Differential use of various types of pessaries in isthmic-cervical insufficiency for prevention of preterm birth: A randomized prospective trial

Abstract

Background. Obstetric pessary comprises one of the methods for treatment of isthmic-cervical insufficiency. Despite the variety of pessaries produced, the common purpose of their use consists in preventing premature birth. Various types of pessaries correct different cervical parameters, which is not always taken into account by doctors when choosing a pessary and reduces their potential effectiveness. Objective. To substantiate a differentiated approach to the selection of pessary type for correcting isthmic-cervical insufficiency and preventing preterm birth based on the evaluation of cervical parameters. Methods. A randomized prospective study enrolled 90 pregnant women diagnosed with isthmic-cervical insufficiency (ICD-10 code — О.34.3) at 19–24 weeks of gestation. Of these, 41 women underwent correction of isthmic-cervical insufficiency with an obstetric unloading pessary and 49 women — with a perforated cervical pessary. Transvaginal ultrasound cervicometry evaluated the parameters of the cervix before correcting isthmic-cervical insufficiency and in dynamics (once every 4 weeks) after inserting various types of pessaries. Statistical data processing was carried out using Statistica 10.0 (StatSoft, Tulsa, USA) and MedCalc 10.2.0.0 (MedCalc, Mariakerke, Belgium). The differences were considered to be statistically significant at p <0.05. Results. Inserting an obstetric unloading pessary in isthmic-cervical insufficiency decreased the uterocervical angle from 115 (110; 130)° to 100 (90; 115)° (p = 0.021). A decrease in the uterocervical angle was observed during 16-week-use of obstetric unloading pessary. After insertion of perforated cervical pessaries, the length of the closed part of the cervical region increased from 23 (21; 24) mm to 25 (21; 27) mm (p = 0.009) for a period of 4 weeks with a subsequent decrease in this parameter. The effectiveness of both types of pessaries in preventing preterm birth was found to be identical. Urgent delivery occurred in 61% of cases of using an obstetric unloading pessary and in 64.7% of cases of using a perforated cervical pessary (p = 0.993). The gestational age at preterm birth against the background of the use of obstetric unloading pessaries and perforated cervical pessaries was found comparable and amounted to 247 (230; 253) days and 245 (225; 254) days, respectively (p = 0.870). Conclusion. A differentiated approach to selecting a type of pessary for the prevention of premature birth in isthmic-cervical insufficiency is determined by the initial ultrasound parameters of the cervix. Thus, an increase in the uterocervical angle serves as an indication for an obstetric unloading pessary, while a shortened part of the cervical region without an increase in the utero-cervical angle determines the use of a perforated cervical pessary. Additional dynamic ultrasound control after inserting pessaries of any type allows such complications as pessary displacement, cervical edema, amniotic fluid sludge, prolapse of fetal membranes in the vagina, and increased myometrial tone to be timely diagnosed and corrected, thereby increasing the effectiveness of using pessaries.