The placenta plays a crucial role throughout pregnancy, and its importance may be overlooked during routine antenatal imaging evaluation. Detailed systematic assessment of the placenta at ultrasonography (US), the standard imaging examination during pregnancy, is important. Familiarity with the normal and abnormal imaging appearance of the placenta along with the multimodality and methodical approach for evaluation of its related abnormalities is necessary, so that radiologists can alert clinicians regarding appropriate prompt management decisions. This will potentially decrease fetal and maternal morbidity and mortality. This article reviews early placental formation and the expected imaging appearance of the placenta during pregnancy, as well as variations in its morphology. It also discusses various placental diseases and their potential clinical consequences. Placental pathologic conditions include abnormalities of placental size, cord insertion, placental and cord location, and placental adherence. Other conditions such as bleeding in and around the placenta, as well as trophoblastic and nontrophoblastic tumors of the placenta, are also discussed. US with Doppler imaging is the initial imaging modality of choice for placental evaluation. Magnetic resonance (MR) imaging is reserved for equivocal cases or when additional information is needed. Computed tomography (CT) has a limited role in evaluation of placental abnormalities because of the ionizing radiation exposure and the relatively limited assessment of the placenta; however, CT can provide important information in specific circumstances, particularly evaluation of trauma and staging of choriocarcinoma. This article also addresses recent techniques and updates in placental imaging, including elastography, diffusion-weighted MR imaging, and blood oxygen level-dependent (BOLD) MR imaging. These advanced imaging techniques may provide additional information in evaluation of abnormal placental adherence and new insights into placental pathophysiology in selected patients. Online supplemental material is available for this article. RSNA, 2017.

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.

The ever-growing prevalence of tuberculosis is a cause for concern among both developing and developed countries. Abdominal tuberculosis is the most common site of extrapulmonary tuberculosis and involves almost all of the visceral organs. Clinical presentation of abdominal tuberculosis is often non-specific. Thus, having a high index of clinical suspicion is necessary to aide early diagnosis and guide prompt initiation of appropriate treatment. In this review, we focus on the entire spectrum of abdominal tuberculosis and other diseases mimicking it with an emphasis on their imaging findings.