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O Thompson

Publications and source records attributed to O Thompson.

10 recordsLinked to original sources
PubMed2004

Time domain measurement of blood flow in the human fetal aorta during normal pregnancy.

OBJECTIVE: To evaluate blood-volume flow-rate measurement in the fetal descending thoracic aorta using a non-invasive, non-Doppler, ultrasound technique. METHODS: This was a cross-sectional, observational study. Volume flow measurements were obtained from the descending thoracic aorta in 59 human fetuses between 20 and 40 weeks' gestation. These were uncomplicated pregnancies that resulted in the live births of appropriately grown infants. The measurements were obtained using a time domain processing technique: color velocity imaging quantification (CVI-Q). RESULTS: The blood-volume flow rate increased consistently from the second trimester until term. The mean values ranged between 100 mL/min at 20 weeks' gestation and approximately 350 mL/min at term. The normalized (weight-adjusted) volume flow rates decreased with increasing gestation, from a maximum of 626 mL/min/kg at 23 weeks to a minimum of 45.6 mL/min/kg at 37 weeks. CONCLUSIONS: The regular measurement of blood-volume flow in the descending fetal thoracic aorta is feasible using CVI-Q. Although there is a considerable learning curve, with adequate training there are potential clinical applications for this non-Doppler technique. However, limitations exist with the currently available technology for clinical use in fetal vascular studies.

Aorta, Thoracic↗
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↗
PubMed2000

Comprehensive analysis of uterine artery flow velocity waveforms for the prediction of pre-eclampsia.

OBJECTIVES: To evaluate the performance of velocimetric indices of uterine artery flow velocity waveforms (FVW's) at 20 weeks' gestation, alone or in combination with qualitative analysis, and establish the optimal screening method for the prediction of pre-eclampsia. METHODS: A total of 614 primiparous women had color flow/pulsed Doppler (CFPD) imaging of both uterine arteries at 20 weeks gestation. Receiver operator characteristic (ROC) curves were created for the systolic/end-diastolic (A/B) ratio, resistance index (RI) and systolic/early diastolic (A/C) ratio for placental and non-placental uterine arteries, individually or in combination with the presence of unilateral or bilateral notches. Based on data from ROC curves, the sensitivity of each method was compared with the false-positive rate set at 17 and 11%. RESULTS: The highest sensitivity (88%) and specificity of (83%) was obtained using bilateral notches/mean RI > or = 0.55 (50th centile) and unilateral notches/mean RI > or = 0.65 (80th centile). When the false-positive rate was set at 17%, the inclusion of bilateral notches significantly improved the sensitivity of RI (P < 0.001), placental RI (P < 0.01), placental A/C ratio (P < 0.05), mean A/C ratio (P < 0.01) and mean A/B ratio (P < 0.05). Bilateral notches/mean RI or A/B cut-offs were also superior to the persistence of a notch in either artery combined with RI (P < 0.01) or A/B ratio (P < 0.05). When the false-positive rate was set at 11%, the inclusion of bilateral notches did not improve the sensitivity of the A/C (P = 1.00) or A/B ratio (P > 0.10). Placental velocimetric indices performed better than mean indices but the differences in sensitivity at the set false-positive rates were not statistically significant. CONCLUSION: At 20 weeks' gestation, bilateral notches with mean RI cut-offs is the best screening method if further screening later in pregnancy is proposed. The A/C ratio is complementary to bilateral notches when the false-positive rate is set at 17% and an effective quantitative substitute when the false-positive rate is set at 11%.

Adult↗
PubMed1999

Second-trimester maternal serum inhibin A concentration as an early marker for preeclampsia.

OBJECTIVE: Maternal serum inhibin A concentration is elevated in established preeclampsia. The aim of this study was to investigate whether this relationship antedates the appearance of the classic signs of preeclampsia. STUDY DESIGN: A retrospective analysis was performed on trisomy 21 screening data from 685 women at between 15 and 19 weeks' gestation. The main outcome measures were preeclampsia and small for gestational age (<5th percentile) infants. RESULTS: Preeclampsia developed in 35 women (5.5%). Women with inhibin A concentration >2.0 multiples of the median were significantly more likely to acquire preeclampsia (P <.00001) and to be delivered of a small for gestational age infant (<5th percentile, P <.00001) than were women with inhibin A concentration </=2.0 multiples of the median. The odds ratios were 9.4 (95% confidence interval 4.6-19.3) for development of preeclampsia and 18.2 (95% confidence interval 6. 0-54.8) for preeclampsia necessitating delivery at <37 weeks' gestation. The association remained statistically significant for nulliparous women. CONCLUSION: Elevated maternal inhibin A concentration in the second trimester was strongly associated with a subsequent risk of preeclampsia. The potential role of second trimester inhibin A measurement in a screening strategy for preeclampsia needs to be investigated further.

Biomarkers↗
PubMed1998

Obstetric outcome in women who present with a reduction in fetal movements in the third trimester of pregnancy.

A complaint of decreased fetal movements is a common indication for the assessment of fetal well being. The aim of this study was to review the outcome of a group of women whose primary indication for referral was decreased fetal movements. Over a 20 month period, 435 patients were seen in the fetal assessment unit of an inner London teaching hospital, following a primary complaint of reduced fetal movements. Investigations included: the fetal abdominal circumference (AC), amniotic fluid volume (AFV), the umbilical artery pulsatility index (UAPI) derived from Doppler ultrasound waveforms and a computerised analysis of fetal heart rate (FHR) recordings or cardiotocograph (CTG). Outcome measures were: gestational age at delivery, Apgar score < 7 at 5 minutes, admission to the Special Care Baby Unit (SCBU), the need for delivery by an emergency cesarean section for fetal compromise (CSFC), and any perinatal deaths. A comparison of actual versus expected outcome for women with decreased fetal movement revealed the following relative risks, with the 95% confidence intervals (CI) in brackets; low 5 minute Apgar score 0.03 vs. 0.05 expected (CI = 0.01, 0.05), SCBU admission, 0.06 vs. 0.07 (0.04, 0.08), and preterm delivery, 0.08 vs. 0.11 (0.05, 0.10). Cesarean sections for fetal compromise, 0.07 vs. 0.053 (0.050-0.096). The addition of FHR monitoring to standard ultrasound assessment of well being did not appear to confer any added benefit. There were no fetal deaths. The outcome for pregnancies where the mother presents with decreased fetal movements in the third trimester is comparable with the outcome for the general population.

Apgar Score↗
PubMed1998

Prevalence of polyhydramnios in the third trimester in a population screened by first and second trimester ultrasonography.

AIMS: To determine the prevalence of polyhydramnios in a routine antenatal population, in which first and second trimester ultrasound screening for fetal abnormality had been performed and to examine the outcome in these pregnancies. METHODS: A retrospective analytical survey of all obstetric ultrasound examinations performed in a university teaching hospital over a thirty-six month period. Polyhydramnios was defined as either the measurement of a single deepest pool of liquor > 8 cm (AFV) or according to the amniotic fluid index, the sum of a four quadrant measurement > 24 cm (AFI). Using the stated definitions, polyhydramnios was diagnosed in 37 women, 16 of whom had a raised AFI. The main outcomes of interest included the mode of onset of labour and mode of delivery (rates of spontaneous and induced labour, cesarean section deliveries), birth weight, presence or absence of fetal anomalies, and the perinatal outcome. RESULTS: The prevalence of polyhydramnios in this study is lower (0.15% AFI > 24 cm and 0.36% AFV > 8 cm) than in previous studies. The association between polyhydramnios, maternal diabetes mellitus (10.8%), fetal abnormalities (5.4%) and fetal macrosomia (10.8%) was also lower than in past reports. There was a better overall fetal outcome compared with previous studies and no perinatal deaths were seen. CONCLUSIONS: In this study, the prevalence of polyhydramnios in the third trimester was lower than in previous studies, as well as being associated with a better prognosis. This may have been the result of a combination of several factors. These include the introduction of multi-level ultrasound screening for fetal abnormality, and the improved care of diabetic women, and mothers with rhesus iso-immunisation.

Amniotic Fluid↗
PubMed1995

Occurrence of respiratory syncytial virus subtypes in Mexican infants with acute lower respiratory tract disease.

The occurrence of respiratory syncytial virus (RSV) subtypes in Mexico City was studied by searching for the virus in nasopharyngeal aspirates of 82 infants, less than 12 months of age, hospitalized for acute lower respiratory tract disease with diagnosis of bronchitis, bronchiolitis, pneumonia and laryngotracheobronchitis. The presence of respiratory virus was determined by observation of cytopathic effect in cell monolayers; samples which produced a clear syncytia were considered positive and were treated with anti-respiratory syncytial virus serum. Viral infectivity was neutralized in 21 samples which were regarded as having RSV. These specimens were characterized into subtypes A and B with specific monoclonals by indirect immunofluorescence. Subtype A predominated over subtype B, 19 vs. 2. Patients with pneumonia and laryngotracheobronchitis had subtype A and both subtypes were found in infants with bronchitis and bronchiolitis.

Acute Disease↗
PubMed1984

Molecular cloning and characterization of a unique type of human papillomavirus from an immune deficient patient.

Several papillomas from a single patient who exhibited an unusual immune deficiency syndrome were analyzed for the presence of specific human papillomavirus (HPV) types. Preliminary analysis indicated that the HPV DNA species present in each of these tissues was quite unlike any of the previously characterized HPV types. In order to more rigorously analyze the HPV from this patient we have isolated the HPV DNA by molecularly cloning it into a bacteriophage lambda vector and have constructed a detailed restriction endonuclease map. Comparative hybridization studies using S1 nuclease analyses showed 6% or less nucleotide sequence homology of this viral DNA with HPV types 1, 2, 3, 4, 5, 6, or an HPV-11, molecularly cloned in this laboratory. Moreover, Southern blot analyses under stringent hybridization conditions revealed little, if any, hybridization to HPV types 1, 2, 4, 5, 7, 8, 10, 11, HPV-EV isolated from a patient with epidermodysplasia verruciformis (EV), or 2 previously described HPVs (HPV-P and HPV-PW) related to HPV-3. There was, however, a very weak sequence homology detected with HPV-6 and an extremely weak homology to HPV-3. No filter hybridization was observed with the recently characterized HPVs 9 or -12 to -24. These data accumulatively indicate that the HPV species from this immunosuppressed patient represents a new, hitherto unidentified HPV type.

Animals↗