Lung and heart volumes by three-dimensional ultrasound in normal fetuses at 12-32 weeks' gestation.

OBJECTIVE: To establish reference intervals for the fetal right, left and total lung volumes and heart volume between 12 and 32 weeks of gestation. METHODS: Fetal lung and heart volumes were measured using three-dimensional (3D) ultrasound in 650 normal singleton pregnancies at 12-32 weeks. The VOCAL (Virtual Organ Computer-aided AnaLysis) technique was used to obtain a sequence of six sections of each lung and the heart around a fixed axis, each after a 30 degrees rotation from the previous one. The rotation axis for the lungs extended from the apex to the upper limit of the diaphragm dome, and the rotation axis for the heart extended from its apex to its connection to the great vessels. The contour of each of these organs was drawn manually in the six different rotation planes to obtain the 3D volume measurement. In 60 cases the fetal lungs and heart volumes were measured by the same sonographer twice and also by a second sonographer once in order to compare the measurements and calculate intra- and interobserver agreement. RESULTS: The total lung volume and heart volume increased with gestation, from respective mean values of 1.6 and 0.6 mL at 12 weeks to 10.9 and 4.3 mL at 20 weeks and 49.3 and 26.6 mL at 32 weeks. The right to left lung volume ratio did not change significantly with gestation (median, 0.7), whereas the heart to total lung volume ratio increased with gestation from about 0.3 at 12 weeks to 0.5 at 32 weeks. In the Bland-Altman plot, the difference between paired measurements by two sonographers was, in 95% of the cases, less than 0.05, 0.5 and 1.9 mL for each lung at 12-13, 19-22 and 29-32 weeks, respectively, and the corresponding values for the heart volumes were 0.04, 0.4 and 2.3 mL. CONCLUSIONS: In normal fetuses the lung and heart volumes increase between 12 and 32 weeks of gestation. The extent to which in pathological pregnancies possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined.     

Congenital bacterial sepsis in very preterm infants.

The results of body fluid and surface cultures from 148 preterm infants less than 33 weeks gestational age obtained routinely on admission to a neonatal intensive care unit were reviewed. The aim was to determine the occurrence of congenital bacterial sepsis in this population and to examine whether surface cultures yielded information helpful in management. Gastric aspirate and umbilical, nasal and ear swabs were cultured and the results were compared to those of blood cultures. Nine infants (5.4%) had congenital bacterial sepsis diagnosed by positive blood cultures. Only the results of microscopy of gastric aspirate were available within hours of birth and before the results of blood culture. Microscopy of gastric aspirate, demonstrating pus cells, alone had a sensitivity of 0.86 in predicting congenital sepsis but a specificity of 0.49; the specificity, however, rose to 0.80 if both organisms and pus cells were observed on microscopy. Thus, only this combination was a useful pre-indicator of congenital sepsis. In infants who did not develop septicaemia, treatment was modified only if Streptococcus agalactiae was cultured from surface sites; in all such cases, the organism was grown from the ear swab. Our results demonstrate that congenital bacterial sepsis is common amongst very preterm infants admitted for neonatal intensive care but routine screening of surface cultures should be restricted to an ear swab only.     

Second-trimester sex hormone-binding globulin and subsequent development of pre-eclampsia.

OBJECTIVE: To investigate whether maternal plasma sex hormone-binding globulin (SHBG) concentrations are reduced in women who subsequently develop pre-eclampsia. METHODS: This was a cross-sectional study, carried out at antenatal clinics in seven hospitals in and around London. Healthy women underwent uterine artery Doppler velocimetry as a screening method for pre-eclampsia at 22-24 weeks of gestation. The first group (408 women) had normal uterine artery Doppler waveforms (mean uterine artery pulsatility index (PI) below 1.6). The second group (274 women) had increased impedance to flow in the uterine arteries (mean PI above the 95th centile, 1.6). Maternal plasma SHBG concentrations were measured retrospectively using a competitive chemiluminescent immunoassay. Pre-eclampsia was as defined by the International Society for the Study of Hypertension in Pregnancy. RESULTS: Plasma SHBG concentrations in the 80 (11.7%) women who subsequently developed pre-eclampsia were significantly lower than in the 585 (85.8%) women with normal pregnancy outcomes (median 336, range 142-674 nmol/l vs. median 336, range 142-674 nmol/l, p = 0.001). There was a strong correlation between SHBG concentrations and body mass index (r =-0.232246, p < 0.0001). There were no significant differences in maternal plasma SHBG concentrations in women with abnormal uterine artery Doppler (n = 274) compared with controls (n = 408) (median 324, range 101-635 nmol/l vs. median 336, range 142-674 nmol/l, p = 0.09). CONCLUSION: Maternal plasma SHBG concentrations are reduced in women who subsequently develop pre-eclampsia.     

Predicting the severity of fetal anemia using time-domain measurement of volume flow in the fetal aorta.

OBJECTIVES: To assess the value of fetal aortic time-domain measurement of volume flow (using color velocity imaging quantification (CVI-Q)) in predicting the severity of fetal anemia. METHODS: This was a prospective observational study, in which 24 pregnant women with suspected fetal anemia due to rising anti-red blood cell antibody titers underwent cordocentesis. The fetal aortic time-domain volume flow was measured before fetal blood sampling for fetal hemoglobin investigation. We examined the correlation between increased fetal aortic time-domain volume flow (>2 SD for gestational age) and fetal anemia (hemoglobin level <2 SD for gestational age). RESULTS: Seventeen fetuses had anemia, and seven had normal hemoglobin. There was a strong correlation between the increase in fetal aortic time-domain volume flow and the drop in hemoglobin value (r = 0.81; P < 0.01). The sensitivity of this technique to predict fetal anemia was 81.3% and the specificity was 71.4%. The mean increase over time in aortic CVI-Q in anemic fetuses was 323.2 mL/min (95% CI, 200.1 to 446.4) compared with 86.9 mL/min (95% CI, -17.7 to 191.5) in the non-anemic group (P = 0.004). CONCLUSION: Fetal aortic time-domain measurement of volume flow is significantly increased in cases of fetal anemia due to red-cell alloimmunization. These findings can be used to improve the sensitivity, specificity and positive predictive value of the non-invasive techniques used to predict fetal anemia, and may help in the selection of pregnancies that require cordocentesis and transfusion.     

Evaluation of the effects of elastic compression in patients with postphlebitic limbs by laser-Doppler flowmetry

Laser-Doppler flowmetry has been used to study the skin microcirculation in 20 normal limbs and 80 limbs of patients with venous hypertension and leg ulceration due to deep venous reflux. It was found that limbs with venous hypertension had a high skin resting blood flow (BRF) and an impaired veno-arteriolar reflex (VR). There was a marked improvement in both BRF and VR after elastic compression for three weeks and an association between this improvement and the rate of healing of the leg ulcers. The results indicate that elastic compression may affect the microcirculation even though it does not alter the venous pressure measurements when the elastic stockings are removed.     

Femorodistal vein bypass graft stenoses

Eighty femorodistal in situ vein bypass grafts have been evaluated at 3-monthly intervals clinically, with ankle:brachial pressure indices (ABI), by intravenous digital subtraction angiography (IV DSA) and by Duplex scanning. Five grafts (6 per cent) failed in the perioperative period. Nineteen (25 per cent) of the remaining 75 grafts subsequently developed stenoses on IV DSA during the first 12 months. All angiographic stenoses were detected by Duplex scanning using velocity ratio criteria before the development of symptoms or a measurable decline in ABI, i.e. while non-haemodynamically significant. This technique involves scanning the entire length of the graft but allows even minor stenoses to be detected and progression of stenoses can be determined. At a mean follow-up of 12 months (3-18 months), four (7 per cent) of the fifty-six grafts without stenoses occluded. Eight (42 per cent) of the nineteen stenosed grafts either occluded or developed symptoms. None of the occluded grafts in this series could be salvaged. Non-haemodynamically significant vein stenoses can be detected non-invasively, occur frequently and are associated with graft failure.     

Sonographic measurement of cervical length and fetal fibronectin testing in threatened preterm labor.

OBJECTIVE: In women presenting with threatened preterm labor, both fetal fibronectin and sonographic measurement of cervical length have been shown to distinguish between true and false labor. The aim of this study was to determine whether the combination of both tests provides a better prediction than the individual tests alone. METHODS: We examined 195 women with singleton pregnancies presenting at 24-36 (median 31) weeks of gestation with regular and painful uterine contractions, intact membranes and cervical dilatation of less than 3 cm. On admission to the hospital fetal fibronectin positivity in cervicovaginal secretions was determined and transvaginal sonographic measurement of cervical length was carried out. The results were not made available to the attending obstetrician. The primary outcome measure was delivery within 7 days of presentation. RESULTS: Delivery within 7 days occurred in 51.4% (18 of 35) of those with cervical length below 15 mm and 0.6% (1 of 160) of those with cervical length of 15 mm or more, in 21.2% (18 of 85) of the fibronectin positive group and in 0.9% (1 of 110) of the fibronectin negative group. There was a significant association between cervical length and the incidence of fibronectin positivity (r = -0.921, P = 0.003). Logistic regression analysis demonstrated that the only significant contributor to the prediction of delivery within 7 days was cervical length, with no significant contribution from fibronectin positivity, ethnic origin, maternal age, gestational age, body mass index, parity, previous history of preterm delivery, cigarette smoking, or use of tocolytics. CONCLUSIONS: In women with threatened preterm labor assessment of fetal fibronectin in cervicovaginal secretions does not improve the prediction of delivery within 7 days provided by the sonographic measurement of cervical length.     

The Physical Inactivity Matrix: Lessons from the classification of physical inactivity interventions

Physical inactivity (PI), a leading modifiable cause of disease and injury, is endemic in industrialised nations. Although considerable research has been undertaken in this field, we lack a system to synthesise the research literature to inform policy and identify research needs. The aims of this study were to (1) develop a system to classify physical inactivity intervention studies, (2) examine the distribution of PI interventions published in the peer-reviewed health literature using the system, and (3) consider implications for future research. We developed the Physical Inactivity Matrix (PIM), with 12 intervention points, created by the intersection of two dimensions: the intervention target (individual, physical environment and social/cultural environment) and the activity focus (transport, work/school, leisure and consumer). A formal search of the health research literature identified 529 eligible studies and each was classified into one of the 12 cells of the PIM. Most studies were categorised as: individual-leisure (68%), individual-work/school (12%) or social/cultural environment-leisure (13%). Only 4% targeted the physical environment. The findings of this initial application of the PIM support the call for greater investment in policies, interventions and research that focus on the relationship between the environment and PI, and transportation in particular. There would be merit in establishing the inter-rater reliability of the PIM and applying it to a wider variety of studies, including those published in the transportation and urban planning literatures. The PIM could be a useful tool for monitoring trends in research directions and funding levels over time and across countries.     

Midpregnancy plasma zinc in normal and growth retarded fetuses--a preliminary study.

OBJECTIVE: To determine plasma zinc concentrations in normally and abnormally growing fetuses. DESIGN: Prospective observational study. SETTING: Fetal Medicine Unit, Queen Charlotte's Maternity Hospital. SUBJECTS: 53 pregnant women attending for fetal blood sampling at between 18 and 40 weeks gestation. 27 fetuses were normal (central group), 11 fetuses were growth retarded and 15 were malformed. MAIN OUTCOME MEASURES: Plasma zinc concentrations in maternal and fetal blood at time of fetal blood sampling. RESULTS: In normally growing fetuses, between 18 and 40 weeks gestation, there was no fall in maternal plasma zinc concentration; the fetal level fell by 36%. In 10 fetuses with symmetrical growth retardation, plasma zinc concentration tended to be low, but was not significantly different from that in the normal control fetuses. CONCLUSION: The results suggest that (i) placental transfer of zinc is an uphill secretory process and that it is a rate-limiting step in the accumulation of zinc by the fetus and (ii) in fetuses with symmetrical intrauterine growth retardation, a low plasma zinc is probably a parallel phenomenon and not necessarily an aetiological factor.