Methods:
In this retrospective cohort study all parturients at the Shaare Zedek Medical Center (SZMC) with a history of two previous CD between August 2005 and November 2019, were enrolled. We included parturients between 24-42 weeks of gestations who had two prior CDs and subsequently had vaginal vertex births and parturients who chose to have a repeat elective CD. Excluded from the study were parturients with non-vertex presentation, placenta previa, placenta accrete, mullerian uterine anomalies, multifetal gestation other than twins and parturients without at least one previous vaginal delivery. A comparison was made between those who attempted TOLAC and those who were scheduled for an elective repeat CD.
In general, our department’s standard recommendation following previous two CD is to undergo an elective repeat CD. However, TOLAC is discussed with those parturients who express interest in attempting labor after CD. TOLAC is discussed only if all the following criteria are validated. The criteria are as follows: 1. The parturient explicitly expresses her request for TOLAC and comprehends the potential risks, benefits, and alternatives. 2. The parturient had a previous vaginal delivery (VD), either before, between or after the second CD. 3. Both previous uterine incisions were low segment transverse, there were no extensions or severe adhesions. 4. Fetal estimated weight is <4000 grams. 5. Vertex presentation. Additionally, the onset of labor must be spontaneous, we do not induce or augment labor in parturient with 2 previous CD. SZMC’s medical record database on all labor and deliveries is updated in real time during labor and delivery by attending healthcare professionals and audited periodically by trained technical personnel to ensure validity of the data. Over 95% of Israeli citizens’ medical care is covered by the Israeli National Health Plan hence continuity of care is granted for long periods of time for most of the patients. Maternal and neonatal records were reviewed and retrieved for relevant data, information was coded and identifiable, and personal information for each patient was protected by anonymization prior to analysis.
Definitions: The terms used were defined as the following: Uterine rupture - complete uterine scar ruptures, i.e. involving the occurrence of a full-thickness defect with direct connection between peritoneal space and the uterine cavity. Diagnosis was made by an attending physician during an explorative laparotomy. Re-laparotomy –additional abdominal operation performed during hospitalization for delivery12 Postpartum hemorrhage (PPH): Was defined using one of the two following definitions: 1. Estimated blood loss of over 500 ml in vaginal delivery (VD) and over 1000 ml in CD13 (In SZMC pads are weighted following VD, but in some cases when pads or weighting is not feasible blood loss is estimated subjectively by the midwife/obstetrician); 2. the transfusion of blood products and/or hemoglobin drop> 4 gr/dL.Prolonged hospitalization : > 5 days for vaginal deliveries and > 7 days for cesarean deliveries.
Primary outcome was defined as a composite adverse maternal outcome : one or more of the following: PPH, hemoglobin drop> 4 gr/dL, blood products transfusion, intensive care unit (ICU) admission.Secondary outcomes were defined as follows: 1. Composite adverse neonatal outcome : a composite outcome of one or more of the following: 5-min Apgar score <  7, neonatal asphyxia, neonatal intensive care unit (NICU) admission, and the need for mechanical ventilation.
2. Composite adverse maternal and neonatal outcome s among the group of parturients attempting TOLAC. We compared those who achieved VBAC and those whose attempt at labor was aborted and necessitated in labor CD
Statistical analysis : An initial univariate analysis was carried out, categorical variables were presented as a percentage and compared using Chi square and Fisher’s exact test as appropriate. Continuous variables presentation was according to each variable distribution, while normal distributed variables were presented as a mean and standard deviation, those displaying non-normal distribution were presented as median with interquartile range. A comparison was made using Student’s t-test and Mann Whitney test, accordingly. All analyses were two sided and a p value < 0.05 was considered statistically significant. Data analysis was conducted according to the group category to which the parturient was initially categorized corresponding to her original request. For instance, if a parturient originally requested an elective CD and presented in active labor, resulting in an emergency CD, she remained in the analysis of the planned elective CD group. However, all parturients analyzed in the TOLAC group attempted TOL even if the result was CD. A multivariate analysis using a binary logistic regression model was used in order to account for the independent association between composite adverse neonatal outcomes, infusion of blood products and TOLAC versus elective CD after 2 CDs. Adjusted Odds Ratios (aOR) and 95% confidence intervals (CI) were computed. A sub-group analysis comparing in-labor CD (=failed TOLAC) versus successful VBAC was conducted. A univariate analysis was followed by a multivariate analysis in order to examine independent factors associated with TOLAC failure.
Data analysis was carried out using SPSS software (version 23 statistical package; IBM, Armonk, NY). The study was approved by the local institutional ethics committee in accordance with the principles of the Declaration of Helsinki (IRB: 001-20-SZMC).