To compare the etiologies and adverse outcomes of pregnancies with short fetal femur length (FL) categorized based on relative proportion and percentile placement.

Fetuses (n = 254) with short FL measured by ultrasound were classified into four groups: severe and disproportionate short FL (group A); severe and proportionate short FL (group B); mild and disproportionate short FL (group C); mild and proportionate short FL (group D). Etiologies and outcomes of pregnancies were compared between groups.

A larger percentage of skeletal dysplasia occurred in group A (28.57%) than in the other three groups (group B: 1.85%; group C: 4.08%; group D: 0). Groups A and B also had higher rates (group A: 40.82%, group B:33.33%) of fetal growth restriction (FGR) than groups C and D (group C: 4.08%; group D:3.92%). No difference in chromosomal and genetic anomalies was detected among groups (P = 0.307); however, the rate of chromosomal and genetic testing in group A was higher than in group D (P = 0.001). Group A (57.14%) had a significantly lower rate of live birth than the other three groups, and group D (98.04%) had a higher live birth rate than groups B (87.04%) and C (83.67%). Considering only living fetuses, higher rates of preterm birth (P < 0.001), low birth weight (LBW) (P < 0.001), neonatal intensive care unit (NICU) admission or pediatric hospital referral (P = 0.004), Apgar score (1 min/5 min) ≤7 (P < 0.001) and fetal distress or neonatal asphyxia (P = 0.004) were found in group A compared to group D.

Fetuses with severe and disproportionate short FL should be flagged for possible skeletal dysplasia. Fetuses with severe short FL should be watched for FGR prenatally. Invasive prenatal tests are recommended for fetuses with severe and disproportionate FL but not recommended for those with mild and proportionate short FL. Outcomes of fetuses with severe and disproportionate short FL were worse than that of fetuses with mild and proportionate short FL.

To determine the efficacy of Doppler-based renal resistive index (RRI) in the prediction of acute kidney injury (AKI) in critically ill patients.

A systematic review and meta-analysis of cohort studies was conducted. Relevant studies were identified in PubMed, Embase and Cochrane Library from inception to November 1, 2020, and reference lists of identified primary studies. Prospective studies that examined the diagnostic accuracy of RRI in AKI were included.

Among the 126 articles identified, 18 were included, with a total of 1656 patients. Bivariate analysis yielded pooled sensitivity and specificity of 0.81 (95% CI 0.74–0.86) and 0.75 (95% CI 0.65–0.83), respectively. The summary positive likelihood ratio was 3.2 (95% CI 2.2–4.6), and negative likelihood ratio was 0.26 (95% CI 0.19–0.36).

Elevated RRI may be an early predictor of AKI in critically ill patients. Further large-scale prospective studies are needed to confirm the predictive efficacy and determine the performance and optimal cutoff value of RRI among the included studies.