Prospects of vaginal delivery after more than two caesarean sections

Objective. To evaluate the prospects for vaginal delivery after more than two cesarean sections (CS). Material and methods. A prospective multicenter cohort study was performed between January 2013 and July 2019 in maternity hospitals 68 and 29 in Moscow. A total of 272 women with a history of previous CSs were identified: with one (1 CS, n=168), two (2 CSs, n=76), and more than two CSs in the past (more than 2 CSs, n=28). Factors justifying and refuting vaginal delivery after more than two CSs were assessed. Results. Among women who had undergone more than two CSs, 10.29% strongly advocated vaginal delivery via natural childbirth; 36.26% of women underwent a second CS solely for uterine scar-related indications; 17.78% of the vaginal delivery attempts after a CS (one or two) were terminated by the clinical signs of a threatening uterine rupture. Pregnant women with 2 or more CSs deliver at comparable times (p=0.08), but a history of more than 2 CSs excludes delivery after 38 weeks’ gestation. Cervical maturity was negatively correlated with the number of previous fetuses (r=0.42; p<0.001); 2CS and 1CS were comparable (Me=4 [3; 7] points and Me=7[3; 7] points; p=0.07). Ultrasonographic scar thickness was comparable for different numbers of CS in the history of CS. A negative correlation between cervical maturity and uterine scar ultrasonographic thickness was found for more than 2CS. Uterine rupture (incomplete) occurred exclusively in women with 1CS and with an ultrasonic scar thickness of 2.5 to 2.7 mm. Intraoperative visualization of scar thinning in labor up to 1 mm throughout was likely with ultrasound thickness of myometrium before delivery greater than 2.0 mm (χ2=9.308; p=0.002). The critical period associated with the detection of an incomplete uterine scar after CS was more than 39 weeks (χ2=4.86; p=0.02). The predominance of muscle tissue in the scar is a marker of 1CS. Muscle tissue with fibrosis foci serves as a marker for more than 2CS, comparable to that in 1CS and 2CS (χ2=2.36; p=0.13). The predominance of fibrotic tissue was more associated with 2CS compared to 1CS (odds ratio 5.39). There was no significant difference in histological examination of scar tissue after 1CS, 2CS or more than 2CS. The risk of rupture with predominantly fibrous tissue is exaggerated. The uterine rupture occurred exclusively with the predominance of muscular tissue with foci of fibrosis in the scar. Conclusion. The number of women with a history of more than 2 CS categorically insisting on vaginal delivery is 10.29%. The global uptake of vaginal delivery after 2 or more CS and a history of vaginal delivery is not unreasonable. An argument for attempting a vaginal delivery after more than 2 CS is the comparability of the thickness of the operated myometrium to that after 1 CS and after 2CS; the absence of a striking contrast between its histological findings and those after 1CS and 2CS, especially after 2CS. The expected maximum risk of rupture with predominance of fibrous tissue is exaggerated: our data show that uterine rupture occurred exclusively with predominance of muscular tissue with foci of fibrosis in the scar. The known risks of uterine rupture are not discounted. Waiting for the onset of regular labor after more than 2CS is limited by a decrease in the ultrasound thickness of the operated myometrium at cervical maturation, up to a critical thinning at delivery at over 39 weeks’ gestation. The refusal to provide a vaginal delivery attempt to 36.26% of women for «scarred» indications leaves doubts about unrealized options and does not rule out the unreasonableness of a repeat CS.