| Circumvallate placenta | |
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| The thickened ring of membranes on the fetal surface of a circumvallate placenta, making it appear as though the central part of the placenta has been exposed. | |
| Specialty | Obstetrics  |
Circumvallate placenta is a rare condition affecting about 1-2% ofpregnancies, in which theamnion andchorionfetal membranes essentially "double back" on thefetal side around the edges of theplacenta.[1] Afterdelivery, a circumvallate placenta has a thick ring of membranes on itsfetal surface.[2] Circumvallate placenta is aplacental morphological abnormality associated with increased fetalmorbidity andmortality due to the restricted availability of nutrients andoxygen to the developingfetus.
Physicians may be able to detect a circumvallate placenta duringpregnancy by using anultrasound. However, in other cases, a circumvallate placenta is not identified untildelivery of the baby. Circumvallate placenta can increase the risk of associatedcomplications such aspreterm delivery andplacental abruption. Occasionally, a circumvallate placenta can also increase the risk ofneonatal death andemergencycaesarean section. Although there is no existing treatment for circumvallate placenta, physicians can attempt to minimize the effects ofcomplications, if they occur, throughfrequent fetal monitoring and, if necessary,emergencycesarean section.[1]
In a circumvallate placenta, thechorionic plate, which forms thefetal surface of theplacenta, tends to be smaller than thebasal plate, which forms thematernal surface of theplacenta. This results in the elevation of theplacental margin and the appearance of an annular shape.[3] Thefetal surface is divided into a central depressed zone surrounded by a thickened white ring which is incomplete. The ring is situated at varying distances from the margin, or edges, of theplacenta. This thick ring of membranes is composed of a double fold ofamnion andchorion with degenerateddecidua vera andfibrin in between.Blood vessels, supplying nutrients and carrying waste products to and from the developingfetus, radiate from theumbilical cord insertion to as far as the ring of membranes, and then disappears from view.[4]
A circumvallate placenta does not always induce associatedsymptoms duringpregnancy, making it extremely difficult todiagnose a circumvallate placenta inasymptomatic mothers. Insymptomatic mothers,physicians may be able to detect a circumvallate placenta based on the presentation of the followingsigns.[1]
Circumvallate placenta has also been associated with a higher incidence ofcomplications includingplacental abruption,low birth weight,premature delivery,perinatal death, andfetal abnormalities.
Unfortunately, there is no known cause of circumvallate placenta and no majorpreventative measures that can be taken to minimize the risk of developing a circumvallate placenta.[1] Circumvallate placenta is not a genetic disorder. Some potential causes of circumvallate placenta includereduced amniotic fluid pressure, circumferentialhemorrhage, andsuperficial ordeepimplantation of the embryo within theuterine wall, although these potential causes are still not well-understood in terms of their relation to circumvallate placenta.[4]
High-risk pregnancies are described aspregnancies in which a mother, thefetus, or both are put at a higher risk for developingpregnancy complications before, during, or afterbirth.Risk factors such ashypertensive medical conditions,maternal age, andsubstance use are just some of the things that can put a woman at an increased risk for developing circumvallate placenta and/or any othercomplications.[5]
Women entering apregnancy withhypertension are considered to be put at a higher risk forpreeclampsia oreclampsia during the course of theirpregnancy. Hypertensive disorders, likehypertension, have been found to affect about 10% ofpregnancies in the United States and have resulted in about 6.8% ofmaternal deaths from 2011 to 2015.High blood pressure duringpregnancy can potentially damage maternalorgan systems such as theliver or thekidneys, which can be life-threatening. To preventpreeclampsia oreclampsia from developing inpregnancy, women withhypertension can be prescribedanti-hypertensive medications duringpregnancy and are advised to monitor theirblood pressure throughout the course ofpregnancy.[5]
Anotherrisk factor for developing anypregnancy complications ismaternal age.Advanced maternal age, considered to be when a woman enterspregnancy at age 35 or above, has also been linked to increased risk ofmaternal mortality,preeclampsia,restricted fetal growth,fetal distress, and a variety of otherpregnancy complications. Conversely,teenage pregnancy is also associated with increased risk ofendometriosis,postpartum hemorrhage, andmild preeclampsia, when compared with pregnant mothers in their 20s.[5]Genetically, the long period of time betweenmeiotic arrest of theegg gamete as afetus and eachovulation cycle occurring after theonset offemale puberty in teenage years can potentially contribute to the increased risk forpregnancy complications in mothers who are age 35 or older at time ofpregnancy.[6]
Further, yet another factor inducingadverse complications in pregnancy issubstance use status.Nicotine,alcohol, andmarijuana are the most commonsubstances used duringpregnancies. Substance use inpregnancy is concerning because of its alarming association with other risk factors, such asmental illness.Depression alone has been associated within increased risk forpreeclampsia,gestational diabetes,hypertension,premature birth, andlow birth weight. Women withsubstance use disorders tend to live in areas that are unable to provide qualityprenatal care or propermanagement of their psychiatric conditions. As a result of improper management ofpsychiatric illnesses, substances are abused duringpregnancy, potentially causing harm to both the mother and thefetus. Somepregnancy complications that can occur as a result of substance use inpregnancy arefetal alcohol syndrome andneonatal abstinence disorder.[5]
Women with these risk factors are recommended additional surveillance duringpregnancy to monitorfetal development and to be able to detectfetal,placental, orumbilical cord abnormalities as early as possible.
Theplacenta is a transient organ developed duringpregnancy that facilitates nutrient, gas, and waste exchange between a mother and a developingfetus. Placental abnormalities, such as circumvallate placenta, can harm a developingfetus, as normal exchange of materials between a mother and a developingfetus is impaired. With placental abnormalities, a developingfetus is unable to receive the vital materials that it needs forproper development, resulting in the possibility ofpregnancy complications,birth defects, and/ordeath of the fetus.
In a normalplacenta, there is a smooth transition from theparenchymalvillouschorion to themembranous chorion at the border of theplacental plate.Fetal blood vessels subdivide from theumbilical cord and spread diagonally throughout theparenchyma towards the edge of theplacental plate.[4]
In a circumvallate placenta, themembranes often become restrained due tomarginal infarct,hemorrhage, orfibrin depositing. This results in the reduction in size of thechorionic plate of theplacenta, further causing themembranes on thefetal side to fold backward on themselves.[medical citation needed] Theparenchymalvillouschorion continues toproliferate beyond the tetheredmembranes and appears to protrude outward. Thefetal blood vessels are directed downward and then horizontally in order to provide blood flow to the most peripheral parts of theplacental plate extending beyond the tetheredmembranes.[4]
Since a portion of theplacenta tends to become exposed in a circumvallate placenta, due to the reduced size of thechorionic plate,vaginal bleeding is more likely to occur at this site of exposure. Likewise,inhibited fetal growth can also ensue due to the decreased exchange of nutrients and waste between mother andfetus, since thefetus is unable to sustain necessary nutritional demands forproper fetal development.Premature rupture of membranes often occurs as a result ofinfection in theuterus, which can be caused by the occurrencevaginal bleeding. Therefore, placental abnormalities such as circumvallate placenta can be extremely detrimental in causing the onset of associated conditions.
In some cases, aphysician may be able todiagnose a circumvallate placenta viaultrasound during one of manyroutine ultrasound screenings. In most cases, a circumvallate placenta is not discovered untilphysical examination of theplacenta afterdelivery of thefetus.[1] For this reason, circumvallate placenta is very difficult to diagnose duringpregnancy.
Onultrasound, a normalplacenta should appear complete and uniform, with thefetal surface of theplacenta appearing slightly shiny and translucent. The appearance of a circumvallate placenta on ultrasound may present with irregular edges, uplifted margins, or placental sheets. In a study conducted in 1994, 62 healthypregnant women were examined withplacental sonography for detection of circumvallate placenta. Of the five experiencedsonologists who interpreted theplacental ultrasounds, all were unable to properly detect and diagnose circumvallate placenta, revealing the difficult nature of circumvallate placenta recognition.[4] Further, these findings indicate thatprenatal sonographic criteria used for detection of circumvallate placenta are not reliable enough forscreening purposes.
Complete circumvallate placenta involves morphological abnormality of the entire dimension of theplacenta, while partial circumvallate placenta does not involve the entireplacenta but rather a portion of theplacenta.[4] Complete circumvallate placenta is very rare, occurring within about 1% ofpregnancies, and has been noted to increase the risks of associatedcomplications such asplacental abruption,premature childbirth,premature rupture of membranes,perinatal death, andcongenital abnormalities.[1] Partial circumvallate placenta is more common but is not found to be asclinically significant as complete circumvallate placenta.[4]
The accurate diagnosis of circumvallate placenta duringpregnancy can have significant implications in the recognition ofpatients who are at risk ofcomplications. Although the ability ofsonography to accurately diagnosis circumvallate placenta duringpregnancy is quite limited,research studies continue to emerge at the possibility of doing so.
Although there is nocure or specific treatment for restoration of the circumvallate placenta, there are ways to decrease the risks of possiblecomplications prior tobirth or attempt to managecomplications if they develop. If circumvallate placenta is diagnosed duringpregnancy,physicians may offer recommendations to reduce the risks of associatedcomplications such aslower birth weight andplacental abruption.[1]
Decreased birth weight is a major concern associated with circumvallate placenta.Infants born with birth weights that are lower than expected per theirgestational age oftentimes end up requiring extra support in theneonatal intensive care unit (NICU). To assist in the monitoring of appropriatefetal growth, aphysician may recommend more frequentgrowth checks duringpregnancy if circumvallate placenta is suspected. If afetus is not growing satisfactorily,premature delivery, viavaginal delivery orcaesarean section, may be recommended, withC-section being more favorable compared tovaginal delivery.[1]
In women experiencing aplacental abruption associated with circumvallate placenta,physicians will normally advocate for frequentgrowth checks, hospitalbed rest,early delivery, and, if necessary,emergencyC-section.[1] Likewise,IV fluids andblood transfusions can also be given topatients with aplacental abruption in attempts to increaseblood pressure and minimize the effects ofsevere blood loss.
Ifoligohydramnios occurs as a result of a circumvallate placenta, a treatment calledamnioinfusion may be considered to replenish the amount of lostamniotic fluid within theamniotic sac.Amnioinfusion may help in preventingunderdevelopment of the lungs.
If diagnosed with a circumvallate placenta, consistentfetal monitoring by a licensedphysician can help to prevent and/or reduce the effects of associatedcomplications that may occur. Additionally, healthylifestyle choices, a well-balanced and nutritious diet, adequate rest, and cessation of alcohol and tobacco products can also help to prevent the incidence of a circumvallate placenta and itsassociated complications.[medical citation needed] If diagnosed with a circumvallate placenta, in association with other threateningpregnancies complications,emergencycesarean section will most likely be suggested by aphysician.[3]
Unfortunately, there is currently not acure available for circumvallate placenta. While some evidence suggests that a circumvallate placenta can increase the risk ofcomplication during pregnancy, otherresearch suggests this increased risk is marginal. Sadly, circumvallate placenta can occasionally result ininfant death depending on the severity of thecomplications encountered. In other cases, circumvallate placenta can result inpremature birth ofinfants who are otherwise healthy after being monitored in theneonatal intensive care unit for a period of time afterbirth. Therefore,proper medical care andmonitoring are crucial in attempting to minimize the likelihood ofcomplications.[1] In other cases,patients diagnosed with circumvallate placenta are able to carry their babies untilterm or near-term.
Circumvallate placenta is a very rare condition affectingpregnant women. This condition is a placental morphological abnormality, with theplacenta being formed during the early periods ofpregnancy. Women are able to becomepregnant with theonset ofovulation andmenstruation in earlyadolescence, with most women becomingpregnant during adulthood. Circumvallate placenta is currently known to affect about 1-2% of pregnancies. It is not virally transmissible to other individuals, nor can it be transferred through contact or respiration.[1]
There are no specificracial or ethnic groups that are morepredisposed to acquiring a circumvallate placenta duringpregnancy, however, as with allpregnancies, there are generalrisks factors that can put a pregnant woman at risk forcomplications, including circumvallate placenta. Notably, certainpregnancy complications, such aspreeclampsia, tend to be almost three times asfatal in African American women compared to non-Hispanic white women, even though both groups tend to experiencepreeclampsia at almost the same rates. This is partially thought to be due toinequalities in accessing qualityprenatal care in lowersocioeconomic neighborhoods and the effect ofstructural racism withinhealthcare systems.[5] Any woman residing in an area with a lowersocioeconomic status, regardless ofrace or age, is predisposed to developingpregnancy complications like circumvallate placenta if qualityprenatal care is not available.
Women withsignificant obstetric histories can also be at higher risk for developing any type ofpregnancy complication, including circumvallate placenta, and are recommended to be screened for placental abnormalities within theirsecond trimester of pregnancy.[3]
Theplacenta plays a dominant role in being responsible for a variety ofcomplications within pregnancy and labor. Placentalpathological studies have significantly contributed to recentobstetric literature. Many studies have examined theclinical significance ofpatients with circumvallate placenta compared topatients with a normalplacenta. They have revealed that incidences ofpreterm birth,oligohydramnios,placental abruption,low birth weight, andfetal death were present in significantly higher rates than when compared tocontrol patients with normalplacentas.
Acase study reported in 2020 observed thecorrelation between circumvallate placenta and theoccurrence ofobstetric complications such asbattledore insertion.Battledore insertion, abnormal insertion of theumbilical cord into theplacenta, occurs in about 7% ofpregnancies and can also result in many of the samepregnancy complications as circumvallate placenta;intrauterine growth restriction,fetal distress, andfetal death. This abnormal insertion of theumbilical cord into theplacenta can result in a loss of adequate blood flow to the developingfetus due to restriction.[3] Thefetus is unable to obtain normal amounts ofrequired oxygen andnutrition through theplacenta, and this can further cause othersevere complications.
In the study, a 22-year-old woman at28 weeks and 2 days of gestation, presented for aroutine third trimester screening. She was noted to have had 2 priormiscarriages at17 and 20 weeks. A previous normalsecond trimesterroutine screening at21 weeks of gestation did not identify any structural abnormalities within theplacenta,decreased fetal size, or abnormally-appearingumbilical cord insertion. Thepatient also did not have any episodes ofvaginal bleeding during the currentpregnancy.[3]
Upon presenting forroutine screening at28 weeks and 2 days of gestation, thepatient was not exhibiting anysigns of activecontractions and acardiotocography was performed as part ofroutine screening.[3]Cardiotocography is adiagnostic tool used during thethird trimester of pregnancy to observefetal heart rates and presence ofuterine contractions. It can also be used to detectsigns of any sort offetal distress.[7] In interpreting thecardiotocography that the 22-year-old pregnant woman had completed, it was noted that thefetus appeared to be much smaller than expected and was exhibiting concerns of decreasedamniotic fluid volume,oligohydramnios, and restricted blood flow through theumbilical cord.Cardiotocographic monitoring also noted decreases infetal heart rate every 25 minutes withoutcontractions.Fetal motion was present, with theplacenta appearing enlarged and spherical.[3]
Decreases in thefetus' heart rate, in addition to the other findings of thecardiotocography, ultimately promptedphysicians todeliver the baby viaemergencycesarean section without major complications. Thenewborn, with normalAPGAR scores andumbilical cord arterial pH levels, was admitted to theneonatal intensive care unit. Upon examining theplacenta afterdelivery, it was noted that theplacenta demonstrated the appearance of a circumvallate placenta, and also showed evidence of abnormalumbilical cord insertion into theplacenta.Postpartum, the mother had a good recovery and thenewborn was discharged from theneonatal intensive care unit 105 dayspost-birth.[3]
This case study discussed the association of circumvallate placenta and abnormalbattledore cord insertion in producingpregnancy complications. Restriction ofumbilical cord blood flow from theplacenta to thefetus and placental abnormalities like circumvallate placenta may work in conjunction to generatefetal distress.Decreased levels of oxygenation and nutrient absorption resulted indecelerations of fetal heart rate and the decision todeliver thefetus viacesarean section to preventfetal death byhypoxia.Routine monitoring offetal growth and development, placental structure, and placental function are recommended withhigh-risk pregnancies. Inpatients diagnosed with circumvallate placenta duringpregnancy, monthly fetal growth assessments are also recommended.Patients found to have blood flow restrictions to or from theplacenta are recommended to undergo weeklyultrasounds with consistent monitoring offetal heart rate.[3]
In a separatecase study reported in 2017, a woman at about35 weeks of gestation presented withpreeclampsia andintrauterine fetal demise, or more commonly known asstillbirth. Afterdelivery of thestillborn fetus, examination of theplacenta revealed a circumvallate placenta withbattledore insertion of the umbilical cord. It was speculated that the combination of circumvallate placenta andbattledore insertion had led to theloss of the fetus prior todelivery, as there was no other discernible cause for thestillbirth. While circumvallate placenta andbattledore insertion are individually very rare conditions that can result in multiplepregnancy complications, the coexistence of these abnormalities likely resulted in theloss of the fetus.[8] The diminishedblood flow and circulation from theplacenta to thefetus, as caused bybattledore insertion, in combination with the impairedexchange of nutrients and wastes between mother andfetus, as caused by circumvallate placenta, likely contributed to thepreeclampsia and thisloss of fetal life.
Thus, it is highly recommended that ifplacental orumbilical cord abnormalities, such as circumvallate placental andbattledore insertion, are suspected or detected prior tobirth, that thepregnancy should be consideredhigh-risk.High-risk pregnancies significantly benefit from frequent follow-ups usingultrasonography to monitorfetal developmental and placental and umbilical cord structure and function.[8]
Research directions continue to investigate methods in which circumvallate placenta may be more commonly diagnosed duringpregnancy beforecomplications can transpire.Biomarkers such as Sflt/PlGF can be used to predict severepregnancy complications inhigh-risk pregnancies. Circumvallate placenta appears to be correlated with reduced placentalefficacy due to increased placental thickness and abnormalvilli function, affecting the Sflt/PlGF ratio. It is thought that obtaining Sflt/PlGF ratios can be used to determine deficiencies in placental function in cases of placental abnormalities.[3] Futureresearch analyzing the contribution ofbiomarkers like Sflt/PlGF to predict placental abnormalities would be influential to our understanding of many placental deformities, including circumvallate placenta.[3]
Due to the rare occurrences of circumvallate placenta, more extensiveresearch trials are unavailable, resulting indata limitations. Therefore, theclinical importance of circumvallate placenta remains uncertain.[3]
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