Selection of Standards for Sonographic Fetal Femur Length by Use of z-scores.

OBJECTIVES: This study aimed to evaluate which of four established norms should be used for sonographic assessment of fetal femur length (FL). STUDY DESIGN: Cross-sectional study using pooled data from four maternal-fetal medicine practices. Inclusion criteria were singleton fetus, gestational age (GA) 220/7 to 396/7 weeks, biometry measured, and fetal cardiac activity present. Four norms of FL were studied: Hadlock et al, the INTERGROWTH-21st Project (IG-21st), the World Health Organization Fetal Growth Curves (WHO), and the National Institutes of Child Health and Human Development Fetal Growth Studies, unified standard (NICHD-U). The fit of our FL measurements to each norm was assessed by these criteria: mean z-score close to 0, standard deviation (SD) of z close to 1, Kolmogorov-Smirnov D-statistic close to zero, Youden J-statistic close to 1, approximately 5% of exams <5th percentile, and approximately 5% of exams >95th percentile. RESULTS: In 26,177 ultrasound exams, our FL measurements had the best fit to the WHO standard (mean z-score 0.15, SD of z 1.02, D-statistic <0.01, J-statistic 0.95, 3.4% of exams <5th percentile, 7.0% of exams >95th percentile). The mean of the IG-21st standard was smaller than the other norms and smaller than our measurements, resulting in underdiagnosis of short FL. The mean of the Hadlock reference was larger than the other norms and larger than our measurements, resulting in overdiagnosis of short FL. The SD of the NICHD-U standard was larger than the other norms and larger than our observations, resulting in underdiagnosis of both short and long FL. Restricting the analysis to a subgroup of 7,144 low-risk patients without risk factors for large- or small-for- GA produced similar results. CONCLUSION: Of the norms studied, the WHO standard is likely best for diagnosis of abnormal FL. KEY POINTS: · There are >30 norms for fetal FL.. · It is unknown which norm should be used.. · Our data fit the World Health Organization standard better than the other norms..

Selection of Standards for Sonographic Fetal Head Circumference by Use of z-Scores.

OBJECTIVE: This study aimed to evaluate which of five established norms should be used for sonographic assessment of fetal head circumference (HC). STUDY DESIGN: Cross-sectional study using pooled data from four maternal-fetal medicine practices. Inclusion criteria were singleton fetus, gestational age 220/7 to 396/7 weeks, biometry measured, and fetal cardiac activity present. Five norms of HC were studied: Jeanty et al, Hadlock et al, the INTERGROWTH-21st Project (IG-21st), the World Health Organization Fetal Growth Curves (WHO), and the National Institutes of Child Health and Human Development Fetal Growth Studies unified standard (NICHD-U). The fit of our HC measurements to each norm was assessed by these criteria: mean z-score close to 0, standard deviation (SD) of z close to 1, low Kolmogorov-Smirnov D-statistic, high Youden J-statistic, close to 10% of exams >90th percentile, close to 10% of exams <10th percentile, and close to 2.28% of exams >2 SD below the mean. RESULTS: In 23,565 ultrasound exams, our HC measurements had the best fit to the WHO standard (mean z-score 0.10, SD of z = 1.01, D-statistic <0.01, J-statistic 0.83-0.94). The SD of the Jeanty reference was much larger than all the other norms and our measurements, resulting in underdiagnosis of abnormal HC. The means of the IG-21st and NICHD-U standards were smaller than the other norms and our measurements, resulting in underdiagnosis of small HC. The means of the Hadlock reference were larger than all the other norms and our measurements, resulting in overdiagnosis of small HC. Restricting the analysis to a low-risk subgroup of 4,423 exams without risk factors for large- or small-for-gestational age produced similar results. CONCLUSION: The WHO standard is likely best for diagnosis of abnormal HC. The Jeanty (Chervenak) reference suggested by the Society for Maternal-Fetal Medicine had poor sensitivity for microcephaly screening. KEY POINTS: · There are >30 norms for fetal HC.. · It is unknown which norm should be used.. · The WHO standard fits our data best.. · The Chervenak reference is not sensitive for microcephaly..

Cesarean Delivery and Risk for Subsequent Ectopic Pregnancy.

OBJECTIVE: This study aims to examine the risk for subsequent ectopic pregnancy in women with prior cesarean delivery. STUDY DESIGN: Women with a history of at least one cesarean delivery in the state of Utah during 1996 to 2011 were identified and compared with women with vaginal delivery only. The primary outcome was subsequent ectopic pregnancy. Data were analyzed by multivariate logistic regression and stratified by first, second, or third live births. Model covariates included maternal age, ethnicity, marital status, education level, gravidity, and prior ectopic pregnancy. RESULTS: Overall, 260,249 women with at least one live birth were identified. After exclusions, 255,082, 154,930, and 70,228 women had at least one, two, and three prior live births that lead to 531, 199, and 62 subsequent ectopic pregnancies, respectively. Women who had one prior cesarean delivery were not at increased risk for subsequent ectopic pregnancy in relation to women with no prior cesarean delivery. However, women with two of two, two of three, or three of three prior cesareans had increased risk for subsequent ectopic pregnancy with odds ratios (95% confidence interval) of 1.54 (1.06-2.22), 3.50 (1.49-8.24), and 1.99 (1.00-3.98), respectively. CONCLUSION: History of two or three cesarean deliveries is associated with increased risk for subsequent ectopic pregnancy.

Prevalence of antiphospholipid antibodies and risk of subsequent adverse obstetric outcomes in women with prior pregnancy loss.

The reported prevalence of antiphospholipid antibodies in women with a chief complaint of pregnancy loss varies, as does the risk of adverse outcomes in subsequent pregnancies. Our objectives were to assess the prevalence of antiphospholipid antibodies meeting revised Sapporo thresholds among women presenting with a chief complaint of pregnancy loss and risks in subsequent pregnancies for these women. We examined a retrospective cohort of patients presenting with a chief complaint of pregnancy loss between 2003 and 2012. Antiphospholipid antibodies were assessed at the providers' discretion, and patients were considered positive if they met the revised Sapporo criteria. Patient data were obtained by review of the medical records. 338/390 women (86.7%) presented with a chief complaint of pregnancy loss and had testing for antiphospholipid antibodies. 19/338 women (5.6%) persistently tested positive for at least one antiphospholipid antibody. Seven women who tested positive had isolated recurrent early pregnancy loss ≤10 weeks, and 12 women who tested positive had venous thromboembolism (VTE), systemic lupus erythematosus (SLE), delivery <34 weeks for pre-eclampsia, and/or placental insufficiency, or fetal demise >10 weeks. Subsequent pregnancy outcomes were available for 13 patients. Compared with women with recurrent early pregnancy loss alone, subsequent obstetric morbidity was significantly more likely in those patients with a history of SLE and/or VTE (p=0.048). We conclude that the prevalence of positive antiphospholipid antibodies in women with a chief complaint of pregnancy loss and without autoimmune disease or prior thrombosis is low and that among these women, subsequent pregnancy outcomes are largely favorable.

Interobserver variability of sonography for prediction of placenta accreta.

OBJECTIVES: The sensitivity of sonography to predict accreta has been reported as higher than 90%. However, most studies are from single expert investigators. Our objective was to analyze interobserver variability of sonography for prediction of placenta accreta. METHODS: Patients with previa with and without accreta were ascertained, and images with placental views were collected, deidentified, and placed in random sequence. Three radiologists and 3 maternal-fetal medicine specialists interpreted each study for the presence of accreta and specific findings reported to be associated with its diagnosis. Investigator-specific sensitivity, specificity, and accuracy were calculated. κ statistics were used to assess variability between individuals and types of investigators. RESULTS: A total of 229 sonographic studies from 55 patients with accreta and 56 control patients were examined. Accuracy ranged from 55.9% to 76.4%. Of imaging studies yielding diagnoses, sensitivity ranged from 53.4% to 74.4%, and specificity ranged from 70.8% to 94.8%. Overall interobserver agreement was moderate (mean κ ± SD = 0.47 ± 0.12). κ values between pairs of investigators ranged from 0.32 (fair agreement) to 0.73 (substantial agreement). Average individual agreement ranged from fair (κ = 0.35) to moderate (κ = 0.53). CONCLUSIONS: Blinded from clinical data, sonography has significant interobserver variability for the diagnosis of placenta accreta.

Sonographic appearance of the placenta.

The placenta forms the interface between the mother and the fetus and is essential to fetal growth and development. In addition to the exchange of gases and nutrients, it serves immunologic and endocrine functions that protect the fetus and support physiological changes in pregnancy. Although often largely ignored during routine obstetric ultrasound and discarded after delivery, careful sonographic evaluation of the placenta can identify abnormalities that have profound implications for pregnancy outcomes and management. After describing the normal sonographic appearance of the placenta and normal anatomical variations, we review pathologic placental conditions, emphasize ultrasound findings, and highlight implications for pregnancy management and outcomes.

Accuracy of ultrasound for the prediction of placenta accreta.

OBJECTIVE: Ultrasound has been reported to be greater than 90% sensitive for the diagnosis of accreta. Prior studies may be subject to bias because of single expert observers, suspicion for accreta, and knowledge of risk factors. We aimed to assess the accuracy of ultrasound for the prediction of accreta. STUDY DESIGN: Patients with accreta at a single academic center were matched to patients with placenta previa, but no accreta, by year of delivery. Ultrasound studies with views of the placenta were collected, deidentified, blinded to clinical history, and placed in random sequence. Six investigators prospectively interpreted each study for the presence of accreta and findings reported to be associated with its diagnosis. Sensitivity, specificity, positive predictive, negative predictive value, and accuracy were calculated. Characteristics of accurate findings were compared using univariate and multivariate analyses. RESULTS: Six investigators examined 229 ultrasound studies from 55 patients with accreta and 56 controls for 1374 independent observations. 1205/1374 (87.7% overall, 90% controls, 84.9% cases) studies were given a diagnosis. There were 371 (27.0%) true positives; 81 (5.9%) false positives; 533 (38.8%) true negatives, 220 (16.0%) false negatives, and 169 (12.3%) with uncertain diagnosis. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 53.5%, 88.0%, 82.1%, 64.8%, and 64.8%, respectively. In multivariate analysis, true positives were more likely to have placental lacunae (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.4-1.6), loss of retroplacental clear space (OR, 2.4; 95% CI, 1.1-4.9), or abnormalities on color Doppler (OR, 2.1; 95% CI, 1.8-2.4). CONCLUSION: Ultrasound for the prediction of placenta accreta may not be as sensitive as previously described.

Risk factors for placenta accreta: a large prospective cohort.

OBJECTIVE: Placenta previa and prior cesarean delivery are known risk factors for placenta accreta. However, other risk factors have not been identified. Our objective was to examine risk factors for accreta using data collected prospectively in a large multicenter cohort. STUDY DESIGN: Secondary analysis of women with accreta compared to those without accreta in a large multicenter cesarean delivery cohort. Potential accreta risk factors were examined by univariate and multivariate analyses. RESULTS: In this study, 196 of 73,257 (0.27%) cesarean deliveries were complicated by accreta. As expected, women with increasing numbers of prior cesareans were more likely to have an accreta (p < 0.001), as were women with previa (adjusted odds ratio [OR], 34.9; 95% confidence interval [CI], 22.4-54.3). We also considered only patients with previa and examined the following variables: maternal demographics, prior cesareans, interval between deliveries, parity, body mass index, tobacco use, and coexisting hypertension or diabetes. In this model, patients with previa and two or three prior cesarean deliveries had an adjusted OR for accreta of 4.9 (95% CI, 1.7-14.3) or 7.7 (95% CI, 2.4-24.9), respectively. However, no other variables were significantly associated with accreta. CONCLUSION: Patients with previa have increased risk for accreta that increases with the number of prior cesarean deliveries. However, no other maternal characteristics were associated with accreta.

Risk factors for unscheduled delivery in patients with placenta accreta.

OBJECTIVE: Patients with suspected placenta accreta have improved outcomes with scheduled delivery. Our objective was to identify risk factors for unscheduled delivery in patients with suspected placenta accreta. STUDY DESIGN: This was a cohort study of women with antenatally suspected placenta accreta. Women who delivered prior to a planned delivery date were compared with women who had a scheduled delivery. Data were analyzed using a Student t test, χ(2), logistic regression, and survival analyses. Variables included in the analyses were episodes of antenatal vaginal bleeding, preterm premature rupture of membranes (PPROM), uterine contractions, prior cesarean deliveries, interpregnancy interval, parity, and patient demographic factors. A value of P < .05 was considered significant. RESULTS: Seventy-seven women with antenatal suspicion for placenta accreta were identified. Thirty-eight (49.4%) had an unscheduled delivery. Demographics were similar between groups. Unscheduled patients delivered earlier (mean 32.3 vs 35.7 weeks, P < .001) and were significantly more likely to have had vaginal bleeding (86.8% vs 35.9%, P < .001) and uterine activity (47.4% vs 2.6%, P < .001). Each episode of antenatal vaginal bleeding was associated with an increased risk of unscheduled delivery (adjusted odds ratio, 3.8; 95% confidence interval, 1.8-7.8). Risk of earlier delivery was even greater when associated with PPROM (P < .001). CONCLUSION: Among women with suspected placenta accreta, those with antenatal vaginal bleeding were more likely to require unscheduled delivery. This risk increases further in the setting of PPROM and/or uterine contractions. These clinical factors should be considered when determining the optimal delivery gestational age for women with placental accreta.

Primaquine-induced hemolytic anemia: role of splenic macrophages in the fate of 5-hydroxyprimaquine-treated rat erythrocytes.

Primaquine-induced hemolytic anemia is known to result from premature sequestration of damaged (but intact) erythrocytes by the spleen. We have shown previously that a phenolic metabolite, 5-hydroxyprimaquine (5-HPQ), is a direct-acting hemolytic agent in rats, suggesting that 5-HPQ is a mediator of the hemolytic response to primaquine. To investigate the fate of erythrocytes in vivo after in vitro exposure to 5-HPQ, rat (51)Cr-labeled erythrocytes were incubated with hemolytic concentrations of 5-HPQ and then readministered intravenously to rats. The time course of loss of radioactivity from blood and uptake into the spleen and liver was measured. In rats given 5-HPQ-treated erythrocytes, an increased rate of removal of radioactivity from the circulation was observed as compared with the vehicle control. The loss of blood radioactivity was accompanied by a corresponding increase in radioactivity appearing in the spleen but not in the liver. When rats were pretreated with clodronate-loaded liposomes to deplete splenic macrophages, there was a decreased rate of removal of radioactivity from the circulation and a markedly diminished uptake into the spleen. A role for phagocytic removal of 5-HPQ-treated red cells was confirmed in vitro using the J774A.1 macrophage cell line. Furthermore, depletion of red cell GSH with diethyl maleate significantly enhanced in vitro phagocytosis of 5-HPQ-treated red cells. The data indicate that splenic macrophages are responsible for removing 5-HPQ-treated red cells and support the postulate that this metabolite is a contributor to the hemolytic anemia induced after administration of the parent compound.

Lipids versus proteins as major targets of pro-oxidant, direct-acting hemolytic agents.

Lipid peroxidation and the accompanying translocation of phosphatidylserine (PS) from the inner to the outer leaflet of the lipid bilayer have recently been identified as key components of a signaling pathway for phagocytosis of apoptotic cells by macrophages. Drug-induced hemolytic anemia has long been known to be caused by an accelerated uptake of damaged (but intact) erythrocytes by macrophages in the spleen, and this process has been associated with enhanced formation of reactive oxygen species (ROS). However, the role of lipid peroxidation in hemolytic injury has remained unclear, and the effect of hemolytic agents on the distribution of PS in the erythrocyte membrane is unknown. The present studies were undertaken to determine whether lipid peroxidation and PS translocation could be detected in rat and human erythrocytes by three types of direct-acting hemolytic agents--dapsone hydroxylamine, divicine hydroquinone, and phenylhydrazine. 2',7'-Dichlorodihydrofluorescein diacetate was employed as a probe for intracellular ROS formation; lipid peroxidation was assessed by GC/MS analysis of F2-isoprostanes; and PS externalization was measured by annexin V labeling and the prothrombinase assay. The data confirmed that all three hemolytic agents generate ROS within erythrocytes under hemolytic conditions; however, no evidence for lipid peroxidation or PS translocation was detected. Instead, ROS production by these hemolytic agents was associated with extensive binding of oxidized and denatured hemoglobin to the membrane cytoskeleton. The data suggest that the transmembrane signal for macrophage recognition of hemolytic injury may be derived from oxidative alterations to erythrocyte proteins rather than to membrane lipids.

Primaquine-induced hemolytic anemia: role of membrane lipid peroxidation and cytoskeletal protein alterations in the hemotoxicity of 5-hydroxyprimaquine.

Primaquine-induced hemolytic anemia is a toxic side effect that is due to premature splenic sequestration of intact erythrocytes. Previous studies have suggested that a phenolic metabolite, 5-hydroxyprimaquine (5-HPQ), mediates primaquine hemotoxicity by generating reactive oxygen species (ROS) within erythrocytes that overwhelm antioxidant defenses. However, the nature of the oxidative stress is not understood, and the molecular targets, whether protein and/or lipid, are unknown. To investigate the mechanism underlying the hemolytic activity of 5-HPQ, we have examined the effect of hemolytic concentrations of 5-HPQ on ROS formation within rat erythrocytes using the cellular ROS probe, 2',7'-dichlorodihydrofluoresein diacetate. In addition, we examined the effect of 5-HPQ on membrane lipids and cytoskeletal proteins. The data indicate that 5-HPQ causes a prolonged, concentration-dependent generation of ROS within erythrocytes. Interestingly, 5-HPQ-generated ROS was not associated with the onset of lipid peroxidation or an alteration in phosphatidylserine asymmetry. Instead, 5-HPQ induced oxidative injury to the erythrocyte cytoskeleton, as evidenced by changes in the normal electrophoretic pattern of membrane ghost proteins. Immunoblotting with an anti-hemoglobin antibody revealed that these changes were due primarily to the formation of disulfide-linked hemoglobin-skeletal protein adducts. The data suggest that cytoskeletal protein damage, rather than membrane lipid peroxidation or loss of phosphatidylserine asymmetry, underlies the process of removal of erythrocytes exposed to 5-HPQ.

Primaquine-induced hemolytic anemia: susceptibility of normal versus glutathione-depleted rat erythrocytes to 5-hydroxyprimaquine.

Primaquine is an important antimalarial agent because of its activity against exoerythrocytic forms of Plasmodium spp. Methemoglobinemia and hemolytic anemia, however, are dose-limiting side effects of primaquine therapy. These hemotoxic effects are believed to be mediated by metabolites, although the identity of the toxic specie(s) and the mechanism underlying hemotoxicity have remained unclear. Previous studies showed that an N-hydroxylated metabolite of primaquine, 6-methoxy-8-hydroxylaminoquinoline, was capable of mediating primaquine-induced hemotoxicity. The present studies were undertaken to investigate the hemolytic potential of 5-hydroxyprimaquine (5-HPQ), a phenolic metabolite that has been detected in experimental animals. 5-HPQ was synthesized, isolated by flash chromatography, and characterized by NMR spectroscopy and mass spectrometry. In vitro exposure of (51)Cr-labeled erythrocytes to 5-HPQ induced a concentration-dependent decrease in erythrocyte survival (TC(50) of ca. 40 microM) when the exposed cells were returned to the circulation of isologous rats. 5-HPQ also induced methemoglobin formation and depletion of glutathione (GSH) when incubated with suspensions of rat erythrocytes. Furthermore, when red cell GSH was depleted (>95%) by titration with diethyl maleate to mimic GSH instability in human glucose-6-phosphate dehydrogenase deficiency, a 5-fold enhancement of hemolytic activity was observed. These data indicate that 5-HPQ also has the requisite properties to contribute to the hemotoxicity of primaquine. The relative contribution of N-hydroxy versus phenolic metabolites to the overall hemotoxicity of primaquine remains to be assessed.