Dawn Chia

Sonographic diagnosis and successful medical management of an intramural ectopic pregnancy

We report a case of posterior wall intramural pregnancy in a 36‐year‐old primigravida at 6 weeks gestation. Sonographic examination showed a viable intramural pregnancy distorting the contour of the uterus. The pregnancy was terminated by intrafetal injection of potassium chloride followed by intra‐amniotic methotrexate injection.

Determination of gestational age in twin pregnancy: Which fetal crown–rump length should be used?

For twin pregnancy, discrepancies in the crown–rump length (CRL) between two fetuses often exist. Evidence is lacking regarding which fetal CRL should be used for estimation of gestational age (GA). Our aim was to determine whether the larger, smaller or the mean CRL is more accurate in determining the GA in the first trimester of pregnancy.

Predominant patterns of median nerve displacement and deformation during individual finger motion in early carpal tunnel syndrome.

Idiopathic carpal tunnel syndrome (CTS) is a common neuropathy, yet the pathologic changes do not explain the fleeting dynamic symptoms. Dynamic nerve-tendon interaction may be a contributing factor. Based on dynamic ultrasonographic examination of the carpal tunnel, we quantified nerve-tendon movement in thumb, index finger and middle finger flexion in normal subjects and those with mild-idiopathic CTS. Predominant motion patterns were identified. The nerve consistently moves volar-ulnarly. In thumb and index finger flexion, the associated tendons move similarly, whereas the tendon moves dorsoradially in middle finger flexion. Nerve displacement and deformation increased from thumb to index finger to middle finger flexion. Predomination motion patterns may be applied in computational simulations to prescribe specific motions to the tendons and to observe resultant nerve pressures. By identification of the greatest pressure-inducing motions, CTS treatment may be better developed. Symptomatic subjects displayed reduced nerve movement and deformation relative to controls, elucidating the physiologic changes that occur during mild CTS.

MID-MOTION DEFORMATION OF MEDIAN NERVE DURING FINGER FLEXION: A NEW INSIGHT INTO THE DYNAMIC AETIOLOGY OF CARPAL TUNNEL SYNDROME

Carpal tunnel syndrome (CTS) exists in a spectrum of severity and symptoms with a dynamic component. We aim to study dynamic nerve-tendon interrelationships in normal and mild CTS wrists during a fist motion, with dynamic ultrasound. We observed that in normal wrists, the nerve arcs in an ulnar-volar direction and changes from a circular shape to a flat oval during motion. In CTS candidates, however, the curvature and distance of the nerves path are reduced, while nerve shape remains relatively constant. In all candidates, the nerve is compressed against the flexor retinaculum, with the nerve subject to less compression in normal candidates as it moves dorsally into a recess. These findings suggest that besides mechanical compression from increased carpal tunnel contents alone, a decrease in nerve gliding movement may lead to CTS symptomatology. Furthermore, we identified that maximum nerve deformation occurs mid-motion, supporting the use of wrist splints for symptom relief.

The Role of Transvaginal Ultrasonography and Colour Doppler Imaging in the Detection of Ectopic Pregnancy

Objective: To assess the use of transvaginal ultrasound and colour Doppler imaging in the detection of ectopic pregnancy.

Routine screening with fetal echocardiography for prenatal diagnosis of congenital heart disease

ABSTRACTCongenital cardiac anomalies are the most common congenital anomalies, occurring in approximately eight of 1000 live births. Proper perinatal and neonatal management is dependent upon accurate prenatal diagnosis. Approximately 10% of fetuses with cardiac abnormalities have identified risk factors; hence, most of the anomalies occur in pregnancies without prenatal risk factors. The application of detailed fetal echocardiography for prenatal screening, at present reserved mainly for high-risk cases, requires further evaluation before being recommended for the general population.This article presents our experience of evaluating the accuracy of fetal echocardiography as a screening method in detecting cardiac anomalies in the general population of Singapore. We reviewed data from 39 808 pregnant women who received antenatal care at the National University Hospital, Singapore, between January 1986 and December 1994, and who underwent routine fetal echocardiography at 21–22 weeks of gestation. We ident...

Functional compartmental space: the missing link in the pathogenesis of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common compressive neuropathy, yet its exact aetiology remains unknown. Ultrasonographic examination of the carpal tunnel inlet showed anechoic areas distributed around the nerve and tendons. The areas were measured during fist motion in 10 asymptomatic and 10 CTS-symptomatic individuals, and correlated with the ‘symptom severity’ and ‘functional status’ scores in the Boston Carpal Tunnel Questionnaire (BCTQ). All candidates exhibited a sinusoidal variation of anechoic spaces during flexion-extension, and the maximum anechoic space for each candidate was termed the ‘functional compartmental space’ (FCS). Normal candidates exhibited a greater FCS than CTS-symptomatic candidates, who consequently displayed decreased tendon translation and increased nerve compression against the flexor retinaculum due to a smaller FCS. A larger FCS appears to accommodate flexor-tendon translation and prevents the mechanical impingement of the nerve. This finding may be a conceptual li...

Early fetal blood sampling--another available option for early prenatal diagnosis.

Fourteen cases had early fetal blood sampling (FBS) performed between 13 and 18 weeks gestation in the Antenatal Diagnostic Centre, National University Hospital, Singapore from Jan 1988 to December 1994. The indications were: a) ultrasound abnormality (n = 6), b) hydrops (n = 1), c) screening for blood disorders (n = 2), d) amnio results inconclusive or to confirm abnormal amnio results (n = 5). This article analyses retrospectively the early FBS procedure and its outcome. There were no procedure related fetal losses in this study. The reliable rapid results obtained following the procedure enabled the obstetrician to counsel the couple regarding the current pregnancy and advise them accordingly for the subsequent pregnancy. Thus we found it useful not only in our patients but also for patients from overseas who get their results within a week to plan their stay.

Characterization of the hemodynamic wall shear stresses in human umbilical vessels from normal and intrauterine growth restricted pregnancies

Significant reductions in blood flow and umbilical diameters were reported in pregnancies affected by intrauterine growth restriction (IUGR) from placental insufficiency. However, it is not known if IUGR umbilical blood vessels experience different hemodynamic wall shear stresses (WSS) compared to normal umbilical vessels. As WSS is known to influence vasoactivity and vascular growth and remodeling, which can regulate flow rates, it is important to study this parameter. In this study, we aim to characterize umbilical vascular WSS environment in normal and IUGR pregnancies, and evaluate correlation between WSS and vascular diameter, and gestational age. Twenty-two normal and 21 IUGR pregnancies were assessed via ultrasound between the 27th and 39th gestational week. IUGR was defined as estimated fetal weight and/or abdominal circumference below the 10th centile, with no improvement during the remainder of the pregnancy. Vascular diameter was determined by 3D ultrasound scans and image segmentation. Umbilical artery (UA) WSS was computed via computational flow simulations, while umbilical vein (UV) WSS was computed via the Poiseuille equation. Univariate multiple regression analysis was used to test for the differences between normal and IUGR cohort. UV volumetric flow rate, UA and UV diameters were significantly lower in IUGR fetuses, but flow velocities and WSS trends in UA and UV were very similar between normal and IUGR groups. In both groups, UV WSS showed a significant negative correlation with diameter, but UA WSS had no correlation with diameter, suggesting a constancy of WSS environment and the existence of WSS homeostasis in UA, but not in UV. Despite having reduced flow rate and vascular sizes, IUGR UAs had hemodynamic mechanical stress environments and trends that were similar to those in normal pregnancies. This suggested that endothelial dysfunction or abnormal mechanosensing was unlikely to be the cause of small vessels in IUGR umbilical cords.