Influence of Sonographic Fetal Weight Estimation Inaccuracies in Macrosomia on Perinatal Outcome

Abstract

Objective To evaluate the influence of inaccurate sonographic fetal weight estimation in macrosomia on the mode of delivery and neonatal outcome (NO). Methods In 14 633 pregnancies between 2002 and 2016, this retrospective study evaluated the association between sonographic fetal weight estimation, true birth weight (BW), mode of delivery (primary cesarean section [pCS], secondary cesarean section, vaginal delivery, and operative vaginal delivery rates) and NO parameters (5-min Apgar < 7, pH < 7.1, neonatal intensive care unit [NICU] admission, shoulder dystocia). Singleton pregnancies > 37 + 0 weeks with ultrasound-estimated fetal weight (EFW) within 7 days before delivery were included. The study population was divided into four groups: Group 1 (false-negative): EFW < 4000 g/BW ≥ 4000 g; Group 2 (true-positive): EFW ≥ 4000 g/BW ≥ 4000 g; Group 3 (false-positive): EFW ≥ 4000 g/BW < 4000 g; and Group 4 (true-negative): EFW < 4000 g/BW < 4000 g. Results As expected, the highest secondary cesarean section (sCS) rate was found in Group 2 (true-positive) (30.62 %), compared with only 17.68 % in Group 4 (true-negative). The sCS rate in the false-positive Group 3 was significantly higher (28.48 %) in comparison with the false-negative Group 1 (21.22 %; OR 1.48; 95 % CI, 1.16 to 1.89; P = 0.002). In comparison with the true-negative Group 4, univariate analyses showed significantly higher rates for sCS in all other groups: odds ratio (OR) 2.06 for Group 2 (95 % CI, 1.74 to 2.42; P < 0.001), 1.85 for Group 3 (95 % CI, 1.54 to 2.22, P < 0.001), and 1.25 for Group 1 (95 % CI, 1.05 to 1.49; P < 0.01). No significant differences were found for NO between Groups 1 and 3 for the parameters 5-min Apgar < 7 (P = 0.75), pH < 7.1 (P = 0.28), or NICU admission (P = 0.54). However, there was a significantly higher chance for shoulder dystocia in Group 1 compared with Group 3 (OR 4.58; 95 % CI, 1.34 to 24.30; P = 0.008). Conclusion Sonographic EFW inaccuracies in fetal macrosomia appear to have a greater impact on the mode of delivery than birth weight itself. Underestimation of fetal weight may be associated with a higher probability of shoulder dystocia.

Fetal Macrosomia and Associated Factors to Perinatal Adverse Outcomes, in Yaounde, Cameroon : A Case Control Study

“…This reinforces the need for good clinical follow-up by regular measurement of symphysis fundal height associated to abdominal circumference [21]. In addition, the absence of influence of third term ultrasonography to predict macrosomia in our study is consistent with previous reports in the literature and emphazises the need to use a multiparametric ultrasound model including umbilical vein flow for optimal performance and accuracy to diagnose macrosomia [22,23]. Finally, in newborns, the parameters most associated with complications within this population of over 4000 g were those with over 4500 g and over 52.7 cm of height.…”

Percent error of ultrasound examination to estimate fetal weight at term in different categories of birth weight with focus on maternal diabetes and obesity

“…The sonographic EFW inaccuracy in fetal macrosomia appears to have a greater impact on the mode of delivery than the BW itself. In a prior study, the caesarean section rate was significantly higher (28.48%) with false-positive estimates than with false-negative estimates [22]. Overall, the current accuracy of EFW formulae with conventional biometric parameters by 2D ultrasound seems to have reached its limits.…”

Obstetric consequences of a false‐positive diagnosis of large‐for‐gestational‐age fetus

“…In such studies the ultrasound scan for the estimation of fetal weight was carried out shortly before delivery at term of pregnancy 11,17–19 . On the contrary, in the present study the estimation of fetal weight in pregnancies at risk for macrosomia was carried out between the 34th and the 37th weeks of gestation, when the estimation can be made with greater accuracy 15,19 .…”

“…Melamed et al, 17 Blackwell et al, 11 and Pretscher et al In such studies the ultrasound scan for the estimation of fetal weight was carried out shortly before delivery at term of pregnancy. 11,[17][18][19] On the contrary, in the present study the estimation of fetal weight in pregnancies at risk for macrosomia was carried out between the 34th and the 37th weeks of gestation, when the estimation can be made with greater accuracy. 15,19 At the end of pregnancy, the resolution of ultrasound and the accuracy of measurements decrease because of the reduction in amniotic fluid, the greater calcification of fetal bones, and the position of the fetal head lower in the pelvis.…”