Operative technique at caesarean delivery and risk of complete uterine rupture in a subsequent trial of labour at term. A registry case-control study.

OBJECTIVE: To estimate the relation of single-layer closure at previous caesarean delivery, and other pre-labour and intra-partum risk factors for complete uterine rupture in trial of vaginal birth after a caesarean (TOLAC) at term. STUDY DESIGN: Population-based case-control study. We identified all women (n = 39 742) recorded in the Danish Medical Birth Registry (DMBR) during a 12-year period (1997-2008) with a singleton pregnancy at term and TOLAC. Among these, all women with a complete uterine rupture were identified (cases). Information from the registry was validated against medical records. Controls were selected in the DMBR as the following two births with TOLAC at term and no uterine rupture. Detailed information from cases and controls was collected from manual review of medical records. Main outcome measure was complete uterine rupture during TOLAC at term. RESULTS: Upon validation, 175 cases and 272 controls met the above criteria. After adjustment for possible confounding factors there was no association between single layer closure and uterine rupture (aOR 1.38, CI: 0.88-2.17). Significant risk factors were: Induction with an unfavourable cervix (aOR 2.10 CI: 1.19-3.71), epidural (aOR 2.17 CI 1.31-3.57), augmentation by oxytocin for more than one hour (aOR 2.03 CI: 1.20-3.44), and birth weight ≥ 4000g (aOR 2.65 CI 1.05-6.64). Previous vaginal delivery (aOR 0.41 CI: 0.25-0.68) and inter-delivery interval of more than 24 months (aOR 0.38 CI: 0.18-0.78) reduced the risk of uterine rupture. CONCLUSION: Single-layer uterine closure did not remain significantly associated to uterine rupture during TOLAC at term after adjustment for confounding factors. Induction of labour with an unfavourable cervix, birth weight ≥ 4000g and indicators of prolonged labour were all major risk factors for uterine rupture.

Can Intrapartum Cardiotocography Predict Uterine Rupture among Women with Prior Caesarean Delivery?: A Population Based Case-Control Study.

OBJECTIVE: To compare cardiotocographic abnormalities recorded during labour in women with prior caesarean delivery (CD) and complete uterine rupture with those recorded in controls with prior CD without uterine rupture. STUDY DESIGN: Women with complete uterine rupture during labour between 1997 and 2008 were identified in the Danish Medical Birth Registry (n = 181). Cases were validated by review of medical records and 53 cases with prior CD, trial of labour, available cardiotocogram (CTG) and complete uterine rupture were included and compared with 43 controls with prior CD, trial of labour and available CTG. The CTG tracings were assessed by 19 independent experts divided into groups of three different experts for each tracing. The assessors were blinded to group, outcome and clinical data. They analyzed occurrence of defined abnormalities and classified the traces as normal, suspicious, pathological or pre-terminal according to international guidelines (FIGO). RESULTS: A pathological CTG during the first stage of labour was present in 77% of cases and in 53% of the controls (OR 2.58 [CI: 0.96-6.94] P = 0.066). Fetal tachycardia was more frequent in cases with uterine rupture (OR 2.50 [CI: 1.0-6.26] P = 0.053). Significantly more cases showed more than 10 severe variable decelerations compared with controls (OR 22 [CI: 1.54-314.2] P = 0.022). Uterine tachysystole was not correlated with the presence of uterine rupture. CONCLUSION: A pathological cardiotocogram should lead to particular attention on threatening uterine rupture but cannot be considered a strong predictor as it is common in all women with trial of labour after caesarean delivery.

Uterine rupture without previous caesarean delivery: a population-based cohort study.

OBJECTIVE: To determine incidence and patient characteristics of women with uterine rupture during singleton births at term without a previous caesarean delivery. STUDY DESIGN: Population based cohort study. Women with term singleton birth, no record of previous caesarean delivery and planned vaginal delivery (n=611,803) were identified in the Danish Medical Birth Registry (1997-2008). Medical records from women recorded with uterine rupture during labour were reviewed to ascertain events of complete uterine rupture. Relative Risk (RR) and adjusted Relative Risk Ratio (aRR) of complete uterine rupture with 95% confidence intervals (95% CI) were ascertained according to characteristics of the women and of the delivery. RESULTS: We identified 20 cases with complete uterine rupture. The incidence of complete uterine rupture among women without previous caesarean delivery was about 3.3/100,000 deliveries. Multiparity (RR 8.99 (95% CI 1.86-43.29)), induction of labour (RR 3.26 (95% CI 1.24-8.57)), epidural analgesia (RR 10.78 (95% CI 4.25-27.39)), and augmentation by oxytocin (RR 9.50 (95% CI 3.15-28.63)) were associated with uterine rupture. Induction of labour was not significantly related to uterine rupture when adjusted for parity, epidural analgesia and augmentation by oxytocin. CONCLUSION: Although uterine rupture is rare, its association with epidural analgesia and augmentation of labour with oxytocin in multipara should be considered. Thus, vigilance should be exercised when labour is obstructed and there is need for epidural analgesia and/or augmentation by oxytocin in multiparous women. Due to the rare occurrence of uterine rupture caution should be exerted when interpreting the findings of this study.

Use of ICD-10 codes to monitor uterine rupture: validation of a national birth registry.

OBJECTIVES: Uterine rupture is a rare but severe complication in pregnancies after a previous cesarean section. In Denmark, the monitoring of uterine rupture is based on reporting of relevant diagnostic codes to the Danish Medical Birth Registry (MBR). The aim of our study was to examine the validity of registration of uterine rupture in the MBR within the population of pregnant women with prior cesarean section by conducting a review of the medical records. STUDY DESIGN: We reviewed 1709 medical records within the population of singleton pregnant woman delivering at term between 1997 and 2007. We retrieved the medical records of all women in the MBR with a code for uterine rupture during labor regardless of whether or not a prior cesarean section had been reported to the registry. In addition medical records of all women with a code for previous cesarean section and delivery of a child with adverse perinatal outcome were retrieved. RESULTS: Among women recorded in the MBR with a previous cesarean section and uterine rupture, only 60.4% actually had a uterine rupture (partial or complete). At least 16.2% of complete uterine ruptures were not reported to the registry. Considering only complete uterine ruptures, the sensitivity and specificity of the codes for uterine rupture were 83.8% and 99.1%, respectively. CONCLUSION: During the study period the monitoring of uterine rupture in the MBR was inadequate.