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.

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.

Sonographically detected caesarean section scar defects and menstrual irregularity.

The purpose of this study was to estimate the frequency of post-caesarean section scar defects (PCSD) on transvaginal ultrasound and to correlate these with the presence of abnormal menstrual bleeding. We reviewed the pelvic ultrasound images of 318 women referred for a gynaecological scan in a private women's ultrasound clinic. The incidence of defects at the expected location of a caesarean scar was evaluated and then correlated with patient responses to a questionnaire on abnormal menstrual bleeding. Of the 318 patients, 71 had a history of caesarean section and technically adequate pelvic ultrasound images. Fluid-filled defects in the hysterotomy incision were noted in 29 (40%). The presence of a PCSD was significantly associated with patients reporting prolonged periods or post-menstrual spotting. The larger the defect, the higher was the incidence of abnormal vaginal bleeding.

Subarachnoideal blood spread following epidural blood patch given to treat spontaneous intracranial hypotension: Can it cause neurological complications?

OBJECTIVE: (1) To determine the frequency of subarachnoid blood spread following epidural blood patch (EBP) in a cohort of subjects with spontaneous intracranial hypotension (SIH). (2) To describe the outcome of these patients. PATIENTS AND METHODS: In a cohort of 106 patients exhibiting SIH, spiral spinal CT scans were obtained post-lumbar EBP and neuroradiological data was reviewed for evidence of subarachnoideal bleeding. RESULTS: Subarachnoideal blood spread was detected on spinal CT scans following EBP in 9 of 106 patients with SIH. All patients exhibited a complete recovery and no neurological complications were observed. CONCLUSIONS: A low incidence of subarachnoideal blood spread was observed following EBP given to treat SIH. Instances of subarachnoideal blood spread were not associated with neurological complications or altered efficacy of the EBP procedure.

Reduction of false-positive diagnosis of fetal growth restriction by application of customized fetal growth standards.

OBJECTIVE: To evaluate the clinical performance of fetal growth charts adjusted for individual maternal characteristics. METHODS: The study group consisted of 267 low-risk singleton pregnancies with normal clinical outcome. Mothers were recruited prospectively after the booking visit, then underwent three to five ultrasound examinations for fetal weight estimation. Individual growth curves were generated from these data and the birth weight, based on logpolynomial growth model. Computer software was written to calculate the number of fetal growth curves that cross the tenth percentile limit, based on an unadjusted, average ultrasound standard for our population, compared with the number that cross this limit if it is customized for known pregnancy characteristics such as maternal height, booking weight, parity, and ethnic group. RESULTS: Individual growth trajectories of this group of pregnancies with normal outcome were significantly less likely to cross below the tenth percentile for fetal weight when using customized growth charts than when the unadjusted standard was used (McNemar's test, P < .001). CONCLUSION: The relationship between maternal characteristics and fetal size needs to be considered in the assessment of fetal growth. The use of a customized standard reduces the false-positive rate for the diagnosis of growth restriction in a normal population.

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.

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.

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.

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.

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.

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.

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.

Duration and variability of normal pregnancy. Implications for clinical practice.

OBJECTIVE: To estimate the true biologic length and variability of normal pregnancy on the basis of early ultrasonography and to assess the implications for clinical practice. STUDY DESIGN: We reviewed the clinical case notes on 476 women whose pregnancies were routinely dated by measurement of the biparietal diameter in the second trimester. After excluding abnormal cases, 355 pregnancies were available for analysis. The duration of pregnancy was studied in relation to maternal characteristics and also to induction of labor for postmaturity. RESULTS: The mean +/- SD for the normal duration of pregnancy were 279.7 and 7.4 days. The length of pregnancy was weakly related to maternal height. Of the 41 women whose labor was induced for postmaturity, only 7 were truly postmature when gestational age was determined by sonography. CONCLUSION: The current definitions of preterm and postterm may need to be revised to allow the increased precision achieved by ultrasound. Inclusion of menstrual data for the determination of gestational age may lead to incorrect clinical decisions.

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.

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.