Evaluation of Fetal Weight Estimation Formulas in Assessing Small-for-Gestational-Age Fetuses.

PURPOSE: The aim of this study was to compare the accuracy of multiple sonographic fetal weight estimation models in assessing small-for-gestational-age (SGA) fetuses. MATERIALS AND METHODS: The cohort included all singleton pregnancies recorded at a single medical center from January 2004 to September 2011, with a minimum of 24 weeks of gestation. SGA was defined as a fetal weight of less than the 10th percentile. We used birth weight (BW) distribution curves for our population, matched according to fetal gender and gestational age. Predicted birth weights were calculated using 26 sonographic fetal weight estimation models, including targeted formulas for SGA fetuses. RESULTS: 1218 cases of SGA fetuses that underwent sonographic fetal weight estimation within one week prior to delivery were found. Prediction of fetal weight was significantly less accurate in SGA fetuses than in the general population. The random error for SGA fetuses ranged from 7.2 % to 13.9 % in different models, while the systematic error ranged from -12.8 % to 26 %. Most non-targeted formulas showed a specificity of over 90 % but a sensitivity of only 20 - 35 % in the detection of SGA fetuses, while most targeted formulas had a low specificity but a high sensitivity. The model by Scott et al. was found to be the most accurate in assessing SGA fetuses in our population. CONCLUSION: Estimation of fetal weight in SGA fetuses is less accurate than in the general population. Some formulas which are designed for SGA are more accurate than others and their use might increase the sensitivity in identifying SGA fetuses, with only a small decline in specificity.

A search for the most accurate formula for sonographic weight estimation by fetal sex - a retrospective cohort study.

OBJECTIVE: The aim of this study was to assess the effect of fetal sex on the accuracy of multiple formulas for sonographic estimation fetal weight (SEFW). METHODS: The cohort included all singleton live births recorded at a single medical center from January 2004 to September 2011. The accuracy of SEFW was compared between male and female fetuses using 6575 SEFW performed within 3 days prior to delivery. Fetal weight was estimated using 27 models. RESULTS: The accuracy of different formulas in predicting birth weight of male and female fetuses was found to be significantly different in almost every accuracy index that was compared (P < 0.05). The model by Sabbagha et al. was found to be the most accurate in assessing female fetuses. The most accurate model for male fetuses was a sex-specific formula by Melamed et al. We also found that a combination of the most accurate formula for each sex to one combined sex-specific model increased SEFW accuracy significantly. CONCLUSION: The accuracy of SEFW is significantly related to fetal sex. The combination of the formulas by Melamed et al. and Sabbagha et al. for male and female fetuses accordingly allowed more accurate SEFW in our research population.

Torsion of normal adnexa in postmenarcheal women: can ultrasound indicate an ischemic process?

OBJECTIVE: Torsion of normal adnexa is a rare event involving steadily increasing congestion and ischemia of the ovary. We investigated whether this process can be characterized by sonographic features. METHODS: Twelve menstrually cycling women with 14 separate episodes of laparoscopic-proven torsion of normal adnexa were identified retrospectively, and the results of their preoperative gray-scale ultrasound examinations and Doppler flow evaluations were analyzed. The cases were classified into 'short-term' (< 24 h; range, 3-24 h) and 'prolonged' (> 24 h; range, 1-10 days) duration of torsion according to the reported period of abdominal pain before admission. Absence of any additional adnexal pathology was confirmed by both intraoperative inspection and postoperative follow-up ultrasound examinations. RESULTS: The median age of the cohort was 24.0 (interquartile range (IQR), 20.5-28.7) years, and parity ranged from 0 to 3. All affected ovaries were significantly enlarged compared with non-affected ones (median cross-sectional area, 18.1 (IQR, 12.4-26.4) cm(2) vs. 4.3 (IQR, 2.9-6.2) cm(2), P < 0.01). We could distinguish two distinct sonographic patterns of torted ovaries: there were numerous small peripheral follicles in the ovarian parenchyma in nine cases, and there was a solid-appearing mass with hypo- and hyperechogenic foci in five cases. Comparison of the ultrasound images of patients with short-term vs. long-term abdominal pain revealed that the solid-appearing ovary was more common in the latter group (0/6 vs. 5/8, P = 0.03), while there was no significant difference between groups in the presence of free pelvic fluid or median ovarian cross-sectional area. Intraovarian blood flow was diminished or absent in five of the eight patients in whom color Doppler imaging was performed. CONCLUSIONS: Ultrasound images of twisted normal adnexa may vary according to the duration of the condition, reflecting the pathological series of events of increased ovarian congestion and necrosis. Recognition of the different sonographic features of twisted normal adnexa may assist in the correct diagnosis of these patients.