Routine ultrasound screening in diabetic pregnancies

Fetal Anomaly Detection in Pregnancies With Pregestational Diabetes

OBJECTIVES

To evaluate fetal anomaly detection in pregnancies with pregestational diabetes, according to the gestational age at the time of specialized sonography, use of follow-up sonography, maternal body mass index, and organ system(s) involved.

METHODS

Women with pregestational diabetes who received prenatal care and delivered a live-born or stillborn neonate at our hospital from October 2011 through April 2017 were ascertained. We included all pregnancies with at least 1 confirmed structural anomaly (EUROCAT classification) who had detailed sonography at 18 weeks' gestation or later. We analyzed detection of anomalous fetuses at the initial detailed sonogram and, if no abnormality was identified, during any follow-up sonograms. Statistical analyses were performed with the χ² test and Mantel-Haenszel χ² test for trend.

RESULTS

Seventy-two anomalous neonates (72 of 1060 [6.8%]) were born. Overall detection was 55 of 72 (76%); 49 of 72 (68%) were detected at the initial detailed sonogram, compared to 6 of 15 (40%) of follow-up examinations (P = .04). Recognition at the initial or follow-up examination was not dependent on gestational age or body mass index category (all P > .05). Of individual organ system anomalies, 67 of 89 (75%) were identified. Detection exceeded 85% for central nervous system, genitourinary, and musculoskeletal abnormalities and 43% for craniofacial anomalies. Sixty-five percent of cardiac anomalies were detected, and 14 of 17 (82%) requiring specialized care in the immediate neonatal period were recognized.

CONCLUSIONS

Approximately three-fourths of anomalous fetuses were identified, with greater detection at the initial detailed examination. Fetuses with central nervous system, genitourinary, musculoskeletal abnormalities and those with cardiac anomalies requiring specialized cardiac care were more likely to come to attention.

Care of Infants Born to Women with Diabetes

PURPOSE OF REVIEW

Infants of women with diabetes are at risk for specific morbidities including congenital anomalies, abnormalities of fetal growth, neonatal hypoglycemia, electrolyte abnormalities, polycythemia, hyperbilirubinemia, and respiratory distress syndrome. Recent studies have shed light on long-term outcomes of these infants and presented advances in treatment. The purpose of this review is to outline the most common neonatal morbidities affecting infants of women with diabetes, the pathophysiology and prevalence of these conditions, and contemporary approaches to treatment.

RECENT FINDINGS

Recent investigative findings have led to advances in treatment approaches for these infants, particularly regarding risks of neonatal hypoglycemia. Optimizing maternal glycemic control during pregnancy is imperative to improving infant outcomes. However, on a population level, maternal diabetes still poses significant risks to the infant. Timely and appropriate treatment of infants of women with diabetes is imperative to decrease short- and long-term morbidity.

Frequency and Importance of Incomplete Screening Fetal Anatomic Sonography in Pregnancy

OBJECTIVES

To determine (1) how often routine screening fetal anatomic sonography fails to completely visualize fetal anatomy; (2) the proportion of women with incomplete ultrasound examinations who are recommended for repeat screening and then undergo repeat sonography; and (3) how often abnormal fetal anatomy is detected on repeat sonography.

METHODS

We conducted a retrospective cohort study at a high-volume academic obstetric ultrasound center. Participants were 16,300 women at 17 through 21 weeks' gestation with a singleton pregnancy presenting for screening anatomic sonography between January 2009 and December 2013. Main outcome measures were (1) incomplete visualization of anatomy at initial screening sonography; (2) among women with incomplete but otherwise normal initial screening ultrasound examinations, recommendation for and performance of repeat sonography; and (3) among women undergoing repeat sonography, discovery of abnormal fetal anatomy within anatomic components that were previously incompletely visualized.

RESULTS

The mean maternal age ± SD was 30.8 ± 6.3 years, and the mean gestational age was 18.8 ± 1.0 weeks. Among 16,300 initial screening ultrasound examinations, 2157 (13.2%) had incomplete visualization of fetal anatomy. Of those women eligible for follow-up, 91.5% were recommended for repeat screening, of whom 92.8% had a subsequent examination. Of 1560 repeat screening ultrasound examinations, 8 (0.5%) showed an abnormality in the components of anatomy that were previously visualized incompletely.

CONCLUSIONS

In this large single-center study, incomplete visualization was common in screening fetal anatomic ultrasound examinations. Recommendations for repeat imaging were nearly universal, but abnormal fetal anatomy was infrequently discovered on repeat screening.

Optimal visualization of the fetal four-chamber and outflow tract views with transabdominal ultrasound in the morbidly obese: Are we there yet?

BACKGROUND

To compare optimal visualization of the four-chamber and outflow-tract views of the fetal heart on sonographic examination between morbidly obese (body mass index [BMI] ≥ 40 kg/m(2) ) and nonobese (BMI < 25 kg/m(2) ) pregnant women.

METHODS

In this retrospective cohort study, we included records and images from 509 pregnant women who had first undergone sonographic examination between 18 and 36 weeks' fetal gestational age.

RESULTS

Compared with the nonobese women, morbidly obese women had lower optimal visualization of the four-chamber and outflow-tract heart views: four-chamber view, morbidly obese, 83/186 (44.6%), versus nonobese, 283/323 (87.6%), and outflow-tract view, morbidly obese, 80/186 (43%) versus nonobese, 258/290 (89%); p < 0.0001 for each comparison. Similar outcomes were observed when the results from each subcategory of morbidly obese women (ie, BMI 40-49.9, 50-59.9, and ≥60 kg/m(2) ) were compared with that from nonobese women; p < 0.0001 for each comparison. These outcomes remained the same regardless of whether this comparison was made among those who had their examination before or at 19 weeks' or more gestational age. Among the morbidly obese women, there was no difference in optimal visualization of the four-chamber or outflow-tract views regardless of whether the examination was performed at <23 weeks' or at ≥23 weeks' gestational age: four-chamber view <23 weeks, 44.8% (78/174), versus four-chamber view ≥23 weeks, 41.7% (5/12); p = 0.8, and outflow-tract view <23 weeks, 43.1% (75/174), versus outflow-tract view ≥23 weeks, 41.7% (5/12); p = 0.9. After controlling for maternal age and race, the odds of visualizing the four-chamber and outflow-tract views in the morbidly obese were reduced compared with those in their nonobese counterparts: odds ratio (OR) for four-chamber, 0.13; 95% confidence interval (CI), 0.08-0.21, and OR for outflow-tract, 0.11; 95% CI, 0.07-0.17.

CONCLUSIONS

Optimal visualization of the fetal four-chamber and outflow-tract views was achieved in less than 50% of morbidly obese women, compared with almost 90% in nonobese women.

Birth defects in pregestational diabetes: Defect range, glycemic threshold and pathogenesis

Currently, 60 million women of reproductive age (18-44 years old) worldwide, and approximately 3 million American women have diabetes mellitus, and it has been estimated that this number will double by 2030. Pregestational diabetes mellitus (PGD) is a significant public health problem that increases the risk for structural birth defects affecting both maternal and neonatal pregnancy outcome. The most common types of human structural birth defects associated with PGD are congenital heart defects and central nervous system defects. However, diabetes can induce birth defects in any other fetal organ. In general, the rate of birth defects increases linearly with the degree of maternal hyperglycemia, which is the major factor that mediates teratogenicity of PGD. Stringent prenatal care and glycemic control are effective means to reduce birth defects in PGD pregnancies, but cannot reduce the incidence of birth defects to the rate of that is seen in the nondiabetic population. Studies in animal models have revealed that PGD induces oxidative stress, which activates cellular stress signalling leading to dysregulation of gene expression and excess apoptosis in the target organs, including the neural tube and embryonic heart. Activation of the apoptosis signal-regulating kinase 1 (ASK1)-forkhead transcription factor 3a (FoxO3a)-caspase 8 pathway causes apoptosis in the developing neural tube leading to neural tube defects (NTDs). ASK1 activates the c-Jun-N-Terminal kinase 1/2 (JNK1/2), which leads to activation of the unfolded protein response and endoplasmic reticulum (ER) stress. Deletion of the ASK1 gene, the JNK1 gene, or the JNK2 gene, or inhibition of ER stress by 4-Phenylbutyric acid abrogates diabetes-induced apoptosis and reduces the formation of NTDs. Antioxidants, such as thioredoxin, which inhibits the ASK1-FoxO3a-caspase 8 pathway or ER stress inhibitors, may prevent PGD-induced birth defects.

Improved antenatal detection of congenital anomalies in women with pre-gestational diabetes: population-based cohort study

AIMS

To compare antenatal detection of congenital anomaly in women with and without pre-gestational diabetes and their pregnancy outcomes in a regional cohort study.

METHODS

Data from a total of 7148 singleton pregnancies with a congenital anomaly delivered between 1 January 1996 and 31 December 2008 were extracted from the Northern Diabetes in Pregnancy and Northern Congenital Abnormality Surveys. Antenatal ultrasound detection rates of congenital anomaly in pregnancies complicated by major non-chromosomal congenital anomaly and resulting in live birth, stillbirth, late miscarriage (20-23 weeks of gestation) or termination of pregnancy for a congenital anomaly, were compared between women with and without diabetes (120 and 7028, respectively).

RESULTS

A significantly higher rate of antenatal detection of congenital anomalies was observed in women with diabetes compared with women without diabetes (50.8 vs. 38.6%, respectively; relative risk 1.32; 95% CI 1.10-1.57; P = 0.003). Cardiovascular anomalies were the only group with a significantly higher antenatal detection rate in women with diabetes (31.8 vs. 10.4%; relative risk 3.05; 95% CI 1.95-4.76; P < 0.00001). This difference remained after excluding cases of ventricular septal defect (52.2 vs. 16.3%; relative risk 3.20; 95% CI 2.13-4.80; P < 0.0001). Among women with diabetes, male fetal sex was the only factor associated with a higher antenatal detection rate. There were no differences in the rates of termination of pregnancy, late miscarriage, stillbirth or infant death between groups.

CONCLUSIONS

Antenatal detection of cardiovascular anomalies was higher in women with diabetes, suggesting that recommendations for enhanced cardiovascular scanning may improve detection. Greater awareness of the increased risk of anomalies in other organ systems is needed.

Obesity and the risk and detection of fetal malformations

The incidence of obesity in pregnancy has increased over the past 2 decades, with nearly 50% of U.S. women aged 15-49 years classified as overweight or obese. Obesity (independent of diabetes) among gravidae poses unique risks that extend toward the fetus, with several large population-based analyses demonstrating independent increased risks for fetal malformations including neural tube defects, cardiac anomalies, and orofacial clefts, as well as stillbirth and macrosomia. Unfortunately, several lines of evidence also suggest that the quality of the prenatal fetal anatomic survey and certain aspects of prenatal diagnostic screening programs are significantly limited. The net effect is that among obese gravidae, the increased risk of fetal anomalies is further offset by a concomitant diminished ability to sonographically detect such malformations in the prenatal interval. The purpose of this summary review is to systematically examine the evidence suggesting an increased risk of fetal malformations in obese gravidae, the contributing role of diabetes, and the limitations of prenatal diagnostic and sonographic screening among this at-risk population.

Obstetrical sonography in obese women: a review

Obstetric sonographic imaging in pregnant women is adversely affected by obesity with a negative impact on the detection rate of congenital anomalies. This review aims to analyze relevant data regarding this issue and to discuss clinical and technical problems associated with sonographic examination of obese pregnant women.

Sonographic evaluation and the pregnancy complicated by diabetes

Sonography is a fundamental tool in the management of pregnancies affected by maternal diabetes. Purposeful use of ultrasound in each trimester provides an invaluable amount of information about the developing fetus including gestational age and growth patterns, anatomical structure and function, assessment of fetal well-being, and prediction of adverse outcome. There are great ongoing research efforts in this field of prenatal diagnosis and management, yet even more are needed.

Impact of maternal obesity on procedure of mid-trimester anomaly scan

A maternal body mass index (BMI) >or= 30 kg/m(2) increases the risk of giving birth to a baby with an anatomical congenital anomaly. Such anomalies can be detected prior to birth using ultrasound as a screening modality. This study documents the impact of maternal obesity on image quality and service provision of the mid-trimester fetal anomaly scan. A prospective observational study of 327 pregnant women demonstrated 21% of women were obese. In this group, sub-optimal views of fetal anatomy and consequent requirement for re-appointment were all significantly greater. We conclude that obese women require information regarding reduced sensitivity of the 20-week anomaly scan. The increasing prevalence of obesity will have a significant effect on resources for maternity ultrasound departments.

Influence of polyhydramnios on perinatal outcome in pregestational diabetic pregnancies

OBJECTIVE

This study was carried out to evaluate the perinatal outcomes of pregnancy with pregestational diabetes mellitus complicated by polyhydramnios.

METHODS

This was a retrospective study of singleton pregnancies, with an antepartum diagnosis of polyhydramnios, seen at the maternal fetal medicine department of Mater Mothers' Hospital, a tertiary-level facility. All pregnancies in women with pregestational diabetes with a singleton pregnancy beyond 24 weeks of gestation, from 1996 to 2006, were reviewed (n = 314), and pregnancies complicated by polyhydramnios were identified (n = 59). Pregnancy outcomes of women whose pregnancy was complicated with polyhydramnios were compared to those without this complication.

RESULTS

The incidence of polyhydramnios in the study population was 18.8%. Women with polyhydramnios had increased hemoglobin A1c (HbA1c) levels throughout the pregnancy, and the difference was significant during the prepregnancy period and in the third trimester (P = 0.003 and P = 0.025, respectively). Significantly more mothers in the polyhydramnios group delivered preterm (54.2% vs. 33.3%, P = 0.004), the majority of which were iatrogenic preterm deliveries (44.1%). More pregnancies with polyhydramnios were delivered by Cesarean section (83.0% vs. 62%; P = 0.006), with the majority being performed electively in both groups (79.6% and 70.3%, respectively). Regardless, there were no significant differences in perinatal mortality rates, congenital abnormality rates, the incidences of low Apgar score, acidemia, hypoglycemia requiring intravenous therapy, phototherapy and ventilatory needs between the babies of the two groups.

CONCLUSION

Pregestational diabetic pregnancy with polyhydramnios is associated with poor diabetic control. Despite this, there is no significant increase in adverse perinatal outcome in these pregnancies, apart from a higher iatrogenic preterm birth rate.

Indications for fetal echocardiography high referral, low yield?

An excellent imaging tool in the prenatal diagnosis and ongoing evaluation of congenital heart defects, fetal echocardiography is indicated in a selected population at increased risk compared with the general population. For certain "soft markers" of fetal congenital heart defects, ambiguity in the indications for fetal echo may result in a high referral rate, but low yield of congenital heart disease. Here, we critically examine 4 conditions, 2 maternal and 2 fetal: maternal gestational diabetes, advanced maternal age, isolated echogenic focus, and single umbilical artery. This critical review reveals that more prospective population-based studies with higher power and minimal bias need to be performed to establish the absolute risk of congenital heart defects in a selected population compared with that of the general population. Nonetheless, our analysis indicates that the absolute risk of congenital heart defects associated with each of these markers is low.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader should be able to define which patients should be referred for fetal echocardiography based on known risks, distinguish between relative and absolute risks for fetal congenital heart disease, and summarize fetal anomaly risks for women with altered glucose metabolism.

Maternal obesity limits the ultrasound evaluation of fetal anatomy

OBJECTIVE

The purpose of this study was to evaluate the effect of maternal habitus on adequate visualization of fetal anatomy during a standard second-trimester ultrasound examination.

METHODS

This was a retrospective cohort study of singleton pregnancies at 18 to 24 weeks that underwent sonography over a 5-year period. Pregnancies complicated by an indication for targeted sonography were excluded. Standard ultrasound examinations were performed according to American Institute of Ultrasound in Medicine criteria. Ten anatomic components were evaluated for adequacy of visualization: atria of the cerebral ventricles, posterior fossa, midline face, 4-chamber view of the heart, spine, ventral wall, umbilical cord vessels, stomach, kidneys, and bladder. The body mass index (BMI) was based on the patient's weight at the first prenatal visit.

RESULTS

Of 10,112 women who underwent a standard ultrasound examination, 2% were underweight; 38% were of normal weight; 34% were overweight; and 26% were obese. Visualization of fetal anatomy decreased significantly with increasing maternal BMI for the complete survey as well as for each individual component with the exception of the fetal bladder (all P < .001). Among those with a normal or underweight BMI, an overweight BMI, and class 1, 2, and 3 obesity, all 10 anatomic components were adequately visualized at the initial examination in 72%, 68%, 57%, 41%, and 30% of cases, respectively (P < .001).

CONCLUSIONS

Increasing maternal BMI limits visualization of fetal anatomy during a standard ultrasound examination at 18 to 24 weeks. In obese women, the fetal anatomy survey could be completed during the initial examination in only 50% of cases. Counseling may need to be modified to reflect the limitations of sonography in obese women.

Effect of maternal obesity on the ultrasound detection of anomalous fetuses

OBJECTIVE

To estimate the effect of maternal habitus on detection of fetuses with major structural anomalies during second-trimester standard and targeted ultrasound examinations.

METHODS

This was a retrospective cohort study of pregnancies 18 to 24 weeks that underwent ultrasonography over a 5-year period. An anomalous fetus was considered detected if a major abnormality of the relevant organ system was identified, regardless of the anticipated ultrasound detection. Anomalies were verified using a prospectively maintained database. Body mass index (BMI) was based on weight at first prenatal visit.

RESULTS

There were 10,112 standard examinations in low-risk pregnancies and 1,098 targeted examinations in pregnancies with either high-risk indications or with an abnormality detected during standard ultrasonography. Detection of anomalous fetuses decreased with increasing BMI. For normal BMI, overweight, and class I, II, and III obesity, detection with standard ultrasonography was 66%, 49%, 48%, 42%, and 25%, respectively, and with targeted ultrasonography, 97%, 91%, 75%, 88%, and 75%, respectively, both P< or =.03. Residual anomaly risk after a normal ultrasound examination increased with increasing BMI, from 0.4% among women of normal BMI to 1.0% among obese women, P=.001. Anomaly detection was lower among women with pregestational diabetes than in those with other high-risk indications, 38% compared with 88% respectively, P<.001.

CONCLUSION

With increasing maternal BMI, we found decreased detection of anomalous fetuses with either standard or targeted ultrasonography, a difference of at least 20% when women of normal BMI were compared with obese women. Anomaly detection was even less in pregnancies complicated by pregestational diabetes. Counseling may need to be modified to reflect the limitations of ultrasonography in obese women.

Outcome of fetuses in women with pregestational diabetes mellitus

OBJECTIVE

To investigate the effects of pregestational diabetes on pregnancy outcome.

METHODS

Data of 126 women with pregestational diabetes prospectively collected and controlled in a single tertiary center. HbA(1C) levels at early pregnancy were registered. Adverse pregnancy outcome was defined as spontaneous abortion, congenital defect, stillbirth, or neonatal death.

RESULTS

There were 10 spontaneous abortions (7.9%) and 17 fetuses with congenital anomalies (13.4%), including 8 major malformations (6.3%). Compared with pregnancies with a favorable outcome, a higher HbA(1C) concentration in early pregnancy was observed in pregnancies with adverse perinatal outcome [mean (SD): 6.3 (1.6) vs. 7.2 (1.7), P=0.001]. A positive correlation between increased maternal HbA(1C) levels and the rate of fetal malformations was observed, and the group of women with poor metabolic control (early maternal HbA(1c) concentration >7%) showed a 3 to 5-fold increase in the major malformation rate. Cardiovascular and genitourinary defects accounted for 58.8% of the anomalies, and the ultrasound examinations detected seven of them (41.2%). For major malformations, the detection rate was 50% (4/8). Perinatal mortality rate was 26 per thousand (3/116). There was almost 5-fold increase in the total pregnancy loss rate in the poor control group compared with the group with fair control [22.2% vs. 5.3%, OR (95% CI): 5.1 (1.4-17.1)]. Only 11.9% of mothers used a preconception care program.

CONCLUSIONS

Pregestational diabetes mellitus is a significant risk factor for the developing fetus. Spontaneous abortions and congenital defects are more common when a poor metabolic control is present in early pregnancy. It is most important to improve access to preconception care programs for achieving a good metabolic control in early pregnancy. Ultrasound examinations have a low performance for detecting congenital defects in diabetic pregnancies.

Suboptimal second-trimester ultrasonographic visualization of the fetal heart in obese women: should we repeat the examination?

OBJECTIVE

The purpose of this study was to determine whether a repeated antenatal ultrasound examination improves fetal cardiac visualization for the obese and nonobese population.

METHODS

A computerized ultrasound database (October 1999-June 2003) was used to identify singleton pregnancies undergoing repeated prenatal ultrasound examinations because of initial suboptimal ultrasonographic visualization (SUV) of the 4-chamber view, outflow tracts, or both. Women with maternal diabetes, abnormal maternal serum screening results, or known fetal anomalies at the initial examination were excluded. Patients were classified by maternal body mass index (BMI): less than 30 kg/mg2 (nonobese), 30 to 34.9 kg/mg2 (class I obesity), 35 to 39.9 kg/mg2 (class II obesity), and 40 kg/mg2 or greater (morbid obesity). The association between maternal BMI and SUV of the fetal heart was analyzed.

RESULTS

Three hundred seventy-two patients were abstracted from the database. The median gestational age was 19.0 weeks at the initial visit (range, 18.0-21.9 weeks) and 21.4 weeks at the second visit (range, 18.9-23.9 weeks). The median BMI was 32.6 kg/m2 (range, 16.4-58.7 kg/m2). Sixty-three percent of patients were obese (BMI >or=30). Cardiac anatomy continued to have SUV in 11% of the women. The rate of SUV was associated with the obesity class (1.5% for nonobese, 12% for obesity I, 17% for obesity II, and 20% for morbid obesity; P < .0001). A cardiac anomaly was found in 1 of 372 repeated examinations (arteriovenous canal defect) for a patient with BMI of 24.8 kg/m2.

CONCLUSIONS

Repeated ultrasound examination for SUV of the fetal heart at a later gestational age dramatically reduces SUV. However, obese patients continue to have much higher rates of persistent SUV.

The impact of maternal obesity on midtrimester sonographic visualization of fetal cardiac and craniospinal structures

OBJECTIVE

To examine the impact of maternal obesity on the rate of suboptimal ultrasound visualization (SUV) of fetal anatomy and determine the optimal timing of prenatal ultrasound examination for the obese gravida.

METHODS

A computerized ultrasound database was used to identify ultrasound examinations for singleton gestations performed between 14(0/7) and 23(6/7) weeks at a tertiary care, university-based hospital. Patients were divided into four groups and categorized based on body mass index (BMI): nonobese (BMI <30 kg/m2), class I obesity (30< or =BMI<35 kg/m2), class II obesity (35< or =BMI<40 kg/m2), and extreme obesity (BMI > or =40 kg/m2). The rates of SUV for fetal cardiac and craniospinal structures were calculated for each group and compared.

RESULTS

A total of 11,019 pregnancies were studied, of which 38.6% of the patients were obese. Overall, the rate of SUV of the fetal structures was higher for obese compared to nonobese women for both cardiac (37.3 [1723/4200] vs 18.7% [1275/6819]; P<0.0001) and craniospinal structures (42.8 [1798/4200] vs 29.5% [2012/6819]; P<0.0001). Increased severity of maternal obesity was associated with SUV rate for both the cardiac (nonobese 18.7% [1275/6819], class I 29.6% [599/2022], class II 39.0% [472/1123], and extreme obesity 49.3% [580/1055]; P<0.0001) and for the craniospinal structures: (nonobese 29.5% [2012/6819], class I 36.8% [744/2022], class II 43.3% [486/1123], and extreme obesity 53.4% [563/1055]; P<0.0001). With increasing gestational age at examination, the rate of SUV decreased for both obese and nonobese women. However, for obese women there was minimal improvement in visualization after 18-20 weeks. Even after adjustment for gestational age and the type of ultrasound machine, obese women (class I, class II, and extreme obesity) were still associated with increased odds for SUV of the fetal cardiac and craniospinal structures compared to nonobese women.

CONCLUSION

Maternal obesity increases the rate of SUV for the fetal cardiac structures by 49.8% and for the craniospinal structures by 31%. The optimal gestational age for visualization of fetal cardiac and craniospinal anatomy in obese patients may be after 18-20 weeks.

Does advanced ultrasound equipment improve the adequacy of ultrasound visualization of fetal cardiac structures in the obese gravid woman?

OBJECTIVE

This study was undertaken to determine the effect of advanced ultrasound equipment on the ability to visualize fetal cardiac structures in obese gravid women.

STUDY DESIGN

Singleton pregnancies undergoing initial ultrasound examination between 14 weeks and 23 weeks 6 days were included. Patients were classified by body mass index (BMI) (nonobese [BMI < 30 kg/m(2)] and obese [BMI > or =30 kg/m(2)]). The rate of suboptimal ultrasound visualization (SUV) of the fetal heart (cardiac axis, cardiac position, 4-chamber, and outflow tracts views) was compared between patients examined by standard (HDI 3000) or advanced ultrasound equipment (HDI 5000) (ATL, Philips Medical Systems, Bothell, Wash).

RESULTS

Over a 5-year period, 7029 singleton gestations met inclusion criteria; 2498 (35.5%) were clinically obese. There was no difference in gestational age, rate of low amniotic fluid volume, anterior placenta, or vertex fetal presentation between the groups. When the advanced ultrasound equipment was used, SUV of the fetal heart was lower in the nonobese population (20.8% vs 16.4%; P <.001), but not in the obese gravid women (38.1% vs 35.5%; P=.27). However, obese patients who were examined by advanced ultrasound equipment after 18 weeks had less SUV of the outflow tracts (28.5% vs 23.1%, P=.04) but not of the 4-chamber view.

CONCLUSION

Despite advanced ultrasound equipment, maternal obesity significantly limits visualization of the fetal heart. However, the advanced ultrasound equipment may somewhat benefit obese gravid women examined after 18 weeks' gestation