Clinical significance of fetal choroid plexus cysts

A Bayesian risk analysis for Trisomy 21 in isolated choroid plexus cyst: combining a prenatal database with a meta-analysis

OBJECTIVE

The purpose of this study was to quantify the possible additional risk of a fetus with an isolated choroid plexus cyst (ICPC) for Trisomy 21 by combining a large controlled cohort study with data from existent studies.

METHODS

We searched our prenatal database between 2000 and 2014 for all singleton pregnancies between 18 + 0 and 26 + 6 gestational weeks with either an isolated choroid plexus cyst (study group) or no abnormality found in the detailed ultrasound scan (control group). We assessed all prenatal karyotyping results if invasive testing was performed and attempted to collect the postnatal outcome reports of all patients. The prevalence of Down syndrome was calculated. By using previous studies that met our inclusion criteria, a meta-analysis following the Bayesian Independent Model was created. From this meta-analysis, we computed the posterior predictive distribution of the probability (Trisomy 21 | ICPC) = P1 including posterior means, standard deviations, quantiles (2.5, 50, and 97.5%). By calculating the posterior of the difference (Δ) between the probability (Trisomy 21 | ICPC) and the probability (Trisomy 21 | Normal Ultrasound) = P2, we investigated the additional risk of an ICPC (ΔB = P1-P2).

RESULTS

Overall, we detected 1220 fetuses with an isolated plexus cyst at 19-27 weeks of gestational age (GA). In our study group, the prevalence of Trisomy 21 was 2/1220 (0.16, 95% CI: 0.1-0.6%). The median of the pooled probability of Trisomy 21 given isolated PC across the studies included in the meta-analysis was 0.2% (CI: 0.1-0.4%). In the given periods (GA and time), 66,606 (74.8%) out of 89,056 investigated fetuses met the inclusion criteria and had a normal ultrasound result without any abnormality. The Δ between our study group and the control group was 0.08% (CIΔA: 0-0.5%). Including the meta-analysis, the median of the posterior distribution of Δ between P1 and P2 was 0.08% (CIΔB: 0-0.4%) (ΔB = P1-P2).

CONCLUSION

The posterior distribution of Δ between P1 and P2 including the meta-analysis corresponds to showing no difference between the cases and controls (95% CIΔB: 0-0.4%). The additional risk of a fetus with an ICPC for Trisomy 21 is 97.5% likely to be lower than 0.4% (about 1/250). However, in our collective, the positive predictive value of ICPC for Down syndrome was 0.16% (about 1/625). In prenatal counseling, the additional risk should be added to the individual risk (based on maternal age, earlier screening test results, and sonographic markers) and the diagnostic options including fetal DNA and diagnostic procedures should be discussed according to the posterior individual risk.

Association of Fetal Choroid Plexus Cysts With Trisomy 18 in a Population Previously Screened by Nuchal Translucency Thickness Measurement

OBJECTIVE

The study's aim was to determine any association between choroid plexus cysts (CPCs) and trisomy 18 in a population of fetuses previously screened by nuchal translucency (NT) thickness measurement.

METHODS

During the study period (May 1999 to December 2004), 7,795 fetuses had an NT scan and second-trimester fetal anatomical scan at our institution. The prevalence of trisomy 18 was determined among four types of pregnancies: 1) those with isolated CPCs, 2) those with CPCs and enlarged NT, 3) those with CPCs and other ultrasound markers, and 4) those with CPCs, enlarged NT, and other ultrasound markers. The fetal outcome according to NT and presence of CPCs was calculated. Incidence rates of enlarged NT and CPCs in fetuses with trisomy 18 and fetuses with normal chromosomes were also evaluated.

RESULTS

For the entire population, ten trisomy 18 cases were diagnosed prenatally (prevalence, 0.13%). Among fetuses with enlarged NT, the likelihood ratio of trisomy 18 was significantly increased in fetuses with CPCs compared with fetuses without such cysts (333.6 versus 15.2, P = .002). However, among fetuses with normal NT, no significant difference was demonstrated for likelihood ratio of trisomy 18 between fetuses with and without CPCs.

CONCLUSION

In pregnancies complicated by isolated CPCs, fetal karyotyping is not indicated when no additional anomaly is detected on ultrasonographic examination and first-trimester NT results are normal.

Neonatal cranial sonography: A concise review for clinicians

Cranial sonography continues to hold an important place in neonatal care. Attributes favorable to sonography that make it almost indispensable for routine care of the newborn includes easy access, low cost, portability, lack of ionizing radiations and exemption from sedation or anaesthesia. Cranial sonography has highest impact in neonates suspected to have meningitis and its complications; perinatal ischemia particularly periventricular leukomalacia (PVL); hydrocephalus resulting from multitude of causes and hemorrhage. Not withstanding this, cranial sonography has yielded results for a repertoire of indications. Approach to cranial sonography involves knowledge of the normal developmental anatomy of brain parenchyma for correct interpretation. Correct technique, taking advantage of multiple sonographic windows and variable frequencies of the ultrasound probes allows a detailed and comprehensive examination of brain parenchyma. In this review, we discuss the technique, normal and variant anatomy as well as disease entities of neonatal cranial sonography.

Ultrasound screening: Status of markers and efficacy of screening for structural abnormalities

Aneuploidy is a major cause of perinatal morbidity and mortality and can have a significant impact on expecting parents and their families. With early screening and diagnosis it is important to be able to educate parents regarding the potential impact of the diagnosis. This knowledge allows parents the opportunity to consider management options early in the pregnancy, permitting more time to mentally and emotionally prepare both for the course of the pregnancy, and after the birth of the child should the pregnancy continue. Prenatal screening provides pregnant women a non-invasive risk assessment for the most common aneuploidies. Those who are considered "high-risk" then have the option for additional diagnostic (invasive) testing. Prior to the 1980s, prenatal screening consisted of risk assessment through maternal age; however, with the advent of maternal serum biochemical analysis and ultrasound, the field of prenatal screening developed significantly. As biochemical and sonographic advances continued into the 1990s, the emphasis shifted to risk assessment in the first trimester, with the combination of maternal serum analytes and sonographic evaluation of the nuchal translucency.(1) Within the last decade, the introduction of non-invasive screening (NIPT/S) has shown great impact on the expansion and evolving practice of prenatal screening. Although in many places the standard for prenatal testing continues to include maternal serum analytes and sonographic evaluation, the role of each marker alone and in combination remains important. In the era of increasingly available screening tests, especially with NIPT/(NIPS), this article attempts to review the current role of ultrasound in prenatal care and elucidate the role of ultrasound markers in prenatal screening.

Sonographic markers for early diagnosis of fetal malformations

Fetal malformations are very frequent in industrialized countries. Although advanced maternal age may affect pregnancy outcome adversely, 80%-90% of fetal malformations occur in the absence of a specific risk factor for parents. The only effective approach for prenatal screening is currently represented by an ultrasound scan. However, ultrasound methods present two important limitations: the substantial absence of quantitative parameters and the dependence on the sonographer experience. In recent years, together with the improvement in transducer technology, quantitative and objective sonographic markers highly predictive of fetal malformations have been developed. These markers can be detected at early gestation (11-14 wk) and generally are not pathological in themselves but have an increased incidence in abnormal fetuses. Thus, prenatal ultrasonography during the second trimester of gestation provides a “genetic sonogram”, including, for instance, nuchal translucency, short humeral length, echogenic bowel, echogenic intracardiac focus and choroid plexus cyst, that is used to identify morphological features of fetal Down’s syndrome with a potential sensitivity of more than 90%. Other specific and sensitive markers can be seen in the case of cardiac defects and skeletal anomalies. In the future, sonographic markers could limit even more the use of invasive and dangerous techniques of prenatal diagnosis (amniocentesis, etc.).

State-of-the-art cranial sonography: Part 2, pitfalls and variants

OBJECTIVE

In the first part of this article, modern cranial sonography techniques and interpretation were discussed, emphasizing ways in which the application of modern imaging technology and techniques are able to enhance detection of pathologic abnormalities on cranial sonography.

CONCLUSION

In this part of the article, we will describe pitfalls and variants that may be confused with pathologic abnormalities. Emphasis will be placed on recognizing normal variations and distinguishing them from pathologic abnormalities that may require additional imaging or clinical follow-up.

The history of the second-trimester sonographic markers for detecting fetal Down syndrome, and their current role in obstetric practice

This review summarizes the development, history and use of second-trimester sonographic markers for the detection of fetal Down syndrome over three decades. Starting with the nuchal fold thickening in 1985 and culminating in the genetic sonogram in the 1990 s. The combination of second-trimester serum screening with the ultrasound markers improved the detection rate of affected fetuses but also allowed patients to decrease their risk of carrying a fetus with Down syndrome if the genetic sonogram was normal. More recently the role of the genetic sonogram and its markers have changed with the wide spread use of first-trimester screening. This prior screening ultimately decreases the prevalence of fetal Down syndrome in the second trimester to less than 85% of what it was in the first-trimester as most fetuses with Down syndrome are now identified early. Current interpretation of the second-trimester Down syndrome markers must be based on the result of the first trimester and combined screening to achieve the most accurate risk estimate of an affected fetus.

A large choroid plexus cyst diagnosed with magnetic resonance imaging in utero: a case report

The incidence of choroid plexus cysts represents approximately 1% of fetal anomalies. We describe a case in which fetal ultrasonography and fetal magnetic resonance scans were used to identify a large choroid cyst in a fetus without the use of a diagnostic amniocentesis to detect aneuploidy. After birth, the child underwent surgery. In conclusion, the nature of prenatal intracranial cysts should be fully evaluated and differentiated between choroid plexus cysts and other types of cysts. We believe that a detailed evaluation of detected cysts and other structural brain abnormalities are essential. Prenatal magnetic resonance scans clearly can decrease the need for risky procedures, such as an amniocentesis, in the evaluation of antenatal choroid plexus cysts.

Parental level of anxiety, sense of coherence and state of mind when choroid plexus cysts have been identified at a routine ultrasound examination in the second trimester of pregnancy: a case control study

The aim of the study was to compare parents' experience of a routine ultrasound examination in the second trimester, when a choroid plexus cyst/cysts (CPC) were found (Study group; n = 22), with matched controls where no fetal deviations were identified (Control group, n = 66). All the parents had participated in a larger cohort study. The instruments used for measuring anxiety were STAI-state/trait, sense of coherence (SOC) and Parents' Expectations, Experiences, Reactions to an Ultrasound examination during pregnancy (PEER-U, State of Mind Index). Regarding the SOC and STAI-state/trait no significant differences were found between the cases and controls or within the respective group before and after the ultrasound examination. The cases had an increase in anxiety (more anxious) as measured by the instrument PEER-U after the examination, while the controls showed a significant better level of State of Mind Index (less anxious) after the examination, compared to before. Therefore PEER-U can be a more reliable instrument when studying state of mind (anxiety) in connection with ultrasound examinations, and as it is specific for this situation it does not appear to be time dependent.

Information for better or for worse: interviews with parents when their foetus was found to have choroid plexus cysts at a routine second trimester ultrasound

The aim of the study was to gain a theoretical understanding of parents' experiences and handling of the situation, when their foetus was diagnosed as having choroid plexus cysts, at a routine second trimester ultrasound examination. Nine couples and one mother were interviewed using one open question. Analysis method was Grounded Theory. The main concern was anxiety and the core category became need for knowledge. The other categories were frightening and confusing, judging risk and making a choice and comforting. The parents felt information during the ultrasound examination was insufficient. The time delay between the diagnosis and the doctor's appointment was also often criticized. Most of the parents in this study wanted to know what can be diagnosed by ultrasound, even if there is a small risk that the child will have a malformation or chromosome abnormality. However, when the diagnosis is made, they need adequate information, otherwise unnecessary anxiety arises. By giving sufficient information without days of delay, anxiety can hopefully be minimized. Some written information was also requested. It is of utmost importance that the staff use the same terminology and the correct name of the soft marker to the parents.

[Mode of delivery and neurosonographic findings in premature infants]

INTRODUCTION

Fetal and preterm infant brain is especially vulnerable to hemorrhagic and ischemic damage at the end of the second and at the beginning of the third trimester. This is due to vascular, cellular and anatomic characteristics of the brain during development. In premature babies, there is a physiological instability and limited autoregulation of cerebral circulation. Hemorrhagic and ischemic damages often occur together, though pathophysiological processes leading to lesions are different.

MATERIAL AND METHODS

The paper deals with a detailed analysis of 860 ultrasound brain scans of prematurely born children. The examinations were performed at the Ultrasound Department of the Institute of Child and Youth Health Care in Novi Sad. 707 vaginally born premature infants and 153 premature infants born by Cesarean section were examined The bleeding was graded according to the Papile classification.

RESULTS AND DISCUSSION

Out of 384 children with diagnosed grade I hemorrhage, 75 premature infants (19.5%) were born by Cesarean section. In the group of children with grade II hemorrhage, operative deliveries account for 14.7%. From the total of 85 children with grade III hemorrhage, (intraventricular bleeding with chamber dilatation), only 6 premature infints were born by Cesarean section (7%). Intra-parenchymal bleeding was diagnosed in a very small number of premature infants: 0.32% of all diagnosed hemorrhages were grade IV hemorrhages. In this group there were no children born by Cesarean section. The increase of hemorrhage grade is accompanied by a greater rate of pelvic presentation and manual assistance by Bracht. There were 240 prematurely born children with no echosonographicallY diagnosed hemorrhage, 38% of all examined premature infants. From this number, 13.3% of neonates were born by Cesarean section.

CONCLUSION

In the etiology of neonatal intracranial hemorrhage, especially prematurely born ones, apart from the trauma, which plays a major role, other factors are also important, above all fetal distress, perinatal hypoxia and junctional immaturity of all organs.

Women's response to fetal choroid plexus cysts detected by prenatal ultrasound

OBJECTIVES

To determine maternal responses to detection of a minor structural variant, the choroid plexus cyst (CPC), in their fetus on prenatal ultrasound.

STUDY DESIGN

We interviewed 34 pregnant women with an isolated CPC detected on mid-pregnancy ultrasound about their objective experience at diagnosis, emotional response and subsequent reactions. Audiotaped, transcribed responses were evaluated by two independent raters and analyzed qualitatively and quantitatively.

RESULTS

All women reported negative emotional responses including shock, distress, fear and decreased attachment, despite counseling by 82% of providers that the CPC was probably benign. Three women underwent amniocentesis purely for reassurance after CPC detection. Most (79%) sought information beyond what their physician provided, frequently on the internet. One half of women reported that intense negative responses were temporary. However, weeks after diagnosis, 62% continued to believe that the CPC presented some danger to their baby.

CONCLUSIONS

Detection of CPC prenatally can evoke profound, negative maternal emotional responses despite accurate provider counseling. Practitioners should consider these responses when counseling parents about these and other structural variants of unclear functional significance.

[An ultrasound protocol in premature infants with intracranial hemorrhage]

INTRODUCTION

Prematurity is a great health problem in our country and in the world. There are more than 11% of premature births in America annually, and in Europe this rate is between 5-10%. In Vojvodina, 9% of babies are born prematurely. Intracranial hemorrhage takes a sifnificant place in the morbidity of prematurely born children.

INTRACRANIAL HEMORRHAGE IN PREMATURE NEWBORN INFANTS

Incomplete CNS development of premature infants causes numerous complications, but it is also the factor which enables survival of extremely immature infants without sequelae. The management protocol depends on the level of hemorrhage. Early diagnosis of intracranial hemorrhage and determination of the level of hemorrhage are of utmost importance for disability prevention.

ULTRASOUND IN MONITORING INTRACRANIAL HEMORRHAGE

Brain monitoring of prematurely born babies is performed by ultrasound. This type of visualization has several advantages over other techniques: it is mobile, so colled "bedside technique", it is relatively cheap, it may be repeated several times, it is possible to define the exact time of hemorrhage and monitor its absorption from day to day. Ultrasound is safe, and there is no ionized radiation. No sedation is required for ultrasound examination. The examination is not painful.

CONCLUSION

The frequency of ultrasound depends on the level of hemorrhage, presence or absence of ventriculomegally/hydrocephalus, as well as on the surrounding cerebral parenchyma.

Antenatal diagnosis of central nervous system anomalies: can we predict prognosis?

Our technical ability to diagnose fetal anomalies of the central nervous system by ultrasonography and by fetal magnetic resonance imaging far exceeds our current knowledge of their possible neurodevelopmental implications later in life. This limitation often makes obstetric and clinical decisions very difficult. We retrospectively reviewed the ultrasonographic records of 6220 women who had been followed up at two large medical centers between 1994 and 1999. One hundred and sixty (2.6%) women had abnormal fetal central nervous system findings. The neurodevelopmental outcome of these children was assessed by a telephone interview with the parents. Small cerebellar size was the most frequent anomaly, followed by isolated mild ventriculomegaly and isolated choroid plexus pathology. Suboptimal neurodevelopmental outcome was found in 24% of children with isolated ventriculomegaly and in 9% with choroid plexus pathology. In the group of children with a "small cerebellum," suboptimal neurodevelopment was found in 19%. The measurement of transcerebellar diameter in respect to its developmental implication is, to our knowledge, described here for the first time. We believe that cerebellar measurements and their possible neurocognitive implications should be an integral part of future studies.

Antenatal neurosurgical counseling: approach to the unborn patient

The detection and diagnosis of structural anomalies of the fetal central nervous system has become commonplace. Therefore, the pediatric neurosurgeon who will eventually care for a child postnatally can be called upon to interpret the meaning of diagnostic studies and advise the prospective parents prenatally. This article discusses some principals of prenatal counseling as they relate to neurosurgical conditions, reviews the diagnostic armamentarium for defining neurosurgical fetal conditions, and describes the common antenatal diagnoses that may be encountered by the neurosurgeon.

Second trimester choroid plexus cysts and trisomy 18

OBJECTIVES

In this study, the aims were to reveal the incidence of isolated choroid plexus cyst in our population, and to discuss the accuracy of distinguishing either an isolated or non-isolated choroid plexus cyst.

METHODS

The study population was consisted of 10594 pregnant women. The patients with choroid plexus cysts were classified into two groups: isolated and non-isolated. Detailed ultrasonographic examination and genetic counseling were performed and triple screening test was ordered. The incidence, sensitivity, specificity, false-positive rate and likelihood ratio of cases with isolated choroid plexus cyst for trisomy 18 were determined.

RESULTS

Choroid plexus cysts were identified in 109 patients (109/10594; 1.02%). In 102 patients isolated choroid plexus cysts, and in seven patients additional fetal anomalies supporting trisomy 18 were detected. Trisomy 18 was detected in four patients, and one of them had isolated choroid plexus cyst. The likelihood ratio in cases of isolated choroid plexus cysts for trisomy 18 was 9.51 (95% confidence interval, 0.2-41).

CONCLUSIONS

According to the study the individual risk for trisomy 18 in isolated choroid plexus cyst should be calculated by using the likelihood ratio. These data allows the physician to express the individual risk of trisomy 18 and permits more accurate genetic counseling.

Sonography of fetal choroid plexus cysts: detection depends on cyst size and gestational age

OBJECTIVE

To establish diagnostic criteria for the diagnosis of fetal choroid plexus cysts across gestation.

METHODS

Prenatal sonographic images of 166 fetuses without choroid plexus cysts were prospectively collected from 13 weeks to term. Texture characteristics of the choroid plexus regions were analyzed to quantify changes as a function of gestational age. A set of 20 fetal sonographic images with choroid plexus cysts were used to create cyst prototypes (1.5-2.5 mm), which were randomly embedded into normal choroid plexus images from varying gestational ages. A test set of 544 images was created, which included 408 images with choroid plexus cysts and 136 images without choroid plexus cysts. Four observers following a blinded study design evaluated the presence of choroid plexus cysts in the images. The influence of cyst size and gestational age on the detection of cysts was measured with receiver operating characteristic analysis and analysis of variance. Observer agreement was characterized by agreement kappa statistics.

RESULTS

Texture analysis indicated greater echo texture heterogeneity at earlier gestational ages. The receiver operating characteristic analysis showed a corresponding decrease in diagnostic accuracy for cyst detection at earlier gestational ages. The cyst detection threshold (area under the receiver operating characteristic curve, 0.8) was 2.4 mm (SE, 0.2 mm) for 13 to 21 weeks' gestation and decreased to 1.9 mm (SE, 0.17 mm) for 22 to 38 weeks' gestation. Average interobserver and intraobserver kappa statistics were 0.37 and 0.53, respectively.

CONCLUSIONS

Because of the changing echo texture of the choroid plexus through gestation, choroid plexus cysts must be at least 2.5 mm in diameter for confident diagnosis before 22 weeks' gestation and at least 2 mm after 22 weeks.

Prenatal diagnosis for detection of aneuploidy: the options

The value of all noninvasive prenatal tests must be viewed with the perspective of the consequences of invasive testing. Regarding second trimester noninvasive testing, biochemical screening is more accurate in establishing risk than maternal age alone. One or more major ultrasound abnormalities, nuchal thickening, or a shortened humerus should raise concern for Down syndrome regardless of the patient's a priori risk based on age or biochemical markers. Isolated minor ultrasound markers should not be used in calculating risk in low-risk patients regarding Down syndrome unless the biochemical profile already places the patient at risk or in a borderline risk zone. If the ultrasound finding is hyperechoic bowel, problems other than aneuploidy may be the cause, including cystic fibrosis, infection, or hemorrhage, and these problems must be considered if hyperechoic bowel is an isolated finding. Improved risk adjustment seems to be applicable to a priori high-risk patients with completely normal sonograms. Genetic sonograms with specific risk adjustment schemata may be used to adjust a priori risk (either maternal age or biochemical screening results) at centers in which this has proven to be accurate, but whether this is statistically sound remains to be determined. The goal of second trimester ultrasound screening is to identify at-risk fetuses better and offer invasive testing to a more select group of patients. As the value of first trimester screening becomes more evident and practical, and if the risk of chorionic villus sampling becomes an acceptable norm, the patient population that reaches the second trimester of pregnancy will be select. Therefore, we can anticipate that second trimester screening and invasive testing may be needed only in a minority of cases, and the practice standards of prenatal testing and sonography (including minor ultrasound markers) will change entirely.

Isolated choroid plexus cyst in low-risk women less than 35 years old

OBJECTIVE

The purpose of this study was to determine the incidence of trisomy 18 in women who are <35 years old and who have sonographically detected isolated choroid plexus cyst.

STUDY DESIGN

A meta-analysis of prospective trials that were published in the English language between 1990 and 2000 was performed. Each trial met the following inclusion criteria: (1) prospective trial, (2) total population screened during the study period reported, (3) maternal age (either numeric or descriptive) reported, and (4) pregnancy/neonatal outcomes reported. An isolated choroid plexus cyst for the purpose of this study was defined as absence of sonographically detected structural abnormalities and normal serum analyte screens, if reported.

RESULTS

Eight trials met the criteria and were used for analysis. A total of 106,732 women were screened through articles that were published between 1990 and 2000. The total number of fetuses with choroid plexus cysts that were identified in second-trimester scans were 1,235 (incidence, 1.2%). The incidence of isolated choroid plexus cysts in women who were <35 years old was 1.0% (n = 1,017 women). There were no cases of trisomy 18 in women with isolated choroid plexus cyst who were <35 years old. Four structural abnormalities were noted on postnatal examination; all four neonates had normal karyotypes.

CONCLUSION

There is no evidence that detection of isolated choroid plexus cyst in women who are <35 years of age increases the risk of trisomy 18. Therefore, amniocentesis is not warranted because of the inherent risk of pregnancy loss that is associated with the procedure. Better algorithms are needed to screen women who have a low risk for trisomy 18.

Choroid plexus cysts in the mid-trimester fetus--practical application suggests superiority of an individualized risk method of counseling for trisomy 18

OBJECTIVES

Analysis of a referral population of patients with choroid plexus cysts (CPCs) was performed to compare an average risk method of counseling to an individualized risk method.

METHODS

A total of 395 patients referred to a Prenatal Diagnosis Center were included, of whom 341 had isolated CPCs and 54 had associated ultrasound abnormalities. For isolated CPCs, an average risk of 1/150 for aneuploidy was compared to an individualized risk assessment [prior risk as determined by maternal age or serum screening multiplied by the likelihood ratio established by Gupta et al. (1997)]. Accuracy, cost, and procedure-related losses were assessed.

RESULTS

Both methods resulted in 100% sensitivity. The individualized method resulted in greater specificity, decreased costs, and (theoretically) fewer procedure-related pregnancy losses.

CONCLUSIONS

An individualized risk method of counseling utilizing the likelihood ratios established by Gupta et al. (1997) was superior to an average risk method for assessing trisomy 18 risk in the setting of CPC detected in mid-trimester.

The value of minor ultrasound markers for fetal aneuploidy

As a result of improvements in ultrasound image quality and scanning technique, an increasing number of subtle morphological changes in fetal anatomy have been identified in the second trimester. Most of these ultrasound features were originally described as normal variants of development with no clinical significance. However, subsequent studies in high-risk populations showed that some of these variants were more prevalent in fetuses with chromosomal defects and therefore proposed as prenatal markers for the detection of aneuploidy. The implications for pregnancy management when one of these so-called minor ultrasound markers is detected have been a matter of continuous controversy in the field of prenatal diagnosis and yet the definitive answer on their clinical significance in the low-risk population is still debated.

Central nervous system anomalies

Fetal central nervous system abnormalities encompass a variety of lesions. Most of the anomalies are seen in association with an increased incidence of fetal aneuploidy and an increase in other anomalies both within and outside of the central nervous system. These associated findings and the underlying lesion all have a role in the eventual prognosis for the ongoing pregnancy. The antenatal diagnosis of a central nervous system abnormality should prompt a careful search for other defects, and consideration should be given for genetic evaluation and testing.

Sonographic markers of fetal aneuploidy

A variety of ultrasound findings can be identified in fetuses with fetal aneuploidy. Typical findings vary with both the chromosome abnormality and gestational age at time of the ultrasound examination. Increased NT is the primary marker during the first trimester, whereas a variety of markers may be seen during the second trimester. The presence of ultrasound markers increases the risk for fetal aneuploidy, whereas a normal ultrasound reduces the risk. Optimal risk assessment includes consideration of other risk factors including maternal age, family history, and biochemical markers. It is expected that combined risks, incorporating ultrasound findings and biochemistry, will be available in the near future. How first-trimester screening is integrated with second-trimester screening remains to be determined.

Parental decision-making differences between patients in two healthcare systems for choroid plexus cysts

We evaluated the medical-sociological implications of parental perception of risk and decision-making choices for prenatally ascertained choroid plexus cysts (CPC) between two obstetric populations. The Wayne State University (WSU) Reproductive Genetics database and the Madigan Army Medical Center (MAMC) experience were reviewed to compare the rates of aneuploidy and invasive testing for cases with CPC. Aneuploidy rates were compared between those with isolated CPC, CPC with advanced maternal age (AMA), and CPC associated with multiple anomalies. In the WSU cohort 186 cases were identified, of whom 27 (15%) declined invasive fetal testing. In the remaining 159 cases, aneuploidy was present in 2/132 (1.5%) isolated CPC, 3/11 (27%) CPC with AMA, and 15/16 (93%) CPC with multiple anomalies. In the MAMC cohort 107 cases were identified, of whom 99 (92%) declined invasive fetal testing. No aneuploidy cases were found in the 3/12 AMA cases or 5/95 non-AMA cases that underwent amniocentesis. The two cases of aneuploidy with isolated CPC cannot be ignored, and provide an estimated attributable risk of at least 0.8%, a higher risk than 38 years of age. However, the parental sociologic context may be as important for decision-making as the genetic-prognostic risk.

Ultrasonographic markers for chromosomal abnormalities in women with negative nuchal translucency and second trimester maternal serum biochemistry

OBJECTIVE

To analyze the value of second trimester ultrasound examination among those women whose fetuses were indicated to be at low risk of chromosomal anomalies on the basis of both first trimester nuchal translucency measurement and second trimester biochemical screening.

METHODS

A retrospective study of 5500 pregnancies carried out at the fetal medicine unit, Royal Free Hospital. During a period of over 3 years 5500 pregnancies underwent a first trimester scan and nuchal translucency measurement which enabled the detection of 62% (20 of 32) of all chromosomal anomalies. From the remaining pregnancies that underwent second trimester biochemical screening, 3548 were considered negative (risk < 1:250; using maternal serum free beta human chorionic gonadotrophin and alpha fetoprotein). The ultrasound markers that were examined were: shortened femur length, echogenic bowel, pyelectasis, choroid plexus cysts and echogenic intracardiac foci. The likelihood ratios for chromosomal aneuploides for each of these markers were calculated.

RESULTS

Of the 3548 screen negative pregnancies, 3541 (99.8%) had a normal karyotype. Seven (0.2%) fetuses had an abnormal karyotype including four (0.11%) with trisomy 21, one with trisomy 18 and two with 47XXY. Second trimester ultrasound markers were found in two of the five (40%) with severe chromosomal anomalies compared to 184 of 3541 (5.2%) with normal karyotypes. Detection of one or more ultrasound markers in a screen negative pregnancy increased the possibility of chromosomal aneuploidy and a negative ultrasound decreased the risk by a likelihood ratio of 0.6 (95% confidence interval, 0.3-1.3). The risk was considerably increased when two or more markers were detected and we would recommend karyotyping under these circumstances.

CONCLUSION

This preliminary data indicates a possible role for abnormal ultrasound markers in assessing the risk of chromosomal abnormalities in patients considered to be at low risk by nuchal translucency and serum screening. However analysis of a much larger study group will have to be conducted to assess the significance of individual markers.

Second trimester markers of aneuploidy

The risks of aneuploidy associated with identification of a sonographic marker in the low risk population is controversial. Prior risk estimates have been derived usually from high risk populations. Screening programmes in the first trimester, second trimester and combined first and second trimester will undoubtedly alter the second trimester scan as a screening tool for aneuploidy. This chapter reviews the current sonographic markers and the difficulties in their application to the general population.

Ultrasound markers of fetal chromosomal abnormality: a survey of policies and practices in UK maternity ultrasound departments

OBJECTIVE

To evaluate the management of pregnancies where the fetus was found to have one or more sonographic markers of possible fetal chromosomal abnormality.

DESIGN

Prospective anonymous postal survey of UK obstetric ultrasound units.

MAIN OUTCOME MEASURES

The management of pregnancies where the fetus is found to have a sonographic marker of aneuploidy.

POPULATION

All 252 maternity ultrasound units in the United Kingdom.

METHODS

Postal questionnaire to the superintendent sonographer in routine maternal ultrasound departments.

RESULTS

Questionnaires were returned from 179 maternity units (71%). Of the respondents 94% offered a fetal anomaly scan at 16-20 weeks' gestation and 59% performed a dating scan at 10-14 weeks. Screening for Down syndrome was available in 99% of all maternity units. The recognition of sonographic 'soft signs' for possible fetal chromosomal abnormality varied considerably between the units. When sonographers were asked about their unit's policy regarding offering amniocentesis to women with sonographic markers, 8-78% discussed amniocentesis when the marker was isolated and 53-88% when another abnormality was found. Eighty nine percent of units documented the abnormal ultrasound findings in the hospital notes and 88% of the women were informed of the findings regardless of the intention to offer amniocentesis.

CONCLUSION

The practice of routine ultrasound examination is well established in UK, though precise policies vary. The existing wide variations in management policies possibly reflect a lack of data derived from low risk populations. There is a need to collect such data from low risk populations with known screening practices so that national guidelines to standardize practice can be formulated.

Isolated fetal choroid plexus cysts: role of ultrasonography in establishment of the risk of trisomy 18

OBJECTIVE

The significance of isolated choroid plexus cysts found by ultrasonographic scan during the second trimester as a marker for trisomy 18 is still debated. We analyzed our data and reviewed the series published in the English-language literature to calculate the likelihood ratio of trisomy 18 in the presence of isolated choroid plexus cysts; that is, the factor by which the individual risk of trisomy 18 is increased in the presence of isolated choroid plexus cysts.

STUDY DESIGN

Likelihood ratios were calculated as ratio of the sensitivity to the false-positive rate. Sensitivity was defined as the rate of isolated choroid plexus cysts detected at midgestation among fetuses with trisomy 18. False-positive rate was defined as the rate of choroid plexus cysts detected at midgestation in the population without trisomy 18. The sensitivities of all published series reporting rates of choroid plexus cysts at the time of the first ultrasonographic examination between 14 and 24 weeks' gestation in populations with trisomy 18 and in low-risk populations were included in the analysis. To these we added all cases of trisomy 18 diagnosed at our institution during the period January 1, 1988, through June 30, 1998, in which prenatal ultrasonographic examination was performed between 14 and 24 weeks' gestation.

RESULTS

The prevalence of second-trimester ultrasonographic detection of isolated choroid plexus cysts among fetuses with trisomy 18 was 6.7% (13/194), whereas that in the population without trisomy 18 was 0.9% (752/79,583). The likelihood ratio associated with isolated choroid plexus cysts was therefore 7.09 (95% confidence interval, 3.97-12.18).

CONCLUSION

The presence of isolated second-trimester choroid plexus cysts increases the base risk of trisomy 18 by a factor of 7.09. This likelihood ratio can be multiplied by the risk calculated according to maternal age to obtain the individual risk of trisomy 18 and thus permit more accurate counseling of the patient.

Ultrasound screening for fetal chromosome anomalies

Ultrasound evidence for aneuploidy may be found in almost every organ of the fetus and can be used to modify the risk of aneuploidy. The diagnosis of these minor anomalies on second-trimester ultrasonography will increase the risk of an abnormal karyotype whereas the absence of these findings may reduce this danger. The most specific and most ominous isolated markers for fetal aneuploidy are nuchal findings (edema or cysts), indicating the need to obtain a fetal karyotype in all cases irrespective of maternal age or results of biochemical serum screening. Hyperechoic fetal bowel is apparently also a strong indicator of fetal aneuploidy. Other isolated sonographic markers may increase the risk of an abnormal karyotype three- to ninefold. Most sonographic markers for aneuploidy specify an increased risk for Down syndrome, but choroid plexus cysts are apparently more specific for trisomy 18. Along with other screening methods, ultrasound screening for fetal aneuploidy should be used routinely to identify additional pregnancies at need for evaluation of fetal karyotype.

Prenatal karyotyping of choroid plexus cysts

OBJECTIVES

A retrospective, descriptive study of 50 cases with choroid plexus cysts diagnosed by ultrasonography.

METHODS

All case charts were studied and additional information was collected regarding children born outside Uppsala.

RESULTS

All 50 cases were offered a test for chromosome aberrations, 46 accepted and were tested by chorion villi sampling or amniocentesis. In ten cases additional malformations were found, including one trisomy 13 and one trisomy 18. No relationship was found between the diameter, bilaterality or the complexity of the cyst.

CONCLUSIONS

Fetus with choroid plexus cysts should be examined carefully by ultrasonography. Since the complication risk of invasive diagnostic procedures is very small these patients may be offered a test for chromosomal aberrations.

The fetal head: borderlines

After more than 20 years of using ultrasound to examine the fetal head, there are still areas of controversy. The size of the ventricular atrium or the anteroposterior measurement of the posterior fossa have been shown to be relatively stable throughout pregnancy. However, there are instances in which intracranial malformations occur with normal ventricular atrial measurements. Although there are more obvious posterior fossa defects such as Dandy-Walker malformation, there are other abnormalities such as Dandy-Walker variant that are difficult to detect. Another area of controversy surrounds dealing with the fetus with a choroid plexus cyst. Review and understanding of the current literature are needed to best manage these fetuses with choroid plexus cysts. Knowledge of central nervous system embryology and of technical pitfalls of sonography, and understanding the overlap between normal and abnormal anatomy are needed to obtain a more precise central nervous system diagnosis. This article will review some of the borderlines in examination of the fetal brain.

Screening for chromosomal abnormality

Screening for fetal abnormalities has become one of the most high profile health care issues of modern times. This issue is predicated on major advances in health care technology that permit wider detection of fetal anomalies, including the development of more advanced biochemical markers and improvements in ultrasound imaging. The effectiveness of these screening methods and their rational application is a point of great controversy, and is the cause of considerable unease in clinical obstetrical practice. This article reviews the general concepts of fetal screening for fetal chromosome abnormalities and then focuses on certain aspects of ultrasound screening that are particularly controversial. The scientific basis for each ultrasound finding (e.g., nuchal translucency) is reviewed, as well as the frequently divergent clinical experience with the finding. Finally, a plea is made for the development of a more scientific database for fetal ultrasound screening, and the setting of fetal screening guidelines for practicing physicians based on diagnostic accuracy and cost-effectiveness.

Choroid plexus cysts and aneuploidy

The association of choroid plexus cysts with fetal aneuploidy, particularly trisomy 18, was first noted in 1986. Through the years there have been numerous reports on this subject, but no consensus has been reached with regard to chromosomal risk. In this review, we attempt to summarise published reports on second trimester choroid plexus cysts, with an emphasis on the strengths and weaknesses of each report. Based on these reports, additional malformations are a significant risk factor for aneuploidy and an indication for determination of fetal karyotype. The management of isolated choroid plexus cysts remains controversial.

The role of ultrasonographic markers for trisomy 21 in women with positive serum biochemistry

OBJECTIVE

To assess the value of particular markers detected by second trimester ultrasound examination among those women whose fetuses were shown to be at increased risk of Down's syndrome on the basis of biochemical screening.

DESIGN

A retrospective study of 459 pregnancies.

SETTING

Fetal Medicine Unit, Royal Free Hospital.

PARTICIPANTS

Four hundred and fifty-nine pregnant women, including four twin pregnancies, registered at the Royal Free Hospital, who were considered screen positive (risk > 1:250) based on the results of mid-trimester biochemical markers (maternal serum free beta human chorionic gonadotrophin and alpha-fetoprotein).

MAIN OUTCOME MEASURES

The ultrasound markers that were examined included structural defects, shortened femur length, echogenic bowel, dilation of the renal pelvis and choroid plexus cysts. The likelihood ratios for trisomy 21 for each of these markers were calculated.

RESULTS

Of the 463 fetuses which were screen positive, 449 (97%) had a normal karyotype detected by amniocentesis (n = 344) or postnatal follow up (n = 105). Fourteen fetuses had an abnormal karyotype including 11 (2.4%) with trisomy 21. Ultrasound markers were found in 9/11 (81.8%) fetuses with trisomy 21, compared with 44/449 (9.8%) with a normal karyotype. Detection of one or more ultrasonographic markers in a screen positive pregnancy increased the risk of trisomy 21 by a likelihood ratio of 8.4, and the absence of such markers decreased the risk by a likelihood ratio of 0.2. The risk was considerably increased when the presence of two or markers were detected (likelihood ratio 41). In trisomy 21 fetuses the two most commonly detected markers, shortened femur and dilation of the renal pelvis, had likelihood ratios of 49.3 and 20.5, respectively. Choroid plexus cysts were detected in 27 of the normal karyotypic fetuses compared with none of those with trisomy 21.

CONCLUSION

The presence or absence of abnormal ultrasonographic markers can significantly change the risk of Down's syndrome among pregnant women already found to have abnormal serum biochemistry. This data may be useful in counselling such women.

Choroid plexus cysts--association with trisomy: prospective review of 16,059 patients

OBJECTIVE

The purpose of the study was to determine the incidence of isolated choroid plexus cysts in association with trisomy 18 and other abnormalities.

STUDY DESIGN

All patients from June 1992 through December 1995 were followed up after a screening ultrasonography. Any patient with a choroid plexus cyst was offered genetic counseling and an amniocentesis. Screening ultrasonographic examinations were performed on 16,059 patients, and 301 patients had a fetus with a choroid plexus cyst. One hundred thirty patients elected to have an amniocentesis. Patients were followed up to delivery.

RESULTS

Two hundred sixty-three patients had an isolated choroid plexus cyst. Thirty-eight patients had a choroid plexus cyst associated with additional risk factors. Risk factors included advanced maternal age, additional ultrasonographic abnormalities, past obstetric history, or family history. No abnormalities were noted in the group with an isolated choroid plexus cyst. Four patients had an abnormality when the choroid plexus cyst was associated with an additional risk factor, including two patients with trisomy 18 and one with trisomy 21.

CONCLUSION

An isolated choroid plexus cyst was not associated with a trisomy or other abnormalities in this study. When a choroid plexus cyst was associated with an additional risk factor, 10.5% of the patients had an abnormality. Amniocentesis is recommended when a choroid plexus cyst is found in association with additional risk factors.

Ultrasonographically adjusted midtrimester risk of trisomy 21 and significant chromosomal defects in advanced maternal age

OBJECTIVE

Our purpose was to determine whether normal midtrimester ultrasonography results reduces the risk of fetal Down syndrome and any clinically significant chromosomal defects in pregnancies with advanced maternal age and to develop risk tables on the basis of age and ultrasonographic results.

STUDY DESIGN

Biometry data were obtained in 4079 women between 15 and 24 weeks undergoing amniocentesis for maternal age. Expected values of humerus, femur, both combined, and abdominal circumference based on biparietal diameter were generated from a normal group. Observed/expected values of each parameter and nuchal thickness > or = 6 mm was used to screen for Down syndrome and any clinically significant chromosome defects. Receiver-operator characteristic curves were used to determine threshold screening values for each parameter. By use of stepwise logistic regression the optimal measurements for detection of chromosome anomalies were established. An abnormal ultrasonography result was defined as either abnormal biometry choroid plexus cysts or a structural defect.

RESULTS

The finding of shortened humerus (observed/expected < 0.90), abnormal nuchal thickness, or an anatomic defect had the highest sensitivity for Down syndrome detection, 70.6%, p < 0.0001, whereas a short humerus, small abdominal circumference, (observed/expected < 0.92), or an anatomic defect had a sensitivity of 46.7%, p < 0.0001, for any significant chromosome defect. With a normal ultrasonography the risk of Down syndrome in a 39-year-old woman falls from 1:100 to < 1:292.

CONCLUSION

A normal ultrasonography substantially reduces the risk of Down syndrome and any chromosome abnormality. This information is useful in counseling women who decline amniocentesis on the basis of maternal age.