Abstract
Objective
Circumvallate placenta has a suggested association with adverse pregnancy outcomes (antenatal bleeding, placental abruption, preterm birth, emergency cesarean, small for gestational age infants, and stillbirth). The aim was to determine if prenatal diagnosis of circumvallate placenta is associated with these adverse pregnancy outcomes.
Study Design
Pregnancies with a singleton gestation prenatally diagnosed with circumvallate placenta between January 1, 2012 and March 31, 2021 were identified. Adverse pregnancy outcomes were obtained. Rates of adverse pregnancy outcomes were compared among those with prenatally diagnosed circumvallate placentas to those without this prenatal diagnosis with a 4:1 control matched group. Pregnancies with known fetal anomalies or other placental abnormalities were excluded. Statistical analyses included Student’s t-test and Χ2 with p < 0.05 considered significant.
Results
Prenatal ultrasound findings of circumvallate placenta were seen in 179 pregnant people (0.20% of all anatomic US studies and 0.17% of all deliveries). Diagnosis was made at a mean gestational age of 19.8±2.4 weeks. Adverse pregnancy outcomes were similar between groups.
Conclusion
Prenatal ultrasound findings of circumvallate placenta do not correlate with adverse pregnancy outcomes. Given overall good prognosis, prenatal diagnosis of circumvallate placenta may not warrant additional surveillance during pregnancy.
Keywords: circumvallate placenta, prenatal diagnosis, adverse pregnancy outcomes, antenatal bleeding
Circumvallate placentas are a form of extrachorial placenta in which the basal plate extends past the margins of the chorion plate resulting in the chorion and amnion folding over one another. The incidence of circumvallate placenta based on historical pathology studies is between 1 in 188 and 1 in 208.1,2 Prior studies have linked circumvallate placenta with poor pregnancy outcomes including antenatal bleeding, placental abruption, preterm birth, emergency cesarean, small for gestational age infants, and stillbirth.2–5
Prenatal diagnosis of circumvallate placenta is made when observed ultrasound findings of a circumvallate fold are seen, including a thick, linear band of echoes extending from one placental edge to the other or a cross-section of two “shelves,” with each lying above an opposing placental margin (►Fig. 1).6 Increased placental thickness on ultrasound has also been investigated as a potential marker for prenatal screening for circumvallate placenta.7
Fig. 1.
Circumvallate placenta. (A) Thick, linear band of echoes extending from one placental edge to the other. (B) Cross-sectional view of the placenta with evidence of a placental shelf, representing folded back chorion and amnion, in the same 18-week pregnancy.
At present there is currently no change in clinical management following prenatal diagnosis of circumvallate placenta if the pregnancy is otherwise uncomplicated. However, based on the associations with small for gestational age and stillbirth, some consider serial growth assessment. Therefore, the aim of our study was to evaluate the association of adverse pregnancy outcomes in pregnant people with prenatally diagnosed circumvallate placenta.
Study Design
This was a retrospective chart review of pregnant people with singleton pregnancies and prenatally diagnosed circumvallate placenta that received prenatal care and delivered at Parkland Hospital from January 1, 2012, through March 31, 2021. Pregnant people with circumvallate placenta were identified from a query of the clinical impression field from our sonography database. The sonography report of each patient identified was then reviewed to confirm the diagnosis of circumvallate placenta, as well as additional sonograms performed in these individuals. All diagnoses were reported by a maternal-fetal medicine specialist or radiologist trained in obstetrical imaging. We used an obstetrical database to obtain maternal demographics including age, race/ethnicity, parity, body mass index (BMI), and gestational age at delivery. Cases of multiple gestations, known fetal anomalies, and placental abnormalities (e.g., placenta previa, placenta accreta spectrum, and placental hematoma) were excluded.
One hundred and seventy-nine pregnant people met the inclusion criteria. These pregnancies were compared to those from a control group selected at random from pregnant people receiving prenatal care and delivering during the study period. The control group was matched for age, race/ethnicity, parity, and obesity (BMI ≥30 kg/m2) at a ratio of 4:1 to account for the contribution of these variables to obstetric outcomes. The same exclusion criteria were applied to the control group. Adverse pregnancy outcomes for all patients assessed included antenatal bleeding, placental abruption, preterm birth, emergency cesarean, small for gestational age infants (birth weight below the 10th percentile),8 and stillbirth. Antenatal bleeding was defined as an antepartum emergency room visit for significant vaginal bleeding, defined as bleeding greater than mild uterine hemorrhage (e.g., light vaginal spotting) either subjectively reported or objectively seen on exam. Cases with mild uterine hemorrhage were excluded. Statistical analysis was performed using Student’s t-test and χ2 with p < 0.05 considered significant. This study was deemed exempt from Institutional Review Board approval under the New Common Rule by the Institutional Review Board of the UT Southwestern Medical Center.
Results
Pregnant people with a prenatal diagnosis of circumvallate placenta (n = 179) comprised 0.20% of all anatomic U.S. studies and 0.17% of all deliveries from January 1, 2012, through March 31, 2021. The mean gestational age at the time of diagnosis was 19.8±2.4 weeks. Of the pregnant people with prenatally diagnosed circumvallate placenta, the mean maternal age was 27±6.4 years, the mean BMI was 32.7±7.1 kg/m2, and the mean gestational age at the time of delivery was 39.0±2.4 weeks. Demographic characteristics of patients with prenatally diagnosed circumvallate placenta compared to those of patients with normal placenta are shown in ►Table 1. Consistent with matching, there were no significant differences in maternal age, parity, race/ethnicity, BMI, or gestational age at delivery between the two groups.
Table 1.
Demographic characteristics of pregnant people with circumvallate prenatal diagnosis and matched control group
| Baseline characteristics | Circumvallate prenatal diagnosis | p-Value | |
|---|---|---|---|
| Yes (n = 179) | No (n = 716) | ||
| Maternal age (y) | 27±6.4 | 27±6.4 | 1 |
| ≥35 | 28 (16%) | 112 (16%) | |
| Race/ethnicity | 1 | ||
| Non-Hispanic Black | 37 (21%) | 148 (21%) | |
| Non-Hispanic White | 4 (2%) | 16 (2%) | |
| Hispanic | 136 (76%) | 544 (76%) | |
| Other | 2 (1%) | 8 (1%) | |
| Parity | 0.54 | ||
| 0 | 45 (25%) | 180 (25%) | |
| 1 | 48 (27%) | 222 (31%) | |
| ≥2 | 86 (48%) | 314 (44%) | |
| BMI (kg/m2) | 32.7 7.1 | 32.2 5.8 | 0.29 |
Note: Data reported as n (%) for categorial variables and mean±standard deviation for continuous variables. p-Value as per χ2 for categorical variables and Student’s t-test for continuous variables.
There were no significant differences between the two groups for rates of antenatal bleeding, preterm birth, placental abruption, or need for emergent cesarean section (►Table 2). There were also no differences in the number of stillbirths or infants that were small for gestational age.
Table 2.
Rates of adverse outcomes with and without prenatal ultrasound diagnosis of circumvallate placenta
| Adverse outcome | Circumvallate prenatal diagnosis | p-Value | |
|---|---|---|---|
| Yes (n = 179) | No (n = 716)a | ||
| Delivery gestational age (wk) | 39.0±2.4 | 39.0±2.3 | 0.99 |
| Antenatal bleedingb | 12 (6.7%) | 26 (3.6%) | 0.07 |
| Preterm birth | 16 (9%) | 74 (10%) | 0.57 |
| Placenta abruption | 2 (1%) | 3 (0.4%) | 0.26 |
| Emergent cesarean | 4 (2%) | 22 (3%) | 0.55 |
| Small for gestational age | 20 (11%) | 68 (9.5%) | 0.50 |
| Stillbirth | 0 (0%) | 5 (0.6%) | 0.26 |
Note: Data reported as n (%) for categorial variables and mean±standard deviation for continuous variables. p-Value as per χ2 for categorical variables.
Controls matched for age, race/ethnicity, parity, and obesity (body mass index ≥ 30 kg/m2).
Antepartum bleeding defined as presentation for emergent care due to bleeding more than mild uterine hemorrhage by report or examination.
Discussion
We found no significant differences in adverse pregnancy outcomes between pregnant people with and without prenatally diagnosed circumvallate placenta, including antenatal bleeding, preterm birth, placental abruption, need for an emergent cesarean, infants born small for gestational age, or stillbirth infants. These findings suggest that prenatal diagnosis of circumvallate placenta does not predispose to adverse pregnancy outcomes.
These findings are contrary to existing literature on the consequences of circumvallate placenta. Other studies have found adverse pregnancy outcomes linked to confirmed circumvallate placenta on pathology; however, the question remains whether diagnosis of circumvallate placenta during pregnancy is an indicator of such outcomes. To our knowledge, our study is the first to examine the outcomes of pregnancies diagnosed prenatally with circumvallate placentas. A Medline search (National Library of Medicine) from 1980 through April 2022 using the MeSH terms “circumvallate placenta,” “adverse outcome,” “ultrasound,” “sonography,” and “prenatal diagnosis” did not identify prior studies investigating this association.
Limitations and Strengths
This study found that pregnant people with prenatally diagnosed circumvallate placenta had no increased association with adverse outcomes. Therefore, the necessity of intervention or change in management of the pregnancy in such patients is questionable. Further prospective research in pregnant people with circumvallate placenta with pathologic correlation may further clarify whether a change in their management is warranted.
A strength of this study was that data were collected from a single institution and, as such, the same institutional protocols set the standard for prenatal and delivery care received by all patients. This study was limited by its retrospective nature. It is also limited by inter-rater reliability due to varying years of experience between physicians prenatally diagnosing circumvallate placenta. The decision for the rate of growth sonography following diagnosis of circumvallate placenta was at the discretion of the provider and was performed specifically for this indication in 39% (69/179) of the circumvallate cohort. No antenatal surveillance was performed for any patient for the indication of circumvallate placenta. Therefore, the lack of these interventions may have impacted our results, though arguably they would have increased our number of adverse events observed. The differences observed in adverse outcomes of patients in this study and in previous studies focused on postnatal diagnosis may be explained by a greater number of false positives present in our population. The false-positive rate may be due to placenta trophotropism or amniotic bands or sheets mistaken as a circumvallate fold. This suggests that the ability of sonography to accurately diagnose circumvallate placenta remains limited. Thus, further study is needed to develop better screening for circumvallate placenta using ultrasound with pathologic correlation, and a well-designed prospective study of the topic is warranted.
Conclusion
While previous studies have linked pathologic diagnosis of circumvallate placenta to adverse obstetric outcomes, this study’s unique exploration of prenatal diagnosis countered that an association between adverse outcomes and circumvallate placenta exists when the diagnosis is made prenatally by ultrasound. No significant differences in the rates of adverse pregnancy outcomes were found in pregnant people who were prenatally diagnosed with circumvallate placenta and those that were not. These findings suggest that prenatal diagnosis of circumvallate placenta may not warrant additional surveillance during pregnancy.
Key Points.
The risk of prenatally diagnosed circumvallate placenta was previously unclear.
Prenatally diagnosed circumvallate placenta is not associated with adverse pregnancy outcomes.
No change in management may be necessary with prenatally diagnosed circumvallate placenta.
Funding
Dr. Herrera is supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development under Award Number K23HD103876. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Footnotes
Conflict of Interest
None declared.
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