The strength of our study lies in the following points: (i) the selection of women undergoing surgery and not only according to the presence of infertility, (ii) the classification of women with endometriosis and controls based on strict surgical and histological criteria.

STUDY DESIGN, SIZE, DURATION: Cross-sectional study using data prospectively collected in all non-pregnant <42-year-old patients, who were surgically explored for a benign gynaecological condition at a university tertiary referral centre between 2004 and 2008. For each patient, a structured questionnaire was completed during a face-to-face interview conducted by the surgeon during the month preceding surgery. AMH levels were measured in serum samples drawn in the month preceding surgery, without regard to menstrual phase or hormonal therapy.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Operations were done on 1262 women between 2004 and 2008, of which 1133 signed the informed consent. Of the 566 women with a visual diagnosis of endometriosis, 411 had histologically proven endometriosis. Frozen serum samples for the AMH measurement were available in 313 of them. Out of the 554 women without visual endometriosis and without past endometriosis surgery, 413 had a frozen serum sample for the AMH measurement. Univariate analysis examined AMH levels according to baseline patient characteristics, the presence and type of endometriosis (superficial lesion, OMA, deep infiltrating lesion) and previous OMA surgery. Analysis of variance-covariance then examined the effects of co-variables on AMH levels. Finally, logistic regressions were conducted to examine the odds ratio (OR) of having AMH levels <1 ng/ml according to the same co-variables.

MAIN RESULTS AND THE ROLE OF CHANCE

The difference in AMH levels between women with endometriosis and controls did not reach significance (3.6 ± 3.1 versus 4.1 ± 3.4 ng/ml, P = 0.06). Analysis of variance-covariance demonstrated that AMH levels significantly decreased with age (P < 0.001) and in women with prior OMA surgery irrespective of whether OMAs were present or not at the time of study (P < 0.05). Logistic regression revealed that two major factors were related to AMH levels <1 ng/ml: (i) age (compared with <29 years; 30-34 years OR = 3.1, 95% CI: 1.5-6.4, P = 0.01; 35-39 years OR = 7.0, 95% CI: 3.5-14.1, P = 0.001; ≥40 years OR = 20.8, 95% CI: 9.1-47.4, P = 0.001) and (ii) prior OMA surgery (OR = 3.0, 95% CI: 1.4-6.41, P = 0.01).

LIMITATIONS, REASONS FOR CAUTION: The selection of our study population was based on a surgical diagnosis. Women with an asymptomatic form of endometriosis are therefore not included in our study. We cannot exclude that infertile women with OMAs associated with a diminished ovarian reserve, as assessed during their infertility work-up, were less likely to be referred for surgery and might therefore be underrepresented.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that OMAs per se do not diminish the ovarian reserve reflected by AMH levels but that alterations seen in women with endometriosis are a deleterious consequence of OMA surgery. These findings should be taken into account in the decision to operate OMAs in women with a desire for future pregnancy.

STUDY FUNDING

none. Potential competing interests: none.