ACR Appropriateness Criteria® Multiple Gestations

Women with twin or higher-order pregnancies will typically have more ultrasound examinations than women with a singleton pregnancy. Most women will have at minimum a first trimester scan, a nuchal translucency evaluation scan, fetal anatomy scan at 18 to 22 weeks, and one or more scans in the third trimester to evaluate growth. Multiple gestations are at higher risk for preterm delivery, congenital anomalies, fetal growth restriction, placenta previa, vasa previa, and velamentous cord insertion. Chorionicity and amnionicity should be determined as early as possible when a twin pregnancy is identified to permit triage of the monochorionic group into a closer surveillance model. Screening for congenital heart disease is warranted in monochorionic twins because they have an increased rate of congenital cardiac anomalies. In addition, monochorionic twins have a higher risk of developing cardiac abnormalities in later gestation related to right ventricular outflow obstruction, in particular the subgroups with twin-twin transfusion syndrome or selective intrauterine growth restriction. Monochorionic twins have unique complications including twin-to-twin transfusion syndrome, twin embolization syndrome, and acardius, or twin-reversed arterial perfusion sequence. 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.

Cardiac Arrest in Pregnancy

This is the first scientific statement from the American Heart Association on maternal resuscitation. This document will provide readers with up-to-date and comprehensive information, guidelines, and recommendations for all aspects of maternal resuscitation. Maternal resuscitation is an acute event that involves many subspecialties and allied health providers; this document will be relevant to all healthcare providers who are involved in resuscitation and specifically maternal resuscitation.

MRI evaluation of maternal cardiac displacement in pregnancy: implications for cardiopulmonary resuscitation

OBJECTIVE

The purpose of this study was to determine, with the use of cardiac magnetic resonance imaging, whether there is vertical displacement of the heart during pregnancy. Cardiopulmonary resuscitation guidelines during pregnancy recommend placing the hands 2-3 cm higher on the sternum than in nonpregnant individuals. This recommendation is based on the presumption that the heart is displaced superiorly by the diaphragm during the third trimester. Whether there is true cardiac displacement because of the expanding uterus in pregnancy remains unknown.

STUDY DESIGN

A total of 34 healthy female volunteers 18-35 years old were enrolled prospectively from 2010-2012 at 2 tertiary care centers. The conditions of all participants were evaluated with cardiac magnetic resonance imaging in the one-half left lateral decubitus position during the third trimester of pregnancy and again at a minimum of 3 months after delivery (surrogate for the nonpregnant state). Superior displacement of the heart was determined by measurement of the distance between the inferior aspect of the clavicular heads and the coronary sinus at both time points.

RESULTS

The study population included 34 women (mean age, 29 ± 3 years; body mass index, 24 ± 4 kg/m(2)). The mean gestational age at third-trimester imaging was 237 ± 16 days (34 weeks ± 16 days); the mean number of days for postpartum imaging (baseline) was 107 ± 25 days (16 weeks ± 25 days). There was no statistical difference between the cardiac position at baseline (10.1 ± 1.2 cm) and during the third trimester (10.3 ± 1.1 cm; P = .22).

CONCLUSION

Contrary to popular assumption, there is no significant vertical displacement of the heart in the third trimester of pregnancy relative to the nonpregnant state. Accordingly, there is no need to alter hand placement for chest compressions during cardiopulmonary resuscitation in pregnancy.

ACR appropriateness criteria(®) on abnormal vaginal bleeding

In evaluating a woman with abnormal vaginal bleeding, imaging cannot replace definitive histologic diagnosis but often plays an important role in screening, characterization of structural abnormalities, and directing appropriate patient care. Transvaginal ultrasound (TVUS) is generally the initial imaging modality of choice, with endometrial thickness a well-established predictor of endometrial disease in postmenopausal women. Endometrial thickness measurements of ≤5 mm and ≤4 mm have been advocated as appropriate upper threshold values to reasonably exclude endometrial carcinoma in postmenopausal women with vaginal bleeding; however, the best upper threshold endometrial thickness in the asymptomatic postmenopausal patient remains a subject of debate. Endometrial thickness in a premenopausal patient is a less reliable indicator of endometrial pathology since this may vary widely depending on the phase of menstrual cycle, and an upper threshold value for normal has not been well-established. Transabdominal ultrasound is generally an adjunct to TVUS and is most helpful when TVUS is not feasible or there is poor visualization of the endometrium. Hysterosonography may also allow for better delineation of both the endometrium and focal abnormalities in the endometrial cavity, leading to hysteroscopically directed biopsy or resection. Color and pulsed Doppler may provide additional characterization of a focal endometrial abnormality by demonstrating vascularity. MRI may also serve as an important problem-solving tool if the endometrium cannot be visualized on TVUS and hysterosonography is not possible, as well as for pretreatment planning of patients with suspected endometrial carcinoma. CT is generally not warranted for the evaluation of patients with abnormal bleeding, and an abnormal endometrium incidentally detected on CT should be further evaluated with TVUS.

Placental origins of angiogenic dysfunction in mirror syndrome

BACKGROUNDL: Mirror syndrome is characterized by preeclampsia-like syndrome in pregnancies complicated by fetal hydrops. We describe a case of mirror syndrome associated with angiogenic dysfunction in maternal plasma and the placenta.

CASE

A pregnant patient with known fetal hydrops presented at 22 weeks gestation with features of severe preeclampsia. Measurements of plasma anti- and proangiogenic factors were consistent with a profound antiangiogenic state. Immunohistochemistry of the placenta for antiangiogenic proteins showed a pattern similar to that seen in patients with severe preeclampsia.

CONCLUSION

Angiogenic imbalance may also be responsible for the preeclampsia-like condition seen in mirror syndrome.

Intravital high-frequency ultrasonography to evaluate cardiovascular and uteroplacental blood flow in mouse pregnancy

OBJECTIVE: The objective of this study is to define the ultrasonographic changes in the cardiovascular and uteroplacental circulation of normal pregnant mice compared to non-pregnant mice using high-frequency, high-resolution ultrasonography. METHODS: Ten to twelve-week-old CD-1 mice (six non-pregnant and six pregnant animals) were used for all experiments. Vevo® 2100 (VisualSonics) was used to evaluate the cardiovascular and uteroplacental circulation physiology. Cardiac echocardiogram and uterine artery Doppler studies were performed on all animals. Pregnant animals were evaluated on embryonic day seven (E7), thirteen (E13) and eighteen (E18). Fetal heart rate and umbilical artery Doppler flows were obtained on pregnant animals. Three-dimensional ultrasonography imaging was utilized for quantification of placental volumes. All data are presented as median {10(th)-90(th) percentiles}. RESULTS: In pregnant mice on E7 compared to non-pregnant mice, there was an increase in cardiac output (p=0.008), stroke volume (p=0.002), ejection fraction, (p=0.02) and fractional shortening (p=0.02). The maternal heart rate increased throughout gestation (p= 0.009). During pregnancy, a gestational sac was clearly visible on E7. Between E13 and E18, the fetal size and fetal heart rate increased (p=0.001) and the umbilical artery peak systolic velocity increased (p <0.001). Minimal diastolic blood flow was observed in the umbilical artery on E13, which increased slightly on day E18 (p=0.01). There was also no change in the uterine artery resistance index between non-pregnant and pregnant mice. The placental volume increased between E13 and E18 (p=0.03). CONCLUSION: Several changes noted in cardiovascular and uteroplacental systems occurring during normal murine pregnancy have striking similarities to humans and can be accurately measured using newer ultrasonographic techniques. Further studies are needed to evaluate changes in these vascular beds in mouse models of diseases such as preeclampsia and intrauterine growth restriction.

Uterine rupture during a trial of labor after previous cesarean delivery

Uterine rupture, which involves complete separation of the uterine wall, occurs in about 1% of those attempting vaginal birth after cesarean. Because uterine rupture is one of the most significant complications of a trial of labor (TOL) after previous cesarean, identifying those at increased risk of uterine rupture is paramount to the safety of a TOL after previous cesarean birth. It seems that both antepartum demographic characteristics and intrapartum factors modify the risk of uterine rupture. The ability to reliably predict an individual's a priori risk for intrapartum uterine rupture remains a major area of investigation.

Use of acetaminophen during pregnancy and risk of preeclampsia, hypertensive and vascular disorders: a birth cohort study

OBJECTIVE

To examine whether pregnant women who used acetaminophen, a prostaglandinG2 synthase inhibitor, had an increased risk of preeclampsia, gestational hypertension, thromboembolic complications, or abruptio placentae.

METHODS

We selected 63,833 women participating in the Danish National Birth Cohort who gave birth to a live born singleton and had information on acetaminophen use during pregnancy reported by three interviews. Through linkage to the National Hospital Discharge Registry we obtained data from hospital diagnose of the outcomes we study.

RESULTS

Women who used acetaminophen during the third trimester of pregnancy had an increased risk of preeclampsia (adjusted relative risk RR = 1.40, 95% CI: 1.24-1.58). The risk was higher among women who had early preeclampsia (before the 32nd gestational week) (RR = 1.47, 95% CI: 1.12-1.93), severe preeclampsia (RR = 1.51, 95% CI: 1.15-2.00), or chronic hypertension (RR = 1.44, 95% CI: 1.13-1.83). Second and third trimester use was associated with an increased risk of pulmonary embolisms (RR = 3.02, 1.28-7.15) and deep vein thrombosis (RR = 2.15, 1.06-4.37), respectively.

CONCLUSIONS

Acetaminophen use during pregnancy is associated with an increased risk of diseases in which a reduction of prostacyclin during pregnancy has been postulated to play a role, including preeclampsia and thromboembolic diseases.

Influence of gestational age and fetal heart rate on the fetal mechanical PR interval

OBJECTIVE

The fetal mechanical PR interval obtained via pulsed Doppler has previously been demonstrated to correlate with electrocardiographic PR interval measured in the neonate. We sought to further analyze the influence of fetal heart rate and gestational age upon the fetal mechanical PR interval.

METHODS

We searched our database for mechanical PR intervals, which were obtained during fetal echocardiography performed in our antenatal diagnostic unit. We included fetuses with a normal cardiac structural survey. The mechanical PR interval is measured from the A wave of the mitral valve to the beginning of ventricular systole corresponding to the opening of the aortic valve. Linear regression curves were generated to examine the correlation of mechanical PR interval with gestational age and fetal heart rate. Analysis of variance was used to compare the mean variation across three gestational age groups: 17-21.9 weeks (n = 24), 22-25.9 weeks (n = 52) and 26-38 weeks (n = 20).

RESULTS

Mechanical PR intervals were measured in 96 fetuses with normal fetal echocardiography. The mechanical PR interval was 123.9 +/- 10.3 ms (mean +/- SD), with a range of 90-150 ms. Linear regression curves correlating mechanical PR interval with fetal heart rate and gestational age demonstrated a flat slope with R2 = 0.016, p = 0.22 and R2 = 0.0004, p = 0.85, respectively. The mechanical PR interval measured over the three gestational ages was as follows (mean +/- SD): 122.3 +/- 10.5 ms for 17-21.9 weeks; 125.0 +/- 9.6 ms for 22-25.9 weeks; and 123.1 +/- 11.9 ms for 26-38 weeks. Analysis of variance revealed no difference among the mechanical PR interval means measured over the three gestational age groups (p = 0.53).

CONCLUSIONS

Fetal mechanical PR interval ranges from 90 to 150 ms in fetuses with sonographically normal fetal cardiac structure and rate. The mechanical PR interval appears to be independent of gestational age and fetal heart rate.

Determining a cutoff for fetal lung maturity with lamellar body count testing

OBJECTIVE

A lamellar body count (LBC) >or= 50,000/microl is suggested to document fetal lung maturity (FLM). We sought to determine the LBC threshold for FLM with the Cell-dyn 4000 hematology analyser.

METHODS

We queried our database for patients who underwent LBC testing from 2001 to 2007. Included were deliveries between 35 and 38 weeks gestation with testing <or=7 days from delivery. We excluded twins, anomalies and cases of ruptured membranes. Data were analysed for sensitivity and specificity of predicting respiratory distress syndrome (RDS) and plotted on a receiver operating characteristic curve.

RESULTS

There were 209 patients meeting study criteria. Of these, 120 had diabetes. Five neonates experienced RDS, all born to non-diabetic mothers with LBC values <or=72,000/microl. At this value the sensitivity is 100%, false positive rate 18% and the p value is 0.0146.

CONCLUSION

Our results question the 50,000/microl threshold and demonstrate the need for hematology analyser specific thresholds.

Frequency of echogenic intracardiac focus by race/ethnicity in euploid fetuses

OBJECTIVE

To determine the frequency of echogenic intracardiac focus (EIF) by race/ethnicity.

METHODS

We performed a retrospective analysis from January 1996 through June 2003. We reviewed all initial sonograms from 14 to 23 weeks gestation in singleton pregnancies. Mothers on admission for delivery provided race/ethnicity.

RESULTS

There were 8207 ultrasounds and deliveries that met study criteria. There were 4636 (56.5%) Caucasian, 2087 (25.4%) African-American, 1261 (15.4%) Hispanic and 223 (2.7 %) Asian subjects. There were 347 (4.2%) EIF detected. The frequency by race/ethnicity varied significantly (p < 0.0001).

CONCLUSIONS

This large, population-based study showed that fetuses born to Asian mothers were significantly more likely to have an EIF. This racial difference should be taken into account when counseling patients about the potential for Down syndrome.

A comparison of reasons for choosing obstetrician/gynecologist subspecialty training

Recently, applications for subspecialty fellowship positions in obstetrics and gynecology have increased dramatically. A survey completed by fellows in Maternal-Fetal Medicine (MFM), Reproductive Endocrinology (REI), Gynecologic Oncology (Gyn Onc), and Urogynecology (Urogyn) training programs in the United States between January and March 2006 was aimed at determining why this trend was occuring. Of 449 fellows in 2006, 192 (42.8%) responded. The two most influential factors in all four subspecialties were interest and lifestyle (P < .001). Although these factors were similar throughout all subspecialties, variations exist in how fellows rated each factor by subspecialty. An overwhelming majority (99%) of fellows were either "very satisfied" or "satisfied" with their decisions to pursue fellowship training. The majority of fellows believe that when compared to a generalist Obstetrician/Gynecologist (OB/GYN) they will have a reduced workload, decreased liability, and a higher salary. The recent increase in the number of fellowship applicants is most likely due to a complex interplay of multiple factors.

Stepwise sequential screening for fetal aneuploidy

OBJECTIVE

The purpose of this study was to evaluate stepwise sequential screening for fetal aneuploidy.

STUDY DESIGN

Women who received first-trimester screening were also offered second-trimester tests with second-trimester risks that were based on both sets of markers. Screen-positive rates, use of second-trimester testing and invasive testing, sensitivity, and changes in risks were evaluated.

RESULTS

Of 1528 women who received first-trimester screening, 133 women (8.7%) had an indication for invasive testing that was based on first-trimester results alone; 1173 women (76.8%) received second-trimester tests, which reduced the net number of women with an indication for invasive testing to 105 (6.9%). In unaffected pregnancies, the addition of the second-trimester testing reduced the median Down syndrome risk from 1:2368 to 1:10,301. Six of 10 chromosome abnormalities (60%) were identified by first-trimester screening, and 9 of 10 chromosome abnormalities (90%) were identified by sequential screening.

CONCLUSION

Sequential screening can be introduced successfully into clinical practice, is effective, and can reduce the number of invasive tests that are performed.

Absent or shortened nasal bone length and the detection of Down Syndrome in second-trimester fetuses

OBJECTIVE

To estimate the accuracy of evaluating nasal bone length, expressed as multiples of the median (MoM), for the detection of Down syndrome in second- trimester fetuses.

METHODS

Expected normal median nasal bone measurements were established for an initial cohort of women receiving fetal ultrasound examinations at 15-24 weeks of gestation. Nasal bone lengths were converted to MoM with adjustment for maternal race and ethnicity using whites as the referent group. Nasal bone MoM were compared in euploid and Down syndrome fetuses. The sensitivity and specificity were evaluated in this initial cohort and in a second cohort in which all ultrasound measurements were carried out prospectively.

RESULTS

For the combined data set, 10 of 21 affected pregnancies had an absence of the nasal bone (sensitivity 47.6%), but absence was noted in only 1 of 2,515 unaffected pregnancies (false-positive rate 0.04%). Using less than 0.80 MoM as a cutoff, the sensitivity was 20 of 21 (95.2%), and the false-positive rate was 185 of 2,515 (7.4%). Changing the cutoff to 0.75 MoM resulted in 18 of 21 (85.7%) sensitivity and 74 of 2,515 (2.9%) false-positive rate. Using medians derived from whites to calculate MoM for the entire population resulted in higher false-positive rates.

CONCLUSION

Nasal bone length expressed as MoM seems to be an useful ultrasound marker for Down syndrome in second-trimester fetuses with a high sensitivity and a low false-positive rate.

LEVEL OF EVIDENCE

III.