Relaparotomy Post Cesarean Delivery: Characteristics and Risk Factors.

Purpose: Relaparotomy following cesarean delivery (CD) is performed at a rate of 0.2-1% of CD. The objective of the present study was to identify risk factors for relaparotomy following CD, and to examine whether there is a difference in the risk of relaparotomy between CD performed during different daytimes. Methods: A retrospective study including all CD over ten years. Cases that underwent laparotomy within one week following CD were compared to those that did not. CDs for placenta accreta were excluded. Results: Sixty-four patients underwent relaparotomy following CD. In univariate analysis relaparotomy was signicantly higher pregnancies following assisted-reproductive technologies (39.1%vs. 16.9%), hypertensive disorders of pregnancy (18.8%vs. 7%), twin pregnancies (29.7%vs. 10%), preterm deliveries (34.4%vs. 17.6%), low birthweight (2815gr vs. 3047gr), placenta previa (7.8% vs. 1.3%) low body mass index (22.4 vs. 24.5) and urgent CD (54.7% vs. 40.8%), especially during the second stage of labor. In a multivariate regression analysis, the adjusted odds ratio for relaparotomy was 10.24 in CD due to placenta previa, and 5.28 in CD performed at the second stage of delivery. At relaparotomy, active bleeding was found in 50 patients (78.1%), nearly half received packed cells, 12.5% developed consumptive coagulopathy, and 17.2% needed hospitalization in the intensive care unit. 6.3% underwent a second relaparotomy, mainly due to bleeding. Conclusion: Hypertensive disease, placenta previa, and urgent CDs mainly those performed at the second stage of labor are risk factors for relaparotomy after CD.


Introduction:
Relaparotomy following cesarean delivery (CD) is de ned as an additional abdominal surgery for exploration within 60 days of CD including skin opening 1 . It is usually an urgent medical condition, complicating about 0.2-1% of CD, and is performed mainly due to abdominal bleeding, abdominal wall hematoma, uncontrolled bleeding and infections [2][3][4][5] . The elevated rate of CD over the years resulted in an increased complications rate including bleeding, infections and injury to adjacent organs resulting in relaparotomy [6][7][8][9] . Although a few studies reported association between relaparotomy and emergent CD 10,11 , none examined the association to the time of day.
Characterizing the patients who underwent relaparotomy may enlighten us about possible risk factors and lead to preventive measures that may be taken in order to avoid such potentially life-threatening events.
The objective of the present study was to detect all the patients that had relaparotomy following CD in a large tertiary center, to compare them to the patients who delivered by CD without this complication, and to identify risk factors for relaparotomy. We aimed to examine whether there is a difference in the risk of relaparotomy between CD performed during different daytimes.

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Material And Methods: A retrospective study including all consecutive CD's between 03/2011 and 04/2020 at the Chaim Sheba Medical Center, a large tertiary referral center at the center of Israel with over 10,000 deliveries per year.
Inclusion criteria included all patients that underwent laparotomy within one week following a cesarean delivery.
Exclusion criteria were pregnancies with placenta accreta. Our medical center specializes in cesarean deliveries complicated by placenta accreta, therefore the rate of placenta accreta is higher than in other medical centers. Since these speci c operations are prone to bleeding complications and to injuries to adjacent organs, these operations were excluded from our analysis.
We compared all relaparotomy cases to all CDs without a subsequent relaparotomy.
Elective CD was de ned as a scheduled CD performed at the planned time, either in the morning at afternoon. The indications for elective CD were maternal, fetal or placental conditions posing a risk for vaginal delivery 12 , for example non-vertex presentation, previous CD, pregnancies with placenta previa or suspected macrosomia. Emergent CD was de ned as a non-elective CD but with no immediate risk for the mother of fetus performed at any time during the day. For example, a patient planned to have an elective CD who came in labor before the scheduled CD or non-progressive labor. Urgent CD was were de ned as CD performed due to immediate maternal or fetal life-threatening risk, such as severe fetal bradycardia or a massive bleeding, performed at any time of the day.
Data included maternal age, maternal body mass index (BMI), gravidity, parity, mode of previous delivery, time from previous cesarean delivery, gestational or pre-gestational diabetes, hypertensive disorders of pregnancy, gestational age at delivery, number of fetuses, birthweight, cause of CD, meconium stained amniotic uid, placenta previa, duration of cesarean delivery, time of cesarean delivery, and cause of relaparotomy. Comparison was made between different hours of the day according to the work-shifts.

Results:
During the study period there were overall 93,626 deliveries at our medical center, 24,239 by cesarean delivery (comprising 25.9%). Sixty-four patients underwent relaparotomy during the rst week following delivery, comprising 0.26% of all cesarean deliveries. There were 348 CDs performed due to placenta accrete, 14 of them (4%) underwent relaparotomy. These patients were excluded from the study population.
In an univariate analysis relaparotomy was associated with the following (Table 1): Lower pre-pregnancy BMI, pregnancies following assisted reproductive technologies, hypertensive disorders of pregnancy, twins, preterm births, smaller birthweight, placenta previa, or urgent CD, and those operated during the second stage of labor. Previous delivery by cesarean delivery did not increase the risk of relaprotomy, nor the interval from the last cesarean delivery. The incidence of relaparotomy did not differ among CDs preformed at different hours in the day.   Table 3 presents the characteristics of the relaparotomy surgery. In 78% of the patients active bleeding was found, and nearly half received blood products, 12.5% developed consumptive coagulopathy, and 17% needed intensive care. There were no cases of maternal death. Four patients (6.3%) underwent a second relaparotomy, mainly due to bleeding complications.

Discussion:
The present study showed an increased risk of relaparotomy following CD in twin gestations, pregnancies complicated by hypertensive disease or placenta previa and following urgent CS, and following CD in the second stage of delivery. There was no difference in the rate of relaparotomy between different hours of the day.
We excluded surgeries with placenta accreta because these operations are prone to bleeding complications and relaparotomy, and our goal was to analyze the more common CD's. The rate of 0.26% of laparotomy following delivery reported in our study resembles the incidence of 0.2-1.04% relaparotomies, previously reported 2-5,10−16 .
As described in previous studies, pregnancies with placenta previa are scheduled for operations earlier than other elective CD, which may explain the signi cantly lower birthweight and lower gestational age in the relaparotomy group for this indication 4,5 . Pregnancies with placenta previa are prone to bleeding from the placental bed, and di culties to control bleeding from the isthmus and upper cervical part 17,18 , leading to the signi cant risk for relaparotomy found in our study. In this study, multiple pregnancies were associated with increased risk of relaparotomy. The di culty to adequately control bleeding in overdistended uterus may explain the increased risk of uterine atony and bleeding 3,19 . Late preterm delivery of multiple pregnancy is common and this explains the earlier gestational age and the lower birthweight found in the relaparotomy group following twins CD 19 . Since ART may result in higher rates of multiple pregnancies, this may explain the statistically signi cant association between ART and relaparotomy found in the univariate analysis.
Although obesity is associated with technically di cult CD, along with postpartum complications such as wound rupture 20 , we did not nd a signi cant risk for relaparotomy in overweight patients. Furthermore, BMI was signi cantly lower in the relaparotomy group.
Several studies reported an association between fetal gender and different complications of pregnancy 21 , including increased risk of relaparotomy in pregnancies with female fetuses 2 . Nevertheless, we did not nd any correlation between relaparotomy and fetal gender.
Similar to previous studies 1,5 , we found that hypertensive diseases of pregnancy were associated with a signi cant risk of relaparotomy. Ahmed et al found that the most common comorbidity in patients with relaparotomy was hypertensive disorders 22 . It has been suggested that the main reason for this association is the coagulation disorders that may complicate severe hypertensive disorders [23][24][25] .
There are controversial reports regarding the association between previous CD to elevated risk of relaparotomy. Several studies reported an association between a history of previous CD and relaparotomy following a repeat CD 1,5 while others did not nd such an association 3 . We did not nd such an association, nor between the interval between the CD's and relaparotomy.
Previous studies reported that increased operative time increases the risk of relaparotomy 2,3 . Contrary to that, we did not nd such an association. Indeed, Rottenstreich et al reported that in repeated CD, prolonged operative time (de ned as longer than the 90th percentile for each speci c surgeon) is associated with adverse maternal complications such as post-operative blood transfusion, prolonged hospitalization, infections, and readmission, but they did not describe an association to relaparotomy 26 .
Previous studies reported increased risk of relaparotomy following emergent CD 10,11 . These studies de ned emergent CD as the non-elective CD. In the present study we divided the non-elective CD to emergent CD, and to urgent CD that included cases with immediate life threatening risk to the mother or the fetus. As expected, elective CD were signi cantly associated with lower risk of relaparotomy. However, there was no increased risk of relaparotomy following emergent CD, such as patients that were operated prior to a scheduled CD, but with no immediate risk of fetal or maternal compromise. We did nd a signi cant increased risk in relaparotomy after urgent CD, with a 2-fold increase in the rate of relaparotomy in urgent CD performed during the second stage of labor. The duration of the second stage did not in uence the risk of relaparotomy. Interestingly, in 12.5% of the cases there were no intraabdominal ndings during relaparotomy. A previous report has found no ndings in 60.7% of the patients 2 .
Laparotomy following delivery increases the risk of maternal morbidity due to bleeding, coagulation disorders, requirement of blood products, infections; increases hospitalization days and creates a burden to the medical system. The most catastrophic complication is maternal death with previous reports ranging from 0 to12% 4,[11][12][13][14][15]20,28 . In our study, 12.5% developed disseminated intravascular coagulation and 17.2% of our patients were admitted to the intensive care unit. Fortunately, there were no cases of maternal mortality.
A third laparotomy was needed in 6.25% of our patients, lower than the 19.6% reported by Seal et al 11 .
Most cases both in our study and in previous studies were due to intraabdominal hemorrhage.
We acknowledge several limitations in our study. Our medical center is a tertiary referral hospital resulting in an increased rate of high risk pregnancies. Thus our results may not represent the numbers in most delivery wards. I order to overcome part of this limitation we excluded pregnancies with placenta accrete.
The large number of CDs over many years in the present study results in a more accurate perspective regarding the risk factors and the characteristics of relaparotomies following CDs.

Conclusions:
Relaparotomy following CD is a rare but a signi cant event. Recognizing the risk factors associated with this complication may be useful for identifying women at risk for relaparotomy and thus to allow for preventive measures to be taken during the surgery, as well as during the post-surgery follow-up.

Declarations
Ethical approval: The study was approved by the IRB board of the Chaim Sheba Medical center No. 7223-20-SMC.