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W Y Fok

Publications and source records attributed to W Y Fok.

8 recordsLinked to original sources
PubMed2006

The effect of learning curve on the outcome of caesarean section.

OBJECTIVE: To evaluate the operative outcomes when trainees first perform caesarean sections independently. DESIGN: A retrospective study in a tertiary obstetric unit. POPULATION: Five hundred caesarean sections, which represented the first 50 caesarean sections performed independently by each of ten trainees, were studied. METHODS: The effect of learning curve on outcome was analysed. MAIN OUTCOME MEASURES: Total operative time, incision-to-delivery interval, operative blood loss, Apgar score, cord arterial pH, incidence of neonatal intensive care unit admission, postoperative complication rates and duration of hospitalisation. RESULTS: The mean operative time for the first five cases by trainees was 52.2 +/- 11.4 minutes. It progressively decreased and reached 39.6 +/- 8.4 minutes for the 46th to 50th cases. The operative time was significantly longer in the first 15 caesarean sections (P < 0.05). Moreover, the incision-to-delivery interval was also longer during the first five cases (P= 0.02). Besides the time of the operation, the trend for operative blood loss stabilised after the first ten caesarean sections (P < 0.05). Otherwise, there were no significant differences among other outcome variables. CONCLUSION: This study shows that trainees need to perform 10-15 caesarean sections before their skills become more proficient. Senior obstetricians may need to provide guidance to the trainees during their first independent 15 caesarean sections.

Apgar Score↗
PubMed2006

Prediction of intrapartum Cesarean delivery for non-reassuring fetal status after a successful external cephalic version by a low pre-version pulsatility index of the fetal middle cerebral artery.

OBJECTIVE: To determine whether a pre-version Doppler assessment of fetal cerebral and umbilical blood flow can predict the ultimate need for intrapartum Cesarean delivery after a successful external cephalic version (ECV). METHODS: A prospective observational study on women undergoing ECV between 36 and 38 gestational weeks was performed over a 5-year period. The pulsatility index (PI) of the fetal middle cerebral artery (MCA) and umbilical artery, heart rate and amniotic fluid index were measured before ECV. Women who had successful ECV were then divided into three groups according to the mode of delivery: (1) vaginal delivery, (2) intrapartum Cesarean delivery for poor progress and (3) intrapartum Cesarean delivery for non-reassuring fetal status. The fetal blood flow parameters were compared between the groups. Potential predictors were further analyzed using receiver-operating characteristics curves. RESULTS: Of 174 women with successful ECV, 140 (80.5%) had vaginal delivery, 19 (10.9%) required emergency intrapartum Cesarean delivery for non-reassuring fetal status and 15 (8.6%) for poor progress. MCA-PI was significantly lower in the group with non-reassuring fetal status. MCA-PI is predictive of intrapartum Cesarean delivery (area under the curve = 0.68, P = 0.021). The sensitivity and specificity at a cut-off level of 1.4 were 62.5% and 76%, respectively, while at a cut-off level of 1.5 they were 68.8% and 63.5%, respectively. CONCLUSION: Intrapartum Cesarean delivery for non-reassuring fetal status after successful ECV is associated with a lower pre-version fetal MCA-PI.

Breech Presentation↗
PubMed2006

The influence of fetal position on amniotic fluid index and single deepest pocket.

OBJECTIVE: To evaluate the effect of fetal position on measurement of amniotic fluid index (AFI) and of the single deepest pocket (SDP). METHODS: This was a prospective observational study, in a university obstetric unit, of women with an uncomplicated singleton pregnancy with longitudinal lie and cephalic presentation at or beyond 28 weeks of gestation. AFI was calculated and SDP measured and the fetal position was characterized in terms of three parameters. These were: the side of the maternal abdomen on which the fetus lay; a numerical representation (laterality score) of the distance that the fetus was from the sagittal midline plane of the maternal abdomen; the orientation of the fetal trunk (ventral anterior, lateral or posterior). RESULTS: Eighty-one women were recruited into the study. There was a significant relationship between the laterality score and the AFI (P = 0.005) but not the SDP (P = 0.23): AFI was on average 4.35 cm higher in fetuses lying centrally compared with those lying laterally inside the uterus. There was no significant difference for either SDP (P = 0.8) or AFI (P = 0.3) between fetuses lying on the right or the left side of the maternal abdomen. Similarly, there was no significant difference in SDP (P = 0.9) or AFI (P = 1.0) for the different orientations of the fetal trunk. CONCLUSION: Fetal position affects the measurement of AFI but not that of SDP. Therefore, SDP may be a more consistent parameter for the estimation of amniotic fluid volume.

Abdomen↗
PubMed2006

Left ventricular diastolic function during normal pregnancy: assessment by spectral tissue Doppler imaging.

OBJECTIVE: Tissue Doppler imaging (TDI) is an echocardiographic technique for assessing the diastolic function that is relatively independent of preload. Since loading conditions change significantly during pregnancy, a load-independent technique will give a more accurate assessment of diastolic function in pregnant women. The aim of this study was to evaluate maternal diastolic function using tissue Doppler imaging. METHODS: This was a prospective observational study on 35 healthy pregnant women. M-mode, transmitral inflow (peak transmitral flow velocities during early diastole (E wave) and atrial contraction (A wave)) and TDI studies (peak myocardial velocities during early diastole (Em wave), during atrial contraction (Am wave) and peak systole in ejection phase (Sm)) were performed in each trimester and postpartum. The differences in variables between trimesters were analyzed. RESULTS: The peak transmitral inflow velocity during early diastole (E wave) was significantly decreased during the third trimester and postpartum. The peak flow velocity during atrial contraction (A wave) was increased in the second trimester, but decreased again in the third trimester and postpartum period. As a result, the E/A ratio progressively reduced as pregnancy advanced. TDI showed that peak myocardial velocities during early diastole (Em) tended to increase during the second trimester, and then decreased significantly in the third trimester or postpartum period. The peak myocardial velocities during atrial contraction (Am) increased significantly with advancing gestational age. As a consequence, both Em/Am and E/Em ratios decreased significantly throughout pregnancy. CONCLUSIONS: This study demonstrates the changes in myocardial relaxation velocity throughout pregnancy. Because of its advantage of being relatively load-independent, TDI may be a useful non-invasive technique for monitoring maternal cardiac function in high-risk pregnancies to detect the early signs of cardiac failure and to prevent further deterioration with prompt interventions.

Diastole↗
PubMed2004

Intrapartum cesarean delivery after successful external cephalic version: a meta-analysis.

OBJECTIVE: We sought to estimate whether the risk of intrapartum cesarean delivery is higher in pregnancies after successful external cephalic version. DATA SOURCES: We searched the MEDLINE, PubMed, EMBASE, and Cochrane Library databases to identify relevant studies. Abstracts of the American College of Obstetricians and Gynecologists Annual Clinical Meeting and the Society for Maternal-Fetal Medicine Annual Meeting were searched by hand. STUDY SELECTION: Studies published between 1980 and 2002 that provided data allowing us to estimate the cesarean rate in both pregnancies after successful version and spontaneous cephalic-presenting pregnancies were selected. TABULATION, INTEGRATION, AND RESULTS: Relative risks (RRs) and 95% confidence intervals (CIs) between the 2 compared groups were calculated. We used a meta-analysis to assess the heterogeneity of the studies and to combine the results from the included studies. Six eligible studies were identified. The cesarean rate was 27.6% in pregnancies after successful version and 12.5% in cephalic-presenting pregnancies. The combined RR and 95% CI was 2.04 (1.43-2.91). The increased cesarean rate in pregnancies after successful version was accounted for primarily by a higher incidence of emergency cesarean delivery for dystocia and fetal distress; the RR (95% CI) for these 2 events was 2.19 (1.38-3.48) and 2.10 (1.18-3.75), respectively. CONCLUSION: The intrapartum cesarean delivery rate after successful version is 2 times that in pregnancies where there is spontaneous cephalic presentation. Pregnancies after successful version should not be considered the same as a normal pregnancy.

Cesarean Section↗
PubMed2000

Effect of external cephalic version at term on fetal circulation.

OBJECTIVE: We sought to investigate the subclinical effect of external cephalic version on fetal circulation. STUDY DESIGN: A prospective observational study was conducted on 136 subjects who had external cephalic version at or beyond 36 weeks of gestation without clinical complication. Doppler ultrasonographic studies of the umbilical and middle cerebral circulations were performed before and after the external cephalic version. The following Doppler indexes were measured: (1) the pulsatility index of the umbilical artery, which represents disturbance of placental circulation, and (2) the pulsatility index of the fetal middle cerebral artery, which represents fetal response. The Wilcoxon signed rank test was used for all statistical analyses. RESULTS: There was no significant difference in pulsatility index of the umbilical artery before and after external cephalic version (P =.674). There was a statistically significant reduction in the pulsatility index of the middle cerebral artery after external cephalic version (P =.043), and this difference existed only among multiparous women (P =.029), among those in whom the external cephalic version was considered to be difficult (P =.038), and when the placenta was posteriorly located (P =.028). The reduction in pulsatility index was not related to whether the external cephalic version was successful. In all cases the Doppler indexes remained within the normal ranges, and there were no associated fetal complications. CONCLUSION: External cephalic version was not associated with any significant disturbance of placental resistance to blood flow. Conversely, external cephalic version was associated with a significant reduction in the pulsatility index of the middle cerebral circulation, especially among the multiparous women, after a difficult procedure or in those with a posterior placenta. This probably represents a normal fetal physiologic response to manipulation of the fetal head.

Bradycardia↗
PubMed2000

Outcome of labour after successful external cephalic version at term complicated by isolated transient fetal bradycardia.

OBJECTIVES: To investigate factors associated with the occurrence of transient fetal bradycardia after external cephalic version, and labour outcome after isolated transient fetal bradycardia. DESIGN: Cohort study. SETTING: Teaching hospital with a policy of offering external cephalic version for breech presentation at or beyond 36 weeks of gestation. POPULATION: Four hundred and twenty-nine external cephalic versions performed over a 5-year period. METHODS: Between group differences were compared with the unpaired t test or the chi2 test. Logistic regression analysis was performed to exclude confounding effects. MAIN OUTCOME MEASURES: Incidence of caesarean section for fetal distress. RESULTS: Transient fetal bradycardia occurred in 8.4% of external cephalic versions, and was associated with a successful version (OR 16.45, P < 0.001), a difficult procedure (OR 3.70, P = 0.001), and nulliparity (OR 2.83, P = 0.007). The incidence of intrapartum caesarean section for fetal distress was 16.7% in pregnancies with transient fetal bradycardia, compared with 7.9% in those without (OR 2.34, 95% CI 0.81, 6.71). CONCLUSIONS: Transient fetal bradycardia after external cephalic version may be associated with a higher risk of intrapartum caesarean section for fetal distress.

Bradycardia↗