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Hepatitis B virus (HBV) infection remains a global threat and causes a substantial disease burden. The World Health Organization has set a goal to eliminate viral hepatitis as a public health threat by 2030. Mother-to-child transmission (MTCT) is the main route of HBV transmission. Most MTCT cases can be prevented by timely active and passive immunisation at birth, but failed immunoprophylaxis in infants continues to occur among women with a high viral load during pregnancy. Hepatitis B virus disease activity in infected mothers should be assessed during early pregnancy, and multidisciplinary management with antiviral medication should be offered to women with a high viral load. In these guidelines, we present management strategies for HBV-infected pregnant women that are intended to reduce the risk of MTCT in Hong Kong.

Introduction: Postpartum haemorrhage is a major cause of maternal mortality and morbidity, commonly due to uterine atony. Prophylactic oxytocin use during Caesarean section is recommended; patients with a high risk of postpartum haemorrhage may require additional uterotonics or procedures. Carbetocin is a long-acting analogue of oxytocin which has shown beneficial results, compared with oxytocin. This study compared the requirement for additional uterotonics or procedures between at-risk women who underwent carbetocin infusion and those who underwent oxytocin infusion. Methods: This retrospective cohort study included women at increased risk of postpartum haemorrhage after Caesarean section for various indications in a public hospital. Women who received carbetocin infusion and women who received oxytocin infusion were compared, stratified by Caesarean section timing (elective or emergency). The primary outcome was the requirement for additional uterotonic agents or procedures. Secondary outcomes included total blood loss, operating time, rate of postpartum haemorrhage, need for blood transfusion, and need for hysterectomy. Results: Of 1236 women included in the study, 752 received oxytocin first and 484 received carbetocin first. The two groups had comparable blood loss, operating time, rate of postpartum haemorrhage, requirement for additional uterotonics or procedures, need for blood transfusion, and need for hysterectomy. There was a reduction in the requirement for additional uterotonics or procedures, and in the rate of postpartum haemorrhage for women with major placenta praevia or with multiple pregnancies, following receipt of carbetocin first. Conclusion: Compared with oxytocin, carbetocin can reduce the requirement for additional uterotonics or procedures in selected high-risk patient groups.

In 2011, a large multicentre study showed significant variation in the cut-off values for mean gestational sac diameter (MSD) and embryo crown-rump length (CRL) used to define miscarriage.3Some cut-off criteria were found to be potentially unsafe with a risk of inadvertent termination of a potentially viable pregnancy.3 Since then, cut-off values of MSD and CRL defining miscarriage have been changed in the United Kingdom and the United States to [greater than or equal to]25 mm (without an obvious yolk sac) and [greater than or equal to]7 mm (without fetal heart activity), respectively.3 4It was noted that in the guidelines for first-trimester ultrasound examination published by the Hong Kong College of Obstetricians and Gynaecologists in 2004, old cut-offs (20 mm for MSD and 5 mm for CRL) were used.5 A review of these cut-offs is required. Care must be taken when CRL measurement is close to any decision boundary for miscarriage or when MSD is being measured because of its high inter-observer limit of agreement, around 20%.6 When a miscarriage is found by one examiner, a repeat scan by another examiner is a reasonable safeguard.4 A repeat scan [greater than or equal to]7 days later will be appropriate if initial scan shows an embryo without heart activity or MSD [greater than or equal to]12 mm without embryo heart activity.4 A repeat scan [greater than or equal to]14 days will be appropriate if MSD [lesser than]12 mm.4 Among women with intrauterine pregnancy of uncertain viability (PUV), the miscarriage rate is 49.3% to 52%.7 8 Prediction of pregnancy outcome is a challenge and is necessary because it can assist counselling and decide frequency of follow-up ultrasonography. Interestingly, the authors found that moderate/ severe abdominal pain is a risk factor on univariate analysis, but this finding was not confirmed on multivariate analysis probably because vaginal bleeding was a cofounding factor.7 When ultrasound shows fetal cardiac activity, the subsequent rate of miscarriage is 5.2% to 10.4%.7 9 10 A meta-analysis of 18 eligible studies on ultrasound markers among 5584 women found that fetal bradycardia is the most significant marker, with a sensitivity of 84.2% in the prediction of miscarriage.11 A more recent study found that the combination of low fetal heart rate and small CRL increases the risk of subsequent pregnancy loss, from 5.0% to 21%.10 Because fetal heart rate varies with gestation, cut-offs for low fetal heart rate of ≤122, ≤123, and ≤158 beats per minute for gestational weeks 6, 7, and 8, respectively, have been proposed.10 Other investigators have suggested a single fetal heart rate cut-off at ≤110 or 100 beats per minute to predict miscarriage.11 12 Other ultrasonographic markers associated with miscarriage include a small difference between MSD and CRL,13 and abnormal size of yolk sac.14Using three-dimensional ultrasonography, small gestational sac volume (below the 5th percentile) is associated with risk of miscarriage with odds ratio of 5.25.15 In a recent study of 61 miscarriages, abnormal size of gestational sac and yolk sac appeared as early as 6 weeks of gestation, followed by abnormal changes in fetal heart rate and CRL at 7 and 8 weeks.14 Although subchorionic haematoma was found to be a predictor of miscarriage in a meta-analysis11and in the study by Wan et al,7 a recent study on pregnancies with detectable fetal heartbeat did not concur with these findings.10 A meta-analysis of 15 studies including 1263 women with threatened miscarriage found that serum CA 125 is the only serum marker that is useful in predicting outcome of a pregnancy with a viable fetus, whereas serum human chorionic gonadotropin and progesterone are not useful.16 Bottomley et al17 proposed a scoring system which included a combination of demographic and ultrasound variables to predict miscarriage. Women with threatened miscarriage are at risk of anxiety and depression,19 and may react to miscarriage in different ways.20 Healthcare professionals should receive training on communication, and provide affected women with information and support in a sensitive and professional manner.18 20 During interpretation of ultrasound guidelines to diagnose miscarriage, other factors should be taken into consideration, including the woman's desire to continue their pregnancy or to postpone intervention to achieve total certainty of miscarriage, and their acceptance of disadvantages of such postponement including emergency admission or procedure for heavy vaginal bleeding and anxiety.12 In summary, it is important to avoid misdiagnosis of miscarriage by using updated protocols and repeating scans if in doubt.

Background Autosomal recessive or compound heterozygous mutations in KLHL40 cause nemaline myopathy 8, which is one of the most severe forms of nemaline myopathy. The KLHL40 c.1516A>C variant has recently been reported as a founder mutation in southern Chinese. Methods We report six cases of nemaline myopathy 8 which involves the c.1516A>C variant, from five unrelated families of non‐consanguineous southern Chinese. The pre‐ and postnatal phenotypes of these cases were reviewed with emphasis on prenatal clinical features. Genetic testing for the founder mutation was performed on three patients with homozygous mutations. Results Common prenatal features included reduced fetal movement, polyhydramnios, breech presentation, and clubfeet. Two pregnancies were terminated. Four live‐born patients had postnatal features typical of nemaline myopathy 8. The length of survival ranged from 49 days to 17 months, with respiratory failure and infections being the principal causes of death. Haplotype analysis in three patients with homozygous mutation showed a shared haplotype block of 1.1727 cM spanning over the c.1516A>C variant, suggesting it is a southern Chinese‐specific founder mutation. Conclusion Analysis of the KLHL40 c.1516A>C variant should be considered in prenatal diagnosis of Chinese pregnant patients with suspected congenital neuromuscular disorders or with significant family history of congenital myopathies. We reported six cases from five unrelated families of non‐consanguineous southern Chinese affected by nemaline myopathy 8, with either homozygous variants or compound heterozygous variants involving c.1516A>C in KLHL40. Pre‐ and postnatal phenotypes of the cases were reviewed, with emphasis on the prenatal clinical features.

Objectives: To determine associations between fetal rib number anomalies detected on ultrasonography and chromosomal anomalies and other structural anomalies, and the outcome of affected pregnancies. Methods:All cases of fetal rib number anomalies referred to the Prenatal Diagnosis Clinic of Queen Elizabeth Hospital between 1 January 2016 and 31 December 2019 were reviewed. Fetal ribs were examined by static threedimensional multiplanar or volume contrast ultrasonography. Genetic counselling was offered. The prenatal and postnatal records were reviewed. Results: 21 fetuses with rib number anomalies were identified over 4 years. The most common presentation was unilateral or bilateral absence of the 12th thoracic rib (n=12, 57.1%), followed by the presence of lumbar rib (n=6, 28.6%) and the presence of cervical rib (n=3, 14.3%). Three (14.3%) fetuses were identified to have anomalies in other systems: unilateral absence of nasal bone (n=1) and minor vascular anomalies (n=2). One patient with multiple anomalies of the fetus underwent amniocentesis, and the chromosomal microarray analysis was normal. Postnatally, 13 babies had chest radiographs taken. Two were confirmed to have normal number of ribs. Prenatal and postnatal findings were consistent in 6 (46.2%) babies. Conclusion: Fetal rib number anomalies were an isolated finding in most cases. The prognosis is good in the absence of other major anomalies. The accuracy of prenatal ultrasonography appears to be low. These findings do not support routine counting of fetal rib number in second-trimester ultrasonography.

Objective: To determine the prevalence of asymptomatic bacteriuria (ASB) and its effects on the obstetric outcome in Hong Kong pregnant women. Methods: This was a 6-month prospective observational study carried out in a local obstetric unit, from December 2011 to June 2012. Singleton pregnant women who attended their first antenatal visit during the first trimester, and without symptoms of urinary tract infection (UTI) were recruited. Midstream urine was collected. ASB was defined as a positive culture of >105 colony forming units per ml (CFU/ml) in the absence of white blood cells on microscopy. Treatment was given as appropriate. Their obstetric outcome was evaluated by statistical analysis using odds ratio, t test, and Chi-square test to determine significance. Results: The incidence of ASB and UTI was 1.7% and 1.6%, respectively. For ASB, the most commonly isolated bacteria was Escherichia coli (38.1%) followed by Streptococcus agalactiae (19.0%). Compared with the control group, the maternal age was younger in the ASB group, but no differences were found in the other characteristics. There was significantly higher risk of neonatal intensive care unit admission and pre-eclampsia with respective odds ratio of 4.2 and 6.8 in the ASB group, but no significant difference was noted in the other outcomes. There was significantly higher risk of low-birth-weight baby (<1500 g) in the borderline bacterial count (≥104 and <105 CFU/ml) group with an odds ratio of 5.9. Conclusion: There was a higher risk of adverse obstetric outcome in Hong Kong pregnant women with ASB detected during the first trimester.