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208: A prospective randomized pilot study of handheld ultrasound assessment of abdominal circumference (HHUS/AC) to detect growth abnormalities

      Objective

      Fetal growth abnormalities are some of the most common and complex problems in obstetrics. Traditional screening for growth abnormalitues with fundal height (FH) measurement has demonstrated mixed results. Our objective was to determine the feasibility of using HHUS/AC to identify growth abnormalities in a low risk setting and obtain pilot data to power future studies.

      Study Design

      A prospective randomized pilot study was performed comparing FH to HHUS/AC in screening for growth abnormalities. Candidates were enrolled prior by 32 weeks from low risk obstetric clinics at the Medical University of South Carolina. Screening was completed at each visit from 32-37 weeks gestation. Formal growth evaluation was completed when FH differed from gestational age by >3 cm or when the HHUS/AC was <10% or >90%. Bi-variable comparisons were completed using chi-square and Student’s t-tests. Sensitivity, specificity, PPV, and NPV were calculated with 95% confidence intervals to detect birth weight abnormalities. Finally, a sample size for future studies was calculated.

      Results

      103 patients were enrolled with equal allocation between the control (FH) group and study (HHUS) group with one patient was excluded due to delivery <32 weeks. There was no significant difference between groups with regard to age, race, BMI, HTN, DM/GDM, smoking, and drug use. HHUS/AC measurements were obtained in 100% of patients with an average time of 2.47 minutes. 22% of patients in the FH group were referred for formal growth versus 36% in the HHUS group. There was a trend toward improved sensitivity of HHUS/AC for detection of IUGR (Sn HHUS AC 50% vs. Sn FH 14.2%, p=0.16) while FH appeared to be superior for detection of LGA (Sn HHUS AC 20% vs. Sn FH 50%, p=0.29).

      Conclusion

      HHUS/AC can be reliably obtained in low risk patients during a routine OB visit. HHUS/AC may be more relevant in the detection of IUGR as opposed to LGA. An appropriately powered RCT comparing HHUS/AC and FH for detection of IUGR would require 72 per group.
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