Multimodality imaging of placental masses: a pictorial review

Rare Pathologic Placenta Ultrasound Findings

Rare ultrasound placenta findings, such as avascular cystic lesions, hyperechogenic and thick placenta, and enlarged placenta, are associated with infarcts, perivillous fibrin deposition, and mesenchymal dysplasia. These lesions can be present in 20% of normal pregnancies but are more frequent in pregnant women with pre-eclampsia (PE) and/or fetal growth restriction, autoimmune diseases, and infections, and can increase the risk of perinatal complications, including fetal death. Evaluation of the placental surface may also identify cases with circumvallate placenta and chorioangiomas. These rare placental findings require close clinical follow-up and serial fetal evaluations to identify those at a higher risk of abnormal perinatal outcomes.

Assessment of Amniotic Fluid Volume in Pregnancy

Amniotic fluid (AF) is an integral part of the fetal environment and is essential for fetal growth and development. Pathways of AF recirculation include the fetal lungs, swallowing, absorption through the fetal gastrointestinal tract, excretion through fetal urine production, and movement. In addition to being a marker for fetal health, adequate AF is necessary for fetal lung development, growth, and movement. The role of diagnostic imaging is to provide a detailed fetal survey, placental evaluation, and clinical correlation with maternal conditions to help identify causes of AF abnormalities and thereby enable specific therapy. Oligohydramnios prompts evaluation for fetal growth restriction as well as genitourinary issues, including renal agenesis, multicystic dysplastic kidneys, ureteropelvic junction obstruction, and bladder outlet obstruction. Premature preterm rupture of membranes should also be clinically excluded as a cause of oligohydramnios. Clinical trials evaluating amnioinfusion are underway as a potential intervention for renal causes of oligohydramnios. Most cases of polyhydramnios are idiopathic, with maternal diabetes being a common cause. Polyhydramnios prompts evaluation for fetal gastrointestinal obstruction and oropharyngeal or thoracic masses, as well as neurologic or musculoskeletal anomalies. Amnioreduction is performed only for maternal indications such as symptomatic polyhydramnios causing maternal respiratory distress. Polyhydramnios with fetal growth restriction is paradoxical and can occur with maternal diabetes and hypertension. When these maternal conditions are absent, this raises concern for aneuploidy. The authors describe the pathways of AF production and circulation, US and MRI assessment of AF, disease-specific disruption of AF pathways, and an algorithmic approach to AF abnormalities. ^©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Placental chorioangioma and pregnancy outcome: a ten-year retrospective study in a tertiary referral centre

BACKGROUND

Placental chorioangioma is a rare disorder in pregnancy. We retrospectively reviewed the perinatal complications and long-term outcomes in pregnancies with placental chorioangioma and evaluated the factors affecting disease prognosis.

METHODS

We reviewed pregnant women who delivered at our hospital in the past decade and whose diagnosis of placental chorioangioma was confirmed by pathological diagnosis. Information on maternal demographics, prenatal sonographic findings and perinatal outcomes was obtained by reviewing the medical records. In the latter part of the study, follow-up of children was conducted by phone interview.

RESULTS

In the 10 years from August 2008 to December 2018, 175 cases(0.17%) were identified as placental chorioangioma histologically and 44(0.04%) of them were large chorioangiomas. Nearly one-third of cases with large chorioangiomas were associated with severe maternal and fetal complications or required prenatal intervention. Although one-fifth of fetuses/newborns complicated with large chorioangiomas were lost perinatally, the long-term prognosis for surviving fetuses was generally good. Further statistical analysis revealed that tumor size and location affect prognosis.

CONCLUSION

Placental chorioangioma may cause an unfavorable perinatal outcome. Regular ultrasound monitoring can provide the tumor characteristics which can be referred to for predicting the tendency of those complications and indicate when intervention may be necessary. It is not clear which factors lead to complications with fetal damage as the main manifestation or polyhydramnios as the main manifestation.

Fetus Acardiac Amorphous Presenting as Placental Tumor: A Rare Case and Differentiating the Two

Fetus acardius is a rare manifestation of twin reversed arterial perfusion and is a parasite due to vascular circulation from donor twin and lacks any resemblance to human embryos. Antenatal diagnosis is challenging as there are no well-defined features. We report here a case which presented as placental mass, the diagnosis of which was evident after delivery. Antenatal diagnosis, review of the literature, and differential diagnosis from the placental mass are discussed. A primigravida in the late third trimester had ultrasonography (USG) showing a 7 cm × 5 cm mass adjacent to the placenta. She had no complaints and fetal biometry was normal. She delivered a healthy baby; placenta showed an attached mass without identifiable fetal body or limbs, and was covered with skin having scanty hairs, which was identified as an amorphous fetus. Early diagnosis is possible by early USG; an acardiac amorphous fetus may present as placental mass. Characteristic feature on USG supplemented by magnetic resonance imaging may help in reaching a correct diagnosis and optimal management.

MRI based morphological examination of the placenta

Ultrasound is widely used as the initial diagnostic imaging modality during pregnancy with both high spatial and temporal resolution. Although MRI in pregnancy has long focused on the fetus, its use in placental imaging has greatly increased over recent years. In addition to the possibilities of evaluating function, MRI with a wide field of view and high contrast resolution allows characterization of placental anatomy, particularly in situations that are difficult to specify with ultrasound, especially for suspected placenta accreta. MRI also appears to be a particularly useful examination for the anatomical evaluation of the placenta independent of maternal body habitus or fetal position. Indeed, surprisingly little attention is paid to the placenta in MRI when the indication for the examination is fetal. Thus, some aspects of the placenta seem to us to be important to be recognized by the radiologist and to be described on the MRI report. In this review, we will describe MRI sequences used for, and common features seen in, imaging of i) the normal placenta, ii) abnormal aspects of the placenta that should be identified on MRI performed for fetal reason, and iii) placental anomalies for which placental MRI may be indicated.

A rare case of a giant placental chorioangioma with favorable outcome

Chorioangioma is the most common type of placental tumor. A primigravida woman was noted on routine scan at 21 weeks of gestation to have a placental mass measuring 1.8 x 2.2cm. A detailed ultrasound scan revealed a well circumscribed, hypoechoic lesion protruding into the amniotic cavity; hence a preliminary diagnosis of placental chorioangioma was made and close prenatal surveillance was scheduled. At 34 weeks of gestation, the mass was measuring 6.27 x 5.38cm. The patient experienced reduced fetal movements at 37 weeks gestation. A small-for-gestational age but normal female neonate was delivered by caesarean section. Histopathological analysis of the placenta confirmed the diagnosis. According to our case, a giant placental chorioangioma may have a favorable outcome without any medical intervention.

Nonfetal Imaging During Pregnancy: Placental Disease

Placenta is a vital organ that connects the maternal and fetal circulations, allowing exchange of nutrients and gases between the two. In addition to the fetus, placenta is a key component to evaluate during any imaging performed during pregnancy. The most common disease processes involving the placenta include placenta accreta spectrum disorders and placental masses. Several systemic processes such as infection and fetal hydrops can too affect the placenta; however, their imaging features are nonspecific such as placental thickening, heterogeneity, and calcifications. Ultrasound is the first line of imaging during pregnancy, and MR imaging is reserved for problem solving, when there is need for higher anatomic resolution.

Placental abruption and hemorrhage-review of imaging appearance

Placental and periplacental bleeding are common etiologies for antepartum bleeding. Placental abruption complicates approximately 1% of pregnancies and is associated with increased maternal, fetal, and neonatal morbidity and mortality. This article reviews the normal placental appearance on ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) and then discusses the different morphological appearance of placental and periplacental hematomas along with their mimics. Hematomas are classified based on the location as retroplacental, marginal subchorionic, preplacental (subamniotic), or intraplacental. Placenta-related bleeding is a common finding during first trimester ultrasound and its detection can help triage the pregnant females into low- and high-risk groups. This article reviews placenta related bleeding in the setting of trauma. Trauma can complicate pregnancy with potential severe maternal and fetal outcomes. CT is usually performed as part of the trauma workup and it can be challenging for placental evaluation. MRI can characterize the age of the hematomas and can differentiate hematomas from tumors.