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Evaluation of Hydrops Fetalis

Summary Key Points Diagnosis of hydrops fetalis requires two or more of the following sonographic abnormalities: scalp and body wall edema (defined as skin thickness >5 mm), ascites, pleural effusion, pericardial effusion, polyhydramnios, and placental thickening (≥4 cm in the second trimester and ≥6 cm in the third trimester). Immune hydrops refers to cases in which the underlying condition is due to fetal anemia developing from maternal red blood…

Ultrasound Features of Fetal Syndromes

Summary of Key Points Congenital anomalies can occur in isolation or be indicative of a more extensive underlying process. The presence of a congenital anomaly should prompt a thorough evaluation for other anomalies and consideration of additional advanced fetal imaging. When an underlying global process is suspected, genetic testing is indicated and a geneticist or genetic counselor should be involved. With advances in molecular diagnostics, fetal…

Fetal Genitourinary Tract

Summary of Key Points Normal renal function is fully established by the 9th week of gestation. It is preferable to describe the findings in the fetal renal pelvis, calyces, ureter, and bladder in cases of urinary tract dilation, rather than using nonspecific terms such as pyelectasis, caliectasis, and hydronephrosis. Renal cystic anomalies may be a manifestation of underlying genetic disorders. Ultrasound findings in cases of lower…

Ultrasound Evaluation of the Fetal Gastrointestinal Tract and Abdominal Wall

Summary of Key Points Detection of gastrointestinal tract obstruction is often difficult. Duodenal and small intestinal obstructions are easily visualized, but usually not until the third trimester, whereas esophageal atresia and anal atresia may be difficult to detect at any gestational age. Echogenic small intestine is a nonspecific finding that is associated with an increased risk for Down syndrome, cystic fibrosis, congenital cytomegalovirus (CMV) infection, fetal…

Sonographic Evaluation of the Fetal Heart

Summary of Key Points Prenatal diagnosis of congenital heart disease (CHD) can reduce morbidity and mortality rates by means of delivery and intervention planning. With the proper technology and skill, some forms of fetal cardiac disease can be detected using first trimester and early second trimester sonography. The addition of outflow tracts to the four-chamber view in the standard midtrimester screening examination greatly improves the detection…

Ultrasound Evaluation of the Fetal Thorax

Summary of Key Points The most common chest masses are congenital pulmonary airway malformations (CPAMs) and congenital diaphragmatic hernias (CDHs). For both, the displacement of the heart from its normal position is the most commonly recognized ultrasound finding. CPAMs are unilateral 98% of the time and appear as echogenic areas of the lung, with or without identified cysts. The CPAM volume ratio (CVR) can be used…

Fetal Musculoskeletal System

Summary of Key Points The prevalence of skeletal dysplasias is about 2.4/10,000 births, and 9.1/1000 among perinatal deaths; the most common anomalies are thanatophoric dysplasia, achondroplasia, osteogenesis imperfecta, and achondrogenesis. The new edition of Nosology and Classification of Genetic Skeletal Disorders includes 436 clinical conditions classified into 42 groups involving 364 affected genes; therefore, molecular diagnosis is possible in about 75% of skeletal disorders. Molecular diagnosis…

Ultrasound Evaluation of the Fetal Face and Neck

Summary of Key Points The diagnosis of a typical orofacial cleft involving the palate can be suspected as early as the first trimester by the presence of an anechoic space or discontinuity in the retronasal triangle (RNT) view. Using two-dimensional (2D) ultrasound, identifying typical clefts in the second trimester is best done by utilizing the coronal view of the nose and lips and the axial view…

Ultrasound Evaluation of the Fetal Central Nervous System

Summary of Key Points Central nervous system (CNS) anomalies are among the most frequent malformations encountered by antenatal sonography. Ultrasound allows detection of a large proportion of all CNS malformations in early gestation. However, in some cases the findings may be subtle, whereas in others the anomaly may be progressive and manifest only in late gestation or after birth. Ultrasound will also frequently demonstrate normal anatomic…

Ultrasound Evaluation of Normal Fetal Anatomy

Summary of Key Points Continued advancement of ultrasound technology including increase in frequency and choice of focal position have improved visualization of fetal anatomy and therefore have also increased the required anatomic knowledge of these structures for those performing and interpreting fetal sonograms. Superficial anatomy of the fetus can be delineated with either two-dimensional or three-dimensional sonography and can be useful in confirming normal formation of…

Ultrasound Evaluation in Multiple Gestations

Summary of Key Points Early diagnosis and determination of chorionicity in the first trimester are critical for the optimal management of multiple gestations. Dichorionic twins may be either monozygotic or dizygotic, whereas essentially all monochorionic twins are monozygotic. In addition to risks for aneuploidy and malformations, increased nuchal translucency (NT) in monochorionic twins reflects the potential for complications related to inter-twin anastomoses within a shared placenta.…

Fetal Biometry and Growth

Summary of Key Points In the first trimester, gestational age should be assigned to the pregnancy based on sonographic findings or mean sac diameter prior to the visualization of the embryo and by embryonic or fetal crown-rump length (CRL) thereafter. In the second trimester, gestational age should be assigned based on head measurements that take into account head shape—namely, the corrected biparietal diameter or head circumference…

Evaluation of Fetal Anatomy in the First Trimester

Summary of Key Points Evaluation of fetal anatomy, including a detailed fetal cardiac examination, is possible in the late first trimester. Many anatomic abnormalities can be detected in the first trimester, giving families time to make important decisions regarding pregnancy management and the opportunity for early termination of pregnancy to reduce maternal morbidity risks. Doppler techniques and four-dimensional spatiotemporal image correlation (4D STIC) are modalities used…

Ultrasound of the Early First Trimester

Summary of Key Points The progression of transvaginal sonographic findings in normal early first trimester pregnancies follows a highly predictable pattern, with a gestational age variability of approximately ±0.5 week: gestational sac at 5.0 weeks, yolk sac at 5.5 weeks, embryo with heartbeat at 6.0 weeks, and amnion at 7.0 weeks. In a woman with a positive pregnancy test and no evidence of an intrauterine or…

Ultrasound Evaluation of Fetal Aneuploidy in the First and Second Trimesters

Summary of Key Points Major fetal malformations are highly associated with fetal chromosomal abnormalities, particularly central nervous system anomalies, facial abnormalities, cystic hygroma, diaphragmatic hernia, cardiac defects, gastrointestinal abnormalities, genitourinary anomalies, nonimmune hydrops fetalis (NIHF), and abnormalities involving the extremities. The combination of nuchal translucency (NT) measurement and maternal serum analytes, pregnancy-associated plasma protein-A (PAPP-A) and free β-hCG (human chorionic gonadotropin), is the most common aneuploidy…

Genetics and Prenatal Genetic Testing

Summary of Key Points In the population, 2% to 3% of newborns have a congenital malformation or genetic disease identified at birth. Despite advances in genetics, the cause of more than half of human congenital abnormalities remains unknown. Chromosomal abnormalities are present in about 0.9% of newborns and include abnormalities of chromosome number as well as abnormalities of chromosome structure. The embryo is most sensitive to…

Obstetric Ultrasound Examination

Summary of Key Points Recent years have seen dramatic advances in ultrasound technology, including improved spatial and contrast resolution, routine use of three-dimensional (3D) and four-dimensional (4D) imaging, volumetric scanning, expanded indications for color and spectral Doppler, new and improved ultrasound scanning probes, and improved digital review workstations. With improved imaging comes the complicating corollary as to what minor findings should be reported to the patient…

Ultrasound Artifacts: A Virtual Chapter

Summary of Key Points Artifacts are common in ultrasound imaging. Knowledge of artifacts can aid in diagnosis. Understanding ultrasound physics allows for correction of artifacts that distort the visualized anatomy. Chapter Outline ASSUMPTIONS IN GRAY-SCALE IMAGING Velocity of Sound Attenuation of Sound Path of Sound Beam Profile PROPAGATION VELOCITY ARTIFACT ATTENUATION ERRORS Shadowing Increased Through Transmission PATH OF SOUND-RELATED ARTIFACTS Mirror Image Artifact Comet-Tail Artifact Refraction…

Pediatric Interventional Sonography

Summary of Key Points Understanding of the different needs of the parents and the child being treated is essential for pediatric interventions. Multimodality interventional suites allow for procedural guidance with varied modalities at different points during the procedure. Although needle guides may be used, they add to the expense of the procedure. Therefore we typically advocate for a single-operator freehand technique with needle entry point chosen…

The Pediatric Hip and Other Musculoskeletal Ultrasound Applications

Summary of Key Points Ultrasound is the preferred technique in the diagnosis and management of development dysplasia of the hip (DDH). DDH is multifactorial: the highest risk factor is female breech delivery. The two basic methods, morphologic and dynamic, share the need for recognition of critical anatomic landmarks of the hip. The dynamic technique emphasizes stability. The American Institute of Ultrasound in Medicine Practice Parameter standard…