The ominous association between severe endometriosis, in vitro fertilisation, and placenta previa: raising awareness, limiting risks, informing women

Untangling the independent effect of endometriosis, adenomyosis, and ART-related factors on maternal, placental, fetal, and neonatal adverse outcomes: results from a systematic review and meta-analysis

BACKGROUND

Women with endometriosis may constitute a group at a particularly increased risk of pregnancy-related complications. Furthermore, women selected for assisted reproductive technology (ART) are exposed to additional endocrinological and embryological factors that have been associated with adverse pregnancy outcomes.

OBJECTIVE AND RATIONALE

This study aimed to investigate the independent effect of endometriosis, adenomyosis, and various ART-related factors on adverse maternal, placental, fetal, and neonatal outcomes.

SEARCH METHODS

Published randomized controlled trials, cohort studies, and case-control studies were considered eligible. PubMed, MEDLINE, ClinicalTrials.gov, Embase, and Scopus were systematically searched up to 1 March 2024. This systematic review and meta-analysis was performed in line with the PRISMA and the MOOSE reporting guidelines. To thoroughly investigate the association between endometriosis/adenomyosis and adverse pregnancy outcomes, sub-analyses were conducted, whenever possible, according to: the method of conception (i.e. ART and non-ART conception), the endometriosis stage/phenotype, the coexistence of endometriosis and adenomyosis, any pre-pregnancy surgical treatment of endometriosis, and the form of adenomyosis. The odds ratio (OR) with 95% CI was used as effect measure. The quality of evidence was assessed using the GRADE approach.

OUTCOMES

We showed a higher risk of placenta previa in women with endometriosis compared to controls (34 studies, OR 2.84; 95% CI: 2.47, 3.26; I2 = 83%, moderate quality). The association was observed regardless of the method of conception and was particularly strong in the most severe forms of endometriosis (i.e. rASRM stage III-IV endometriosis and deep endometriosis (DE)) (OR 6.61; 95% CI: 2.08, 20.98; I2 = 66% and OR 14.54; 95% CI: 3.67, 57.67; I2 = 54%, respectively). We also showed an association, regardless of the method of conception, between endometriosis and: (i) preterm birth (PTB) (43 studies, OR 1.43; 95% CI: 1.32, 1.56; I2 = 89%, low quality) and (ii) cesarean section (29 studies, OR 1.52; 95% CI: 1.41, 1.63; I2 = 93%, low quality). The most severe forms of endometriosis were strongly associated with PTB. Two outcomes were associated with adenomyosis both in the main analysis and in the sub-analysis that included only ART pregnancies: (i) miscarriage (14 studies, OR 1.83; 95% CI: 1.53, 2.18; I2 = 72%, low quality) and (ii) pre-eclampsia (7 studies, OR 1.70; 95% CI: 1.16, 2.48; I2 = 77%, low quality). Regarding ART-related factors, the following associations were observed in the main analysis and confirmed in all sub-analyses conducted by pooling only risk estimates adjusted for covariates: (i) blastocyst stage embryo transfer (ET) and monozygotic twinning (28 studies, OR 2.05; 95% CI, 1.72, 2.45; I2 = 72%, low quality), (ii) frozen embryo transfer (FET) and (reduced risk of) small for gestational age (21 studies, OR 0.59; 95% CI, 0.57, 0.61; P < 0.00001; I2 = 17%, very low quality) and (increased risk of) large for gestational age (16 studies, OR 1.70; 95% CI, 1.60, 1.80; P < 0.00001; I2 = 55%, very low quality), (iii) artificial cycle (AC)-FET and pre-eclampsia (12 studies, OR 2.14; 95% CI: 1.91-2.39; I2 = 9%, low quality), PTB (21 studies, OR 1.24; 95% CI 1.15, 1.34; P < 0.0001; I2 = 50%, low quality), cesarean section (15 studies, OR 1.59; 95% CI 1.49, 1.70; P < 0.00001; I2 = 67%, very low quality) and post-partum hemorrhage (6 studies, OR 2.43; 95% CI 2.11, 2.81; P < 0.00001; I2 = 15%, very low quality).

WIDER IMPLICATIONS

Severe endometriosis (i.e. rASRM stage III-IV endometriosis, DE) constitutes a considerable risk factor for placenta previa and PTB. Herein, we recommend against superimposing on this condition other exposure factors that have a strong association with the same obstetric adverse outcome or with different outcomes which, if coexisting, could determine the onset of an ominous obstetric syndrome. Specifically, we strongly discourage the use of AC regimens for FET in ovulatory women with rASRM stage III-IV endometriosis or DE. We also recommend single ET at the blastocyst stage in this high-risk population.

REGISTRATION NUMBER

CRD42023401428.

Endometriosis Increases the Risk of Placenta Previa in Both IVF Pregnancies and the General Obstetric Population

Is there a relationship between endometriosis and placenta previa (PP)? To investigate if there is a relationship between endometriosis and PP, a retrospective study was carried out, using prospectively recorded data from two different databases from Cruces University Hospital. Two different populations were included in the study. The ART (assisted reproduction techniques) population consisted of 246 cesarean sections (CS), from a total of 1170 deliveries, and the obstetric population consisted of 7045 CS, from a total of 50,298 deliveries. A representative subset from the obstetric population was established selecting 4 CS without PP for each CS with PP. In our ART population, the PP rate was 1.71% among all deliveries and 8.13% among CS. In our general obstetric population, the PP rate was 0.34% among all deliveries and 2.41% among the CS. Among the CS in ART pregnancies, the PP rate was 20% in the women with endometriosis vs 5.47% in women without endometriosis (OR = 4.32; 95% CI = 1.67-11.17), while considering all ART deliveries, the PP rates were 6.43% and 1.07%, respectively (OR = 6.36; 95% CI = 2.59-15.65). In the CS-obstetric population, the rate of PP was 9.61% among women with endometriosis vs 2.19% among women without endometriosis (OR = 4.74; 95% CI = 2.91-7.73). Considering all deliveries, the PP rate was 1.35% among women with endometriosis vs 0.30% in women without endometriosis. Differences persisted when adjusting for age, IVF, multiplicity, and previous deliveries. In the CS-obstetric population with PP, mean surgical time and hospital stay were significantly higher in women with endometriosis. Endometriosis is associated with a higher risk of PP even after adjusting for other parameters.

A unique placenta previa risk factor profile for pregnancies conceived with assisted reproductive technology

OBJECTIVE

To define specific risk factors for placenta previa in pregnancies conceived with assisted reproductive technology (ART).

DESIGN

Retrospective cohort.

SETTING

Fertility centers and inpatient obstetric units in Massachusetts.

PATIENT(S)

Patients conceiving with ART and delivering at 20 weeks gestation or later between 2011 and 2017 in Massachusetts.

INTERVENTION(S)

Patient demographic and medical factors and specific components of their cycles. Data were obtained by linking vital records of the State of Massachusetts to reproductive clinic data obtained from the Society for Assisted Reproductive Technology Clinic Outcome Reporting System, and then supplementing this information with laboratory and obstetric data from 2 large academic hospitals.

MAIN OUTCOME MEASURE

Associations were tested between multiple cycle- and patient-related factors and placenta previa or low-lying placenta at delivery. After testing for confounders, multivariate models were adjusted for maternal age, history of prior cesarean delivery and birth plurality, and are reported as adjusted relative risks (aRR).

RESULT(S)

We included 18,939 pregnancies, with 553 (2.9%) having placenta previa at delivery. Advanced maternal age (aRR, 1.25; 95% confidence interval [CI], 1.06-1.48), endometriosis, (aRR, 2.22; 95% CI, 1.71-2.86), and controlled ovarian hyperstimulation (aRR, 1.33; 95% CI, 1.12-1.59) were associated with placenta previa, whereas multiple births (aRR, 0.63; 95% CI, 0.48-0.81) and a history of polycystic ovary syndrome or ovulation disorders (aRR, 0.59; 95% CI, 0.46-0.75) had negative associations. The endometriosis association was strong in nulliparas and the controlled ovarian hyperstimulation association was strong in parous patients in a stratified analysis. No association was seen with prior history of cesarean delivery.

CONCLUSION(S)

Patients conceiving with ART do not have the typical previa risk factors of prior cesarean delivery and multiple gestations, whereas endometriosis and fresh embryo transfers contributed moderate risk. The embryo transfer process itself may affect previa development in this population.

Horizontal Cervix as a Novel Sign for Predicting Adhesions on the Posterior Extrauterine Wall in Cases of Placenta Previa

We aimed to identify a magnetic resonance imaging (MRI) feature that can predict posterior extrauterine adhesion (posterior adhesion) antenatally, in patients with placenta previa. We retrospectively reviewed patients with placenta previa who underwent a preoperative MRI examination of placenta accreta spectrum. We categorized the patients into two groups based on whether the cervix was anterior or posterior to a line perpendicular to the anatomical conjugate on the MRI. We projected the perpendicular line toward a straight line through the broad of the back on T2-weighted sagittal MRI images and measured the angle between this line and the line passing through the cervical canal. We analyzed the correlation of the cervical canal angle with the presence of posterior adhesions. Of the 96 patients analyzed, 71 patients had an anteverted cervix and 25 patients had a retroverted cervix. There were 21 posterior adhesions. The adhesion rate was significantly higher in patients with a retroverted cervix than those with an anteverted cervix (8.5% vs. 60%; p = 0.00). The cervical canal angle was ≤10° in 25 patients; of these 17 had adhesions (sensitivity, 81.0%; specificity, 89.3%; area under the curve, 0.887; 95% confidence interval, 0.792–0.981). This finding, labeled “positive horizontal cervix sign,” may be a promising indicator of posterior adhesions in patients with placenta previa.

Bowel surgery as a fertility-enhancing procedure in patients with colorectal endometriosis: methodological, pathogenic and ethical issues

Bowel surgery for colorectal endometriosis is being promoted to infertile women without severe sub-occlusive symptoms, with the objective of improving the likelihood of conception. Contrary to rectal shaving, bowel surgery involving full-thickness disk excision and segmental resection entails opening of the intestinal lumen thus increasing the risk of postoperative infectious complications. About 1 in 10 patients undergoing colorectal resection for intestinal endometriosis will experience severe sequelae, including anastomotic dehiscence, rectovaginal fistula formation, and bladder and bowel denervation. Similar to other surgical procedures aiming at enhancing fertility in women with endometriosis, bowel surgery has been introduced into clinical practice without adequate evaluation through randomized controlled trials. According to systematic literature reviews based mainly on case series, the incremental gain of adding bowel procedures to standard surgery appears uncertain in terms of pregnancy rate after both natural attempts and IVF. Considering the methodological drawbacks and the high risk of bias in the available observational studies, it is not possible to exclude the suggestion that the benefit of colorectal surgery has been overestimated. Given the risk of harms to women's health and the important ethical implications, less emphasis should be put on strict statistical significance and more emphasis should be placed on the magnitude of the effect size. In this regard, the published data may not be generalizable, as the surgeons publishing their results may not be representative of all surgeons. Until the results of adequately designed and conducted RCTs are available, colorectal surgery with the sole intent of improving the reproductive performance of infertile patients with intestinal endometriosis should be performed exclusively within research settings and by highly experienced surgeons. Women should be informed about the uncertainties regarding the harms and benefits of bowel surgery in different clinical conditions, and preoperative counselling must be conducted impartially with the objective of achieving a truly shared medical decision.