Results
During the study period, 41 uterine rupture cases were identified among a total of 209,112 deliveries. The incidence of UR was 1.96/10 000 births. There were no maternal deaths, hysterectomy and obstetric injury secondary to uterine rupture in our study. Among all cases, there were 16(39.0%) cases with complication and 25(61.0%) cases without. 15 (36.6%) were complete rupture cases, and 26 (63.4%) incomplete rupture cases. 38(92.7%) were scarred uterus and 3 (7.3%) unscarred uterus.
The total number of deliveries, scarred uterus and VBAC rate have increased over the eight years period. However, the proportion of uterine rupture remained consistent (Figure. 1.Due to the large number difference, a logarithmic axis is applied). UR rate was not associate with VBAC rate (Correlation coefficient: -0.095, p =0.826)
Demographic data and clinical characteristics of mothers and fetuses between uterine rupture and non-uterine rupture were presented in Table 1. Patients in UR group were significantly older and more than half (58.5%) of them were over 35 years old, compared with 18.8% of the non-UR. The mean gravidity of the case women of the UR group was 2.95±1.41, significantly higher than that of the non-UR group (1.85±1.09). The proportion of primiparity in non-UR group (72.7%) were much higher than UR group (24.4%). There was a statistically significant difference in the gestational age at delivery, birth weight and maternal hospital stay between the groups (39.0±1.6 vs 37.04±3.52, 3296.9±470.1 vs 3016.59±755.1, 4.3±4.1vs 7.71±5.28; p<0.05). The incidences of gestational hypertension, artificial reproductive technology, cesarean delivery, postpartum hemorrhage, preterm birth and 5-minute Apgar score<7 in the uterine rupture group were higher than those in non-UR group (7.3% vs 1.1%, 12.2% vs 4.0%, 100% vs 39.9%, 31.7% vs1.5%, 39.0% vs 6.6%, 19.5% vs 1.0%; p <0.05).
Table 2 displayed the occurrence of obstetrical risk factors in complicated and not complicated uterine rupture groups. Among all patients with uterine rupture, 16 (39.0%) had maternal and fetal complications. Compared with not complicated uterine rupture, women in complicated uterine rupture group had more primiparity, a higher prevalence of uterine myomectomy history, artificial reproductive technology use, blood transfusion, Intensive Care Unit (ICU) admission and complete UR. Complicated UR group also presented a larger amount of bleeding, a longer hospital stay, a higher probability of preterm birth, multiple pregnancy, a smaller rupture gestational weeks, a lower birth weight and prevalence of previous cesarean history.
Patients’ rate with abnormal fetal heart rate and vaginal bleeding (68.8%vs 24.0%,43.8%vs 24.0%) were significantly higher in the uterine rupture group with maternal and fetal complications. In complicated group, the earliest and the latest ruptured gestational week were 23 weeks and 40 weeks. In not complicated group, the earliest and the latest ruptured gestational week were 35 weeks and 40 weeks. There was no maternal death. The perinatal mortality attributable to uterine rupture was 7.3%. 21 (51.2%) mothers were diagnosed with uterine rupture preoperatively, 20 (48.8%) were diagnosed intraoperatively. The diagnosed time and the proportion of TOLAC were similar in the 2 groups (p=0.16; 0.156).
Multiple logistic regression analysis was employed to examine whether signs and symptoms were associated with the presence of UR with complication (Table 3). The model, which included all signs and symptoms as independent variables, showed that abnormal fetal heart rate emerged as a significant and independent factor associated with the complicated uterine rupture compared with other signs. (p<0.05 and OR 12.45, 95% CI 1.16-133.54). Other clinical signs, however, were not different.
Figure 2 shows the rupture sites involved. 24 (59%) cases were anterior lower uterine segment; 3(7%) cases had posterior segment rupture; 9 (22%) cases were ruptured at the lateral segment; 4 (10%) cases were fundal segment rupture and one ruptured more than one place (2%).
Detailed clinical information on all uterine rupture cases following laparoscopic myomectomy is shown in Table 4