Factors influencing the mode of delivery and associated pregnancy outcomes for twins: a retrospective cohort study in a public hospital.

OBJECTIVES: To determine current trends for different modes of delivery in twin pregnancies, factors affecting the mode of delivery, and associated outcomes. DESIGN: Retrospective cohort study. SETTING: A public hospital in Hong Kong. PARTICIPANTS: All twin pregnancies booked at Kwong Wah Hospital during a 3-year period from 1 April 2006 to 31 March 2009. RESULTS: Of 197 sets of twins, 35 (18%) were delivered vaginally and 162 (82%) by caesarean section (47% were emergencies and 53% elective). In all, 32 (37%) of the elective and 21 (28%) of the emergency caesarean sections were in response to maternal requests. Vaginal delivery was more common in mothers with a history of vaginal delivery and monochorionic diamniotic twins. Women who conceived by assisted reproduction or those who had a tertiary education were more likely to deliver by caesarean section. The type of conception and the presentation of the second twin were statistically significant factors affecting maternal choice on the mode of delivery. Maternal age did not affect the choice of delivery mode. Except for the higher frequency of sepsis and cord blood acidosis in second twins delivered vaginally, there were no significant differences in neonatal morbidity between the groups that attempted vaginal delivery or requested caesarean sections. All the women who had compression sutures or hysterectomy to control massive postpartum haemorrhage were delivered by caesarean section. CONCLUSION: A high caesarean section rate observed in our cohort was associated with maternal requests for this mode of delivery. The type of conception and the presentation of the second twin were statistically significant factors affecting maternal choice on mode of delivery. Women's requests for caesarean delivery out of the concern for their babies are not supported by current evidence. In response to a woman with a twin pregnancy requesting caesarean delivery, the pros and cons of vaginal deliveries and caesarean sections should be fully explained before the woman's autonomy is respected.

Is ultrasound alone enough for prenatal screening of trisomy 18? A single centre experience in 69 cases over 10 years.

OBJECTIVES: To evaluate ultrasound scan and other prenatal screening tests for trisomy 18 in a regional obstetric unit and to review the management approach for women with positive trisomy 18 screening results. METHODS: Prenatal diagnosis databases were accessed to identify fetuses that had confirmed trisomy 18 karyotypes or were at high risk for trisomy 18 on second-trimester biochemical screening or first-trimester combined screening tests over a period of 10 years from 1 September 1997 to 30 September 2007. RESULTS: Sixty-nine women were confirmed to have trisomy 18 fetuses by karyotyping either prenatally (n = 61) or postnatally/post-miscarriage (n = 8) during the study period. The detection rate of ultrasound scan ≤ 14 weeks and 18 to 21 weeks to detect trisomy 18 was 92.7 and 100%, respectively. A total of 80 and 87% of fetuses had two or more ultrasound abnormalities detected in the ≤ 14 weeks and 18 to 21 weeks anomaly scans, respectively. Forty-eight women screened positive for trisomy 18 by second-trimester biochemical screening with human chorionic gonadotrophin (hCG) and alpha fetoprotein (AFP). Only one was true positive (positive predictive value = 1/48 or 2%). Eleven women screened positive for trisomy 18 by first-trimester combined screening with nuchal translucency scan and maternal serum for pregnancy-associated plasma protein A (PAPP-A) and hCG between 11 and 13 + 6 weeks. Three were true positive (positive predictive value = 3/11 or 27%). All four cases with positive screening had ultrasound abnormalities. CONCLUSIONS: Ultrasound scan for fetal anomalies is the most effective screening test for trisomy 18. A policy of conservative management for women with positive second-trimester biochemical screening or first-trimester combined screening for trisomy 18 is reasonable in the absence of ultrasound fetal abnormalities. Unnecessary invasive tests can be avoided.

Screening options for Down syndrome: how women choose in real clinical setting.

OBJECTIVE: To study pregnant women's preference among various screening options for Down syndrome (DS) in routine clinical setting, and its potential association with women's demographic characteristics. METHODS: Women aged 35 years and older carrying singleton pregnancy were offered a variety of screening tests for DS before 14 weeks of gestation. Their preference was confirmed by the test they actually underwent. The association between women's choice of test and a number of demographic characteristics was studied using multinomial regression. RESULTS: Among 1967 eligible women, 619 opted for first-trimester screening test (FTS), 924 for partial integrated test (PIT), and 424 for full integrated test (FIT). Nulliparous women and working mothers were more likely to choose FTS and FIT. Women with history of subfertility were more likely to choose FIT. Women with family history of chromosomal abnormalities were more likely to choose FTS. The choice of screening test could be predicted for 49.9% of women using four demographic characteristics. CONCLUSIONS: Among older women of predominantly Chinese ethnicity, integrated test is a favorite alternative to FTS. Their choice of DS screening test can be predicted by their obstetric and socioeconomic characteristics. Many women show willingness to pay for a test with a lower false-positive rate.

Effect of fetal diagnosis on the outcomes of second-trimester pregnancy termination for fetal abnormalities: a pilot study.

OBJECTIVE: To explore whether the outcomes of second-trimester pregnancy termination for fetal abnormalities are affected by fetal diagnoses. METHODS: This was a retrospective review of cases undergoing second-trimester pregnancy termination for the fetal diagnoses of hemoglobin Barts, trisomy 21, and trisomy 18 during the period from 1999 to 2006. The affected pregnancies were terminated by vaginal misoprostol. The outcome measures were: (1) abortion within 24 hours after misoprostol commencement, (2) histology-confirmed incomplete abortion, and (3) experience of significant side effects during termination (temperature over 39 degrees C or need for metoclopramide for vomiting). RESULTS: One hundred and twenty cases were available for analysis. After adjusting for maternal age, parity, history of cesarean delivery, body mass index, gestation, and fetal hydrops, pregnancy termination for trisomy 21 was associated with a higher risk of incomplete abortion than trisomy 18 and hemoglobin Barts (odds ratio 5.25, 95% confidence interval 1.24-22.19, p = 0.024). The chance of abortion within 24 hours and experience of significant side effects were not found to be associated with fetal diagnosis. CONCLUSIONS: Pregnancy termination for trisomy 21 is associated with a higher risk of incomplete abortion. Fetal diagnosis affects the outcome of pregnancy termination.

The effect of gestational age on the outcome of second-trimester termination of pregnancies for foetal abnormalities.

OBJECTIVE: To explore the effect of gestational age on the outcome of second-trimester termination of pregnancies for foetal abnormalities. METHOD: A retrospective study was conducted on 280 pregnancies terminated for foetal abnormalities in the second trimester using vaginal misoprostol. The gestational age at termination was divided into three groups: 13-16 weeks, 17-20 weeks and 21-23 weeks. The likelihood of (1) abortion within 24 h of commencement of misoprostol, (2) incomplete abortion and (3) experiencing significant side effects was compared among these three gestational groups after adjusting for maternal age, parity and body mass index (BMI). RESULTS: Compared to termination after 20 weeks, pregnancy termination for foetal abnormality before 17 weeks of gestation was associated with higher chance of incomplete abortion (OR 2.2, 95% CI 1.07-4.61, p = 0.032) and lower chance of experiencing significant side effects (OR 0.11, 95% CI 0.01-0.91, p = 0.041). CONCLUSION: Women undergoing pregnancy termination for foetal abnormalities in the early second trimester should be informed of possible higher chance of incomplete abortion.

Universal screening of human immunodeficiency virus infection in pregnant women in Hong Kong: prospective study.

OBJECTIVE: To evaluate universal screening with an opt-out approach of pregnant women for human immunodeficiency virus infection. DESIGN: Prospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: All women booked or delivered in Kwong Wah Hospital from 1 January 1999 to 30 November 1999 were recruited. MAIN OUTCOME MEASURES: Numbers of women who received the human immunodeficiency virus antibody screening test, refused the test (and the reasons why), tested positive, and tested positive with confirmation by immunoblot study. RESULTS: A total of 5597 women were recruited and 5459 screening tests performed in this study. Of the 16 screened positive cases, three were confirmed by immunoblot study. The overall acceptance rate for the test was 97.5%. The acceptance rate among the 5191 women recruited through the hospital's booking clinic was not significantly different from that among the 406 women who did not go through the hospital's booking clinic (97.6% versus 96.6%). CONCLUSION: Universal screening of pregnant women for human immunodeficiency virus infection with an opt-out approach is practical, feasible, and clinically acceptable in Hong Kong.

Interparticle forces in binary and ternary ordered powder mixes.

An ultracentrifuge technique, previously described by Staniforth et al (1981), has been used to study the adhesion profiles of several binary and ternary ordered powder mixes of pharmaceutical interest. The adhesion profile of an ordered mix provides information about the proportion of drug powder adhering with different forces of attraction to the carrier excipient particle surface. The excipient particle size is shown to affect adhesion between the components of a binary ordered mix-recrystallized lactose formed more stable ordered mixes with drug powder when the carrier particle size was increased. Changes in the adhesion profile of each binary system on adding three different fine-powder excipients to form a ternary ordered mix are also examined. The physical properties of carrier particles and the charge interactions of a third powder component with previously formed binary ordered mixes, are found to influence the physical stability of ternary ordered mixes.