Three-dimensional transvaginal sonographic assessment of uterine volume as preoperative predictor of need to morcellate in women undergoing laparoscopic hysterectomy

OBJECTIVE

In light of recent statements from the United States Food and Drug Administration warning against the use of power morcellation of uterine leiomyomas during laparoscopy, we sought to evaluate the use of preoperative two- (2D) and three- (3D) dimensional transvaginal ultrasound (US) assessment of uterine volume to predict the need for morcellation in women undergoing laparoscopic hysterectomy (LH).

METHODS

This was a prospective observational study performed between October 2008 and November 2011 in a tertiary referral laparoscopic unit. All women scheduled to undergo LH were included and underwent detailed preoperative transvaginal US. Uterine volumes were calculated using 2D-US measurements (ellipsoid formula), and using Virtual Organ Computer-aided AnaLysis (VOCAL™) having acquired 3D-US volumes of the uterus. Age, parity, need to morcellate and final uterine dry weight at histology were recorded. The estimated uterine volumes were then incorporated into a previously published logistic regression model to predict the need to morcellate for both nulliparous and parous women. The probability threshold cut-off of 0.14 (95% sensitivity) was evaluated in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LRs). The performance of the models incorporating 2D- and 3D-US calculations were compared with 2D- and 3D-US-generated volumes alone, using receiver-operating characteristics (ROC) curves.

RESULTS

Of 76 women who underwent LH during the study period, 79% (n = 60) had complete background and 3D-US data. Their mean age was 43.7 years, 91.7% were parous and 35% underwent morcellation. The greatest uterine volume that did not require morcellation was 404 mL estimated using 3D-US, which corresponded to a uterine volume of 688.8 mL using 2D-US. The smallest uterine volume that required morcellation was 118.9 mL using 3D-US, which corresponded to a uterine volume of 123.4 mL using 2D-US. The 3D-US uterine volume for parous women with a sensitivity of 95% based on ROC-curve analysis was approximately 120 mL, which equated to a predicted probability of morcellation cut-off of 0.14. For this cut-off, specificity was 55.00%, PPV was 51.35%, NPV was 95.65%, LR+ was 2.11 and LR- was 0.09. Areas under the ROC curves for the morcellation logistic regression model were 0.769 (95% CI, 0.653-0.886) and 0.586 (95% CI, 0.419-0.753) using uterine volumes obtained by 3D-US and by 2D-US, respectively, and they were 0.938 (95% CI, 0.879-0.996) and 0.815 (95% CI, 0.681-0.948) using 3D-US and 2D-US volumes alone.

CONCLUSIONS

The need to morcellate can be predicted preoperatively using 3D-US uterine volumes obtained by transvaginal US with a fair degree of accuracy. Uteri with volumes smaller than 120 mL at 3D-US are very unlikely to require morcellation. The incorporation of 3D-US-estimated uterine volume into the previously published logistic regression model does not seem to confer any significant improvement when compared with 3D-US uterine volume alone to predict the need to morcellate in women undergoing total LH. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Accuracy of ultrasound dating formulae in the late second-trimester in pregnancies conceived with in-vitro fertilization

Purpose: To investigate the accuracy of ultrasound dating formulae in the late second trimester of pregnancy.

Material and Methods: A dataset of 136 singleton pregnancies conceived by artificial reproductive techniques was studied to assess the accuracy of ultrasound dating formulae in the late second trimester, and compared with early second trimester. A total of 21 published ultrasound-dating formulae were tested.

Results: For most formulae, late second trimester scans yielded results that were marginally less accurate than the early second trimester. The best performance was obtained with dating formulae based on femur length, either alone or combined with the biparietal diameter. These formulae had mean absolute errors of 3–3.5 days. Combining two or more parameters did not result in any substantial gain in accuracy.

Conclusions: Pregnancy dating by ultrasound in the late second trimester is sufficiently accurate for routine clinical use. Formulae based on femur length appear to be at least as accurate as head measurements.

The K-P algorithm: a new first-trimester growth model - comparison with other formulae and correlations with recorded embryonic lengths

OBJECTIVE

To generate and validate individually fitted first-trimester growth curves using a new growth model. Secondary aims were to compare this new model with actual recorded embryonic measurements and validate its predictive accuracy.

METHODS

A prospective study of women presenting to the Early Pregnancy Unit in the first trimester. Women with viable singleton pregnancies at the end of the first trimester who had had at least two crown-rump length (CRL) measurements were selected. An individual power function of CRL was derived from serial CRL measurements. Individual curves were fitted using computer software to estimate a dating adjustment factor ('k'), and a growth coefficient ('P') for each case. The predictive accuracy of the growth curves was then tested in a validation subset of the population that had a third CRL measurement. The population average curve from the developed model was also extrapolated to day 27 menstrual age (Carnegie stage 6), day 30 menstrual age (Carnegie stage 7) and day 84 menstrual age, and values were compared to previously reported measurements.

RESULTS

326 viable pregnancies were selected for CRL growth curve development. The mean time interval between CRL measurements was 20.5 days (range 2-44). The mean value for 'P' was 2.058, and for 'k' 24.6. Testing the model on a subset of 81 cases showed that the average error in predicting a third CRL measurement was 1% (SD 9.1%).

CONCLUSIONS

These new, individually fitted growth curves for the first trimester correlate more closely with the recorded embryonic lengths than other standards.

Does chewing coca leaves influence physiology at high altitude?

Andean Indians have used coca leaves (Erythroxylon coca and related species) for centuries to enhance physical performance. The benefits and disadvantages of using coca leaf have been a subject of many political debates. The aim of this study was to investigate the effects of chewing coca leaves on biochemical and physiological parameters. Cutaneous microdialysis catheters were used to estimate systemic biochemical changes. We subjected 10 healthy adult males (local residents) in Cajamarca (Peru, altitude 2700 m) to a standardised exercise routine on a stationary cycle ergometer. The blood pressure, oxygen saturation (digital), pulse, VO2 max and ECG (Holter monitor) were recorded before the exercise. Cutaneous microdialysis catheters were introduced in the forearm. The subjects were given to chew 8 g of coca leaves with a small amount of lime. They were then placed on the cycle ergometer for 20 min. Blood pressure, oxygen saturation, pulse, ECG and VO2 max were recorded. Pyruvate, glucose, lactate, glycerol and glutamate levels were estimated. Oxygen saturation, blood pressure, and pulse rate did not show any significant changes between the two groups. Glucose levels showed hyperglycaemic response. Glycerol, Lactate and Pyruvate increased. Glutamate remained unchanged. Similar changes were not seen in the controls. These results suggest that coca leaves have blocked the glycolytic pathway of glucose oxidation resulting in accumulation of glucose and pyruvate. The energy requirement for exercise is being met with beta-oxidation of fatty acids. The glycerol released was also getting accumulated since its pathway for oxidation was blocked. These experimental findings suggest that chewing coca leaves is beneficial during exercise and that the effects are felt over a prolonged period of sustained physical activity.

Z-velocity in screening for intrauterine growth restriction

OBJECTIVES

Ultrasound scans provide the basis for detection of intrauterine growth restriction (IUGR) but often fail to distinguish IUGR from small-for-gestational age (SGA) fetuses. This study introduces the concept of Z-velocity, calculated as changes in Z-scores over time, as an additional criterion in the diagnosis of IUGR.

METHODS

A computer program simulated 50 000 fetal abdominal circumference (FAC) scans based on published growth formulae. False-positive rates were calculated to determine optimal scan time and scan intervals. Using an independent simulation of 32 500 FAC scans, the two methods were compared using receiver-operating characteristics (ROC) curve analysis.

RESULTS

ROC showed areas under the curve of > 0.74 over the complete range of scan intervals. The positive predictive value of growth arrest as the only diagnostic criterion was, however, too low to recommend it as an exclusive or the first diagnostic criterion.

CONCLUSIONS

Z-velocity can be used to decide whether further investigations for growth abnormality are required in fetuses that fall below the 10(th) percentile. The gain of combined diagnostic approaches should be calculated from large databases that include the neonatal ponderal index as the gold standard.

Ultrasound diagnosis of fetal macrosomia: a comparison of weight prediction models using computer simulation

OBJECTIVE

To assess the frequency of the diagnosis of macrosomia in relation to differing weight estimation formulae in unselected pregnancies.

METHODS

Computer modeling techniques were employed. Computer modeling software generated correlated fetal biometry measurements according to published British standards, from 37 to 41 weeks' gestation. For each set of measurements, estimated fetal weights were obtained by a panel of 18 ultrasound weight formulae. The diagnosis of macrosomia was made if the fetal weight estimate was greater than 4500 g. Cohorts of 5000 pregnancies for each week of gestation were studied.

RESULTS

The frequency of diagnosis of macrosomia increased progressively with advancing gestational age, with large increases between 40 and 41 weeks. The type of weight estimation formula had a profound influence on the frequency of diagnosis of macrosomia. Five of the formulae tested almost never returned a weight estimate greater than 4500 g. Three formulae yielded false positive rates in excess of 15%. The Hadlock group of formulae yielded frequencies of 0.3% to 14.6%.

CONCLUSIONS

Most formulae tend to over-diagnose macrosomia at term. Intervention rates for suspected fetal macrosomia may be influenced by gestational age at the time of scan and the type of fetal weight estimation formula in use.

Third-trimester ultrasound dating algorithms derived from pregnancies conceived with artificial reproductive techniques

OBJECTIVE

To derive an accurate formula for ultrasound estimation of gestational age in late pregnancy.

METHODS

A database of 123 singleton pregnancies conceived by artificial reproductive techniques with third-trimester ultrasound measurements was studied. Biometry variables included the fetal head circumference (HC) and femur length (FL). The dataset was equally divided into a derivation sample and a target sample. To derive the equations of best fit, regression analysis was used, with true menstrual age as the dependent variable and fetal biometry measurements as independent variables. The formulae were tested on the target set and the menstrual age estimates were compared with the actual menstrual age. Clinical performance was estimated in terms of systematic and random errors, absolute errors and their 95% CI values.

RESULTS

The menstrual ages at time of scanning ranged from 26 to 41 weeks, with a mean of 33 weeks. The best performing derived formula was a combination of HC and FL. This had a random error of 7.5 days and prediction errors within a 95% confidence limit of -13 to +17 days. With FL only, the random error was 8.2 days, whereas using the HC only yielded a random error of 9.4 days.

CONCLUSIONS

Ultrasound estimation of gestational age in late pregnancy is better than indicated by older publications. It is more accurately estimated by combining the HC with the FL than by using the FL measurements alone.

Accuracy of ultrasound dating formulae in the late second-trimester in pregnancies conceived with in-vitro fertilization

PURPOSE

To investigate the accuracy of ultrasound dating formulae in the late second trimester of pregnancy.

MATERIAL AND METHODS

A dataset of 136 singleton pregnancies conceived by artificial reproductive techniques was studied to assess the accuracy of ultrasound dating formulae in the late second trimester, and compared with early second trimester. A total of 21 published ultrasound-dating formulae were tested.

RESULTS

For most formulae, late second trimester scans yielded results that were marginally less accurate than the early second trimester. The best performance was obtained with dating formulae based on femur length, either alone or combined with the biparietal diameter. These formulae had mean absolute errors of 3-3.5 days. Combining two or more parameters did not result in any substantial gain in accuracy.

CONCLUSIONS

Pregnancy dating by ultrasound in the late second trimester is sufficiently accurate for routine clinical use. Formulae based on femur length appear to be at least as accurate as head measurements.

Factors influencing fetal growth

Birth weight remains one of the most important measures we have of the health status of a population, and is a strong predictor of both neonatal mortality and morbidity. It reflects maternal nutritional status and fetal growth rates in the antenatal period. Although a large number of physiological and pathological variables can affect the growth rate, for most cases of growth-restricted fetuses a cause cannot be determined. Awareness of the physiological aspects of fetal growth is important in assessing whether the fetus is growing normally. This article is a review of recent findings and key historical material on factors influencing birth weight.

Attitudes of Singapore women toward cesarean and vaginal deliveries

OBJECTIVES

To assess the attitude, knowledge, and expectations of Asian pregnant women toward cesarean and vaginal deliveries.

METHODS

Written questionnaires were given to pregnant women attending the National University Hospital antenatal clinics, and 160 responses were tabulated and analyzed using SPSS software.

RESULTS

The participation rate was 65% and 50% of the respondents were Chinese, 20% Indian, 21% Malay, 2% White, and 9.2% Other. The median age was 31 years, and approximately 43% were primiparas. Only 3.7% of them would prefer an elective cesarean delivery, and although 50% had friends or relatives who requested one, only 3% felt that this influenced their preference. The most common reasons for choosing a cesarean delivery were avoiding labor pains and lowering the risk of fetal distress. When asked which modality they would recommend to their friends, only 2% expressed that they would recommend cesarean delivery; however, 71% stated that women should have the right to request a cesarean delivery. Awareness of complications arising from vaginal and cesarean deliveries was generally low and related to the frequency of these complications. There was no significant correlation between demographic characteristics and maternal preference for mode of delivery.

CONCLUSIONS

Asian women largely prefer a vaginal delivery, and their attitude toward cesarean delivery on demand is comparable with that of Western women. Cultural or ethnic differences are unlikely to affect maternal preference for cesarean delivery in Singapore women.

Induction policy and missed post-term pregnancies: a mathematical model

The aim of this study was to compare the clinical performance of ultrasound dates and ultrasound dates combined with menstrual dates for the detection of post-maturity. A computer model was designed which uses the statistical distributions of the duration of normal pregnancy, day of ovulation in relation to the menstrual cycle and ultrasound error for estimating gestational age. The clinical performance of the different dating methods was then analysed from these variables, on simulations of 30,000 cases. The efficacy of different dating methods for detecting post-maturity was determined by generating receiver-operator characteristics (ROC) curves. The proportion of post-term pregnancies (294 days and over) predicted by the model (3.5%) agrees with published values. There is a steep rise in missed cases if induction is delayed beyond 10 days from the expected date of delivery, reaching 20% on day 294. Elective delivery on day 290 will detect 98.9% of cases destined to deliver post-term, with an induction rate of 10%; the respective figures for induction on day 294 are 79% and 3.8%. The ROC curves for the detection of post-maturity suggest that use of the mid-trimester biparietal diameter (BPD) is better than a 7-day or 10-day rule. Timing of elective delivery is the most important variable affecting the detection rate for post-maturity There is no advantage in using menstrual dates when ultrasound biometry is available.

A fetal growth standard derived from multiple modalities

OBJECTIVE

To create a fetal weight growth standard from published data on ultrasound-dated pregnancies.

METHODS

A fetal growth standard was calculated from published birth weight data, sonographic weight standards, and one MRI study. The birth weights from the East Midlands Obstetric Database were modified by an incremental function to compensate for the lower weights of preterm infants. Published sonographic and MRI standards, and the modified birth weight curve were transformed to yield fractional growth curves that express fetal size as a proportion of the expected term weight. These three curves were then averaged, and the standard deviation was taken as 12% of the median. Curves for Europeans and Chinese were then generated.

RESULTS

The average curve for fetal weight is a virtually linear function of gestational age, with a weekly weight gain of 5.2% of the expected term birth weight.

CONCLUSIONS

Ultrasound-derived fetal growth curves are subject to bias inherent in weight estimation formulae. A standard derived from multiple modalities is likely to be a more robust estimate of normal fetal growth.

Sociobiological variables and pregnancy outcome

Recent advances are beginning to shed light on the mechanisms whereby adverse psychosocial factors can influence pregnancy outcome. High levels of maternal stress have been linked to endocrine disturbances, which in turn increases the risk of preterm labor considerably. These observations have been supported by experimental animal models. Birth weight is subject to considerable ethnic variation, and on its own is a nonspecific indicator of pregnancy outcome. The benefits of social and psychological intervention have been best documented in the intrapartum situation, whereas antenatal intervention is most likely to be of benefit when focused on improving socioeconomic conditions and access to healthcare providers.

Fetal growth

Recent epidemiological and experimental studies show that abnormal fetal growth can lead to serious complications, including stillbirth, perinatal morbidity and disorders extending well beyond the neonatal period. It is now clear that the intrauterine milieu is as important as genetic endowment in shaping the future health of the conceptus. Maternal characteristics such as weight, height, parity and ethnic group need to be adjusted for, and pathological factors such as smoking excluded, to establish appropriate standards and improve the distinction between what is normal and abnormal. Currently, the aetiology of growth restriction is not well understood and preventative measures are ineffective. Elective delivery remains the principal management option, which emphasizes the need for better screening techniques for the timely detection of intrauterine growth failure.

Effect of labour and delivery on plasma hepatic enzymes in the newborn

OBJECTIVE

To study the relationship between cord blood hepatic enzymes and obstetric and neonatal outcome in a Chinese population.

MATERIALS AND METHODS

The study group consisted of 288 low-risk Chinese women with singleton term pregnancies. The following enzymes were assayed in cord blood: lactate dehydrogenase (LDH), glutamyl transferase (GGT), aspartate aminotransferase (AST) and alanine transferase (ALT). These were correlated to maternal and neonatal characteristics.

RESULTS

A strong correlation was noted between cord blood AST and LDH (R = 0.582, p < 0.01), which was absent amongst those infants delivered by elective cesarean section. LDH, AST and ALT were negatively correlated with cord arterial pH and base excess (BE). GGT was inversely related only to gestational age (R = -0.18, p < 0.01). Both LDH and AST were weakly correlated with the duration of the first and second stages of labour. LDH was most closely linked to arterial pH, whereas AST was related to both arterial BE and duration of the second stage.

CONCLUSIONS

The reference values are comparable to those published for Caucasian populations. There are moderate elevations in LDH and AST associated with the onset of labour and changes in acid-base status.

Symphysis-fundus height and pregnancy characteristics in ultrasound-dated pregnancies

OBJECTIVE

To investigate the relation between maternal and pregnancy characteristics and symphysis-fundus height values at term in an obstetric population dated by sonography.

METHODS

Three hundred twenty-five women were recruited from the antenatal clinics of the Queen's Medical Centre, Nottingham, United Kingdom for measurement of fundal height and for ultrasound scans. Symphysis-fundus height measurements were analyzed by multivariate regression analysis in relation to gestational age, maternal height and weight, ethnic group, and smoking.

RESULTS

Gestational age and maternal characteristics explained nearly half of the variability in symphysis-fundus height. Gestational age was the most important determinant, followed by maternal weight, parity, and sex of the infant. The other variables were not significantly correlated.

CONCLUSION

Maternal characteristics had statistically significant effects on the expected symphysis-fundus height, which suggests that individually adjusted fundal height charts may improve the precision of clinical screening for fetal growth restriction.

[Pericardial involvement as initial manifestation of multiple myeloma]

Pericardial involvement is a rare complication of multiple myeloma, caused by amyloidosis, infections, or plasmacell infiltration, usually at late or terminal disease stage. We report a patient with pericarditis coming from a department of Cardiology where a preceding (15 years before) diagnosis of breast cancer and present bloody pericardial effusion with probably malignant cells permitted at first to orientate towards metastatic pericardial involvement in breast cancer. Laboratory findings (pancytopenia, hypogammaglobulinemia, proteinuria) suggested to perform bone marrow aspirate, serum and concentrated urine immunoelectrophoresis, measurement of 24-h urine protein excretion, and further cytologic and immunocytochemical assay of pericardial fluid. Acquired data allowed to diagnose light chain multiple myeloma with pericardial involvement caused by plasmacell infiltration. We diagnosed this complication, representing first and main clinical feature of multiple myeloma, owing to a complete clinical and laboratory evaluation and repetition of cytologic and immunocytochemical assay of pericardial fluid.

Fetal and maternal levels of lipid peroxides in term pregnancies

OBJECTIVE

To examine the relationships between maternal and fetal concentrations of lipid peroxides in term pregnancies before the onset of labor.

METHODS

Umbilical cord arterial and venous blood samples were collected from 114 singleton term pregnancies delivered by elective cesarean section. Base excess, oxygen, carbon dioxide and pH were measured in both samples and compared to identify double venous samples. Maternal venous and umbilical cord arterial and venous concentrations of organic hydroperoxides and malondialdehyde were assayed.

RESULTS

Maternal plasma malondialdehyde was, on average, double that of cord blood, whereas maternal organic hydroperoxide was only 18% higher. Maternal organic hydroperoxide was correlated with cord arterial and venous levels of organic hydroperoxide but not with pH, carbon dioxide, oxygen or base excess. Maternal malondialdehyde concentration was significantly correlated with both umbilical arterial and venous values of malondialdehyde and with arterial oxygen. Multiple regression shows that 70% of the variation in maternal malondialdehyde can be accounted for by variation in arterial and venous malondialdehyde, and arterial oxygen and base excess. A similar regression analysis with maternal organic hydroperoxide as dependant variable incorporated only umbilical arterial organic hydroperoxide concentration.

CONCLUSION

These findings suggest that there is significant trans-placental transport of malondialdehyde from the fetal circulation.

Screening for fetal growth restriction: a mathematical model of the effect of time interval and ultrasound error

OBJECTIVE

We estimated the effect of ultrasound error and time interval between examinations on the false-positive rate for detecting fetal growth restriction (FGR).

METHODS

Using published growth curves for the fetal abdominal circumference and a coefficient of variation for ultrasound error of 5%, computer simulation was used to estimate false-positive rates in relation to the time interval between ultrasound examinations. Growth restriction was diagnosed when there was no apparent growth in fetal abdominal circumference between two consecutive examinations. In separate studies, the false-positive rate was plotted against gestational age at the first ultrasound examination.

RESULTS

There was a dramatic increase in false-positive rates as the time interval between examinations was reduced. When the initial scan was performed at 32 weeks, the false-positive rate increased from 3.2% for an interval of 4 weeks to 30.8% for an interval of 1 week. At a 2-week interval, the error was 16.9%. There was a significant increase in the false-positive rate as the gestational age at the initial ultrasound was increased. At 28 weeks, the false-positive rate with a 2-week interval was 11.8%, increasing to 24.1% at 38 weeks. By varying the coefficient of variation of the ultrasound error, the false-positive rate increased from 0.8% at an error of 2% to 31.9% at an error of 10%.

CONCLUSION

Ultrasound scanning at 2-week intervals is associated with false-positive rates for growth restriction in excess of 10%, increasing to much higher rates late in the third trimester. Improved screening performance should be attainable by increasing the interval between scans and reducing measurement errors.

Analysis of birthweight and gestational age in antepartum stillbirths

OBJECTIVE

To study the characteristics of birthweight and gestational age of third trimester fetal deaths which occurred before the onset of labour.

DESIGN

Review of computerised confidential perinatal mortality records. Data originated from the 1992 Trent Region Perinatal Mortality Survey.

SAMPLE

One hundred and forty-nine antepartum stillbirths of at least 24 weeks of gestation confirmed by early ultrasound scan. Congenital abnormalities and multiple pregnancies were excluded.

MAIN OUTCOME MEASURES

Reported causes of stillbirth; weight-for-gestational age centiles based on a standard derived from normal pregnancies; pregnancy characteristics compared with the local maternity population.

RESULTS

Of 149 stillbirths, 83 (56%) were preterm and 66 were at term, and the majority (126; 85%) occurred from 31 weeks. Most of the deaths (97; 65%) were reported as 'unexplained' even though post-mortems had been carried out in 60% of all cases. Using a gestational age-specific fetal weight standard derived from normal, term live births, 41% of all cases of stillborn infants were small-for-gestational age (< 10th centile; OR 6.2; 95% CI 3.3-11.5); 39% of which had been classified as unexplained were small for gestational age (OR 5.6; 2.6-12.0). This excess of small stillbirths was most pronounced between 31 and 33 weeks, where the weights of 63% of all stillbirths and 72% of unexplained fetal deaths were < 10th centile. Overall, a higher proportion of preterm (< 37 weeks) than term stillbirths were small for gestational age: 53% vs 26% (OR 3.3; 1.6-6.5). However, at term there were also more subtle differences in weight deficit, with more fetuses with a weight between the 10th and 50th centiles than between 50th and 90th (36 vs 11; OR 3.3; 1.4-7.8). Mothers of pregnancies ending in stillbirth were similar in age, size, parity and ethnic group to mothers of live born babies, but were more likely to be smokers (37 vs 27%, OR 1.6; 1.2-2.3).

CONCLUSIONS

Many stillborn babies are small for gestational age. In the absence of significant differences in physiological pregnancy characteristics, this is unlikely to be a constitutional smallness, but represents a preponderance of intrauterine growth restriction. For a full appreciation of the strength of this association, appropriate weight standards and classifications need to be applied in perinatal mortality surveys. Many antepartum stillbirths which are currently designated as unexplained may be avoidable if slow fetal growth could be recognised as a warning sign.

Lipid peroxidation in cord blood at birth: a marker of fetal hypoxia during labour

OBJECTIVE

This prospective study examined purine metabolism in relation to free oxygen radical activity, as reflected by lipid peroxide levels in umbilical cord blood at birth.

SETTING

Departments of Obstetrics and Gynaecology and of Chemical Pathology, the Chinese University of Hong Kong, Hong Kong, and Purine Research Laboratory, UMDS of Guy's and St. Thomas' Hospitals, London, UK.

METHODS

Umbilical cord arterial and venous blood samples were collected from 132 singleton term deliveries for determination of hypoxanthine, xanthine, inosine, uric acid, organic hydroperoxides (OHP) and malondialdehyde. Oxygen saturation, PO2, pCO2, pH, and base excess (BE) were also measured.

RESULTS

There was a significant correlation between umbilical arterial and venous levels of hypoxanthine, xanthine, inosine, uric acid and all acid-base parameters (p < 0.001). Significant arteriovenous differences were observed for all parameters with the exception of inosine, uric acid and OHP. Umbilical arterial xanthine and potassium correlated significantly with OHP, but hypoxanthine, inosine and uric acid did not. In 13 babies classified as severely asphyxiated at birth (umbilical arterial pH <7.15, BE <-8), xanthine and OHP levels were significantly elevated when compared with non-asphyxiated babies. No significant differences were observed for hypoxanthine, inosine or uric acid.

CONCLUSION

The findings indicate that OHP, either in cord arterial or venous blood, is the best marker of free oxygen radical activity in the fetus, and that this correlates with other evidence of cellular hypoxia-reperfusion injury. We propose OHP is a better measure of perinatal outcome than either acid-base balance or hypoxanthine.

Computerised estimation of the baseline fetal heart rate in labour: the low frequency line

OBJECTIVE

To develop and evaluate a computerised algorithm for the estimation of the fetal heart rate baseline (low frequency line) during labour.

DESIGN

Retrospective observational study.

METHODS

Fetal heart rate signals were obtained from women in labour using the Nottingham fetal ECG monitor. The computerised algorithm for the baseline estimation was developed for intrapartum applications and is based on averaging modal fetal heart rate values. Evaluation was carried out on sixty cardiotocographic recordings by 12 experts and by the computer. These estimates were compared with those obtained from the computerised system using paired differences and intraclass correlation.

RESULTS

The study showed that it is possible to produce a low frequency line from data obtained from intrapartum records. The system could not estimate the low frequency line in four records, whereas experts were also unable to estimate between one and seven tracings. The 95% CI for the paired differences between computer and experts was -12 to 15 bpm, whereas between the experts this was -10 to 10. With the exception of one expert, there was a high concordance between experts and between computer and experts (intraclass correlation > 0.9).

CONCLUSIONS

The performance of this computerised algorithm cannot be distinguished from that of experienced clinicians. There were no significant differences between baseline values obtained by the computerised algorithm and those by the clinicians.

Oxygen free radical activity in the second stage of labor

OBJECTIVE

To assess fetal cellular injury arising from oxygen free radical activity in relation to the duration of the second stage of labor.

PATIENTS AND METHODS

Cord arterial pH, malondialdehyde and organic hydroperoxides levels were determined following vaginal delivery of 326 term singleton pregnancies. Of these, 35 (11%) received epidural analgesia. The length of the second stage was recorded from the time of full dilatation to delivery.

RESULTS

Arterial cord pH, malondialdehyde and organic hydroperoxides were significantly correlated with duration of second stage of labor (r=-0.4492; r=0.2542; r=0.2244; respectively, p<0.001). The association of lipid peroxidation products with second stage duration was independent of cord pH. This correlation was unchanged when cases of operative delivery were excluded. However, the relationship lost statistical significance amongst cases who received epidurals.

CONCLUSIONS

The duration of the second stage is correlated with raised reactive oxygen species-derived lipid peroxidation products. Caution should be exercised in the management of prolonged second stage of labor.

Are Hong Kong babies getting bigger?

OBJECTIVE

To establish recent birth weight trends in Hong Kong.

METHOD

A total of 10,512 confinements for the years 1985-86, and 7857 for the years 1995-96 were analyzed.

RESULT

There was a significant increase in maternal height, weight at booking, and maternal age, whereas the body-mass index was reduced slightly (P < 0.0001). Parity increased significantly, with the percentage of parous women rising from 44.1% to 55.6% (P < 0.0001). The percentage of female infants decreased from 49.5% to 47.9%. Despite these changes there was no significant difference in mean birth weights between the two groups. When birth weight was controlled for sex, parity, maternal height and weight there was a trivial increase of 15 g over time (P = 0.01).

CONCLUSION

Birth weight has reached a plateau in Hong Kong despite a continuing increase in the regions' socioeconomic status, and evidence of improved nutritional well-being.

The development of a hybrid expert system for the interpretation of fetal acid-base status

This article presents the development of an expert system for the interpretation of fetal scalp acid-base status. The system consists of logistic transformations, back-propagation neural networks and decision algorithms connected in series. It checks for out-of-range errors and the physiological coherence between measurements. It then determines whether acidosis should be diagnosed, and if so, whether it is more likely to be metabolic, respiratory or mixed. It will also flag those cases where it is difficult to interpret the data in physiological terms. The system was tested on a database of 2174 scalp blood samples collected at the Queens Medical Centre, Nottingham. Of these 88 samples were rejected as erroneous; 13 because of an out-of-range pH alone (> or = 7.48); 73 because more than one measurement was marginally out of range, and two because the relationship between measurements did not make sense. A total of 527 cases (24.2%) were diagnosed as being acidotic; of these, 139 were respiratory, 114 mixed and 274 metabolic. We were unable to fault the system's interpretation when the cases at the margins between diagnostic categories were reviewed clinically.

Birth weight, prematurity and accuracy of gestational age

OBJECTIVE

To investigate commonly used birth weight categories in relation to gestational age assignment by menstrual (LMP) or ultrasound dates.

METHODS

A total of 34,249 cases were retrieved from the East Midlands Obstetric Database. Of these, 2281 (6.7%) delivered preterm (< 37 weeks) by ultrasound dating. The percentage of preterm and post-term cases was calculated for birth weight categories from < 1500 g to > 4499 g at 500 g intervals. The incidence of preterm delivery was estimated for birth weights from < 1500 g to 3400 g.

RESULTS

For the 'low birth weight' cut-off of 2500 g, only 64% were actually preterm as assessed by ultrasound, as opposed to 59% as judged by menstrual dates. Nearly 95% of infants weighing over 3000 g are full-term. For birth weights under 2900 g, there is a trend for LMP-derived gestational age to underestimate preterm delivery, by up to 35.5%. By ultrasound dating, 90% of infants under 1800 g are preterm, rising to 98.2% for those under 1500 g.

CONCLUSIONS

As nearly 40% of 'low birth weight' infants are born at term, the old classification of 'low birth weight' should be replaced by gestational age-specific percentile categories. Menstrual dates systematically underestimate the prevalence of preterm delivery. Previous estimates of preterm delivery rates based on LMP data have under-stated their true incidence.

The epidemiology of urinary dysfunction in Chinese women

The epidemiology of urinary dysfunction in a Chinese population living in Hong Kong was investigated. Fifteen hundred ethnic Chinese women answered a telephone questionnaire including symptoms of urinary dysfunction, anthropometric measurements, obstetric history and place of birth. The relative predictive value of these factors was analyzed using logistic regression. The prevalence of urinary dysfunction was 13%. Ten percent reported stress incontinence, and 4% had urgency or urge incontinence. The strongest predictor was place of birth, with women born in mainland China having the highest prevalence of pure stress incontinence (OR 1.33, CI 1.1-1.6). For the symptoms of detrusor instability age was the strongest predictor, with women over 50 years being at greater risk (OR 2.8, CI 1.6-5.0). Contrary to earlier beliefs, urinary dysfunction in Chinese women is as common as in Caucasian women. Place of birth is the strongest predictor for pure stress incontinence, with women born in mainland China being at greater risk. This suggests that environmental factors in early life have a differential effect on the development of urinary incontinence.

Fetal weight estimation by symphysis-fundus height and gestational age

A new method for estimating the fetal weight is described, based on symphysis-fundus height and gestational age. The relationship between ultrasound-estimated fetal weight, gestational age, and symphysis-fundus height was determined using multiple regression analysis in a low-risk group. The accuracy of the regression formula was tested retrospectively on two target populations: a second low-risk group and a higher risk group undergoing elective delivery. The formula overestimated weight by 3.6%. The standard deviation of the random errors for the first group was 10.3% whereas in the second it was 11.9%. Fetal weight estimation using symphysis-fundus height and gestational age can be performed with an accuracy comparable to that of ultrasound.

A comparative analysis of second-trimester ultrasound dating formulae in pregnancies conceived with artificial reproductive techniques

A dataset of 64 pregnancies conceived by artificial reproductive techniques was studied to assess the accuracy of second-trimester dating formulae when these were applied in routine ultrasound clinics in different centers. Dating formulae for biparietal diameter (BPD) and femur length (FL) were derived for a gestational age range of 14-23 weeks. The best fit curves represented linear equations: gestational age (days) = 44.2 + 2 x BPD; and gestational age (days) = 67.4 + 2.3 x FL. Twelve published formulae for biparietal diameter and femur length were reviewed and systematic and random errors were calculated for these formulae when they were applied to second-trimester scan measurements in precisely dated pregnancies. Overall, published dating formulae performed well in predicting gestational age. The 95% confidence interval was 8.3 days for biparietal diameter and 10.2 days for femur length. The study confirms the accuracy of ultrasound dating in routine ultrasound clinics and supports the use of ultrasound measurement alone in preference to menstrual history for dating pregnancy.