Gerald Mason

Ultrasound screening for chromosomal abnormality: Women's reactions to false positive results

Objective. Ultrasound scans have become a routine part of antenatal care. Recent developments have meant that ultrasound has gone beyond monitoring the pregnancy and diagnosis of major abnormalities. Its routine use now includes screening for subtle fetal abnormalities and indications of chromosomal abnormality. Unfortunately ultrasound screening for chromosomal abnormalities has a low positive predictive value (similar to maternal serum screening), and only about 2% of pregnancies identified as ‘high risk’ will be diagnosed with a chromosomal abnormality. The other 98% of ‘high risk’ results are termed ‘false positive’. The aim of this paper is to elucidate the range of subjective experiences of women in response to having these results. Method. The approach employed was interpretative phenomenological analysis. Semi-structured interviews were carried out with 24 pregnant women after ‘false positive’ ultrasound results. These were subjected to a qualitative analysis. Results. Participants perceived the ultrasound scan primarily as a social, non-medical event and were unprepared for the result the scan elicited. Two-thirds described residual feelings of anxiety even after normal diagnostic results were known, sometimes attributed to continued fears about fetal abnormality, but more often attributed to a generalized feeling that something else unexpected could happen to threaten the pregnancy. Conclusions. The paper has pointed to important discrepancies in the experiences of women undergoing ultrasound screening and the aims of informed choice. We would suggest consideration should be given to providing information on both the medical purposes of screening and on possible outcomes from it. The study also points to the possible need for counselling support for the majority of women who go on to receive confirmation of a negative diagnosis, counselling addressed at helping women to readjust to having a ‘low risk’ pregnancy.

CLINICAL SIGNIFICANCE OF FETAL CHOROID PLEXUS CYSTS

Choroid plexus (CP) cysts are commonly detected on routine mid-trimester ultrasound scan. When associated anomalies are detected, the risk is sufficient to justify an invasive diagnostic test such as amniocentesis. However, the risk when no associated anomalies are detected is much less well defined. This information is required to determine the appropriate management in cases of apparently isolated CP cysts. We thought the only way to resolve the difficulties in counselling prospective parents was to conduct a prospective study in a large unselected population. A registry of fetal CP cysts detected over 3 years in the Yorkshire Region was compiled and we identified 524 CP cysts. These cases were then amalgamated and analysed with 1361 cases from prospective studies reported in the world English literature and a further 71 unpublished cases identified from a 2 year prospective series from Ninewells Hospital, Dundee. The risk of chromosomal abnormalities was 1 in 150 (95% CI 1 in 85, 1 in 261) when no fetal anatomic abnormalities, apart from the CP cysts themselves, were detected antenatally. The risk increased to approximately 1 in 3 if any other associated ultrasound abnormalities were detected antenatally. The risk did not appear to be related to whether or not cyst size diminished as gestation progresses, whether they were unilateral or bilateral, and whether they were small or large in size (60-80% < 10 mm). 76% of aneuploidic cases were trisomy 18 and 17% were trisomy 21. The risk of Downs syndrome in fetuses with CP cysts but no other anomalies detected antenatally is 1 in 880. The probability of a chromosomal abnormality is high when CP cysts are associated with any other antenatally detected anomaly, indicating a clear need to offering amniocentesis. The predictive value is much lower when no other anomalies are detected. In such cases, it is probably advisable to regard CP cysts as an indication for detailed ultrasound assessment, rather than invasive testing.

Symphysis pubis dysfunction—a cause of significant obstetric morbidity

OBJECTIVES To investigate the prevalence and severity of symphysis pubis dysfunction (SPD) in pregnancy and the postnatal period. DESIGN A postnatal questionnaire was sent to 248 women who had been referred to the Obstetric Physiotherapy Department in 1997 and 1998 with symptoms of pubic pain either during pregnancy or soon after delivery. SETTING A north of England teaching hospital, The Clarendon Wing, Leeds General Infirmary. PARTICIPANTS Questionnaires were sent to 248 women. One hundred and forty-one were returned (response rate 57%). RESULTS The condition is associated with much unrecognised obstetric morbidity. The prevalence in our unit over the 2-year study period was 1/36 women. Many medical and midwifery staff have little knowledge of SPD. Patients often felt ignored when they complained of pain. One out of four of the respondents were still symptomatic 6 months later. CONCLUSION Further research is needed to identify the best practice in the antenatal care provided, including the provision of support belts, the most appropriate mode of delivery and postnatal treatment.

Differentiation of growth retarded from normally grown fetuses and prediction of intrauterine growth retardation using Doppler ultrasound

Objective To assess the hypothesis that infants exhibiting catch‐up growth as an indicator of intrauterine growth retardation (IUGR) have a higher incidence of predelivery abnormal Doppler results.

A randomised trial of two methods of issuing prenatal test results: the ARIA (Amniocentesis Results: Investigation of Anxiety) trial

Background  Many pregnant women experience anxiety while waiting for the results of diagnostic tests. Policies and practices intended to reduce this anxiety require evaluation.

Poor maternal weight gain between 28 and 32 weeks gestation may predict small-for-gestational-age infants

Summary. In a retrospective analysis of 158 women considered to have had normal, low‐risk pregnancies, 30 gave birth to infants with a birth‐weight less than the 10th centile for gestation. These 30 women had a significantly poorer mean increase in weight (0·99 kg) between 28 and 32 weeks gestation than the other 128 women (1·95 kg) who gave birth to infants with birthweights above the 10th centile for gestation. There was no statistically significant difference in booking weight, overall weight gain or other variables associated with low birthweight between the two groups of women which suggests that poor maternal weight gain specifically between 28 and 32 weeks gestation may predict small‐for‐gestational‐age infants.

Non‐invasive RNA‐based determination of fetal Rhesus D type: a prospective study based on 96 pregnancies

Objectives To develop a non–invasive method for determining fetal RhD status in order to provide improved care for women most at risk.

Preliminary experience with twenty perineal repairs using Indermil tissue adhesive.

OBJECTIVE To assess the use of Indermil tissue adhesive for perineal repair. SETTING Leeds General Infirmary, a teaching hospital with 4500 deliveries annually. METHOD Over a period of five months, 20 women who sustained either a second degree tear or who had an episiotomy at vaginal delivery had their perineal skin repaired with Indermil tissue adhesive. They were followed up prior to discharge and then by telephone once discharged. RESULTS Ten repairs followed normal vaginal deliveries, six were after ventouse deliveries, three after midcavity forceps delivery and one after a rotational forceps delivery. Three women noticed a burning sensation during application of adhesive. At follow up, 13 women were completely without problems, two complained of a sharp sensation from excess adhesive, one had silver nitrate applied at the six week check, two had small defects in the skin which healed well and in two women the skin edges broke down completely but did not need resuturing. CONCLUSION Indermil tissue adhesive appears to be a safe and effective method of skin closure for episiotomies and second degree tears. The skin closure is quick and painless.

The efficacy of intrapartum fetal surveillance when fetal pulse oximetry is added to cardiotocography

OBJECTIVE To determine if oxygen saturation measurement with pulse oximetry (SpO2) in combination with cardiotocograghy (CTG), improves the assessment of the intrapartum fetal condition. STUDY DESIGN Four expert obstetricians individually evaluated 119 cases that were monitored during labor: during the first session the CTG data were available, and in the second session CTG and SpO2 data were evaluated. They were instructed to indicate the need for intervention and to estimate the umbilical artery pH. RESULTS In the non-acidotic group (umbilical artery pH > or = 7.15, n = 112) the average(+/-S.D.) number of interventions decreased from 27(+/-17) to 16(+/-9) when SpO2 was available. This reduction in number of interventions resulted in an significantly increased specificity for two referees. In the acidotic group (n = 7) the average number of interventions also decreased, from 6(+/-2) to 4(+/-2), and as a consequence the sensitivity decreased. The pH estimate based on CTG + SpO2 was higher in both acidotic and non-acidotic fetuses than the estimated pH based on CTG alone. CONCLUSION In this study all referees intervened less frequently when SpO2 was used as an adjunct to CTG. This resulted in fewer unnecessary operative interventions, but may also lead to unidentified fetal acidosis. The number of acidotic newborns (n = 7) was too small, however, to draw definite conclusions. Larger studies should address the efficacy of SpO2 in detecting fetal compromise before clinical use can be advocated.

Pubic symphysis separation

Musculoskeletal complaints are a common source of antenatal and peripartum morbidity, yet are frequently dismissed by healthcare professionals. Although increasing pelvic laxity is thought to be physiological as pregnancy advances, a number of women develop pain and disability out of proportion to the degree of joint distension. The term ‘symphysis pubis dysfunction’ is one of the many used to describe the constellation of typical symptoms and signs. (Table 1) The first formal documentation of the condition is accredited to Snelling in 1870. “The affection appears to consist of a relaxation of the pelvic articulations, becoming apparent suddenly after parturition, or gradually during pregnancy; and permitting of a degree of mobility of the pelvic bones which effectively hinders locomotion, and gives rise to the most peculiar, distressing and alarming sensations.” Although dated his description still provides a succinct description of the condition.