Introduction
The incidence of adnexal mass in pregnancy is about 41 in 1500 pregnancies [
1]. These tumors are mostly benign, corpus luteum cyst is the most common type, it will disappear in 90% cases by the second trimester of pregnancy, followed by serous cystadenoma and dermoid cyst, which is the most common pathologies found [
2‐
5]. Only approximately 1 in 25,000 pregnancies were observed to be malignant ovarian tumors [
6]. Surgery is deemed to be dangerous for both the mother and the fetus, especially in emergency situations [
2,
7,
8], which may lead to a high incidence of maternal complications, fetal death and premature birth [
9]. However, for pregnant women with acute pelvic pain or an adnexal mass greater than 6 cm in diameter, selective surgical excision is not disputed. As the pregnancy progresses, they may occur in torsion, rupture, or leakage of the cyst, which may cause damage to both the mother and the fetus [
2,
10]. In all, ovarian tumors in pregnancy requiring surgical intervention vary from 0.0004 to 0.36% [
11,
12]. The procedures include resection of the tumor, oophorectomy, or salpingo-oophorectomy and so on. And the best surgical approach for a pregnancy with adnexal masses remains controversial. Since the mid-1990s, laparoscopy has been widely used in non-pregnant women’s gynecologic diseases. Nowadays, a growing number of evidence shows that laparoscopy can be safely and effectively used during pregnancy, and provides several advantages, including reduced postoperative pain, analgesic use and hospitalization time [
13‐
19]. At the same time, some surgeons have been hesitant to perform minimally invasive surgery on pregnant patients. Potential concerns associated with pregnancy laparoscopic surgery include limited surgical manipulations, perforation of gravid uterus and hypercarbia [
20,
21]. Laparoscopic surgery for a pregnancy with adnexal mass has been limited to case reports and retrospective studies in the last decade [
9,
22‐
25]. No prospective controlled studies have been reported yet. Therefore, a meta-analysis was conducted.
The main purpose was to investigate and compare the pregnancy outcomes of two methods in the treatment of ovarian tumors during pregnancy, including fetal loss rate, premature delivery rate, operative time, bleeding volume and hospital stay.
Discussion
Our systematic reviews and meta-analysis investigated all controlled clinical trials according to the inclusion criteria. The search strategy employed in the present meta-analysis was broad. Those derived from searching proceedings databases were not specifically excluded. According to the quality evaluation of Newcastle–Ottawa Scale results (NOS) for meta-analysis of non-randomized studies, the quality of most of the studies was considered to be high. The results of this meta-analysis suggest that laparoscopic surgery in pregnancy results in almost 51% lower risk of preterm labor, shorter hospital stay and lower blood loss compared with open surgery. No significant difference in fetal loss and operation time was observed between the two groups.
To date, a considerable number of studies demonstrate that laparoscopic surgery during pregnancy has been performed successfully for many conditions, such as cholecystectomy and appendectomy [
18,
19,
35,
36], which have an advantage of good maternal outcomes, such as earlier ambulation, less pain after surgery and shorter hospital stay than open surgery [
37]. At the same time, previous controlled studies have shown that it is not associated with higher rates of abortion and preterm deliveries in comparison with laparotomy [
33,
34]. A meta-analysis has been published to review the effects of laparoscopic and open appendectomy in pregnancy [
29]. However, previous randomized studies of laparoscopy versus open surgery in pregnant patients with adnexal mass are limited.
The risk of fetal loss has become the top priority in many studies of the relative safety of laparoscopy in pregnancy [
38,
39]. The main consideration is laparoscopy requires carbon dioxide pneumoperitoneum [
40]. Increased intra-abdominal pressure can lead to reduced uterine blood flow and maternal venous return, resulting in the fetal intrauterine hypoxia [
41,
42]. Another factor associated with pneumoperitoneum is that carbon dioxide can be absorbed across the peritoneum, causing fetal acidosis [
43]. However, Curet MJ hold no substantial adverse effect on the fetus when the maximum pressure of the pneumoperitoneal is less than 12 mmHg and the duration is less than 30 min [
40]. To avoid this risk, the gasless laparoscopic technique was, therefore, recommended for pregnancy surgery [
20,
31,
44,
45]. Another concern for the application of laparoscopic surgery during pregnancy is the risk of injury to the enlarged uterus [
46,
47]. In the study of Balthazar [
15], initial port was placed through an open method (80%) or a left upper quadrant entry (11%), thereby reducing the potential risk of penetrating injury to the gravid uterus. In all, although there is no statistical significance, the present results suggest that the risk of fetal loss may be increased in those undergoing laparoscopic surgery compared with open surgery. It is likely that this analysis did not have enough statistical capabilities to detect a significant difference, because a sample size of 985 would be required in each group to detect a RR of 1.36.
The risk of preterm labor after laparoscopy compared with open surgery has been discussed in many reports of the relative safety of laparoscopy in pregnancy [
32,
48,
49]. The relative risk (RR) of the preterm labor between laparoscopy versus open surgery in this study was estimated as carried out by Wilasrusmee et al. [
29], because the number of fetal loss is not excluded in data processing; it is difficult to reach a conclusion that laparoscopy has an advantage in preterm labor though the result indicates that the odds of preterm labor was 51% lower in the laparoscopy than the open surgery group (
P = 0.014). In this study the increase of operating time in laparoscopic surgery is not statistically significant, probably due to the influence of the learning curve. Meanwhile, similar to the findings in non-gravid patients, laparoscopy was associated with improved short-term operative outcomes including decreased blood loss and shorter hospital stay. The results showed that the amount of blood loss (83.81 ml,
P = 0.00) in the laparoscopy group was significantly reduced, which may attribute to the better visualization of deep vascular structures, and possibly more precise and accurate surgery. The length of hospital stay was approximately 2 days shorter in laparoscopy than that of open surgery (
P < 0.000). However, these results should be interpreted with caution as the total number of patients is small and significant heterogeneity.
Meta-analytical research has several limitations that must be taken into account when its results are considered. One major potential limitation here is that all studies included in the review were observational, and summary data published within each study were included in the analysis. While not all cases in the studies were adnexal mass, some were found to be appendicitis or cholecystitis during surgery, or considered to be malignant by pathologic results, and these, therefore, limited the comparability of the results. Besides, many other factors (such as patient age, gravidity, duration of pregnancy, weight gain, tocolytic treatment, mass size, the percentage of emergency operations undertaken, variation in the surgical procedures and the surgeon’s experience) may affect the clinical heterogeneity. Confounding bias cannot be ignored as the included studies were retrospective. There were no available data on pregnancy complications, nor was it possible to assess whether the effects of laparoscopic surgery on pregnancy outcomes were associated with other pregnancy complications. Therefore, further large-scale randomized trials are needed to confirm the present findings. However, it may be difficult to perform a randomized trial due to the particularity of pregnant women. In addition, the statistically significant difference in fetal outcomes was not possible to be identified owing to the limited number of studies available for pooling. Neither the allocation of surgical methods nor the assessment of outcome was blind, and it is important to bear in mind publication bias, particularly in meta-analytical research based on published studies.
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