S212 SMFM Abstracts 706 REAL-WORLD PERFORMANCE OF MCA-PSV FOR THE DETECTION OF FETAL ANEMIA KRISTIINA PARVIAINEN1, HILARY S. GAMMILL1, LYNDON HILL1, 1University of Pittsburgh, Obstetrics, Gynecology and Reproductive Sciences, Pittsburgh, Pennsylvania OBJECTIVE: Middle cerebral artery peak systolic doppler velocimetry (MCA-PSV) has been rapidly accepted as the standard approach for the detection of fetal anemia. Validation of MCA-PSV, however, is based on studies designed to explicitly compare MCA-PSV immediately prior to cordocentesis or delivery. We sought to examine the real-world performance of MCA-PSV in clinical practice at a tertiary care center. STUDY DESIGN: We conducted a retrospective review, following IRB approval, of all women undergoing fetal MCA-PSV at Magee-Womens Hospital for risk of isoimmunization from January 1, 2000 to March 1, 2006. We abstracted demographic information, anemia risk factors, ultrasounds, maternal and neonatal outcomes. We evaluated the prediction of severe anemia (hemoglobin !7 gm/dl or intrauterine transfusion), by the accepted MCA-PSV threshold of O1.55 multiples of the median (MOM) as established by Mari et al. RESULTS: We studied 75 women with 81 pregnancies with MCA-PSV studies. 31 of the 75 pregnancies had a neonatal or cordocentesis hemoglobin documented within 7 days of MCA-PSV. In these 31 cases, MCA-PSV O1.55 MOM detected severe anemia with 77.7% sensitivity and 86.4% speciﬁcity. The PPV was 70%, and the NPV was 90.4%. In order to assess the utility of following trends in MCA-PSV, we calculated test performance characteristics for a 50% increase in MCA-PSV MOM above baseline on the examination immediately preceding delivery or cordocentesis. For 29 pregnancies, serial examinations for trend in MCA-PSV were available. This showed a sensitivity of 57% and a speciﬁcity of 95%. CONCLUSION: MCA-PSV performs well in clinical settings for the detection of fetal anemia in pregnancies at risk for isoimmunization. Some investigators have suggested that a trend in MCA-PSV may be more clinically useful than a single point estimate. However, our results suggest that caution should be used with such an approach, as the improvement in speciﬁcity comes at the cost of decreased sensitivity. 0002-9378/$ - see front matter doi:10.1016/j.ajog.2006.10.765 707 GESTATIONAL AGE AND PEAK SYSTOLIC VELOCITY OF THE MIDDLE CEREBRAL ARTERY: A PRACTICAL ALGORITHM FOR ESTIMATING FETAL ANEMIA KIMBERLY DESTEFANO1, EFTICHIA KONTOPOULOS1, PATRICIA BORNICK2, RUBEN QUINTERO1, 1University of South Florida, Ob/Gyn/Maternal Fetal Med, Tampa, Florida, 2University of South Florida, Obstetrics and Gynecology/Division of Maternal Fetal Medicine, Tampa, Florida OBJECTIVE: To review the numeric relationship between gestational age and peak systolic velocity of the MCA (PSV-MCA) to provide a quick bedside method for estimating fetal anemia. STUDY DESIGN: A literature review was performed of studies on isoimmunization and the values at which MCA dopplers correlate with signiﬁcant fetal anemia. RESULTS: Published studies have consistently conﬁrmed PSV-MCA multiples of the median (MOM) of 1.5 and 1.55 to correlate with moderate and severe fetal anemia respectively. While absolute values for fetal anemia are gestational age dependent, the drop in fetal hemoglobin that results in moderate and/or severe anemia is a constant of % 0.65 MOM allowing for standardized measurements. Using Mari’s originally published reference table (N Engl J Med 2000;342:9-14) we assessed the relationship of gestational age and PSVMCA consistent with moderate and severe anemia. Figure 1 demonstrates the PSV-MCA consistent with anemia at each gestational age. Figure 2 demonstrates our ﬁnding that the PSV-MCA correlating with moderate and severe anemia are approximately 2 times the gestational age (PSV /gestational age = 2 G 0.3).
CONCLUSION: A factor of two times the gestational age can be used as a ‘‘poor man’s method’’ of detecting fetal anemia. When access to tables with gestational age speciﬁc values is limited, such as in outreach clinics or at the bedside on labor and delivery, this relationship can be used to quickly determine those fetuses that may be in danger due to anemia. 0002-9378/$ - see front matter doi:10.1016/j.ajog.2006.10.766 708 CESAREAN DELIVERY AND BIRTH EXPERIENCE IN CHILE KIER VAN REMOORTERE1, JUAN VARGAS1, RICARDO GOMEZ2, IVAN ROJAS2, JORGE ROBERT3, AARON CAUGHEY1, 1University of California, San Francisco, Department of Obstetrics, Gynecology and Reproductive Sciences, San Francisco, California, 2CEDIP, Sotero del Rio Hospital, Department of Obstetrics and Gynecology, Puente Alto, Chile, 3Clinica Las Condes, Santiago, Chile OBJECTIVE: With the current focus on patient autonomy, elective cesarean has become an area of intense debate. We sought to examine how prior birth experiences inﬂuence a pregnant woman’s preferred mode of delivery as well as her anticipated birth experience in a setting where elective cesarean is not uncommon. STUDY DESIGN: Pregnant women were surveyed in prenatal clinics in Santiago, Chile over a six month period. They were queried regarding prior deliveries, current delivery preference, their anticipated birth experience during the upcoming delivery, and the maximum amount of pain they expected to feel. Dimensions of birth experience were assessed by Salmon’s item list, and pain was assessed using the visual analog scale. RESULTS: Of the 643 women surveyed, 142 (33.2%) had delivered by cesarean at least once, and these patients were more likely to prefer another cesarean (42.6% versus 6.6%, p!0.001). There were diﬀerences in the anticipation of satisfaction, anxiety, and pain based on a history of prior cesarean and the type of cesarean performed (elective, medically necessary, or emergency). In particular, women who had delivered via Cesarean in the past felt more anxious about their upcoming delivery but also expected to feel less pain. Patients who had delivered via an elective cesarean anticipated less pain during delivery than others in the prior cesarean group (3.12 vs. 6.40, p=0.003). CONCLUSION: A woman’s obstetric history strongly inﬂuences her prospective choices regarding mode of delivery. Furthermore, prior obstetric history aﬀects her perception of pain and anxiety regarding her upcoming birth. In order to facilitate informed decision making regarding mode of delivery, such perceptions need to be understood and possibly alleviated by clinicians. Anticipation of Birth Experience (statistically significant results only) Birth Experience Variables
No Prior Cesarean
0002-9378/$ - see front matter doi:10.1016/j.ajog.2006.10.768 709 PREFERENCES REGARDING MODE OF DELIVERY: QUANTITATIVE ASSESSMENT KIER VAN REMOORTERE1, JUAN VARGAS1, RICARDO GOMEZ2, IVAN ROJAS3, JORGE ROBERT4, AARON CAUGHEY1, 1University of California, San Francisco, Department of Obstetrics, Gynecology and Reproductive Sciences, San Francisco, California, 2CEDIP, Sotero del Rio Hospital, Puente Alto, Chile, 3 CEDIP, Sotero del Rio Hosp., OB-GIN, Univ.Catolica de Chile, Puente Alto, Stgo., Chile, 4Clinica Las Condes, Santiago, Chile OBJECTIVE: Whether pregnant women should have the option to choose their mode of delivery is increasingly debated among clinicians and policymakers in the U.S. Thus, to better understand the importance of mode of delivery, we sought to obtain quantitative estimates of their preferences in a country where many women do have the option to choose their mode of delivery. STUDY DESIGN: Pregnant women were surveyed in prental clinics in Santiago, Chile over a six month period. The time tradeoﬀ (TTO) utility metric and willingness to pay (WTP) were utilized to quantitatively assess valuation of mode of delivery. Statistical comparisons were made utilizing the Kruskal-Wallis and Wilcoxon Rank Sum nonparametric tests. RESULTS: Of 622 women who completed the questionnaire, 447 preferred vaginal delivery (72%), 92 preferred cesarean delivery (15%), and 83 had no preference (13%). Assuming that the preferred delivery was a utility score of 1, utilizing the TTO metric those preferring vaginal delivery had a utility score of 0.988 for cesarean and those preferring cesarean had a utility score of 0.992 for vaginal (p = 0.0499). The median willingness to pay to achieve the preferred mode of delivery was 25,000 CP ($46) for vaginal delivery and 50,000 CP ($91 US) for cesarean delivery (p = 0.1318). Women in the private clinic had a higher median willingness to pay for their preferred mode of delivery, 100,000 CP ($182 US), as compared to the public clinic, 25,000 CP ($46 US), p = 0.0038. CONCLUSION: In a country where many women do have the option to choose their attempted mode of delivery, the majority stated they would choose vaginal delivery. When quantitative measures were utilized to assess their preferences, the diﬀerences between the preferred mode of delivery and the alternative were small for the majority of women. With such small diﬀerences in preferences, it may be that the medical risks and beneﬁts of mode of delivery should override these small diﬀerences. 0002-9378/$ - see front matter doi:10.1016/j.ajog.2006.10.769