European Journal of Obstetrics & Gynecology and Reproductive Biology
Risk factors for pelvic endometriosis in women with pelvic pain or infertility: Gruppo Italiano per lo Studio dell’ endometriosi1
Introduction
Epidemiological studies have suggested that reproductive and menstrual history are associated with the risk of pelvic endometriosis [1], [2], [3], [4], [5], [6]. Nulliparous women were at increased risk of endometriosis in case–control studies conducted in Italy and in the US [1], [4], [5]. Age at menarche was younger in cases with endometriosis than in controls in a case–control study conducted in the US [1], but no significant association between age at menarche and endometriosis was reported in an Italian study [4].
With regard to the characteristics of menses, a lifelong regular menstrual pattern and heavy flows were associated with an increased risk of endometriosis [1], [4], [6], [7].
However, caution has been suggested in the interpretation of these findings, considering the potential biases which may act in epidemiological studies of this condition [7]. First of all, infertility and pelvic pain are clinical findings in endometriosis [8], and are often the reason for diagnostic procedures. This selective mechanism raises the frequency of infertile women or women with an abnormal menstrual pattern among the cases. In order to take this selection bias into account some studies have analysed only cases in which the diagnosis of endometriosis was an incidental finding in women who underwent surgery for other benign gynecological conditions [4]. However, this methodological approach may introduce other potential biases.
To re-analyze the epidemiological characteristics of pelvic endometriosis and reduce the potential difference in selective mechanisms between cases with the disease and the comparison group, we considered the reproductive and gynecological history of women with and without endometriosis who underwent laparoscopy for infertility or pelvic pain in a network of hospitals cooperating in the Gruppo Italiano per lo Studio dell’Endometriosi. This analysis may offer also the opportunity of reconsidering in a large data-set, the clinical impressions on risk factors for endometriosis.
Section snippets
Materials and methods
Eligible for the study were women with primary or secondary infertility or pelvic pain requiring laparoscopy consecutively observed in 15 obstetrics and gynecology departments in Italy. Women with a previous diagnosis of endometriosis were specifically excluded.
Infertility was defined as an active effort at pregnancy for 2 years or more, with no specific diagnostic work-up before laparoscopy, but participating centres agreed to exclude any women whose partner had severe oligozoospermia (<10×106
Results
Out of the 424 women included for pelvic pain and the 393 included for infertility, respectively 210 (49.5%) and 135 (34.4%) had a diagnosis of endometriosis. Among women with endometriosis who entered the study for infertility, 42 (31.1%) were at stage 1, 32 (23.7%) at stage 2, 38 (28.1)% at stage 3, 8 (5.9%) at stage 4 and in 15 cases (11.1%) information regarding the stage was missing. The corresponding figures for pelvic pain were: 46 women at stage 1 (21.9%), 39 at stage 2 (18.6%), 78 at
Discussion
Strengths and limitations of this study should be considered. This study offers the opportunity of analysing the characteristics of women with and without endometriosis undergoing laparoscopy with a specific indication: pelvic pain or infertility. Thus the results are not formally generalizable to the whole population.
This is the main limitation of this study. This “selected” control group may be cause of bias particularly in the analysis of obstetric and gynecological factors, but could be
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Cited by (0)
- 1
The following clinicians are co-authors of the present paper: Milano, Istituto Mario Nejei, Milano (Fabio Parazzini), Benevento (Italo Ardovino, Elisario Struzziero); Bologna (Ettore Zanardi, Daniela Pungetti); Cagliari (Valerio Mais, Silvio Ajossa); Catania (Giovanni Mignemi, Luciano Di Leo); Ferrara (Albino Bianchi, Carlo Campobasso); Firenze (Gian Franco Scarselli, Gianluca Bracco); Milano “M. Melloni” (Piero Capetta, Carlo Bertulessi); Milano “Mangiagalli” (Simona Moroni, Patrizia Mazza, Paolo Vercellini, Pier Giorgio Crosignani); Parma (Alfio Bacchi Modena); Roma (Alessandro Casa); Torino “Mauriziano” (Marco Massobrio, Cristina Ansaldi); Torino “S. Luigi” (Gian Franco Trossarelli); Treviso (Maria Teresa Gervasi, Vittorio Marsoni); Trieste (Secondo Guaschino, Luigi-Troiano, Giuseppe Ricci); Varese (Paolo Beretta, Massimo Franchi).