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Kyle, P.M., Coghlan, P., Matthews, J., de Ryke, R. and Reid, R. 2009. Accuracy of prenatal diagnosis in a tertiary fetal medicine unit. NZMJ 122(1288): 50-61.
Since the main purpose of the introduction section is to furnish the theoretical basis of the paper, it should include a research hypothesis, statement and a research question (Branson, R. D. 2004). Kyle. P. M. et al (2009) hypothesized that the main objectives of a foetal medicine unit are to provide accurate diagnosis of the foetal condition and accordingly accurate information about prognosis, management and necessary care on diagnosing abnormalities. Further, they stated that the variability of prenatal screening and foetal diagnosis resulted in worries about the amount of information given, diagnostic accuracy of each modality, which may influences resources allocation. The authors forwarded the research question is prenatal ultrasound application for foetal screening accurate enough as compared to pregnancy outcome whether alive or in the post-mortem? In the introduction section, they provided a short review of previous studies and considered these results either inconsistent, under-diagnosing foetal abnormalities or focusing on specific abnormalities. Therefore, they addressed accuracy in pregnant females referred to a tertiary foetal medicine unit where obtained information will be available to both the referred female and referring physician.
The authors included all cases (681 cases) referred to the Christchurch foetal medicine unit, New Zealand (draining nearly 10000 maternity units) over 18-month period (06/2004 to 11/2005). They later collected relevant outcome data of these pregnancies from neonatal units including post-mortem information. Thus, for a research design they selected a descriptive longitudinal study that is repetitive observations at specified points for all participants during the time-period of the study thus allowing the observation of development (Hedeker, D. and Gibbons, R. D. 2006).
The study results showed that nearly 56% of pregnancies were normal (381 cases), 27% (198 pregnancies) showed major abnormality as a prenatal diagnosis, 46 (6%) pregnancies were minor abnormality and 8% of cases (56) showed nuchal translucency. The pregnancy outcomes were 625 live born neonates (92%), of them prenatal diagnosis was confirmed in 93.6%, 5.1% showed resolution of prenatal diagnosis, which was supported by soft markers. Additional major abnormalities were present in 1.3% of cases (mainly cleft palate, oesophageal and anal atresia). Postmortem examination was performed on 29% of lost pregnancies with only one case (Smith-Lemli-Optiz syndrome) showed significant difference from prenatal diagnosis.
The authors recognized the factors that influence the rate of additional diagnosis after delivery as some abnormalities evolve later in pregnancy, parents refusal of additional testing and difficulty in diagnosis of certain abnormalities as cleft palate and oesophageal atresia. They also identified oligohydramnios and increased maternal BMI as obstacles for accurate ultrasound diagnosis especially in the last trimester. They inferred although the accuracy of prenatal ultrasound diagnosis is high, yet, not all abnormalities can be detected and there is a need to develop clinical indicators to compare outcomes to prenatal ultrasound results.
Articles strengths, weaknesses and reasons for selection.
Longitudinal studies provide significant information about the continuity of a phenomenon or a trend over a period of time and permits tracking of pregnancy changes overtime. However, repeated observations from the same subject are difficult to correlate properly; besides, it provides unsuitable independent information to use for a correlation or regression statistical analysis (Hedeker, D. and Gibbons, R. D. 2006). This was probably the reason why the authors did not provide any statistical analysis for the data obtained. Data collection showed high rate of postnatal data retrieval for live born neonates (only two cases were missed), although postmortem was done in a low percentage of cases. The authors presented their data clearly and the tables were informative, clear and significant. The main weakness of this study is despite having a high rate of normal prenatal diagnosis for a tertiary referral hospital, the authors did not recommend indication for referral based on their results. Thus, the article was selected because of the idea of comparing prenatal ultrasound application to postnatal outcome is interesting, informative and explains the need for other supplementary methods (amniocentesis, MRI&) in selected cases.
Loncar, D. 2007. Comparison of Ultrasonographic Placenta Examination with Pathophysiological Verification of Fetal Anomalies. Acta Medica Medianae 46(2): 71-75.
Loncar, D. (2007) recognised ultrasonography as an important diagnostic modality for growth and developmental disorders of the foetus. The author identified that routine ultrasound application can determine the number of foetuses, foetal position, the amount of fluid surrounding it and providing important foetal biometrics that helps to confirm normal development and growth. Regarding the placenta, routine ultrasound application helps to evaluate placental anatomy about site (localisation), size (volume), insertion and limitation. The research question in this paper was to compare ultrasonographic placental findings to histopathological examination finding in pregnancies verified to be of foetal abnormalities; thus, a decision taken to terminate these pregnancies. In a research article, the introduction is the part that provides an outline of the subject studied highlighting the theoretical framework and the need to study this particular subject. Thus, introduction of a research article has three main components a brief description of the topic, statement of research problem and the background literature. The research problem statement is the part that attracts the readers attention to the scope, impact and the status of the problem studied (Fawcett, J. and Garity, J. 2009). The author provided a research question however did not provide a background literature review nor did the author provide a research problem statement.
The study, retrospectively, included 15 pregnant females scheduled for termination of pregnancy because of foetal anomalies at gestational age between 24 and 28 weeks. Ultrasound examination of the placenta done immediately before the procedure of pregnancy termination and the placental examination performed after the procedure have finished. Thus, the author selected a cross section research design that is examining a population sample at a given time; the sample included is a non-representative convenience (accidental) sample. Non-representative samples are of limited value regarding generalisation since they do not truly represent a population. On the other hand, the cohort effect influences cross-sectional studies design where factors like age or associated systemic disease (as hypertension) can pass unobserved especially with a small sample size (Chaudhuri, A. and Stenger, H. 2005). Based on pregnancy outcome, foetal abnormalities were hydrocephalus, other CNS growth abnormalities and other organ abnormalities. Ultrasound application resulted in three groups of placental abnormalities identifies, which were: group 1, cystic placental degeneration, hydrops placenta or homogenous structure placenta. Group 2 placental abnormalities included placental hypertrophy or hypoplasia and non-homogenous structure placenta with calcification. Group 3 included placental hypoplasia, hydrops placenta and homogenous structure placenta. Based on histopathological examination, 14 placentas showed abundance of progressive inflammatory-degenerative changes with normal umbilical cord blood vessels. Ultrasonography placental finding in different cases with different foetal abnormalities did not show significant changes, which can be because of small sample size.
Articles strengths, weaknesses and reasons for selection.
In addition to the weaknesses mentioned, the author did not comment on pregnancy characteristics as they relate to placental or foetal abnormalities. The small sample size is a main weakness, besides the absence of any statistical analysis. The literature review is poor and the number of references is little (only seven) with more than half of them published before 2000. In addition, the author did not explain properly the theoretical framework of the study; however, the paper is not without strengths. The author forwarded the results in a proper descriptive form and the tables are comprehendible and informative. Besides, the author provided some high quality photographs of placental abnormalities as shown by ultrasonography. This paper was selected because of the importance of the subject of ultrasonic placental examination and linking the changes to placental histopathology. The was looked upon as a possible pilot study for further research on larger samples properly randomised to correlate placental changes observed by ultrasound examination to pregnancy outcome and placental histopathological changes.
Scotet, V., De Braekeleer, M., Audrezet, M-P., Quere, I., Mercier, B., Dugueperoux, I., Andrieux, J., Blyau, M. and Ferec, C. 2002. Prenatal detection of cystic fibrosis by ultrasonography: a retrospective study of more than 346 000 pregnancies. J. Med. Genet. 39: 443-448.
Scotet, V. et al (2002) fulfilled all three components of a research article introduction described by Fawcett, J. and Garity, J. (2009). They pointed to the importance of their research showing that cystic fibrosis is the commonest severe congenital malformation in white race. Further, they showed the gene responsible for this abnormality displays over 1000 mutations, which makes it difficult to identify all mutation by simple genetic screening. In their literature review, the authors recognized that foetal echogenic bowel (bowel shows equal sonographic density as adjacent bone) is identified in a number of chromosomal abnormalities including cystic fibrosis. In addition, although this sign is extensively studied yet, the risk varies from 0 to 33%. Therefore, they tried to assess how effective ultrasonography is in predicting prenatal cystic fibrosis. The research design was a retrospective longitudinal study of 346544 pregnancies in Brittany (west of France) where the region has the highest incidence of cystic fibrosis (CF) in the world over a 10-year period (1991-2000). All females have had routine ultrasonography examination at 22 weeks of pregnancy. Data collected underwent Bayesian analysis to calculate the risk of CF in foetuses with echogenic bowel. Bayesian calculation differs from inferential statistics in that it considers probability a measure of the state of knowledge rather than understanding it as a frequency. Thus, it is useful to resolve problems related to testing a hypothesis or assessing the confidence areas for unknown parameters (Koch, K-R 2007).
Results showed 142 foetuses with ultrasonographic diagnosis of echogenic bowel (4.1%), all were referred for CF prenatal testing. Of the referred cases, 14 foetuses (9.9%) had two gene mutations indicating CF disease, pregnancy was terminated in 9 of these cases. In another 11 cases (7.7%) one gene mutation was detected indicating a carrier rate higher than that of the general population. All 142 infants were examined after birth for CF and none of the negative echogenic bowel was positive for the disease. Congenital abnormalities in non-CF infants were Turner syndrome, Trisomy 21 and Trisomy 18, congenital viral infection, toxaemia gravidis and Fallot tetralogy. Based on their results, the authors inferred that echogenic bowel is significantly linked to increased risk of CF; further, echogenic bowel is a reliable justification to proceed for further genetic prenatal testing to confirm or deny the diagnosis. CF screening by ultrasound application is reliable especially in geographic regions where the disease is common. The main purpose of further genetic workup should focus on identifying one or two gene mutations. The authors considered their results a contribution towards modifying the epidemiology data of the disease particularly in their geographic region.
Articles strengths, weaknesses and reasons for selection.
Although the article is nearly 7 years old, yet, the authors provided a reliable literature review in the introduction and discussion parts with an excellent number of relevant references. The detailed and clear methods section enables readers to assess the work done and to repeat the study if they need to (Hittleman, D., and Simon, A. J. 2006). The selection of Bayesian analysis suited the authors declared objective of assessing the risk of CF in echogenic bowel foetuses. In Bayesian analysis, a probability can be assigned to a hypothesis unlike inferential statistics where the main objective is either accept or reject the null hypothesis (Koch, K-R 2007). Finally the huge sample size is one of a kind so that findings obtained from more than one third of a million cases should be reliable, representative and lead to proper conclusions. For the above mentioned reasons this article was selected for critique and presentation.
Sfakianaki, A. K. and Han, C. S. 2009. Ultrasound in the evaluation of twin pregnancy. Minerva Ginecol, 61(2):127-39
The authors provided a background of the problem volume stating that whereas multiple pregnancies represent 3% of live birth rate; yet, it unequivocally represents 15% of maternal mortality. Their research hypothesis was ultrasound examination proved effective in diagnosing multiple pregnancies and accordingly allows for proper management, which can reduce maternal mortality. This lead the authors to conduct a literature review study on the indications and role-played by ultrasound examination in diagnosing this common occurrence. The authors identified that advances and propagation of assisted reproductive technology has contributed (as an external factors) in increased incidence of twin pregnancy, further they recognised zygosity and chorionicity as the main outcome determining factors. Twins are classified according to zygosity to mono and dizygotic (either from one zygote or from two zygotes respectively), according to chorionicity, they can be mono or dichorionic (one or two sacs with one or two chorions), whereas twins can have one or two amnions (mono or diamniotic). It is understandable that combinations can occur like monochorionic-diamniotic or dichorionic-diamniotic& (Fox, T. B. 2006). The authors suggested that ultrasonography is a reliable tool to diagnose chorionicity but is not able to predict zygosity. Based on their review, the authors summarised the uses of ultrasound in twin pregnancies according to the expected complication as follows; in threatening abortion, ultrasonography is helpful to determine foetal viability, chorionicity and amnionicity. When there are doubts about congenital anomalies, the authors recommend screening for foetal chromosomal abnormality (aneuploidy screening) in the first trimester. In the second trimester, they recommended detailed ultrasound anatomical survey with consideration of foetal echocardiography in special cases like IVF twin pregnancies. In cases of suspected growth delay in relation to gestational age, they advocate serial ultrasonographic examination every 3-4 weeks for dichorionic twins and every 2 weeks for monochorionic ones. In twin-to-twin transfusion syndrome, early diagnosis of chorionicity is important with more frequent surveillance in monochorionic twins, this has to combine with serial ultrasonic growth assessment with attention to foetal bladder and amniotic fluid evaluation every two weeks. At each anatomical ultrasound survey, the cord and placental insertion are assessed. In cases of cord enlargement monoamniotic gestation needs early identification. The authors inferred that ultrasound is an essential part of pregnancy care practice, follow up and early diagnosis of impending complications.
Articles strengths, weaknesses and reasons for selection.
Although the article is recent (April, 2009) and is written by two eminent staff at Yale School of Medicine, yet, the authors did not provide a methodology section, which should includes search terms and their definitions, methods of search and criteria of articles inclusion or exclusion. This article was selected to briefly discuss what is, types and reasons for writing a literature review. Voget, W. P. (1999) defined literature review as a methodical study and interpretation of the research findings published in the scientific literature about a specific topic. In this context, there are three major reasons for writing a literature review; to display a deeper knowledge about a topic, to summarise the current status of knowledge and come up with recommendations for future research. Finally, a literature review may serve to introduce the best evidence-based practice, where in this case it is either an annual review or guidelines for management or diagnosis. There are three main types of literature review, first is the descriptive or narrative type, which is the simplest and just describes the sources available. Second, the critical literature review, which aims at assessing the value of the sources available, comparing sources on quantitative or qualitative grounds, identifying the gaps in current knowledge and producing ideas for future research. Third, is the systematic literature review that uses a more thorough well-defined approach to reviewing the literature and serves to answer a targeted question in a specific area of clinical practice (Ridley, D. 2008). From this perspective, the article discussed is a stand-alone systematic literature review.
Van den Hof, M., Wilson, R. D., et al. 2005. Fetal Soft Markers in Obstetric Ultrasound. J Obstet Gynaecol Can 27(6): 592-612.
The authors defined foetal soft markers in obstetric ultrasound as those findings that can be normal variants; yet, the link to possible foetal chromosomal abnormalities. Although these markers are not diagnostic and vary in the degree of association to chromosomal anomalies, yet, they warrant for consideration especially if accompanied by other non-sonographic factors as maternal age and positive past or family history. Therefore, the authors sponsored by the Society of Obstetricians and Gynaecologists of Canada designed a critical literature review to introduce the best evidence-based practice in assessing foetal soft markers in obstetric ultrasound. The authors outlined five research questions to answer; first to assess the efficacy of each marker, second to determine what specific marker (s) to look for. Third is to assess possible non-karyotypic inferences of these markers, fourth to suggest follow up recommendations and finally to provide an assessment of the quality of information for each marker. The authors used the likelihood ratio to measure the degree of association between markers and risk of foetal abnormality. This ratio encompasses both sensitivity of a test and its specificity providing a direct assessment of how ultrasonography result might link to a chromosomal anomaly (Peat, J., and Barton, B. 2005).
The authors classified foetal soft markers into those useful for screening ultrasound (can be detected at 16-20 weeks screening US), those useful for comprehensive ultrasound examination (diagnosis is considered at tertiary level evaluation) and soft markers not established for clinical practice. The first group included echogenic intracardiac focus, mild pyelectasis, single umbilical artery, echogenic bowel, thickened nuchal fold, mild ventriculomegaly, choroid plexus cysts and enlarged cysterna magna. The second group included short femur length, short humerus length, nasal bones hypoplasia and fifth finger clinodactyly. The third group included brachycephaly, increased iliac angle, small foetal ear length and sandal gap. The authors acknowledged that prenatal diagnosis of foetal chromosomal abnormalities is of importance particularly to parent and that further investigative procedures can be invasive and can lead, although rarely, to foetal loss. Therefore, the decision should always be voluntary; however, the counselling healthcare giver should be capable of integrating all risk factors and be non-directive in advice. Van de Hof et al (2005) inferred identification of soft markers for foetal chromosomal abnormalities implies correlation with other risk factors like maternal age and serum testing results. In order to augment management options, apt referral to confirm diagnosis, counselling and further investigations are necessary.
Articles strengths, weaknesses and reasons for selection.
Tharpe, N (2005) defined clinical practice guideline as the rules a healthcare provider uses to determine a diagnostic test or a treatment plan for an individual patient. Intended as practice guidelines, this review article included all items of a proper literature review, search terms and their definitions, criteria for quality of evidence assessment and criteria of recommendations. It included well-phrased research questions, and came in a well organized comprehensive format. Analysis of each soft marker ended with concise specific recommendations, with the discussion section wrapping things up. The article included photographs for each foetal soft marker described. For these reasons this article was selected.
Notes
Branson, R. D. 2004. Anatomy of a research paper. Respiratory Care 49(10): 1222-1228.
Chaudhuri, A. and Stenger, H. 2005. Survey Sampling Theory and Methods Second Edition. Boca Raton, FL: Chapman & Hall/CRC.
Fawcett, J. and Garity, J. 2009. Evaluating Research for Evidence-Based Nursing Practice. Philadelphia, PA: F. A. Davis Company.
Fox, T. B. 2006. Multiple Pregnancies: Determining Chorionicity and Amnionicity. Journal of Diagnostic Medical Sonography 22: 59-64.
Hedeker. D. and Gibbons, R. D. 2006. Longitudinal Data Analysis. Hoboken, NJ: Wiley Interscience.
Hittleman, D. and Simon, A. J. 2006. Interpreting educational research: an introduction for consumers of research (4th edition). Upper Saddle River, NJ: Merrill.
Koch, K-R. 2007. Introduction to Bayesian Statistics Second Edition. New York: Springer.
Kyle, P.M., Coghlan, P., Matthews, J., de Ryke, R. and Reid, R. 2009. Accuracy of prenatal diagnosis in a tertiary fetal medicine unit. NZMJ 122(1288): 50-61.
Loncar, D. 2007. Comparison of Ultrasonographic Placenta Examination with pathophysiological Verification of Fetal Anomalies. Acta Medica Medianae 46(2): 71-75.
Peat, J. and Barton, B. 2005. Medical Statistics A Guide to Data Analysis and Critical Appraisal. Oxford, UK: Blackwell Publishing Ltd.
Ridley, D. 2008. The Literature Review: A Step-by-Step Guide for Students (Sage Study Skills Series). Thousand Oaks, CA: Sage Publications.
Scotet, V., De Braekeleer, M., Audrezet, M-P., Quere, I., Mercier, B., Dugueperoux, I., Andrieux, J., Blyau, M. and Ferec, C. 2002. Prenatal detection of cystic fibrosis by ultrasonography: a retrospective study of more than 346 000 pregnancies. J. Med. Genet. 39: 443-448.
Sfakianaki, A. K. and Han, C. S. 2009. Ultrasound in the evaluation of twin pregnancy. Minerva Ginecol, 61(2):127-39.
Tharpe, N. 2004. 2004-2005 Clinical Practice guidelines for Midwifery & Women Health. Boston, USA: Jones & Bartlett Publishers.
Van den Hof, M., Wilson, R. D., et al. 2005. Fetal Soft Markers in Obstetric Ultrasound. J Obstet Gynaecol Can 27(6): 592-612.
Voget, W. P. 1999. Dictionary of Statistics and methodology. Thousand Oaks, CA: Sage Publications.
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