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Biomedical subjects

B Thilaganathan

Publications and source records attributed to B Thilaganathan.

At least 37 records · Page 2Linked to original sources
PubMed2002

Uterine artery resistance and anxiety in the second trimester of pregnancy.

OBJECTIVE: To investigate the association between maternal anxiety and uterine artery resistance index (RI) at 20 weeks of gestation. METHODS: Uterine artery blood flow was assessed using color Doppler ultrasound and maternal anxiety was measured using the Hospital Anxiety and Depression (HAD) scale in 96 healthy primigravid women attending consecutively for their routine 20-week anomaly scan. RESULTS: The mean uterine artery RI was 0.54 (95% confidence interval, 0.52-0.56) and the median HAD anxiety score was 6 (range, 0-20). There was no association between RI and anxiety scores (r = 0.09, P = 0.36). Women scoring as definite cases of anxiety did not have a significantly elevated uterine artery RI or increased frequency of waveform notching compared to women with doubtful or no anxiety. CONCLUSIONS: The data of this study do not suggest a significant association between maternal anxiety and uterine artery RI at 20 weeks of gestation in healthy primigravid women with normally developing pregnancies. A prospective cohort study would be useful to determine the nature of the relationship between maternal anxiety, alteration in uterine artery blood flow and abnormal pregnancy outcome.

Anxiety↗
PubMed2002

The human ductus venosus between 13 and 17 weeks of gestation: histological and morphometric studies.

BACKGROUND: Doppler studies of the ductus venosus are increasingly being integrated in the assessment of fetal well-being. Establishing the precise morphology and structure of the ductus venosus would provide a better understanding of Doppler findings during fetal adaptation. There is conflicting evidence from previous studies about the structure of the ductus venosus, especially with regard to the presence of a sphincter at the ductus venosus inlet. The aim of this study was to examine the morphology and histological structure of the ductus venosus wall and surrounding tissues at 13-17 weeks' gestation. DESIGN: This was a prospective study on 28 fetuses obtained from medical termination of pregnancies between 13 and 17 weeks' gestation. Scanning electron microscopy and histological and immunohistochemical studies were carried out on ductus venosus sections obtained from different spatial planes. RESULTS: The inlet of the ductus venosus contained a shelf which was rich in elastin, but devoid of any evidence of a smooth muscle sphincter. The isthmus of the ductus venosus above the inlet was narrowed, giving the lumen of the vessel an hourglass appearance. The endothelial surface of the ductus venosus, above the level of the inlet, showed longitudinal corrugations along its entire length. Longitudinally arranged elastin fibers were also seen along the length of the ductus venosus. A single layer of longitudinally arranged smooth muscle cells was present along the entire length of the ductus venosus, with occasional individual nerve cells visible in this layer. CONCLUSIONS: The presence of an elastin-rich shelf and a narrow ductus venosus inlet orifice may act to accelerate flow from the portal sinus into a high-velocity system in the ductus venosus. The abundant elastin fibers in the adventitia of the ductus venosus may help antegrade wave propagation by elastic recoil. This study clearly demonstrates the lack of an anatomical smooth muscle sphincter at the ductus venosus inlet. However, the combination of endothelial corrugations and innervated smooth muscle support the hypothesis that the ductus venosus is an actively regulated vessel with the capacity to rapidly change diameter along its entire length in response to certain stimuli.

Endothelium, Vascular↗
PubMed2002

Outcome of antenatally diagnosed talipes equinovarus in an unselected obstetric population.

OBJECTIVE: To investigate the natural history and outcome of fetal talipes diagnosed by routine ultrasound scanning at 18-23 weeks' gestation. PATIENTS AND METHODS: This was a retrospective study of 103 228 pregnancies undergoing routine ultrasound scanning at 18-23 weeks' gestation. A computer search was made to identify all cases of fetal talipes and the records of these patients were examined to determine the incidence of other defects and pregnancy outcome. RESULTS: The incidence of fetal talipes following routine ultrasound examination was 0.10% (107/103 228) and was bilateral in 64 (59.8%) and unilateral in 43 (40.2%) cases. In 52 (48.6%) cases, talipes was of complex etiology, as it was associated with other defects, while, in 55 (51.4%) cases, it was classified as idiopathic. In 19% of cases, an initial diagnosis of idiopathic talipes was changed to complex, because of the subsequent development of associated features. Perinatal death and long-term neurodevelopmental or musculoskeletal problems were significantly more common when the talipes was complex rather than idiopathic (odds ratio, 150; 95% confidence interval, 34-665). Adverse outcomes were also seen more frequently with bilateral compared to unilateral talipes (odds ratio, 3.44; 95% confidence interval, 1.50-7.90). CONCLUSION: The outcome of antenatally detected talipes is mainly dependent on the presence or absence of other defects. A significant proportion of cases, thought to be idiopathic at presentation, will develop associated complex features when reassessed on subsequent scans or postnatally.

Clubfoot↗
PubMed2002

Comparison of feticide carried out by cordocentesis versus cardiac puncture.

OBJECTIVE: Feticide may be achieved by the injection of strong potassium chloride (KCl) into the fetal circulation via the cardiac route, or less frequently, into the umbilical cord. Despite the relative frequency of this procedure, little published information is available on the subject. SUBJECTS AND METHODS: This was a retrospective analysis of all feticide procedures carried out prior to legal pregnancy termination in mid trimester of pregnancy from January 1996 to July 2001, in a tertiary fetal medicine referral center. The effect of gestational age and the route of access to fetal the circulation on the dose of strong KCl required to achieve cardiac asystole was evaluated. RESULTS: A total of 106 women underwent the procedure of feticide during the study period. Gestational age had no effect on the dose of strong KCl. The median dose of KCl administered by cordocentesis (5 mL) was significantly less (P < 0.001) than the dose required when fetal cardiocentesis was performed for administration of the drug (10 mL). CONCLUSION: This is the first comparative study of feticide by the administration of strong KCl by fetal cardiocentesis and cordocentesis. The study demonstrates that both cardiac and umbilical routes can be used to achieve feticide effectively, without compromising maternal safety. A finding of this study is that significantly smaller doses of KCl were required to achieve fetal cardiac asystole when using the umbilical compared to the cardiac route, although this may be explained by differences in technique. Strong 15% KCl can safely be used to achieve feticide in volumes up to 20 mL for cardiocentesis and 8 mL for cordocentesis.

Abortion, Induced↗
PubMed2002

Improving the effectiveness of routine prenatal screening for major congenital heart defects.

OBJECTIVE: To evaluate the effectiveness of adding outlet views to the four chamber view in routine prenatal ultrasound screening for major congenital heart defects (CHD) as performed by trained sonographers, and to compare the procedure with current practice. DESIGN AND SETTING: Prospective observational study at a London teaching hospital. PARTICIPANTS AND METHODS: 9277 women booked at a single institution (80% had first trimester nuchal translucency measurement) due to have routine fetal cardiac screening using the four chamber and outflow tract views at > 18 weeks of gestation. MAIN OUTCOME MEASURE: Identification of major CHD in chromosomally normal and abnormal pregnancies antenatally or postnatally. RESULTS: There were 40 abnormalities (4.3/1000), of which 30 were chromosomally normal (3.3/1000). The overall antenatal detection rate was 75% (95% confidence interval (CI) 59% to 87%) and 70% (95% CI 51% to 85%) for euploid pregnancies. Abnormal cardiac views accounted for 70% of all prenatal diagnoses, 30% of which were made at < or = 18 weeks. The sensitivity of cardiac views during the first scan at > 18 weeks was 52%. Of all patients undergoing nuchal translucency screening, 34 had major CHD, nine with increased nuchal translucency (26.5%). Factors influencing the results of this screening programme were training and audit of operators, adequate equipment for antenatal examination, ease of access, and low threshold for referral to specialised fetal echocardiography. CONCLUSION: Adding ventricular outlet views to the four chamber assessment of the heart at routine fetal anomaly scans at > 18 weeks is the most effective technique to detect CHD prenatally. The success of such a programme depends on an infrastructure committed to continuous in house training of obstetric ultrasonographers coupled with feedback from specialised fetal cardiologists, as well as adequate resource allocation to obstetric hospitals involved with antenatal screening.

Adolescent↗
PubMed2002

Sensitivity and accuracy of routine antenatal ultrasound screening for isolated facial clefts.

Facial clefts, as a group, represent one of the most frequently occurring congenital abnormalities detectable on prenatal mid-trimester scan. It has been estimated that, at term, approximately 1 in 1000 infants will be diagnosed with an isolated facial cleft. The aim of this study was to determine the sensitivity and accuracy of routine second trimester ultrasound screening for facial clefts. This was a prospective study of isolated fetal facial clefts, detected at 18-23 weeks gestation, in a routine obstetric population. The antenatal detection rate of facial clefts was derived by comparing the number of cases identified antenatally with the number of neonatal cleft surgeries performed in this centre, for the local population only. The accuracy of antenatal diagnosis of facial clefts was calculated by matching data from the ultrasound database to birth registries and neonatal cleft surgeries performed in this centre, including the referred cases. During the study period, 17,551 women underwent a routine anomaly scan at 18-23 weeks of gestation. A total of 30 babies underwent surgery for isolated facial cleft in this centre during that period. There were no false positive diagnoses of facial clefts, and in five cases (all unilateral), the antenatal diagnosis was found to be inaccurate. 12 babies were from the local population, of which 9 had an antenatal diagnosis of facial cleft, giving a sensitivity of 75%. The current study highlights the effectiveness of antenatal screening for facial clefts. Additionally, it highlights the appropriate terminology that needs to be used in the accurate description of antenatally diagnosed facial clefts.

Cleft Lip↗
PubMed2001

Reproducibility and repeatability of transabdominal uterine artery Doppler velocimetry between 10 and 14 weeks of gestation.

OBJECTIVE: To assess the intraobserver repeatability and interobserver reproducibility of Doppler flow velocity measurements of the uterine arteries in pregnant women between 10 and 14 weeks of gestation. METHODS: In this prospective study, Doppler velocimetric indices (maximum peak systolic velocity, end-diastolic velocity, peak systolic velocity/end-diastolic velocity ratio, pulsatility index and resistance index) were measured twice by the same trained observer in each uterine artery of 63 women. In 47 of these women, a second trained observer then repeated the measurements. In addition, both observers classified qualitatively the blood flow with regard to the presence or absence of an early diastolic notch. The coefficient of variation, intraclass correlation coefficients, within observer and between observers repeatability coefficient and Cohen's kappa coefficient were calculated. RESULTS: The best parameter in terms of repeatability and reproducibility in both uterine arteries was the resistance index with a low coefficient of variation and high intraclass correlation coefficient. The other parameters (pulsatility index, peak systolic velocity/end-diastolic velocity ratio, peak systolic velocity and end-diastolic velocity) performed poorly with high coefficients of variation on both sides. Agreement between the repeated observations (inter- and intraobserver) with regard to the presence or absence of an early diastolic notch was good. CONCLUSION: Doppler velocimetry of uterine artery blood flow is technically feasible between 10 and 14 weeks of gestation. This study demonstrates that this technique is prone to measurement errors. Quantitatively, the resistance index appears to be the most repeatable and reproducible measurement at this gestational age. Qualitative assessment of the waveform morphology also shows high levels of intra- and interobserver agreement.

Adult↗
PubMed2001

The anatomy of the umbilical, portal and hepatic venous systems in the human fetus at 14-19 weeks of gestation.

BACKGROUND: Ultrasound imaging of the fetal ductus venosus is becoming increasingly commonplace in clinical practice. The true anatomical relationships of the fetal umbilical and portal venous systems have not been clearly defined due to paucity of published data on the relevant anatomy. This has led to confusing terminology when describing the fetal umbilical, portal and hepatic circulations. The aim of the present study was to examine and document the anatomy of the umbilical, portal and hepatic venous systems and to propose a standardized nomenclature. METHODS: This was a prospective study on 11 fetuses obtained from medical termination of pregnancies between 14 and 19 weeks of gestation. The liver was microdissected to expose the branching pattern and anatomical relations of the umbilical, portal and hepatic venous systems. RESULTS: A wide L-shaped venous confluence at the terminal end of the umbilical vein, termed the portal sinus, was identified. The portal sinus was connected to the right and left hepatic lobes, by the right and left intrahepatic portal veins, respectively. The extrahepatic portal vein drained into the portal sinus just before the origin of the right intrahepatic portal vein. The ductus venosus, a branchless straight vessel, originated from the portal sinus and ascended steeply in the direction of the diaphragm. Numerous small vessels draining the liver converged into three main hepatic veins, which open into the subdiaphragmatic vestibulum. CONCLUSION: Based on detailed sequential anatomical dissection and clear illustrations, the present study documents the anatomy of the umbilical, portal and hepatic venous systems. Taking into account the embryological origin of the vessels, a new anatomically appropriate and simplified nomenclature of these venous systems is proposed. In clinical practice, the consistent use of the suggested terminology would allow collection of comparable data between units and enable operators to be confident of which vessels they are sampling by Doppler ultrasound.

Dissection↗
PubMed2001

Natural history of fetal hydronephrosis diagnosed on mid-trimester ultrasound.

OBJECTIVES: Renal tract dilatation is a common finding in routine prenatal ultrasound. However, there is no consensus as to the criteria used for differentiating pathological from physiological dilatation. The aim of this study was to evaluate the natural history and postnatal outcome of fetal hydronephrosis in an unselected obstetric population. DESIGN: This was a prospective study of fetal hydronephrosis, detected at 18-23 weeks' gestation, in a routine obstetric population. Fetal hydronephrosis was diagnosed as 'mild' if the antero-posterior renal pelvic diameter (APRPD) measured >or = 4 mm and as 'moderate/severe' if the APRPD measured > or = 7 mm or if there was associated calyceal dilatation. The postnatal outcome of fetuses with persistent hydronephrosis (> or = 10 mm in the third trimester) was determined from a postal questionnaire. RESULTS: During the study period, 11 465 women underwent an anomaly scan at 18-23 weeks of gestation. Fetal hydronephrosis was identified in 2.3% (268/11 465) of women. Mild hydronephrosis was present in 80.6% (216/268) and moderate/severe hydronephrosis in 19.4% (52/268). The hydronephrosis resolved in the antenatal or early neonatal period in 88% of fetuses. None of the fetuses with mild hydronephrosis and approximately one in three fetuses with persistent moderate/severe hydronephrosis required postnatal surgery. Overall, only one in every 1000 total births in the study population required postnatal urological surgery. CONCLUSIONS: The current study highlights the natural history of antenatally detected hydronephrosis. Mild fetal hydronephrosis appears to be associated with an excellent prognosis and probably represents the group with physiological renal pelvic dilatation. Moderate/severe fetal hydronephrosis is associated with poorer outcome and is perhaps the group that will need more intense follow up both antenatally and postnatally.

Adult↗
PubMed2001

Limitations of using first-trimester nuchal translucency measurement in routine screening for major congenital heart defects.

OBJECTIVE: To evaluate the effectiveness of nuchal translucency (NT) measurement in screening for major congenital heart disease (CHD) in chromosomally normal fetuses. DESIGN: A population based cohort study of all women having fetal NT measurement at 10-14 weeks of gestation in an unselected population over a 3-year period. The outcome measure was the identification of major CHD in chromosomally normal pregnancies either antenatally or postnatally. RESULTS: Major defects of the heart and great arteries were identified in 26 out of 7339 pregnancies (prevalence 3.5 per 1000 pregnancies). Out of 26 cases, only four (sensitivity 15.4%, 95% CI 4-35) were in the group of 258 pregnancies (3.5%) with increased NT of > or = 2.5 mm. The prevalence of major CHD increased from 3.1 per 1000 for NT < 2.5 mm to 50 per 1000 for NT > or = 3.5 mm (likelihood ratio of 14.1, 95% CI 4.2-47.9). The positive and negative predictive values for NT > or = 2.5 mm were 1.6% and 99.7%, respectively. CONCLUSIONS: The prevalence of major CHD in this study was 3.5 per 1000, suggesting that ascertainment of CHD in our study population was thorough. Fetuses with NT measurements > or = 3.5 mm have a significantly increased risk of major CHD, and this identifies a subgroup of high-risk patients in whom early fetal echocardiography would be advocated. The low sensitivity of NT for major CHD in the general population, however, indicates that NT cannot be relied on as the sole or major screening tool for this condition as previously reported.

Adult↗
PubMed2001

The role of ultrasound in the expectant management of early pregnancy loss.

OBJECTIVE: To define the sonographic criteria which best determine the likelihood of successful expectant management of early pregnancy failure (EPF). METHODS: Women with an ultrasound diagnosis of EPF at 7-14 weeks' gestation were offered the option of expectant management or surgical evacuation. RESULTS: Five hundred and forty-five women had a diagnosis of EPF; 298 with incomplete miscarriage and 247 with missed miscarriage or an embryonic pregnancy. A total of 305 women opted for expectant management, with an overall success rate of 86%. The success rate for incomplete miscarriage (96%) was significantly better than that for missed miscarriage (62%). CONCLUSION: This study demonstrates that EPF can be safely managed expectantly. Ultrasound has an invaluable role in predicting the likelihood of successful expectant management enabling patients to make an informed choice about their medical care.

Abortion, Incomplete↗
PubMed2001

Improved early prediction of pre-eclampsia by combining second-trimester maternal serum inhibin-A and uterine artery Doppler.

OBJECTIVE: To evaluate the screening efficacy of second-trimester maternal serum inhibin-A combined with uterine artery Doppler studies performed at 20 weeks' gestation for the prediction of pre-eclampsia. METHODS: Six hundred and eighty-nine consecutive unselected women who had inhibin-A levels measured between 15 and 19 weeks' gestation subsequently had color flow pulsed Doppler of both uterine arteries at the time of the anomaly scan (mean 20.5, range 18-22 weeks' gestation). The main outcome measures were pre-eclampsia and pre-eclampsia requiring delivery before 37 weeks' gestation. The presence or absence of notches in the flow velocity waveform was noted, and the resistance index measured. Receiver operator curves were created for inhibin-A and uterine artery Dopplers alone and in combination. Sensitivities for each method were compared at false-positive rates of 3% and 7%. RESULTS: Thirty-five women developed pre-eclampsia, of whom 15 required delivery before 37 weeks' gestation. For a false-positive rate of 7%, the sensitivity using bilateral notches/mean resistance index > or = 0.65 was 60% with a positive likelihood ratio of 8.6 (confidence interval 5.7-12.6). For the same false-positive rate, when bilateral notches/mean resistance index > or = 0.55 and unilateral notches/mean resistance index > or = 0.65 were combined with inhibin-A > or = 1.0 multiples of the median, the sensitivity improved to 71% and the positive likelihood ratio to 10.8 (confidence interval 7.4-15.4). For pre-eclampsia requiring delivery before 37 weeks for a false-positive rate of 3%, the sensitivity for bilateral notches improved from 27% to 60% and the positive likelihood ratio improved from 9.2 to 20.8 when uterine artery notch data was combined with inhibin-A. The improvement in sensitivity for the combined method, compared to either inhibin-A or uterine artery Dopplers alone, was statistically significant for both pre-eclampsia ( P < 0.05) and preterm pre-eclampsia ( P < 0.02). CONCLUSION: Combination of second-trimester serum inhibin-A and uterine artery Doppler at 20 weeks improves the screening efficacy for the prediction of pre-eclampsia especially when this necessitates early delivery. This combination might form the basis of an effective and practical early screening test for the condition.

Adult↗
PubMed2001

Intraobserver and interobserver variability of transabdominal Doppler velocimetry measurements of the fetal ductus venosus between 10 and 14 weeks of gestation.

OBJECTIVE: To assess the intraobserver repeatability and interobserver reproducibility of transabdominal Doppler ultrasound measurements of ductus venosus blood flow in fetuses between 10 and 14 weeks of gestation. DESIGN: A prospective study with the following end-points: coefficient of variation, intraclass correlation coefficients within and between observers, repeatability coefficient and Cohen's kappa coefficient. SUBJECTS AND METHODS: Doppler velocimetry indices (maximum peak systolic velocity during ventricular systole, end-diastolic velocity during atrial contraction, peak systolic velocity/end-diastolic velocity ratio and pulsatility index for veins) were successfully measured three times by the same trained observer in 67 fetuses. Of these, in 24 fetuses, the measurements were then repeated by a second trained observer. In addition, both observers classified qualitatively the blood flow as being normal or abnormal with regard to the presence or absence/reversal of flow during atrial contraction. RESULTS: The intraobserver repeatability of the pulsatility index for veins measurements was considered good with a coefficient of variation of 8.9% and an intraclass correlation coefficient value of 0.62. However, inconsistencies occurred in maximum peak systolic velocity, end-diastolic velocity and systolic/diastolic ratio measurements, which had coefficients of variation of 19%, 28.5%, and 25.4%, respectively. The corresponding intraclass correlation coefficient values were 0.70, 0.69 and 0.60. Interobserver reproducibility of these indices was unsatisfactory, the coefficient of variation varying between 11.5% and 47.2% and the intraclass correlation coefficient between 0.18 and 0.44. Agreement between the repeated observations with regard to interpretation of normal or abnormal blood flow varied from moderate (interobserver) to very good (intraobserver). CONCLUSIONS: There was considerable variability in all Doppler indices except for the intraobserver repeatability of the pulsatility index for veins measurement. This makes the implementation of the semiquantitative Doppler indices in a screening setting difficult. On the contrary, qualitative classification of the flow velocity waveforms seemed to be a reproducible method.

Adolescent↗
PubMed2001

Significance of chromosome 22q11 analysis after detection of an increased first-trimester nuchal translucency.

OBJECTIVE: To determine the value of performing routine fluorescent in situ hybridization (FISH) for microdeletions of chromosome 22q11 when karyotyping fetuses with increased nuchal translucency. DESIGN: This was a prospective observational study carried out over an 18-month period. Fetal karyotyping by chorionic villus sampling was offered to 5429 women attending for a routine booking scan in the first trimester when their nuchal translucency adjusted risk for Down syndrome was > or = 1 in 300. Cytogenetic samples were routinely tested for the 22q11 microdeletion when the nuchal translucency was > or = 3 mm. RESULTS: The prevalence of increased nuchal translucency > or = 2.5 mm was 180 (3.3%) and > or = 3.5 mm was 42 (0.8%). None of 75 fetuses with an increased nuchal translucency and normal karyotype demonstrated a 22q11 microdeletion on FISH analysis. In the same cohort, 3 of 20 (15%) cases of major congenital heart defects in which nuchal translucency was measured, had a nuchal translucency measurement > or = 2.5 mm. CONCLUSIONS: Routine FISH analysis for chromosome 22q11 microdeletions at the time of chorionic villus sampling for increased first-trimester nuchal translucency is of limited value. As a significant proportion of fetuses with increased nuchal translucency will be found to have congenital heart defects later in the pregnancy, FISH analysis for chromosome 22q11 microdeletions can be targeted to fetuses with specific congenital heart defects. Tissue from the chorionic villus sampling should therefore be stored for subsequent analysis, until after detailed echocardiography is performed.

Adolescent↗
PubMed2001

Fetal anemia as a consequence of hemorrhage into an ovarian cyst.

Fetal ovarian cysts are usually benign in nature and resolve spontaneously. Complications such as torsion and rupture have been described previously. A case of presumptive spontaneous hemorrhage into a fetal ovarian cyst is presented. Serial ultrasound and Doppler assessments revealed the development of fetal anemia, which was managed by intrauterine blood transfusion.

Adult↗