Ultrasound Biometry Threshold Values
| Measurement / Threshold | Clinical Interpretation |
|---|---|
| DVP < 2 cm | Oligohydramnios in singleton or twin gestation. |
| DVP ≥ 8 cm | Polyhydramnios in singleton or twin gestation. Severity may be described as mild (8–11 cm), moderate (12–15 cm), or severe (≥16 cm). |
| AFI ≥ 24 cm | Polyhydramnios in singleton gestation. Severity may be described as mild (24.0–29.9 cm), moderate (30.0–34.9 cm), or severe (≥35 cm). |
| MCA PSV ≥ 1.5 MoM | Increased likelihood of fetal anemia. |
| Cerebroplacental ratio (CPR) < 1.08 | Associated with increased risk for adverse perinatal outcomes in the growth-restricted fetus. |
| Femur length to abdominal circumference ratio < 0.16 | Increased likelihood of lethality in skeletal dysplasia. |
| Inferior facial angle < 49° | Increased likelihood of micrognathia. |
| Jaw index < 23 | Reported 100% sensitivity and 98.1% specificity for diagnosis of micrognathia in the cited study. |
| Fetal head circumference ≥ 3 SD below the mean for gestational age | Fetal microcephaly. |
| Fetal head circumference ≥ 5 SD below the mean for gestational age | Pathologic microcephaly considered highly likely. |
| Atrial diameter of the lateral ventricle ≥ 10 mm | Fetal cerebral ventriculomegaly. Severity may be described as mild (10–12 mm), moderate (13–15 mm), or severe (>15 mm). |
References
- Reddy UM, Abuhamad AZ, Levine D, Saade GR, et al. Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med. 2014;33(5):745-757. PMID: 24764329
- Dashe JS, Pressman EK, Hibbard JU; Society for Maternal-Fetal Medicine (SMFM). SMFM Consult Series #46: Evaluation and management of polyhydramnios. Am J Obstet Gynecol. 2018;219(4):B2-B8. PMID: 30048635
- Mari G, Deter RL, Carpenter RL, Rahman F, et al. Noninvasive diagnosis by Doppler ultrasonography of fetal anemia due to maternal red-cell alloimmunization. N Engl J Med. 2000;342(1):9-14. PMID: 10620643
- Odibo AO, Riddick C, Pare E, Stamilio DM, Macones GA. Cerebroplacental Doppler ratio and adverse perinatal outcomes in intrauterine growth restriction: evaluating the impact of using gestational age-specific reference values. J Ultrasound Med. 2005;24(9):1223-1228. PMID: 16123182
- Savarirayan R, et al. Best practice guidelines regarding prenatal evaluation and delivery of patients with skeletal dysplasia. Am J Obstet Gynecol. 2018;219(6). PMID: 30048634
- Rotten D, Levaillant JM, Martinez H, Ducou Le Pointe H, Vicaut E. The fetal mandible: a 2D and 3D sonographic approach to the diagnosis of retrognathia and micrognathia. Ultrasound Obstet Gynecol. 2002;19(2):122-130. PMID: 11876802
- Paladini D, Rustico M, Todros T, Palmieri S, Giani U. Objective diagnosis of micrognathia in the fetus: the jaw index. Obstet Gynecol. 1999;93(3):382-386. PMID: 10074984
- Society for Maternal-Fetal Medicine Publications Committee. Ultrasound screening for fetal microcephaly following Zika virus exposure. Am J Obstet Gynecol. 2016;214(6):B2-B4. PMID: 26901275
- Fox NS, Monteagudo A, Kuller JA, Craigo S, Norton ME; Society for Maternal-Fetal Medicine (SMFM). Mild fetal ventriculomegaly: diagnosis, evaluation, and management. Am J Obstet Gynecol. 2018;219(1):B2-B9. PMID: 29959947
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