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With rising rates of cesarean deliveries and their attendant complications, the ability to predict uterine scar separation would be welcome in helping women and clinicians make informed decisions about obstetric management of subsequent pregnancies. In a prospective single-institution cohort study that involved 162 women who had ever undergone cesarean deliveries, investigators used transvaginal sonography to assess hysterotomy scars 6 to 9 months after the most recent cesarean delivery. Outcomes of subsequent pregnancies within 3 to 5 years were assessed in 69 women; of these, 26 had repeat cesarean deliveries and the others delivered vaginally.
Overall, uterine rupture or dehiscence occurred in 4 women and was more likely to occur among those with large scar defects than those with small or no defects, although the finding did not reach statistical significance (odds ratio, 12.7; 95% confidence interval, 0.9–724). Among women who underwent repeat cesarean deliveries, risk for rupture or dehiscence also was higher for those with large scar defects than among those with small or no defects, but this finding likewise failed to reach significance (OR, 11.8; 95% CI, 0.7–746).
Vikhareva Osser O and Valentin L. Clinical importance of appearance of cesarean hysterotomy scar at transvaginal ultrasonography in nonpregnant women. Obstet Gynecol 2011 Mar; 117:525.
Spong CY and Queenan JT. Uterine scar assessment: How should it be done before trial of labor after cesarean delivery? Obstet Gynecol 2011 Mar; 117:521.
Comment
These results suggest a role for sonographic imaging in women who have undergone prior cesarean deliveries to assess myometrial thickness in the vicinity of the hysterotomy scar, but the study's small population is only one of the limitations that make this protocol “not ready for prime time.” Another important concern is that women who achieved vaginal deliveries after cesarean did not undergo uterine examination for undiagnosed scar dehiscence or rupture; thus, the true clinical significance of the findings at repeat cesarean cannot be evaluated in context. If we hope to lower the cesarean rate, evidence-based methods for selecting appropriate trials of labor will be critical; thus, studies with greater statistical power are needed.