Nomogram of fetal middle cerebral artery peak systolic velocity at 23-35 weeks of gestation in a Brazilian population: pilot study

ACR Appropriateness Criteria® Multiple Gestations: 2024 Update

The incidence of twin pregnancies has been rising, largely attributable to increasing use of artificial reproductive techniques. Ultrasound plays a critical role in establishing the chorionicity and amnionicity of multiple gestations, a key predictor of the expected risk and complications, along with guiding future clinical and imaging follow-up examinations and intervals. People carrying multiple gestations will typically undergo more ultrasound examinations (and occasionally fetal MRI) than those carrying singletons, at minimum including a first trimester dating scan, nuchal translucency scan at 11 to 14 weeks, an anatomy scan at 18 to 22 weeks, and other scans in the second and third trimesters for growth and surveillance. This document clarifies the most appropriate imaging guidelines for multiple gestations for seven clinical scenarios/variants, which range from initial imaging, follow-up imaging, growth and surveillance for uncomplicated multiple gestations, and those complicated by a known abnormality or discordance between fetuses. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

A prospective cross-sectional study of fetal middle cerebral artery peak systolic velocity in a normal obstetric population attending an Indian Medical College

PURPOSE

Fetal middle cerebral artery peak systolic velocity (MCA-PSV) is now an established method of noninvasive diagnosis of moderate to severe fetal anemia of different origins. This being a population-based parameter, it may have different values in individuals from different locations. A standard local reference range of normal individuals specific to each geographic locality is therefore needed.

MATERIALS AND METHODS

Fetal MCA-PSV was measured in 1,015 healthy pregnant women attending the antenatal ultrasound clinic at least once between 12 and 40 weeks of gestation (35 patients per week of gestation). Statistical analysis was done using the SPSS 12 software.

RESULTS

A positive correlation between MCA-PSV and gestational age was found. MCA-PSV was seen to increase with advancing gestational age. The Tukey-Kramer multiple comparisons test showed a normal distribution that was highly significant (p < 0.01). The multiples of median values of fetal MCA-PSV to label a fetus as severely anemic were consistently and significantly lower than internationally accepted values.

CONCLUSIONS

A normal reference range of fetal MCA-PSV for local use was thus scientifically and successfully constructed. Significant differences between local values and internationally accepted value were found.