The history of imaging in obstetrics

Clinical Ultrasound Applications in Obstetrics and Gynecology in the Year 2024

Ultrasound imaging stands as a fundamental technology in the realms of obstetrics and gynecology, utilizing high-frequency sound waves to create detailed images of the internal structures of the body [...].

Interface-Stabilized Fiber Sensor for Real-Time Monitoring of Amniotic Fluid During Pregnancy

Diseases in pregnancy endanger millions of fetuses worldwide every year. The onset of these diseases can be early warned by the dynamic abnormalities of biochemicals in amniotic fluid, thus requiring real-time monitoring. However, when continuously penetrated by detection devices, the amnion is prone to loss of robustness and rupture, which is difficult to regenerate. Here, an interface-stabilized fiber sensor is presented for real-time monitoring of biochemical dynamics in amniotic fluid during pregnancy. The sensor is seamlessly integrated into the amnion through tissue adhesion, amniotic regeneration, and uniform stress distribution, posing no risk to the amniotic fluid environment. The sensor demonstrates a response performance of less than 0.3% fluctuation under complex dynamic conditions and an accuracy of more than 98% from the second to the third trimester. By applying it to early warning of diseases such as intrauterine hypoxia, intrauterine infection, and fetal growth restriction, fetal survival increases to 95% with timely intervention.

Incidental maternal findings on fetal MRI

AIM

To evaluate the type and frequency of maternal findings incidentally identified during fetal magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A retrospective single-centre study was undertaken which included all consecutive fetal MRI studies performed between July 2017 and May 2021 at a tertiary institution. Two fellowship-trained radiologists reviewed the studies independently to determine the type and frequency of incidental maternal findings of both no clinical significance (requiring no further follow-up) and of clinical significance (requiring further follow-up, work-up, and/or management). Differences in acquisition were resolved by two-reader consensus. Non-diagnostic MRI examinations or abdominal MRI examinations indicated for maternal complications were excluded from review.

RESULTS

A total of 455 consecutive fetal MRI examinations performed in 429 women were included. Mean age was 30 years (SD 5.5 years). At least one incidental maternal finding was identified in 58% (265/455) of studies. Umbilical hernias (35%), maternal hydronephrosis (19%), and maternal hydro-ureter (15%) were the most common. Only two studies (0.5%) showed clinically significant incidental maternal findings (pancreatic pseudocyst and ovarian cyst).

CONCLUSIONS

Incidental maternal findings are common on fetal MRI but rarely require further follow-up, work-up, and/or management.

Point of care maternal ultrasound in obstetrics

Ultrasound is the hallmark imaging modality traditionally used by obstetricians for fetal diagnosis and surveillance. The COVID-19 pandemic highlighted the role of point of care ultrasound for expeditious assessment of the maternal cardiopulmonary status. The familiarity of obstetricians with ultrasound, coupled with the availability of ultrasound equipment without the need to transport the patient, make point of care ultrasound particularly valuable in the labor and delivery unit. The rising contribution of cardiopulmonary disorders to maternal morbidity and mortality carves out many potential applications for point of care ultrasound during labor and delivery. Obstetricians have access to the technology and the skills to obtain the basic views required to assess for the presence of pulmonary edema, ventricular dysfunction, or intra-abdominal free fluid. Point of care ultrasound can be used routinely for the evaluation of pulmonary complaints or in the assessment of hypotension and may play an essential role in the diagnosis and management of life-threatening emergencies such as shock, an amniotic fluid embolism, or cardiac arrest. We reviewed the currently established point of care ultrasound protocols for the evaluation of cardiopulmonary complaints through the lens of the obstetrician. We call on educators and academic leaders to incorporate maternal point of care ultrasound teachings into existing curricula. Point of care ultrasound is of enormous value for providers with limited access to diagnostic imaging or subspecialty providers. With the growing complexity of the obstetrical population, acquiring the clinical skills to meet these evolving needs is a requisite step in the ongoing efforts to reduce maternal morbidity and mortality.

Diagnosis of placenta accreta spectrum in high-risk women using ultrasonography or magnetic resonance imaging: systematic review and meta-analysis

OBJECTIVES

To perform a systematic review and meta-analysis of the diagnostic test accuracy of ultrasound and magnetic resonance imaging (MRI) and compare the performance of the two modalities in the diagnosis of placenta accreta spectrum (PAS).

METHODS

This was a systematic review conducted following the Cochrane Diagnostic Test Accuracy Reviews guideline. A literature search was performed in five databases: PubMed, EMBASE, PMC, The Cochrane Library and BVS-Bireme between 27 July and 4 August 2020. The search was updated on 18 August 2021. We included observational studies evaluating diagnostic accuracy in women with risk factors for PAS who had undergone both ultrasound and MRI examinations, published in English between 2011 and 2021. Quality Assessment of Diagnostic Accuracy Studies-2 was used to evaluate the quality of the studies. Forest plots for sensitivity and specificity with 95% CIs and receiver-operating-characteristics curves for ultrasound and MRI were constructed.

RESULTS

The literature search identified 266 studies. After reviewing the titles and abstracts of the articles, 51 were selected for full-text review and 17 studies including 1301 women with MRI and ultrasound data available were selected for the meta-analysis. The study population included 457 cases with PAS diagnosed using the gold standard method (intraoperative or histopathological analysis). The overall quality of the evaluated studies was considered satisfactory according to QUADAS-2. The meta-analysis revealed a sensitivity of 0.833 (95% CI, 0.776-0.878) and specificity of 0.834 (95% CI, 0.746-0.897) for ultrasound. For MRI, sensitivity was 0.838 (95% CI, 0.786-0.879) and specificity was 0.831 (95% CI, 0.770-0.878). There was no statistically significant difference between the two modalities. The Cochran's Q values indicated a high level of heterogeneity of sensitivity and specificity of ultrasound and MRI across studies.

CONCLUSIONS

Ultrasound and MRI have similar accuracy in the diagnosis of PAS. These results suggest that, in a setting with a high prevalence of risk factors, the choice of imaging modality for initial screening for PAS should depend on the availability of equipment and the examiner's expertise. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Controversies in Fetal Surgery: Prenatal Repair of Myelomeningocele in the Modern Era

Fetal surgery is a constantly evolving field that showed noticeable progress with the treatment of myelomeningocele (MMC) using prenatal repair. Despite this success, there are ongoing questions regarding the optimal approach for fetal myelomeningocele repair, as well as which patients are eligible. Expansion of the inclusion and exclusion criteria is an important ongoing area of study for myelomeningocele including the recent Management of Myelomeningocele Plus trial. The significant personal and financial burden required of families seeking treatment has likely limited its accessibility to the general population.

Two-Dash Line: A New Approach for Prenatal Ultrasound Measurement of Iliac and Ischial Bones to Estimate Gestational Age

OBJECTIVES

There has been a dearth of an accurate and reliable method for the measurement of fetal pelvic bones. In this study, we describe a novel, easy-to-use method for ischial and iliac bone measurement in fetal ultrasound scanning.

METHODS

This prospective cross-sectional study was performed on 1179 pregnant women at 12 to 40 weeks of an uneventful gestation. Pelvic biometric indices, including the length of the ilium and ischium, were measured by a novel and easy method. Then data were analyzed by regression models to develop a formula for gestational age (GA) estimation based on pelvic bones.

RESULTS

The approximate ossification time of the ischium was determined to range between the 13th and 20th gestational weeks. We calculated 3 formulas using linear regression models: formula 1, GA (days) = 92.563 + (11.604 × ischial length); formula 2, GA (days) = 57.006 + (7.819 × iliac length); and formula 3, GA (days) = 65.809 + (5.610 × iliac length) + (3.431 × ischial length).

CONCLUSIONS

The 2-dash line method can contribute to efficient and precise ultrasound measurement of the ilium and ischium in pelvic biometry of the fetus.

ACR Appropriateness Criteria® Second and Third Trimester Screening for Fetal Anomaly

The Appropriateness Criteria for the imaging screening of second and third trimester fetuses for anomalies are presented for fetuses that are low risk, high risk, have had soft markers detected on ultrasound, and have had major anomalies detected on ultrasound. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

"Pseudogestational Sac" and Other 1980s-Era Concepts in Early First-Trimester Ultrasound: Are They Still Relevant Today?

OBJECTIVES

To determine whether an intrauterine round or oval fluid collection ("saclike structure") can prove to be either an intrauterine pregnancy or intrauterine fluid in conjunction with an ectopic pregnancy (sometimes termed "pseudogestational sac") and whether ultrasound features, including the presence or absence of an echogenic rim, "double sac sign" (DSS), or "intradecidual sign" (IDS), are helpful for establishing the diagnosis or predicting the prognosis.

METHODS

We identified all sonograms obtained from women with positive serum human chorionic gonadotropin results at our institution between January 1, 2012, and June 30, 2018, meeting the following criteria: presence of an intrauterine saclike structure without a yolk sac or embryo; no extraovarian adnexal mass; and follow-up information identifying the location of the pregnancy as intrauterine or ectopic. Study authors reviewed sonograms in all cases and recorded the following information: presence or absence of each of an echogenic rim around the collection, a DSS, and an IDS, as well as the mean sac diameter. The indications for the initial ultrasound examinations were recorded.

RESULTS

A total of 649 sonograms met the inclusion criteria. Of these, 598 fluid collections showed an echogenic rim, 182 a DSS, and 347 an IDS (findings not mutually exclusive). In all 649 cases, a subsequent sonogram or other clinical follow-up confirmed that the patient had an intrauterine pregnancy. That is, none of the fluid collections proved to be a pseudogestational sac. In total, 41.2% were live at the end of the first trimester, and 58.8% miscarried. The prognosis was better in cases with, compared to without, an IDS (P = .01, χ² ), but no ultrasound feature was clinically useful for ruling in or excluding a good prognosis.

CONCLUSIONS

In a woman with positive human chorionic gonadotropin results and no extraovarian adnexal mass, the ultrasound finding of an intrauterine saclike structure is virtually certain to be a gestational sac. Ultrasound features of the structure are of no diagnostic or clinically useful prognostic value. Concepts introduced 30 to 40 years ago when ultrasound equipment had far lower resolution than currently, including a DDS, an IDS, and a pseudogestational sac, have no role today in assessing early pregnancy.

A survey of current use, dilemma and outlook of antenatal ultrasonography in Taiwan

OBJECTIVE

According to World Health Organization's Jungner and Wilson criteria for competent screening programs, routine antenatal ultrasound screening is legit and effective to improve both maternal and perinatal outcomes. Health Promotion Administration, Ministry of Health and Welfare in Taiwan followed expert recommendations and started reimbursing one antenatal ultrasonography around mid-second trimester since 1995. However, medical disputes pertaining to examination results grew, while confusions challenged doctors and patients alike. The aim of this study is to assess current use of antenatal ultrasonography for low-risk pregnancies in Taiwan. Specifically, the indications, test frequencies, test items, methods of payment, obstetricians' opinions on important scan timing and areas to be improved are surveyed and analyzed. An overview of international antenatal ultrasound practice guidelines are examined and compared to enhance the quality of antenatal ultrasound screening in Taiwan.

MATERIALS AND METHODS

From December 2015 to December 2016, 925 questionnaires were distributed to all licensed obstetricians registered to Taiwan Association of Obstetrics and Gynecology as well as Taiwan Society of Perinatology. A 10-min self-reporting questionnaire was sent by mail, with stamped return envelopes included. Respondents remained entirely anonymous and disclosed no personal information. Data was collected and analyzed for statistical analysis.

RESULTS

Most hospitals are well equipped with ultrasound machines of 3 or more functions. Eighty-eight percent of the obstetricians in Taiwan perform prenatal ultrasonography in every office visit for their patients, mostly free of charge. Scans at gestational age 15-22 weeks, <10 weeks, 11-14 weeks and 28-32 weeks are polled as the most importance in the order of significance. In general, they perceive the one-time antenatal scan offered by the Health Promotion Administration as for general obstetrics scan but not higher-leveled studies. Patient education and doctor-patient communications are opined as the 2 most important aspects to enhance antenatal ultrasound quality.

CONCLUSION

This report is the first of its kind in Taiwan. It could potentially serve as guidance for national health policy innovations in maternal and fetal care, such as increasing frequency of scans, specifications of scan timing, indications and consequences as well as patient education about this screening modality.

Evolution of third-trimester pregnancy terminations in France

OBJECTIVE

To study changes in the reasons for third-trimester termination of pregnancy (TOP) for fetal anomalies over a 20-year period in France.

STUDY DESIGN

We compared a consecutive series of third-trimester TOPs from a single centre in 2005-2014 to those performed by Dommergues et al. in a similar centre in 1986-1994, using the same criteria.

MAIN OUTCOME MEASURES

The process leading to late TOP, using the same categories in both studies.

RESULTS

In the present series, 205 of 1409 TOPs were performed in the third trimester, vs. 305/956 in the historical series. There were 33 (16.1 %) diagnoses missed at the screening before the third trimester, 55 (26.8 %) cases in which the anomaly was impossible to diagnose until the third trimester, 86 (42 %) cases in which fetal prognosis could not be established until the third trimester despite earlier diagnosis, 31 (15.1 %) TOPs postponed to allow more time for the women/couples to contemplate, versus respectively 113 (37 %), 55 (18 %), 122 (40 %), and 15 (5%) in the historical series.

CONCLUSION

There was a significant drop in the rate of anomalies missed earlier. The increase in late TOP due to couples requiring additional time for contemplation might result from changes in counselling processes.

Pneumothorax: A Rare Entity During Pregnancy

Pneumothorax is a rarely seen condition during pregnancy, when changes in the respiratory physiology can sensitize the mother and fetus to the signs of hypoxia. Symptoms of pneumothorax, such as dyspnea, tachypnea, and chest pain, can also be attributed to pregnancy and complications with pregnancy and this can lead to misdiagnoses. The limitations in the use of diagnostic tests, such as chest X-ray and computed tomography, make treatment more difficult. Here, we report of two cases admitted to our hospital due to spontaneous pneumothorax during pregnancy. The diagnosis of pneumothorax was made based on a thorax ultrasonography in both patients, whereas a chest X-ray was used in the follow-up period, without the need for a thorax tomography. While one patient was treated via a tube thoracostomy, the other was treated via video-assisted thoracoscopic surgery.

The prenatal diagnosis and classification of cleft palate: the role and value of magnetic resonance imaging

OBJECTIVE

The aim of this study was to evaluate the value of MRI in the prenatal diagnosis and classification of cleft palate (CP).

METHODS

We collected 94 fetal cases that were suspected of cleft palate with or without cleft lip by prenatal ultrasound (US) and then carried out further MRI to examine the entire body of each fetus within 1 week. The diagnoses resulting from MRI and US examination were compared separately with the final diagnoses obtained from postnatal physical examination or fetal autopsy. The diagnostic accuracy between MRI and US was then determined.

RESULTS

During the follow-up period, the results for 6 fetuses (6.38%) were lost. Of the remaining 88 cases, the final diagnoses identified 23 cases of cleft lip (CL), 45 cases of unilateral cleft lip with cleft palate (UCLP), 4 cases of median cleft lip with cleft palate (MCLP), 12 cases of bilateral cleft lip with cleft palate (BCLP), 3 cases of unilateral cleft lip and cleft alveolus (CLA), and 1 case of isolated cleft palate (CPO). The total accuracy rate of US was 59.09%, while that of MRI was 92.05%. More importantly, 81 cases were accurately identified by MRI; the accuracy rate for CL, UCLP, MCLP, BCLP, CLA, and CPO was 86.96%, 95.56%, 100%, 91.67%, 66.67%, and 100%, respectively.

CONCLUSION

Our results suggest that MRI could be a useful adjunct to US examination in the prenatal diagnosis of fetuses with cleft palate, and further demonstrates the classification and degree of involvement of the cleft palate.

KEY POINTS

• MRI is a useful adjunct to prenatal ultrasound. • MRI has a higher accuracy rate for CP. • The accurate classification of CP diagnosed by MRI can guide clinical management.

Use of pre-operative imaging for symptomatic uterine myomas during pregnancy: a case report and a systematic literature review

PURPOSE

Uterine fibroids (UFs) occur in 10% of pregnancies and may lead to severe maternal-fetal complications, mainly depending on UFs characteristics and the distance to the uterine cavity (UC). When symptomatic, UFs are managed medically. Nevertheless, in about 2% of cases, surgery becomes necessary. Entry into the UC should be avoided during myomectomy. Consequentially, pre-operative assessment of this risk could be beneficial. Ultrasonography (US) represents the gold standard for UFs assessment; however, scarce evidence has been produced to assess the role of magnetic resonance imaging (MRI). The aim of the present study was to summarize current evidence about the pre-operative use of imaging techniques for UFs during pregnancy.

METHODS

A systematic research of the literature was conducted in Scopus, PubMed/MEDLINE, ScienceDirect and the Cochrane Library, including case reports and case series. A case report was also discussed. We collected data regarding patients, imaging assessment, UFs characteristics, surgical information, timing and modality of delivery.

RESULTS

According to our search strategy, 66 articles were selected and 210 patients were included. US assessment was reported in 36 (17%) cases. MRI was reported in 10 (4.7%) cases. Only in one case, MRI was used to measure the distance between UFs and UC.

CONCLUSION

US allows an adequate pre-operative evaluation of anterior, submucosal or pedunculated symptomatic UFs in pregnancy. However, compared to US, MRI may provide a more accurate evaluation of multiple, large, intramural or posterior UFs and could measure the distance between UFs and UC more accurately.

Safety of Ultrasound Exposure: Knowledge, Attitudes, and Practices of Australasian Sonographers

Introduction:

While perceived as safe, diagnostic ultrasound has the potential to cause biological effects on the body tissues. The aim of this study was to evaluate knowledge, attitudes, and practices of Australasian sonographers on bioeffects and safety of ultrasound scanning.

Methods:

Focus groups were used to develop a questionnaire to explore knowledge, attitudes, and practices of ultrasound safety, which was then distributed to Australasian sonographers. Thematic (focus groups) and descriptive (questionnaires) analyses were undertaken.

Results:

A 37-item questionnaire addressed knowledge, attitudes, and practices of ultrasound safety. In 47 collected responses, sonographers demonstrated good familiarity of thermal index (TI) (79%), mechanical index (MI) (68%), and “as low as reasonably achievable” (ALARA) principle (85%). However, most sonographers could not accurately define TI (13%) and had poor knowledge of safety guidelines relating to TI (19%) and MI (14%). Over 30% were uncertain about their attitudes to ultrasound safety issues. While 52% always and 30% most of the time adhere to ALARA, 37% of sonographers reported never monitoring TI and MI.

Discussion:

While familiar with safety terms, knowledge of safety guidelines was lacking. Many sonographers were uncertain about their attitudes to the safety of scans, and safety practices involving monitoring for bioeffects were not a high priority.

Fetal MRI in management of complicated meconium ileus: Prenatal and surgical imaging

OBJECTIVE

To review fetal MRI cases surgically proven to have meconium ileus (MI) and obstruction, describe the common fetal MRI findings that distinguish cases of complicated MI, and to compare these findings with surgical images and perinatal outcomes.

METHOD

We performed a retrospective review of all fetal MRI examinations and the corresponding medical record from our tertiary care children's hospital over an 18-month period. Postnatal management and outcomes were reviewed for these patients, and those patients with surgical or postmortem diagnosis of complicated MI were included in the study.

RESULTS

Our analysis revealed 7 cases. In this cohort, 3 imaging features of the fetal bowel were repeatedly seen: gradient appearance of intraluminal bowel contents, abnormally localized meconium signal, and collapsed appearance of the colon on MRI. Surgical diagnoses confirmed MI. All live-born infants underwent surgical repair.

CONCLUSION

Fetal MRI should be included in the diagnostic algorithm of any pregnancy where fetal bowel obstruction is suspected to better risk stratify patients.

The LMSR method for providing a multidimensional understanding of growth standard in human fetuses

A new nonlinear multivariate regression method called the LMSR method is proposed, by which a multidimensional understanding for the development process of human fetuses can be provided. Statistically important quantities such as median, skewness, coefficient of variation, and correlation of underlying structure can be described by corresponding smooth curves. Those curves can be obtained by a fine combination of a multivariate power transformation of data and penalized likelihood. It will be shown that the LMSR method and some associated tools are clearly efficient in analyzing development process of human fetuses.

The Empirical Foundations of Teleradiology and Related Applications: A Review of the Evidence

INTRODUCTION

Radiology was founded on a technological discovery by Wilhelm Roentgen in 1895. Teleradiology also had its roots in technology dating back to 1947 with the successful transmission of radiographic images through telephone lines. Diagnostic radiology has become the eye of medicine in terms of diagnosing and treating injury and disease. This article documents the empirical foundations of teleradiology.

METHODS

A selective review of the credible literature during the past decade (2005-2015) was conducted, using robust research design and adequate sample size as criteria for inclusion.

FINDINGS

The evidence regarding feasibility of teleradiology and related information technology applications has been well documented for several decades. The majority of studies focused on intermediate outcomes, as indicated by comparability between teleradiology and conventional radiology. A consistent trend of concordance between the two modalities was observed in terms of diagnostic accuracy and reliability. Additional benefits include reductions in patient transfer, rehospitalization, and length of stay.

Three- and four-dimensional ultrasound in fetal echocardiography: an up-to-date overview

Congenital heart diseases (CHD) are the most commonly overlooked lesions in prenatal screening programs. Real-time two-dimensional ultrasound (2DUS) is the conventionally used tool for fetal echocardiography. Although continuous improvements in the hardware and post-processing software have resulted in a good image quality even in late first trimester, 2DUS still has its limitations. Four-dimensional ultrasound with spatiotemporal image correlation (STIC) is an automated volume acquisition, recording a single three-dimensional (3D) volume throughout a complete cardiac cycle, which results in a four-dimensional (4D) volume. STIC has the potential to increase the detection rate of CHD. The aim of this study is to provide a practical overview of the possibilities and (dis)advantages of STIC. A review of literature and evaluation of the current status and clinical value of 3D/4D ultrasound in prenatal screening and diagnosis of congenital heart disease are presented.

Ultrasound screening: Status of markers and efficacy of screening for structural abnormalities

Aneuploidy is a major cause of perinatal morbidity and mortality and can have a significant impact on expecting parents and their families. With early screening and diagnosis it is important to be able to educate parents regarding the potential impact of the diagnosis. This knowledge allows parents the opportunity to consider management options early in the pregnancy, permitting more time to mentally and emotionally prepare both for the course of the pregnancy, and after the birth of the child should the pregnancy continue. Prenatal screening provides pregnant women a non-invasive risk assessment for the most common aneuploidies. Those who are considered "high-risk" then have the option for additional diagnostic (invasive) testing. Prior to the 1980s, prenatal screening consisted of risk assessment through maternal age; however, with the advent of maternal serum biochemical analysis and ultrasound, the field of prenatal screening developed significantly. As biochemical and sonographic advances continued into the 1990s, the emphasis shifted to risk assessment in the first trimester, with the combination of maternal serum analytes and sonographic evaluation of the nuchal translucency.(1) Within the last decade, the introduction of non-invasive screening (NIPT/S) has shown great impact on the expansion and evolving practice of prenatal screening. Although in many places the standard for prenatal testing continues to include maternal serum analytes and sonographic evaluation, the role of each marker alone and in combination remains important. In the era of increasingly available screening tests, especially with NIPT/(NIPS), this article attempts to review the current role of ultrasound in prenatal care and elucidate the role of ultrasound markers in prenatal screening.

Extrafetal Findings on Fetal Magnetic Resonance Imaging: A Pictorial Essay

Although US is the mainstay of fetal imaging, magnetic resonance imaging (MRI) has become an invaluable adjunct in recent years. MRI offers superb soft tissue contrast that allows for detailed evaluation of fetal organs, particularly the brain, which enhances understanding of disease severity. MRI can yield results that are similar to or even better than those of US, particularly in cases of marked oligohydramnios, maternal obesity, or adverse fetal positioning. Incidentally detected extrafetal MRI findings are not uncommon and may affect clinical care. Physicians interpreting fetal MRI studies should be aware of findings occurring outside the fetus, including those structures important for the pregnancy. A systematic approach is necessary in the reading of such studies. This helps to ensure that important findings are not missed, appropriate clinical management is implemented, and unnecessary follow-up examinations are avoided. In this pictorial essay, the most common extrafetal abnormalities are described and illustrated.

Ultrasound evaluation of the first trimester

Ultrasound is a valuable diagnostic test throughout the first trimester of pregnancy. Early in this trimester, it is used to distinguish between normal intrauterine, failed intrauterine, and ectopic pregnancies. Later it can be used with maternal blood tests to screen for trisomy 21 and other forms of aneuploidy, and in some centers to assess fetal anatomy and diagnose structural anomalies. First trimester sonography is also useful for accurate assessment of gestational age. This article reviews these applications, the approach to establishing diagnoses, and ways to avoid diagnostic mistakes that can lead to serious errors in patient management and adverse pregnancy outcome.