Cervical incompetence is also known as cervical laxity or internal os insufficiency. In recent years, an increasing number of women have developed cervical incompetence in China. If no active and effective treatment is given or in case of inappropriate treatment, pregnant women will have an increased risk of adverse events such as miscarriage and premature delivery, probably with more serious consequences. Research has shown that the rate of premature births in women with cervical incompetence is 3.3 times that of those without cervical incompetence.
Correlation between vaginal microecology and cerclage outcome
Transvaginal cervical cerclage, as an effective surgical procedure to prevent miscarriage and premature delivery, has been used for more than 60 years, which is characterized by short operation time, fast postoperative recovery and easy acceptance by the patients . This procedure can avoid cervical bone dilation and lower uterine extension, and share the weight of the fetus and amniotic fluid with the cervix, thus effectively prolonging the gestational age of patients with cervical incompetence. and improving pregnancy outcomes . In this study, 104 out of 125 pregnant women underwent successful surgery, while 21 failed, with a success rate of 83.20%, suggesting higher success rates of transvaginal cervical banding. In this study, gestational age and number of weeks of delayed pregnancy were both higher in the successful group than in the unsuccessful group, suggesting that transvaginal cervical cerclage may prolong patients’ gestational age. According to univariate analysis, surgical timing, gestational age of cerclage, preoperative cervical canal length, genital tract infections, and preoperative invasive procedures were the risk factors for cervical cerclage failure (P P
Various microorganisms reside in the vaginal mucosa of women, which restrict and interact with each other to maintain a healthy vaginal microenvironment. Imbalance in vaginal microecology is governed by etiologic, environmental, and host factors. Pregnancy is a particular physiological period, during which physiological hormonal variations easily cause changes in the environment of the vaginal flora, thus leading to an imbalance of the vaginal microecology. [9, 10]. This greatly increases the risk of various types of vaginal inflammation. However, extensive research evidence demonstrates that genital tract infections caused by vaginal microecological imbalance are a significant cause of preterm labor. Through the analysis of vaginal flora density between the successful and unsuccessful groups, this study revealed a higher vaginal flora density in pregnant women in the unsuccessful group than in those whose pregnancies were unsuccessful. eventually. This suggests a likely association of cervical cerclage failure with vaginal microecological changes.
Research has shown that Lactobacillus is the most common normal flora in the vagina, which is a resident vaginal flora in normal mature women. Its function is to lower the vaginal pH by converting glycogen into lactic acid, so that normal healthy women’s vaginal pH can be maintained between 3.8 and 4.2, which is acidic and helps maintain vaginal pH. balance of the vaginal flora . According to the results of this study, pregnant women in the failed group had a significantly higher pH than those in the successful group. The concentration of H2O2 has been shown to be associated with the number of lactobacilli. If the H2O2 test result is negative, this indicates a high level of lactobacilli in the vagina and a good state of the flora. As the results of this study suggest, the group that failed had a significantly higher positive level of H2O2 that the successful group (P 4.5 and H2O2 in the failure group were significantly higher than those in the success group (P
Correlations of IL-1β, IL-6, IL-8, and TNF-α Levels in Vaginal Secretions with Cerclage Outcome
IL-1, as one of the main regulators of the inflammatory response, affects almost all cell types . IL-1β is an important mediator of the inflammatory response and a major pro-inflammatory cytokine. In a study by Barlik et al. , a high concentration of IL-1β in cervical secretions was linked to an increased risk of preterm delivery, showing agreement with the results of the present study. IL-6 is a pluripotent inflammatory cytokine, the level of which in the amniotic fluid increases during the onset of an intra-amniotic infection. During the inflammatory response, IL-6, as a cytokine secreted after infection and stimulation, can promote T and B cell maturation and differentiation, mediate the acute inflammatory response, and potentiate the effects of chemokine. Research has shown that elevated serum IL-6 is strongly associated with adverse obstetric events such as premature rupture of membranes, intrauterine infections, and preterm delivery, suggesting the potential for serum IL-6 as predictor of early intrauterine infection and threatened preterm delivery. . In this study, the concentration of IL-6 in the vaginal secretions of women with unsuccessful cervical cerclage was higher than those with successful cerclage, which confirmed the involvement of IL-6 in the occurrence of premature birth. IL-8 can promote neutrophil chemotaxis and lead to cervical ripening, which is closely associated with preterm labor. Spontaneous preterm birth has been reported to be correlated with elevated IL-8 in cervical mucus and a short cervix [17, 18]. This is also consistent with the findings of this study. TNF-α, a pluripotent cytokine, is a product of maternal and fetal tissues. By increasing the production of prostaglandins, it activates the myometrium, induces the activation and apoptosis of matrix metalloproteinase and promotes the occurrence of premature labor, thus affecting the outcome of pregnancy. . Although the serum level of TNF-α is low during physiological pregnancy, it can rise sharply during infections, especially in the case of infections of the genitourinary system. Sidelnikova and Sukhikh found that the serum TNF-α level of pregnant women at risk of preterm birth in the third trimester was approximately 9 times higher than that of normal pregnant women . In this study, the level of TNF-α in the cervico-vaginal secretions of women with failed cerclage was higher than those with successful cerclage. This result agrees with that of the serum level of TNF-α, which further proves the involvement of TNF-α in the occurrence of preterm labor.
BV is a common bacterial infection of the vagina in clinical settings. As a mixed infection caused primarily by Gardnerella bacillusBV can cause vaginal microecological disturbances, resulting in a reduction or even loss of Lactobacilliand the excessive reproduction of pathogenic bacteria, which further increases the incidence of the threat of premature labor in pregnant women. This study found a significantly higher cervical cerclage failure rate in patients with BV than in those in the BV negative group. Levels of IL-1β, IL-6, IL-8, and TNF-α in the vaginal secretions of enrolled pregnant women were examined, revealing significantly higher expressions of inflammatory cytokines in the failure group than in the success group (P
The pregnancy outcome of patients undergoing cervical cerclage is closely related to the imbalance of the vaginal microecology. Elevated levels of IL-1β, IL-6, IL-8, and TNF-α in cervico-vaginal secretions are likely associated with decreased clearance of pathogenic bacteria and improved inflammatory response caused by a vaginal microecological imbalance. Thus, in pregnant women, the imbalance of the vaginal microenvironment increases the risk of premature delivery, which has adverse effects on both the pregnant woman and the fetus. Assessing microecological changes can better guide clinical treatment, increase the success rate of cervical cerclage, and improve maternal and infant outcomes.