title: The utility of ultrasound surveillance of fluid and growth in obese women.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the utility of ultrasound surveillance in obese women.
  
  
  METHODS
  This is a retrospective cohort of all obese women who underwent sonography at a single center from 2005-2013. Inclusion criteria were body mass index ≥30 kg/m(2), singleton, ≥1 ultrasound scan performed at <20 weeks of gestation, and ≥1 ultrasound scan performed at ≥24 weeks of gestation. Pregnancies with medical complications, fetal anomalies, or preterm premature rupture of membranes were excluded. Outcomes that were considered were small for gestational age, large for gestational age (LGA), macrosomia, oligohydramnios, and polyhydramnios. We calculated the number needed to screen (NNS) and 95% confidence interval (CI) for scans that were performed during 3 gestational age ranges (24-31 weeks 6 days, 32-35 weeks 6 days, and ≥36 weeks).
  
  
  RESULTS
  Two thousand two sonograms were performed in 1164 obese women at ≥24 weeks of gestation. Small for gestational age was diagnosed in 59 pregnancies (5.1%); 7 pregnancies (0.6%) were diagnosed at <32 weeks of gestation (NNS, 159; 95% CI, 69-490). LGA was diagnosed in 38 cases (3.3%); only 1 case was identified at <32 weeks of gestation and was not LGA at birth. For every 29 (95% CI, 19-46) scans performed at >36 weeks of gestation, 1 case of macrosomia was identified. Amniotic fluid abnormalities were diagnosed in 44 pregnancies (3.8%; oligohydramnios, 19; polyhydramnios, 25); 34.1% abnormalities were diagnosed at <32 weeks of gestation (NNS: oligohydramnios, 113; 95% CI, 55-282 for oligohydramnios; polyhydramnios, 100; 95% CI, 50-230). At ≥36 weeks of gestation, 7 (95% CI, 6-8) scans were needed to diagnose any fluid or growth abnormality.
  
  
  CONCLUSIONS
  In obese women without comorbidities, few sonographic diagnoses of amniotic fluid or fetal growth abnormalities are made at <32 weeks of gestation. Therefore, if a policy of serial sonographic surveillance is used, we suggest ultrasound scans for fluid and growth in obese women to begin at ≥32 weeks of gestation.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL. Electronic address: lmharper@uabmc.edu.
authors.forename: Lorie M
authors.initials: LM
authors.lastname: Harper
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Victoria C
authors.initials: VC
authors.lastname: Jauk
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: John
authors.initials: J
authors.lastname: Owen
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Biggio
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000000981:diagnostic imaging*; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging*; D005320:Fetal Macrosomia / Q000000981:diagnostic imaging*; D006801:Humans; D009765:Obesity; D016104:Oligohydramnios / Q000000981:diagnostic imaging*; D006831:Polyhydramnios / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011248:Pregnancy Complications; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal; D055815:Young Adult
keywords: amniotic fluid; fetal growth; obesity; surveillance; ultrasound