In our study, we compared the presenting characteristics and clinical outcomes of EM and non-EM groups in TOA. Among these women, we found that the abdominal pain, fever, a history of prior pelvic surgery and pelvic inflammation all have no obvious significant difference. While TOA patients with EM were more likely to have lower pregnancy parities and a higher risk of infertility history. Characteristics and treatment of women with TOA were similar regardless of whether they were complicated with EM. However, the EM group was significantly more likely to have operative blood loss and complications.
A previous retrospective analysis was performed to evaluate the prevalence of the coexistence of EM and pelvic inflammatory disease (PID), which report that the prevalence of PID in women with EM is sufficiently higher than the general population [14]. Shai E. ELIZUR also reported the prevalence of women hospitalised with PID or TOA combined with EM is also higher than the prevalence of EM [9]. Our study found the prevalence EM in the study population (20/113, 17.70%) is higher than the reported prevalence of EM (6%-10%) [15]. The results shown that our study is consistent with previous studies. It is likely that EM is a risk factor for the development of TOA.
We also analysed the type of EM combined with TOA which include ovary EM (17/20, 85%), peritoneal EM (3/20, 15%). Meanwhile, all EM patients were diagnosed with Stage III/IV EM according to rASRM classification. As previous study reported, a more severe EM (stage III and IV disease) seems to be found in women with diagnosis of PID and TOA [6]. There are two main theories to explain the reason, one is the bloody content of the endometrioma or in the peritoneal cavity. The other possible reason may be as the dysfunction of immune system. Whether the TOA associated with the pathogenesis of EM still remains unknown.
Several classic theories have been proposed regarding the exact origin of EM. One of the most accepted theory is Sampson’s retrograde menstruation, which occurs in more than 90% of menstruating women [16]. Accumulating evidence suggests the multifactorial nature of the pathogenesis of EM, such as immune cells, adhesion molecules, extracellular matrix metalloproteinase and pro-inflammatory cytokines activate/alter peritoneal microenvironment, which created the conditions for differentiation, adhesion, proliferation and survival of ectopic endometrial cells [17-19]. The inflammatory conditions of TOA may support the point of view of new theories about the pathogenesis of EM.
TOA is one of the most serious complications of PID and potentially life-threatening. Early diagnosis and appropriate treatment are important for preventing long-term morbidity, such as tubal factor infertility, ectopic pregnancy, chronic pelvic pain. Recent studies reported that the predictive markers of TOA [20-21]. Lee S.W et al reported that increased CRP and CA-125 level were the independent factors predictive of TOA [20]. Demirtas O et al found that the level of CRP and ESR was statistically significantly higher in TOA group, and associated with longer duration of hospitalization and disease severity of TOA [21]. While the predictive markers for the development of TOA in EM patients still remains unclear. In this study, we compared clinical risk factors and laboratory parameters of EM and non-EM groups in TOA. Clinical risk factors and inflammatory markers, including fibrinogen, C-reactive protein (CRP) and PCT levels, were found no significant difference in the EM group than the non-EM group. While the incidence of elevated blood platelet in EM group was notably higher than the non-EM group. It has been reported that EM is considered a hormonal disease and an inflammatory condition. Simultaneously, activated platelets play an important role in the occurrence and development of EM [22-23]. It is suggested that the result of our study is consistent with previous studies, which indicates the elevated blood platelet may be as a predictive marker.
As we all know, CA125 is a glycoprotein in the blood, which is derived from coelomic epithelia in the female genital tract, including the fallopian tube, endometrium, ovary, and peritoneum [24]. In routine clinical practice, CA125 has been investigated extensively as a biomarker of EM. Several studies have found that CA-125 serum levels were related to the occurrence of TOA and have a prognostic role during conservative parenteral antibiotic therapy [25,26]. Whether CA125 can be used as the predictive marker for the development of TOA in EM patients. In this study, we also reported that the CA-125 levels in TOA patients with EM and non-EM. However, the results showed no obvious difference in the CA-125 level between the EM and non-EM group. It is possible that CA-125 may be elevated in benign ovarian cysts, hyperstimulation syndrome, ectopic pregnancy and fibroids, which imply it is nonspecific marker [24,26].
This study reported that patients with TOA and EM had more serious perioperative surgical complications than the non-EM group. Among the 3 patients who had complications in the EM group, most (2/3, 66.7%) had septic shock. Through further analysis, we found that 1 case had septic shock followed by IVF treatment. Infertility treatment and related procedures undermine the integrity of the ovarian sac, which increases the risk of TOA [27]. EM is a risk factor for the infection of pelvic organs. However, the incidence of TOA after in vitro fertilization and oocyte removal is very low in patients suspected of EM by ultrasound [28]. Several case reports described sporadic cases of abscesses as serious post-ART complications [29-31]. Consumptive coagulation dysfunction is a serious complication of septic shock. If not treated in time, it may be life-threatening. Therefore, we should pay more attention to patients with TOA and EM followed by infertility treatment and the associated procedures.
The present study was not without any limitations. As this is a retrospective study, it is inherently limited by the possibility of type II error. Moreover, the sample size of patients is limited, and this was a single center study. This result needs to be further validated in a multicenter study for more patients. In addition, to be able to use antibiotics, the treating physicians may alter the management plan and may also change the clinical process.