- Email: [email protected]
356: Estimated fetal weight 10-19% is an independent risk factor for small for gestational age infants
www.AJOG.org
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
354 Qualitative performance of fetal MRI compared to ultrasound in cases of multiple fetal anomalies Christina Herrera1, Amber Samuel1, Sherelle Laifer-Narin1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Pregnancies complicated by multiple fetal anomalies are a common indication for fetal MRI as an adjunct to diagnostic ultrasound (US). This study investigated the diagnostic performance of fetal MRI when compared to US alone for the accurate characterization of fetuses with multiple anomalies. STUDY DESIGN: In a retrospective review from 2003 to 2011 at a single tertiary-care center, potential cases were identified if an MRI was performed following sonographic concern for multiple fetal anomalies. Inclusion required documented neonatal outcomes or postmortem assessments. Inter-study reliability between MRI and US was assessed by calculating kappa. Diagnostic accuracy of adjunct MRI compared to US alone was assessed using qualitative statistics. RESULTS: 121 MRIs were performed due to antenatal sonographic concern for multiple fetal anomalies, of which 60 cases possessed documented neonatal or pathologic outcomes. The kappa for MRI compared with US was 0.28. The correct diagnosis was secured in 47% of cases by US and 50% of cases by MRI (table). Nearly all inaccurate sonographic diagnoses were due to additional postnatal findings (48%). While MRI was most commonly inaccurate due to additional postnatal findings (27%), discrepant postnatal findings (3%), discrepant and additional postnatal findings (13%), and false-positive imaging findings (5%) also contributed significantly to study inaccuracies. CONCLUSION: Agreement is poor between MRI and US for the characterization of fetuses with multiple anomalies. For either imaging modality, complete and accurate diagnosis of fetal anomalies occurs in approximately half of cases, with the majority of inaccuracies due to incomplete antenatal characterizations.
Qualitative performance of fetal MRI compared to ultrasound
Poster Session II
mented neonatal outcomes or postmortem assessments. Cases were classified by diagnosis. Test performance characteristics were calculated for each group, from which the number needed secure an additional accurate diagnosis by MRI was determined. Applying the cost per MRI at the study center to this estimate, the cost per additional accurate diagnosis was calculated using qualitative statistics. RESULTS: 799 MRIs were performed, of which 406 subjects possessed documented neonatal or pathologic outcomes. 131 distinct postnatal diagnoses were secured, of which MRI identified 51 (12.6%) that ultrasound failed to correctly characterize. When the most common diagnosis groups were considered, meningomyelocele had the lowest cost per additional correct diagnosis by MRI, and ventriculomegaly the highest (table). Cost per additional accurate diagnosis for cases of CDH, omphalocele, vein of Galen malformation, and Dandy Walker complex could not be calculated, as there were no pregnancies where MRI was accurate but ultrasound alone was not. CONCLUSION: There is a variable cost per additional diagnosis correctly secured that should be weighed when considering a pregnancy for adjunct fetal MRI. Further study should be directed at assessing the global cost-benefit of fetal MRI, as well as considering the value of MRI for prognostication and surgical planning purposes.
Cost per additional accurate diagnosis of fetal MRI
356 Estimated fetal weight 10-19% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: ACOG states that estimated fetal weight (EFW) ⬍10%
355 Comparative effectiveness of fetal MRI for the improvement of diagnostic accuracy Amber Samuel1, Sherelle Laifer-Narin1, Christina Herrera1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Fetal MRI is performed as an adjunct to routine ultrasound with the intent of improving diagnostic accuracy, yet data are limited to substantiate benefit to this costly imaging modality. This study analyzed the billed cost of fetal MRI relative to diagnostic information gained for patients with antenatal diagnoses of a fetal anomaly and known postnatal outcomes. STUDY DESIGN: This was a retrospective case review of all fetal MRIs performed between 2003 and 2011 at a single tertiary-care center. Potential cases were identified if an MRI was performed following sonographic concern for a fetal anomaly. Inclusion required docu-
suggests neonatal growth restriction. Data are poor to suggest whether EFW 10-19% (EFW10-19) is also predictive of small for gestational age (SGA) neonates. Therefore, our objective was to determine whether EFW10-19 is associated with both subsequent EFW ⬍10% (EFW10), as well as SGA ⬍10% (SGA10) or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between EFW10-19 and subsequent EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of growth restriction with EFW10-19 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV), and areas under the receiver-operator curve (AUC) of EFW10-19 and EFW10 to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of EFW10 was 8.0%, EFW10-19 was 12.3%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). EFW10-19 on first growth scan (US1) was associated with a 4.4-fold increase (95%CI 1.7-11.5) in the risk of EFW10 on subsequent ultrasound, an 8.9-fold increase (95%CI 7.36-10.77) in SGA10, and a 7.5-fold increase (95%CI 5.9-9.8) in SGA5. EFW10 alone on US1 missed nearly 70% of SGA10 and 56.5% of SGA5 infants. EFW10-19 identified an additional 40.0% of SGA10 and 42.5% of SGA5 neonates. Test characteristics of EFW10-19 were not as strong as EFW10 (Table). AUCs to predict SGA were significantly greater for EFW10-19 than EFW10 but were only fair (10: 0.66 vs. 0.50, p⬍0.001; 5: 0.66 vs. 0.51, p⬍0.001).
Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology
S157
Poster Session II
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
CONCLUSION: EFW10-19 as a screening tool for SGA increases the
number of SGA neonates identified compared to EFW10 alone (false positive rate 9-12%). Fetuses with EFW10-19 are at increased risk of subsequent growth restriction and should be followed closely during pregnancy.
Test characteristics of EFW10 and EFW10-19 to predict SGA
NPV5, negative predictive value for SGA5; NPV10, negative predictive value for SGA10; PPV5, positive predictive value for SGA5; PPV10, positive predictive value for SGA10; SN5, sensitvity to predict SGA5; SN10, sensitvity to predict SGA10; SP5, specificity to predict SGA5; SP10, specificity to predict SGA10.
357 Isolated abdominal circumference <5% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: Evidence suggests that fetal abdominal circumference (AC) ⬍10% or ⬍5% is associated with small for gestational age (SGA) neonates, but data are poor to support whether an isolated AC ⬍5% (AC5) in absence of estimated fetal weight ⬍10% (EFW10) accurately predicts the development of subsequent EFW10, SGA ⬍10% (SGA10), or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan performed at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between isolated AC5 and EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of EFW10, SGA10, and SGA5 with AC5 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV) and areas under the receiver-operator curve (AUC) of ultrasound parameters to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of isolated AC5 was 11.4%, EFW10 was 8.0%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). AC5 on first growth scan (US1) was associated with a 4.0-fold increase (95% CI 1.3-12.1) in the risk of EFW10 on subsequent ultrasound, a 6.0-fold increase (95% CI 4.6-7.4) in SGA10, and a 5.4-fold increase (95%CI 4.1-7.2) in SGA5. EFW10 alone on US1 missed almost 70% of SGA10 and 56.5% of SGA5 infants. Isolated AC5 identified an additional 16.0% of SGA10 and 20.8% of SGA5 neonates. Using both EFW10 and AC5 improved specificity and PPV compared to either parameter alone (Table). AUCs for EFW10 and AC5 to predict SGA were not clinically different and were only fair (10: 0.64 vs. 0.66, p⬍0.001; 5: 0.69 vs. 0.71, p⫽0.02). CONCLUSION: Isolated AC5 as a screening tool for SGA increases the number of SGA neonates identified compared to EFW10 alone (false positive rate ⬍5%). Fetuses with AC5 are at increased risk of subsequent growth restriction and should be monitored closely during pregnancy.
Test characteristics for EFW10 and AC5 to predict SGA
NPV5, negative predictive value for SGA5; NPV10, negative predictive value for SGA10; PPV5, positive predictive value for SGA5; PPV10, positive predictive value for SGA10; SN5, sensitvity to predict SGA5; SN10, sensitvity to predict SGA10; SP5, specificity to predict SGA5; SP10, specificity to predict SGA10.
S158
www.AJOG.org
358 Predicting infant and placental weight at birth (PLWB) using customized models including first-trimester 3D placental volume, crown-rump length (CRL) and maternal characteristics Anthony Odibo1, Alison Cahill1, Linda Odibo1, George Macones1 1 Washington University in St. Louis, Obstetrics and Gynecology, St Louis, MO
OBJECTIVE: To determine if a combination of 3D placental volume, CRL and maternal characteristics can be used to estimate infant birthweight (BW) and PLWB. STUDY DESIGN: A prospective study was performed of women with singleton pregnancies from 11 to 14 weeks. To evaluate placental volume (PV) 3D power Doppler was applied and the volume acquired was analyzed using the Virtual Organ Computer-aided Analysis (VOCAL™) program by a reader blinded to pregnancy outcome. Coefficients for significant maternal variables, CRL and PV affecting fetal and placental growth (growth potential at term) were obtained using backward stepwise multiple regression. The predicted BW and PLWB were then compared with actual BW and placental weight. The primary outcome was an absolute error between predicted BW and actual BW ⬎500g, and between predicted PLWB and actual PLWB ⬎100g. RESULTS: PV was rendered in 712 pregnancies. Significant variables associated with BW and their coefficients are shown in the Table. These variables were used to predict the expected birthweight at term. The constant for the birthweight prediction model is: 3550g [standard error (SE) 593g]. PV was significantly associated with PLWB with a constant for the model of 409.2g (SE 10.6g). Of 569 patients delivering at term, 53 (9.3%) had an absolute error ⬎500g using predicted BW. Of 149 patients with placental weight assessed at term, 15 (10.1%) had an absolute error ⬎100g using predicted PLWB. CONCLUSION: The findings suggest that placental weight and birthweight can be predicted with good precision in the first-trimester using customized models combining 3D ultrasound and maternal characteristics.
Variables and coeeficients used for birthweight prediction
CRL, crown rump length; GA, gestational age.
359 MSAFP does not improve detection rate for open neural tube defects in patients who receive first- and early secondtrimester ultrasounds for fetal anatomical survey Ashley Roman1, Simi Gupta1, Nathan Fox2, Daniel Saltzman3, Chad Klauser3, Andrei Rebarber2 1 New York University School of Medicine, Obstetrics and Gynecology, New York, NY, 2Mount Sinai School of Medicine, Obstetrics and Gynecology, New York, NY, 3Carnegie Imaging for Women, Maternal Fetal Medicine, New York, NY
OBJECTIVE: Maternal serum alpha-fetoprotein (MSAFP) is used to identify patients at high risk for open neural tube defects (ONTD). Many centers have started performing anatomical surveys during the first- and early second-trimester in addition to the routine 18-20 week scan. This study evaluates whether MSAFP improves the detection rate of ONTD in patients undergoing first- and early second-trimester anatomical surveys. STUDY DESIGN: A historical cohort of patients undergoing fetal ultrasound in a single ultrasound practice between May 2005 and August 2011 met criteria for inclusion. All patients were offered nuchal trans-
American Journal of Obstetrics & Gynecology Supplement to JANUARY 2013
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
354 Qualitative performance of fetal MRI compared to ultrasound in cases of multiple fetal anomalies Christina Herrera1, Amber Samuel1, Sherelle Laifer-Narin1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Pregnancies complicated by multiple fetal anomalies are a common indication for fetal MRI as an adjunct to diagnostic ultrasound (US). This study investigated the diagnostic performance of fetal MRI when compared to US alone for the accurate characterization of fetuses with multiple anomalies. STUDY DESIGN: In a retrospective review from 2003 to 2011 at a single tertiary-care center, potential cases were identified if an MRI was performed following sonographic concern for multiple fetal anomalies. Inclusion required documented neonatal outcomes or postmortem assessments. Inter-study reliability between MRI and US was assessed by calculating kappa. Diagnostic accuracy of adjunct MRI compared to US alone was assessed using qualitative statistics. RESULTS: 121 MRIs were performed due to antenatal sonographic concern for multiple fetal anomalies, of which 60 cases possessed documented neonatal or pathologic outcomes. The kappa for MRI compared with US was 0.28. The correct diagnosis was secured in 47% of cases by US and 50% of cases by MRI (table). Nearly all inaccurate sonographic diagnoses were due to additional postnatal findings (48%). While MRI was most commonly inaccurate due to additional postnatal findings (27%), discrepant postnatal findings (3%), discrepant and additional postnatal findings (13%), and false-positive imaging findings (5%) also contributed significantly to study inaccuracies. CONCLUSION: Agreement is poor between MRI and US for the characterization of fetuses with multiple anomalies. For either imaging modality, complete and accurate diagnosis of fetal anomalies occurs in approximately half of cases, with the majority of inaccuracies due to incomplete antenatal characterizations.
Qualitative performance of fetal MRI compared to ultrasound
Poster Session II
mented neonatal outcomes or postmortem assessments. Cases were classified by diagnosis. Test performance characteristics were calculated for each group, from which the number needed secure an additional accurate diagnosis by MRI was determined. Applying the cost per MRI at the study center to this estimate, the cost per additional accurate diagnosis was calculated using qualitative statistics. RESULTS: 799 MRIs were performed, of which 406 subjects possessed documented neonatal or pathologic outcomes. 131 distinct postnatal diagnoses were secured, of which MRI identified 51 (12.6%) that ultrasound failed to correctly characterize. When the most common diagnosis groups were considered, meningomyelocele had the lowest cost per additional correct diagnosis by MRI, and ventriculomegaly the highest (table). Cost per additional accurate diagnosis for cases of CDH, omphalocele, vein of Galen malformation, and Dandy Walker complex could not be calculated, as there were no pregnancies where MRI was accurate but ultrasound alone was not. CONCLUSION: There is a variable cost per additional diagnosis correctly secured that should be weighed when considering a pregnancy for adjunct fetal MRI. Further study should be directed at assessing the global cost-benefit of fetal MRI, as well as considering the value of MRI for prognostication and surgical planning purposes.
Cost per additional accurate diagnosis of fetal MRI
356 Estimated fetal weight 10-19% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: ACOG states that estimated fetal weight (EFW) ⬍10%
355 Comparative effectiveness of fetal MRI for the improvement of diagnostic accuracy Amber Samuel1, Sherelle Laifer-Narin1, Christina Herrera1, Lynn Simpson1, Russell Miller1 1 Columbia University Medical Center, Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, New York, NY
OBJECTIVE: Fetal MRI is performed as an adjunct to routine ultrasound with the intent of improving diagnostic accuracy, yet data are limited to substantiate benefit to this costly imaging modality. This study analyzed the billed cost of fetal MRI relative to diagnostic information gained for patients with antenatal diagnoses of a fetal anomaly and known postnatal outcomes. STUDY DESIGN: This was a retrospective case review of all fetal MRIs performed between 2003 and 2011 at a single tertiary-care center. Potential cases were identified if an MRI was performed following sonographic concern for a fetal anomaly. Inclusion required docu-
suggests neonatal growth restriction. Data are poor to suggest whether EFW 10-19% (EFW10-19) is also predictive of small for gestational age (SGA) neonates. Therefore, our objective was to determine whether EFW10-19 is associated with both subsequent EFW ⬍10% (EFW10), as well as SGA ⬍10% (SGA10) or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between EFW10-19 and subsequent EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of growth restriction with EFW10-19 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV), and areas under the receiver-operator curve (AUC) of EFW10-19 and EFW10 to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of EFW10 was 8.0%, EFW10-19 was 12.3%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). EFW10-19 on first growth scan (US1) was associated with a 4.4-fold increase (95%CI 1.7-11.5) in the risk of EFW10 on subsequent ultrasound, an 8.9-fold increase (95%CI 7.36-10.77) in SGA10, and a 7.5-fold increase (95%CI 5.9-9.8) in SGA5. EFW10 alone on US1 missed nearly 70% of SGA10 and 56.5% of SGA5 infants. EFW10-19 identified an additional 40.0% of SGA10 and 42.5% of SGA5 neonates. Test characteristics of EFW10-19 were not as strong as EFW10 (Table). AUCs to predict SGA were significantly greater for EFW10-19 than EFW10 but were only fair (10: 0.66 vs. 0.50, p⬍0.001; 5: 0.66 vs. 0.51, p⬍0.001).
Supplement to JANUARY 2013 American Journal of Obstetrics & Gynecology
S157
Poster Session II
Clinical Obstetrics, Diabetes, Labor, Medical-Surgical-Disease, Physiology/Endocrinology, Prematurity
CONCLUSION: EFW10-19 as a screening tool for SGA increases the
number of SGA neonates identified compared to EFW10 alone (false positive rate 9-12%). Fetuses with EFW10-19 are at increased risk of subsequent growth restriction and should be followed closely during pregnancy.
Test characteristics of EFW10 and EFW10-19 to predict SGA
NPV5, negative predictive value for SGA5; NPV10, negative predictive value for SGA10; PPV5, positive predictive value for SGA5; PPV10, positive predictive value for SGA10; SN5, sensitvity to predict SGA5; SN10, sensitvity to predict SGA10; SP5, specificity to predict SGA5; SP10, specificity to predict SGA10.
357 Isolated abdominal circumference <5% is an independent risk factor for small for gestational age infants Amy Turitz1, Hayley Quant1, Nadav Schwartz1, Michal Elovitz1, Jamie Bastek1 1 University of Pennsylvania Perelman School of Medicine, Maternal and Child Health Research Program, Obstetrics and Gynecology, Philadelphia, PA
OBJECTIVE: Evidence suggests that fetal abdominal circumference (AC) ⬍10% or ⬍5% is associated with small for gestational age (SGA) neonates, but data are poor to support whether an isolated AC ⬍5% (AC5) in absence of estimated fetal weight ⬍10% (EFW10) accurately predicts the development of subsequent EFW10, SGA ⬍10% (SGA10), or ⬍5% (SGA5). STUDY DESIGN: Retrospective cohort study (1/2008-12/2011) of all women with singleton pregnancies 26-36 weeks and ⱖ1 growth scan performed at our institution. Ultrasound-based weight was determined by the Hadlock equation (1984) and percentile growth by the Alexander growth curve. The association between isolated AC5 and EFW10, SGA10, and SGA5 were compared using chi square analyses. Odds of EFW10, SGA10, and SGA5 with AC5 were calculated using MVLR to control for confounders. Sensitivity (SN), specificity (SP), positive and negative predictive values (PPV, NPV) and areas under the receiver-operator curve (AUC) of ultrasound parameters to predict SGA10 and SGA5 were calculated. RESULTS: The prevalence of isolated AC5 was 11.4%, EFW10 was 8.0%, SGA10 was 17.6%, and SGA5 was 8.3% (N⫽10,642). AC5 on first growth scan (US1) was associated with a 4.0-fold increase (95% CI 1.3-12.1) in the risk of EFW10 on subsequent ultrasound, a 6.0-fold increase (95% CI 4.6-7.4) in SGA10, and a 5.4-fold increase (95%CI 4.1-7.2) in SGA5. EFW10 alone on US1 missed almost 70% of SGA10 and 56.5% of SGA5 infants. Isolated AC5 identified an additional 16.0% of SGA10 and 20.8% of SGA5 neonates. Using both EFW10 and AC5 improved specificity and PPV compared to either parameter alone (Table). AUCs for EFW10 and AC5 to predict SGA were not clinically different and were only fair (10: 0.64 vs. 0.66, p⬍0.001; 5: 0.69 vs. 0.71, p⫽0.02). CONCLUSION: Isolated AC5 as a screening tool for SGA increases the number of SGA neonates identified compared to EFW10 alone (false positive rate ⬍5%). Fetuses with AC5 are at increased risk of subsequent growth restriction and should be monitored closely during pregnancy.
Test characteristics for EFW10 and AC5 to predict SGA
NPV5, negative predictive value for SGA5; NPV10, negative predictive value for SGA10; PPV5, positive predictive value for SGA5; PPV10, positive predictive value for SGA10; SN5, sensitvity to predict SGA5; SN10, sensitvity to predict SGA10; SP5, specificity to predict SGA5; SP10, specificity to predict SGA10.
S158
www.AJOG.org
358 Predicting infant and placental weight at birth (PLWB) using customized models including first-trimester 3D placental volume, crown-rump length (CRL) and maternal characteristics Anthony Odibo1, Alison Cahill1, Linda Odibo1, George Macones1 1 Washington University in St. Louis, Obstetrics and Gynecology, St Louis, MO
OBJECTIVE: To determine if a combination of 3D placental volume, CRL and maternal characteristics can be used to estimate infant birthweight (BW) and PLWB. STUDY DESIGN: A prospective study was performed of women with singleton pregnancies from 11 to 14 weeks. To evaluate placental volume (PV) 3D power Doppler was applied and the volume acquired was analyzed using the Virtual Organ Computer-aided Analysis (VOCAL™) program by a reader blinded to pregnancy outcome. Coefficients for significant maternal variables, CRL and PV affecting fetal and placental growth (growth potential at term) were obtained using backward stepwise multiple regression. The predicted BW and PLWB were then compared with actual BW and placental weight. The primary outcome was an absolute error between predicted BW and actual BW ⬎500g, and between predicted PLWB and actual PLWB ⬎100g. RESULTS: PV was rendered in 712 pregnancies. Significant variables associated with BW and their coefficients are shown in the Table. These variables were used to predict the expected birthweight at term. The constant for the birthweight prediction model is: 3550g [standard error (SE) 593g]. PV was significantly associated with PLWB with a constant for the model of 409.2g (SE 10.6g). Of 569 patients delivering at term, 53 (9.3%) had an absolute error ⬎500g using predicted BW. Of 149 patients with placental weight assessed at term, 15 (10.1%) had an absolute error ⬎100g using predicted PLWB. CONCLUSION: The findings suggest that placental weight and birthweight can be predicted with good precision in the first-trimester using customized models combining 3D ultrasound and maternal characteristics.
Variables and coeeficients used for birthweight prediction
CRL, crown rump length; GA, gestational age.
359 MSAFP does not improve detection rate for open neural tube defects in patients who receive first- and early secondtrimester ultrasounds for fetal anatomical survey Ashley Roman1, Simi Gupta1, Nathan Fox2, Daniel Saltzman3, Chad Klauser3, Andrei Rebarber2 1 New York University School of Medicine, Obstetrics and Gynecology, New York, NY, 2Mount Sinai School of Medicine, Obstetrics and Gynecology, New York, NY, 3Carnegie Imaging for Women, Maternal Fetal Medicine, New York, NY
OBJECTIVE: Maternal serum alpha-fetoprotein (MSAFP) is used to identify patients at high risk for open neural tube defects (ONTD). Many centers have started performing anatomical surveys during the first- and early second-trimester in addition to the routine 18-20 week scan. This study evaluates whether MSAFP improves the detection rate of ONTD in patients undergoing first- and early second-trimester anatomical surveys. STUDY DESIGN: A historical cohort of patients undergoing fetal ultrasound in a single ultrasound practice between May 2005 and August 2011 met criteria for inclusion. All patients were offered nuchal trans-
American Journal of Obstetrics & Gynecology Supplement to JANUARY 2013