Assessment of uterine rupture in placenta accreta spectrum: pre-labor vs in-labor

Placenta accreta spectrum (PAS) disorder encompasses conditions caused by morbidly adherent placenta to the myometrium of the gravid uterus.1Jauniaux E. Collins S. Burton G.J. Placenta accreta spectrum: pathophysiology and evidence-based anatomy for prenatal ultrasound imaging.Am J Obstet Gynecol. 2018; 218: 75-87Google Scholar PAS is associated with significant maternal morbidity and mortality, and the incidence of PAS is increasing.2Matsuzaki S. Mandelbaum R.S. Sangara R.N. et al.Trends, characteristics, and outcomes of placenta accreta spectrum: a national study in the United States.Am J Obstet Gynecol. 2021; 225: 534.e1-534.e38Google Scholar One understudied area with regards to PAS is uterine rupture during pregnancy. PAS is characterized by the markedly distended and thinned lower uterine segment with hypervascularity because of the placental implantation that may be at increased risk for rupture. Patients with PAS commonly have a history of cesarean delivery, a known risk factor for subsequent uterine rupture.3Sangara R.N. Youssefzadeh A.C. Mandelbaum R.S. et al.Prior vertical uterine incision: effect on subsequent pregnancy characteristics and outcomes.Int J Gynaecol Obstet. 2023; 160: 85-92Google Scholar Given the paucity of data examining uterine rupture in PAS,4Akhade S.P. Ghormade P.S. Bhengra A. Chavali K. Hussain N. Uterine scar rupture at the site of the placenta accreta presenting as a case of sudden death.Autops Case Rep. 2021; 11e2020226Google Scholar this study examined clinical and pregnancy characteristics related to uterine rupture among patients with PAS in the United States. This cross-sectional study used data from the Healthcare Cost and Utilization Project's National Inpatient Sample.5Agency for Healthcare Research and QualityOverview of the national (nationwide) inpatient Sample (NIS).https://www.hcup-us.ahrq.gov/nisoverview.jspDate accessed: August 12, 2023Google Scholar Weighted data for national estimates obtained from >4500 participating centers represent >97% of the US population. The study population comprised 18,180 patients with a diagnosis of PAS from 2017 to 2020. The exposure was uterine rupture identified by the World Health Organization's International Classification of Diseases, 10th Revision, codes that were classified into pre-labor uterine rupture (O71.0) or in-labor uterine rupture (O71.1).3Sangara R.N. Youssefzadeh A.C. Mandelbaum R.S. et al.Prior vertical uterine incision: effect on subsequent pregnancy characteristics and outcomes.Int J Gynaecol Obstet. 2023; 160: 85-92Google Scholar The main outcomes were patient and pregnancy characteristics related to uterine rupture, assessed using a multinomial regression model. The University of Southern California Institutional Review Board deemed the study to be exempt from review because it included only publicly available, de-identified data. Uterine rupture occurred in 220 patients, which corresponds to an incidence of 12.1 per 1000 PAS cases. When examined for the timing of uterine rupture, 110 (6.1 per 1000) cases had pre-labor rupture and the remaining 110 (6.1 per 1000) cases had in-labor rupture. Patients who had pre-labor rupture were older than those without uterine rupture (age ≥35 years; adjusted odds ratio [aOR], 2.05; 95% confidence interval [CI], 1.37–3.05) (Table). Patients with placenta percreta were 4 times more likely to have pre-labor uterine rupture than those with accreta (aOR, 4.26; 95% CI, 2.81–6.46). A previous vertical or low-transverse incision was not associated with pre- or in-labor uterine rupture.TableClinical demographics associated with uterine rupture in PASCharacteristicPAS with no rupturePAS with pre-labor rupturePAS with in-labor ruptureNumbern=17,960n=110n=110Age (y)aUnknown cases were suppressed because of small numbers33 (29–37)37 (32–38)31 (29–36) <3559.036.468.2 ≥3541.063.631.8 aOR (95% CI)1.00 (ref)2.05 (1.37–3.05)bAdjusted P<.050.68 (0.45–1.02)Obesity No82.710059.1 Yes17.3040.9 aOR (95% CI)1.00 (ref)n/a3.16 (2.14–4.66)Previous LTCD No60.054.563.6 Yes40.045.536.4 aOR (95%CI)1.00 (ref)1.32 (0.89–1.97)0.85 (0.57–1.27)Previous vertical CD No94.095.590.9 Yes6.0cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines.cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines. aOR (95% CI)1.00 (ref)0.68 (0.27–1.74)1.31 (0.66–2.62)PAS subtype Accreta80.154.572.7 Increta8.7cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines.13.6 aOR (95% CI)1.00 (ref)0.65 (0.26–1.63)1.40 (0.79–2.48) Percreta11.240.913.6 aOR (95% CI)1.00 (ref)4.26 (2.81–6.46)bAdjusted P<.051.19 (0.67–2.11)Placenta previa No66.677.368.2 Yes33.422.731.8 aOR (95% CI)1.00 (ref)0.31 (0.19–0.50)bAdjusted P<.050.69 (0.45–1.08)Placental abruption No96.895.595.5 Yes3.2cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines.cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines. aOR (95% CI)1.00 (ref)1.19 (0.47–2.97)1.27 (0.51–3.17)IUFD or still birth No98.686.495.5 Yes1.413.6cSmall numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines. aOR (95% CI)1.00 (ref)3.69 (1.93–7.05)bAdjusted P<.051.86 (0.69–4.96)Gestational ageaUnknown cases were suppressed because of small numbers ≥3652.013.640.9 28–3539.450.040.9 aOR (95% CI)1.00 (ref)5.61 (3.09–10.16)bAdjusted P<.051.28 (0.81–2.03) <285.727.313.6 aOR (95% CI)1.00 (ref)13.35 (6.71–26.57)bAdjusted P<.052.66 (1.38–5.14)bAdjusted P<.05Percentage per group or median (interquartile range) is shown. A multinomial regression model was used for effect size estimates. All the listed covariates were entered in the model.aOR, adjusted odds ratio; CD, cesarean delivery; CI, confidence interval; IUFD, intrauterine fetal demise; LTCD, low-transverse cesarean delivery; PAS, placenta accreta spectrum.Komatsu. Placenta accreta spectrum and uterine rupture. Am J Obstet Gynecol 2024.a Unknown cases were suppressed because of small numbersb Adjusted P<.05c Small numbers were suppressed according to the Healthcare Cost and Utilization Project guidelines. Open table in a new tab Percentage per group or median (interquartile range) is shown. A multinomial regression model was used for effect size estimates. All the listed covariates were entered in the model. aOR, adjusted odds ratio; CD, cesarean delivery; CI, confidence interval; IUFD, intrauterine fetal demise; LTCD, low-transverse cesarean delivery; PAS, placenta accreta spectrum. Komatsu. Placenta accreta spectrum and uterine rupture. Am J Obstet Gynecol 2024. Pre-labor uterine rupture occurred more often in cases of extreme prematurity (<28 vs ≥36 weeks, aOR, 13.35; 95% CI, 6.71–26.57), followed by early preterm cases (28–35 vs ≥36 weeks; aOR, 5.61; 95% CI, 3.09–10.16) (Table). In-labor uterine rupture occurred more often in extreme prematurity (aOR, 2.66; 95% CI, 1.38–5.14) but not in early preterm cases (aOR, 1.28; 95% CI, 0.81–2.03). Pre-labor uterine rupture, but not in-labor rupture, was associated with fetal demise or stillbirth (aOR, 3.69; 95% CI, 1.93–7.05). This nationwide analysis suggests that uterine rupture can occur in nearly 1 in 80 patients with PAS and that pre- and in-labor uterine ruptures have distinct differences in the clinical and pregnancy characteristics. The incidence of uterine rupture among patients with PAS seems to be higher than among those in an unselected population of patients with a previous cesarean delivery reported in the same database in a different time period (12.1 vs 3.5 per 1000).3Sangara R.N. Youssefzadeh A.C. Mandelbaum R.S. et al.Prior vertical uterine incision: effect on subsequent pregnancy characteristics and outcomes.Int J Gynaecol Obstet. 2023; 160: 85-92Google Scholar