Comparison of the Accuracy of INTERGROWTH-21 and Hadlock Ultrasound Formulae for Fetal Weight Prediction.

OBJECTIVE: To compare the accuracy of INTERGROWTH-21 (IG-21) versus Hadlock1 formulae for birth weight prediction on third-trimester ultrasound in a North American population. METHODS: This single-centre retrospective cohort study included all pregnant patients who had a third-trimester ultrasound between 340 and 366 weeks gestation and delivered a term singleton at our maternal-fetal medicine reference centre between April 1 and July 30, 2019. Estimated ultrasound fetal weight was calculated with both Hadlock1 and IG-21 formulae for each fetus, then reported on a centile curve to adjust for gestational age at delivery, and compared with the actual birth weight. RESULTS: The cohort included 600 women. The IG-21 formula had a comparable accuracy to Hadlock1 with mean absolute percentage errors (MAPEs) of 8.64 and 8.86, respectively (P = 0.191). Success rate, defined by a <10% discrepancy range of the actual birth weight, was significantly higher for IG-21 than for Hadlock1 (67.5% vs. 64.3%; P = 0.044). CONCLUSION: Our results do not support the superiority of IG-21 to Hadlock1. There is a need for continued research to improve birth weight prediction with the ultimate objective of increasing the detection of small for gestation age and macrosomic fetuses.

MRI Quantification of the Impact of Ankle Position on Syndesmosis Anatomy.

BACKGROUND: Despite the common occurrence of syndesmotic injuries in ankle trauma, the distal tibiofibular relationship remains poorly understood. The aim of this study was to evaluate the anatomical impact of ankle sagittal positioning on the tibiofibular relationship in intact ankles by using a validated magnetic resonance imaging (MRI)-based measurement system. METHODS: In this radiologic study, 34 healthy volunteers underwent a series of ankle MRIs with the ankle stabilized in 3 positions: neutral position (NP), dorsiflexion (DF), and plantarflexion (PF). Using a previously validated measurement system, 6 fixed translational measurements and 2 fixed angles were recorded on each MRI and compared using paired t tests. RESULTS: When comparing PF to DF, the anterior distance between the tibial incisura and the fibula varied from 2.5 mm to 3.9 mm ( P < .001), respectively. The middle distance between the tibial incisura and the fibula varied from 1.5 mm to 2.6 mm ( P < .001). Fibular angle varied from 8.7 degrees to 7.8 degrees of internal rotation ( P = .046), respectively. When comparing NP to DF, only the anterior distance was found to be significantly different, varying 0.4 mm ( P < .002). CONCLUSIONS: Ankle dorsiflexion leads to an increase in external rotation and lateral translation of the fibula. These changes could be measured on MRI using a validated measurement system. Ankle motion did have an impact on the distal tibiofibular relationship and should be considered in studies pertaining to syndesmosis imaging. CLINICAL RELEVANCE: This is the first in vivo study demonstrating the impact of sagittal ankle position on the distal tibiofibular relationship in an uninjured ankle. Our findings also support the practice of placing the ankle in dorsiflexion when fixing a disrupted syndesmosis. LEVEL OF EVIDENCE: Level III, comparative study.