Accuracy of sonographic fetal weight estimation: influence of the scan-to-delivery interval in combination with the applied weight estimation formula.

INTRODUCTION: To evaluate the influence of the time interval between examination and delivery on the accuracy of sonographic fetal weight estimation (WE). MATERIALS AND METHODS: 8723 singleton pregnancies were included in this retrospective cohort study. Fetuses were divided into eight groups with regard to the time interval between estimation and delivery (group 1: 0 days; group 2: 1-3 days; group 3: 4-7 days; group 4: 8-14 days; group 5: 15-21 days; group 6: 22-28 days; group 7: 29-35 days; group 8: 36-42 days). The accuracy of WE was compared between the different time interval groups and five commonly used formulas using means of percentage errors (MPE), medians of absolute percentage errors, and proportions of estimates within 10 % of actual birth weight. RESULTS: In group one, the Hadlock I and Warsof formula showed a systematic underestimation of fetal weight (negative MPEs). No systematic error was found with the Hadlock II formula and the equations of Merz and Shepard showed a systematic overestimation (positive MPEs). MPE values of the Hadlock I, II and Warsof formulas were closest to zero in WEs of group two. From group three to six, MPE values decreased continuously. With the Merz and Shepard equations MPEs were closest to zero in group four. DISCUSSION: The best accuracy of sonographic WE with most of the commonly used equations is achieved within a scan-to-delivery interval of 1 week.

Sonographic weight estimation in fetal macrosomia: influence of the time interval between estimation and delivery.

PURPOSE: To evaluate the influence of the time interval between examination and delivery on the accuracy of sonographic weight estimation (WE) in fetal macrosomia. MATERIALS AND METHODS: 896 singleton pregnancies (birth weight > 4,000 g) with a total of 1,281 sonographic weight estimations were included in this retrospective cohort study. Fetuses were divided into six groups with regard to the time interval between estimation and delivery: group 1: scan-to-delivery interval: 0 days; group 2: scan-to-delivery interval: 1-3 days; group 3: scan-to-delivery interval: 4-7 days; group 4: scan-to-delivery interval: 8-14 days; group 5: scan-to-delivery interval: 15-21 days; group 6: scan-to-delivery interval: 22-42 days. The accuracy of WE was compared between five commonly used formulas using means of percentage errors (MPE), random error, medians of absolute percentage errors (MAPE), and proportions of estimates within 10 % of actual birth weight. RESULTS: Significant differences were found between the time interval groups with regard to MAPE and MPE values (p < 0.001). All formulas showed a systematic underestimation of fetal weight (negative MPEs) (p < 0.05). MPE values were closest to zero in time interval group 1 and 2. From group 3 to 6, a continuous decrease was observed. The lowest MAPE was found with the Merz formula in group 1 and 2. Values increased continuously from group 3 to 6. Differences between time interval group one and three did not reach statistical significance. CONCLUSIONS: WE in fetal macrosomia shows the best results when examinations are performed within 7 days before delivery, using the formula of Merz et al. Accuracy significantly decreases after this time period.

Intrapartum sonographic weight estimation.

PURPOSE: To evaluate the accuracy of intrapartum sonographic weight estimation (WE). MATERIALS AND METHODS: This retrospective, cross-sectional study included 1958 singleton pregnancies. Inclusion criteria were singleton pregnancy with cephalic presentation, vaginal delivery and ultrasound examination with complete biometric parameters performed on the day of delivery during the latent or active phase of labor, and absence of chromosomal or structural anomalies. The accuracy of intrapartum WE was compared to a control group of fetuses delivered by primary cesarean section at our perinatal center and an ultrasound examination with complete biometric parameters performed within 3 days before delivery (n = 392). Otherwise, the same inclusion criteria as in the study group were applied. The accuracy of WE was compared between five commonly applied formulas using means of percentage errors (MPE), medians of absolute percentage errors (MAPE), and proportions of estimates within 10 % of actual birth weight. RESULTS: In the whole study group, all equations showed a systematic underestimation of fetal weight (negative MPEs). Overall, best MAPE and MPE values were found with the Hadlock II formula, using BPD, AC and FL as biometric parameters (Hadlock II, MPE: -1.28; MAPE: 6.52). MPEs differed significantly between WE in the study and control group for all evaluated formulas: in the control group, either no systematic error (Hadlock III, IV and V) or a significant overestimation (Hadlock I, II) was found. Regarding MAPEs, application of the Hadlock III (HC, AC, FL) and V (AC) formula resulted in significant lower values in the control group (Hadlock III, MAPE: 7.48 vs. 5.95, p = 0.0008 and Hadlock V, MAPE: 8.79 vs. 7.52, p = 0.0085). No significant differences were found for the other equations. CONCLUSIONS: A systematic underestimation of fetal weight has to be taken into account in sonographic WE performed intrapartum. Overall, the best results can be achieved with WE formulas using the BPD as the only head measurement.

[Prenatal diagnosis and prognosis of oligo-anhydramnia]. / Pränatale Diagnostik und Prognose der Oligo-Anhydramnie.

From 1986 to 1987, a total of 56 cases with oligoanhydramnia as indicative symptom were examined and treated in the Prenatal Unit of the Gynaecological Department of the University of Erlangen. In cases of difficult fetal imaging, new antenatal diagnostic methods, like artificial instillation of amniotic fluid, transabdominal chorionic villus sampling and blood flow measurement by Doppler sonography were used. With the exception of three cases of primary placental disturbances, an accurate prenatal diagnosis was established in 95%. As expected, development disorders of the fetal urinary tract were in 45% of all cases most frequent. In 39% a malformation could be ruled out. Chromosomal aberrations appeared in 7%. Doppler sonography was helpful in differentiating the cases of fetal growth retardation caused by a disturbed placental circulation, from those cases emanating from congenital fetal anomalies. Compared to polyhydramnia, in which 70% of the cases are idiopathic, oligoanhydramnia as primary symptom is, in our opinion, of greater clinical significance. This is proved by a high rate of both malformations (60%) and mortality (68%). Considering the frequently delayed admission of such patients and, in most cases the poor outcome, increased attention to the symptom of oligoanhydramnia, during sonographic screening examinations, is necessary. Early admission to a prenatal diagnostic unit for clarification by differentiated methods permits the establishment of the presence or absence of a disease picture incompatible with a healthy life status.

Histamine-release in rat gastric mucosa by pentagastrin.

The release of histamine from isolated gastric mucosa of the rat was studied by a superfusion model. Pentagastrin increased the basal efflux of histamine in a dose dependent manner. Secretin failed to influence the release of histamine under similar conditions. The results are compatible with the view that in gastric mucosa pentagastrin releases histamine which then may react with the receptors of the parietal cell thus serving as mediator in the acid secretory process.