title: Risk factors for complete uterine rupture.
abstract: BACKGROUND
  Complete uterine rupture is a rare peripartum complication associated with a catastrophic outcome. Because of its rarity, knowledge about its risk factors is not very accurate. Most previous studies were small and over a limited time interval. Moreover, international diagnostic coding was used in most studies. These codes are not able to differentiate between the catastrophic complete type and less catastrophic partial type. Complete uterine rupture is expected to increase as the rate of cesarean delivery increases. Thus, we need more accurate knowledge about the risk factors for this complication.
  
  
  OBJECTIVE
  The objective of the study was to estimate the incidence and risk factors for complete uterine rupture during childbirth in Norway.
  
  
  METHODS
  This population-based study included women that gave birth after starting labor in 1967-2008. Data were from the Medical Birth Registry of Norway and Patient Administration System, complemented with information from medical records. We included 1,317,967 women without previous cesarean delivery and 57,859 with previous cesarean delivery. The outcome was complete uterine rupture (tearing of all uterine wall layers, including serosa and membranes). Risk factors were parameters related to demographics, pregnancy, and labor. Odds ratios for complete uterine rupture were computed with crude logistic regressions for each risk factor. Separate multivariable logistic regressions were performed to calculate the adjusted odds ratios and 95% confidence intervals.
  
  
  RESULTS
  Complete uterine rupture occurred in 51 cases without previous cesarean delivery (0.38 per 10,000) and 122 with previous cesarean delivery (21.1 per 10,000). The strongest risk factor was sequential labor induction with prostaglandins and oxytocin, compared with spontaneous labor, in those without previous cesarean delivery (adjusted odds ratio, 48.0, 95% confidence interval, 20.5-112.3) and those with previous cesarean delivery (adjusted odds ratio, 16.1, 95% confidence interval, 8.6-29.9). Other significant risk factors for those without and with previous cesarean delivery, respectively, included labor augmentation with oxytocin (adjusted odds ratio, 22.5, 95% confidence interval, 10.9-41.2; adjusted odds ratio, 4.4, 95% confidence interval, 2.9-6.6), antepartum fetal death (adjusted odds ratio, 15.0, 95% confidence interval, 6.2-36.6; adjusted odds ratio, 4.0, 95% confidence interval, 1.1-14.2), and previous first-trimester miscarriages (adjusted odds ratio, 9.6, 95% confidence interval, 5.7-17.4; adjusted odds ratio, 5.00, 95% confidence interval, 3.4-7.3). After a previous cesarean delivery, the risk of rupture was increased by an interdelivery interval <16 months (adjusted odds ratio, 2.3; 95% confidence interval, 1.1-5.4) and a previous cesarean delivery with severe postpartum hemorrhage (adjusted odds ratio, 5.6; 95% confidence interval, 2.4-13.2).
  
  
  CONCLUSIONS
  Sequential labor induction with prostaglandins and oxytocin and augmentation of labor with oxytocin are important risk factors for complete uterine rupture in intact and scarred uteri.
authors: Norwegian National Advisory Unit on Women's Health, Oslo University Hospital, Oslo, Norway; Women and Children's Division, Rikshospitalet, Oslo University Hospital, Oslo, Norway. Electronic address: ialzirqi@ous-hf.no.
authors: Iqbal
authors: I
authors: Al-Zirqi
authors: Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway; Medical Birth Registry of Norway, Norwegian Institute of Public Health, Bergen, Norway.
authors: Anne Kjersti
authors: AK
authors: Daltveit
authors: Norwegian National Advisory Unit on Women's Health, Oslo University Hospital, Oslo, Norway; Norwegian Institute of Public Health, Oslo, Norway.
authors: Lisa
authors: L
authors: Forsén
authors: Women and Children's Division, Rikshospitalet, Oslo University Hospital, Oslo, Norway; Faculty of Medicine, University of Oslo, Oslo, Norway.
authors: Babill
authors: B
authors: Stray-Pedersen
authors: Norwegian National Advisory Unit on Women's Health, Oslo University Hospital, Oslo, Norway; Norwegian Institute of Public Health, Oslo, Norway.
authors: Siri
authors: S
authors: Vangen
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology; D000328:Adult; D001721:Birth Intervals; D005260:Female; D005313:Fetal Death; D006801:Humans; D015994:Incidence; D007751:Labor, Induced / Q000706:statistics & numerical data*; D016015:Logistic Models; D008423:Maternal Age; D015999:Multivariate Analysis; D009664:Norway / Q000453:epidemiology; D016017:Odds Ratio; D010120:Oxytocics; D010121:Oxytocin; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011453:Prostaglandins; D012307:Risk Factors; D014597:Uterine Rupture / Q000453:epidemiology*; D016064:Vaginal Birth after Cesarean / Q000706:statistics & numerical data*
chemical_list: D010120:Oxytocics; D011453:Prostaglandins; D010121:Oxytocin
keywords: antepartum fetal death; augmentation of labor with oxytocin; complete uterine rupture; medical records; previous cesarean delivery; previous miscarriage; prostaglandin; risk factor; sequential induction of labor