Should i have chorionic villus sampling

For example, for women 35 years of age, the risk is 1 per births 0. Before widespread use of amniocentesis, several controlled studies were conducted to evaluate the safety of the procedure. The major finding from these studies was that amniocentesis increases the rate for miscarriage i.

Subsequent to these studies, amniocentesis became an accepted standard of care in the s. In , more than , amniocentesis procedures were performed in the United States 4. In the s and s, exploratory studies were conducted revealing that the placenta i. In the United States, this procedure was initially evaluated in a controlled trial designed to determine the miscarriage rate 5. The difference in fetal-loss rate was estimated to be 0. Because that study was designed to determine miscarriage rates, it had limited statistical power to detect small increases in risks for individual birth defects.

CVS had become widely used worldwide by the early s. More than 80, procedures were reported to the International Registry from 6 ; approximately , procedures were registered from L. Jackson, personal communication. CVS is performed in hospitals, outpatient clinics, selected obstetricians' offices, and university settings; these facilities are often collectively referred to as prenatal diagnostic centers. Some investigators have reported that the availability of CVS increased the overall utilization of prenatal diagnostic procedures among women greater than or equal to 35 years of age, suggesting that access to first-trimester testing may make prenatal chromosome analysis appealing to a larger number of women 7.

Another group of obstetricians did not see an increase in overall utilization when CVS was introduced 8. The increase in CVS procedures was offset by a decrease in amniocentesis, suggesting that the effect of CVS availability on the utilization of prenatal diagnostic testing depends on local factors.

Although maternal age-related risk for fetal aneuploidy is the usual indication for CVS or amniocentesis, prospective mothers or fathers of any age might desire fetal testing when they are at risk for passing on certain mendelian single-gene conditions. Fetal movement is usually felt and uterine growth is visible at weeks' gestation, the time when abnormalities are detected by amniocentesis; thus, deciding what action to take if an abnormality is detected at this time may be more difficult psychologically Using CVS to diagnose chromosomal abnormalities during the first trimester allows a prospective parent to make this decision earlier than will amniocentesis.

Maternal morbidity and mortality associated with induced abortion increase significantly with increasing gestational age; thus, the timing of diagnosis of chromosomal abnormalities is important. Results of studies of abortion complications conducted by CDC from through indicated that the risk for major abortion complications e. For example, from through , the major complication rate was 0.

However, the risk for developing major complications from abortion at any gestational age decreased during the s. More contemporary national morbidity data based on current abortion practices are not yet available. CDC surveillance data also indicate an increase in the risk for maternal death with increasing gestation.

From through , the risk for abortion-related death was 1. The lower risk associated with first-trimester abortions may be an important factor for prospective parents who are deciding between CVS and amniocentesis. Amniocentesis is usually performed at weeks' gestation, but more amniocentesis procedures are now being performed at weeks' gestation.

Adjusting for confounding factors such as gestational age, the CVS-related miscarriage rate is approximately 0. Although uterine infection i. In one study, no episodes of septic shock were reported after 4, CVS procedures, although less severe infections may have been associated with 12 of the 89 observed fetal losses 5.

Overall infection rates have been Cytogenetically ambiguous results caused by factors such as maternal cell contamination or culture-related mosaicism are reported more often after CVS than after amniocentesis 2. In these instances, follow-up amniocentesis might be required to clarify results, increasing both the total cost of testing and the risk for miscarriage.

However, ambiguous CVS results also may indicate a condition e. Thus, in these situations, CVS may be more informative than amniocentesis alone. CVS Certain congenital defects of the extremities, known as limb deficiencies or limb-reduction defects, have been reported among infants whose mothers underwent CVS.

This section addresses 1 the expected frequency and classification of these birth defects, 2 the physical features of reported infants in relation to the timing of associated CVS procedures, and 3 cohort and case-control studies that have been done to systematically examine whether CVS increases the risk for limb deficiencies.

Population-based studies indicate that the risk for all limb deficiencies is from per 10, live births Limb deficiencies usually are classified into distinct anatomic and pathogenetic categories. The most common subtypes are transverse terminal defects, which involve absence of distal structures with intact proximal segments, with the axis of deficiency perpendicular to the extremity.

Transverse deficiencies occur as either isolated defects or with other major defects. Although the cause of many isolated limb deficiencies and multiple anomalies that include transverse deficiencies is unknown, researchers have hypothesized that these deficiencies are caused by vascular disruption either during the formation of embryonic limbs or in already-formed fetal limbs 17, Reports of clusters of infants born with limb deficiencies after CVS were first published in Three studies illustrate the spectrum of CVS-associated defects Data from these studies suggest that the severity of the outcome is associated with the specific time of CVS exposure.

Exposure at greater than or equal to 70 days' gestation has been associated with more limited defects, isolated to the distal extremities, whereas earlier exposures have been associated with more proximal limb deficiencies and orofacial defects. For example, in a study involving 14 infants exposed to CVS at days' gestation and examined by a single pediatrician, 13 had isolated transverse digital deficiencies In another study in Oxford of five infants exposed to CVS at days' gestation, four had transverse deficiencies with oromandibular hypogenesis In a review of published worldwide data, associated defects of the tongue or lower jaw were reported for 19 of 75 cases of CVS-associated limb deficiencies Of those 19 infants with oromandibular-limb hypogenesis, 17 were exposed to CVS before 68 days' gestation.

Cohort studies usually measure rates of a specified outcome in an exposed group compared with an unexposed group. Ideally, both groups should be selected randomly from the same study population. The three largest collaborative trials of CVS in Europe, Canada, and the United States were designed originally in this way; however, in these studies, the outcome of interest was fetal death.

The report of the first U. After the initial case reports in , neonatal outcomes from the collaborative trials were analyzed more intensively However, rather than comparing rates for limb defects in the CVS-exposed cohorts with those of amniocentesis-exposed cohorts from the same study population, the rates in the CVS groups were compared with population-based rates.

Consequently, these comparisons must be interpreted with caution because population-based rates are derived differently i. CVS-associated risk for limb deficiencies could be underestimated by these comparisons if follow-up of pregnancies in the exposed cohort is incomplete.

Other epidemiologic issues must also be considered when interpreting comparisons of crude rates. Unless a formal meta-analysis is performed, these comparisons neither account for heterogeneity between studies nor assign individual "weights" to studies. Comparisons of crude rates also do not adjust for potential confounding variables, such as maternal age.

Methods of anatomic subclassification also vary between registries and can differ from methods applied to CVS-exposed cohorts. In addition, comparing overall rates of limb deficiency in groups exposed to CVS with groups unexposed to CVS might overlook an association with a specific phenotype, such as transverse deficiency.

These rates include studies that describe affected limbs in sufficient detail to exclude nontransverse defects. Rates calculated for the smaller cohorts i. The range of rates for these two populations 1. The threefold to fivefold increase in the overall rate for the 65 centers compared with the rates for Victoria or Boston is statistically significant chi-square: p Investigators participating in the International Registry also have combined birth-defect data from multiple CVS centers, including some of the 65 CVS centers 16, An abstract published in includes information about , procedures reported to the International Registry.

The rate of transverse deficiencies in the reporting centers was 1. Different methods of classification. The method of classification of limb deficiencies for the International Registry resulted in a smaller proportion of transverse deficiencies compared with all limb deficiencies than some population based studies 17,32,36, The reason for this smaller proportion is that the definition of "transverse terminal deficiencies" is more restrictive and includes only defects that extend across the complete width of a limb and excludes terminal deficiencies of fewer than five digits.

Ascertainment of outcomes. Ascertainment of outcomes may be incomplete in CVS registries because deliveries can occur at a hospital remote from where the CVS was performed and might not be reported back to the CVS center. The effect of this incomplete ascertainment would be to underestimate risk for adverse outcomes. Differences among centers in the performance of CVS. Investigators have compared rates of miscarriages and rates of limb deficiencies at individual facilities.

This comparison is based on the assumption that the causes of both miscarriage and limb defects might be related to particular techniques of sampling by individual obstetricians. The association between high miscarriage and limb-deficiency rates in one U. CVS center was cited as potential evidence of the role of surgical inexperience A cluster of limb deficiencies in another U. Chorionic villus sampling can reveal whether a baby has a chromosomal condition, such as Down syndrome, as well as other genetic conditions, such as cystic fibrosis.

Although chorionic villus sampling can provide valuable information about your baby's health, it's important to understand the risks — and be prepared for the results. Chorionic villus sampling can provide information about your baby's genetic makeup. Generally, chorionic villus sampling is offered when the test results might have a significant impact on the management of the pregnancy or your desire to continue the pregnancy.

Chorionic villus sampling is usually done between weeks 11 and 14 of pregnancy — earlier than other prenatal diagnostic tests, such as amniocentesis. Chorionic villus sampling can't detect certain birth defects, such as neural tube defects. If neural tube defects are a concern, an ultrasound or genetic amniocentesis might be recommended instead. Your health care provider might caution against transcervical chorionic villus sampling — which is done through the vagina — if you have:.

Rarely, your health care provider might caution against transabdominal chorionic villus sampling — which is done through the abdominal wall — if:. Rh sensitization. Chorionic villus sampling might cause some of the baby's blood cells to enter your bloodstream.

If you have Rh negative blood and you haven't developed antibodies to Rh positive blood, you'll be given an injection of a blood product called Rh immune globulin after chorionic villus sampling. This will prevent your body from producing Rh antibodies that can cross the placenta and damage the baby's red blood cells. A blood test can detect if you've begun to produce antibodies.

Some older studies suggested that chorionic villus sampling might cause defects in a baby's fingers or toes.

However, the risk appears to be a concern only if the procedure is done before week 10 of pregnancy. You might need to have a full bladder for chorionic villus sampling. Check with your provider about how much fluid you might need to drink, as well as any other pre-test preparation that might be necessary before your appointment. Your health care provider will explain the procedure and ask you to sign a consent form before the procedure begins.

Consider asking someone to accompany you to the appointment for emotional support or to drive you home afterward. Chorionic villus sampling is usually done in an outpatient facility or the health care provider's office. First, your health care provider will use ultrasound to verify your baby's gestational age and the position of the placenta.

You'll lie on your back on an exam table with your abdomen exposed. Your health care provider will apply a special gel to your abdomen, and then use a small device known as an ultrasound transducer to show your baby's position on a monitor. Next, your health care provider will use the ultrasound image as a guide and take the tissue sample from the placenta while you lie still.

Transcervical CVS can also be performed using small biopsy forceps. Tissue samples are sent to the laboratory for culturing and further testing, including conventional karyotype, fluorescence in situ hybridization, and chromosomal microarray. Rapid assessment results return in 2 to 4 days, and cultured samples result in 1 to 2 weeks.

Families should meet with their provider to discuss further management. Additional ultrasounds may be performed, and MSAFP may be collected at 16 weeks to screen for open neural tube defects. The risks of chorionic villus sampling are similar to those of amniocentesis and include pregnancy loss, bleeding, infection, rupture of membranes, and uncertain results. The pregnancy loss rate has decreased with ultrasound guidance and increasing skill and technique; however, chorionic villus sampling has a long learning curve.

A systematic review of the complications of chorionic villus sampling determined a total fetal loss of 0. In the amniocentesis group, the total rate of fetal loss within 14 days was 0. Additionally, limb reduction defects and oromandibular hypogenesis have been described in the literature as risks of chorionic villus sampling. The risk of limb defects, for example, is estimated to be about 6 per 10, per the World Health Organization, which does not differ from the general population risk.

The incidence of culture failure, leakage of amniotic fluid, or infection after CVS is reported to be less than 0. Chorionic villus sampling is a safe and established option for early diagnostic prenatal genetic testing. Complications are minimal with a skilled provider and the advancement of ultrasound.

Results of a chorionic villus sampling can help families make informed decisions about their pregnancy. A maternal-fetal medicine specialist generally performs chorionic villus sampling. Some pregnant patients who are candidates for CVS may present for care to a general obstetrician, family medicine, or internal medicine provider. Given the specific time frame in which a CVS can be performed, early referral to MFM is a key factor in ensuring patients have access to the procedure.

Genetic counselors are an additional resource for families, helping them understand risks and options for prenatal testing.

Clear and efficient communication between maternal-fetal Medicine specialists and the referring provider is crucial to ensure timely discussion of results and outline further recommendations for pregnancy management. This book is distributed under the terms of the Creative Commons Attribution 4. Turn recording back on. National Center for Biotechnology Information , U. StatPearls [Internet]. Search term. Chorionic Villus Sampling Taylor M. Author Information Authors Taylor M.

Affiliations 1 Augusta University of Georgia. Continuing Education Activity Chorionic villus sampling is a prenatal diagnostic test performed between 10 and 13 weeks gestation. Introduction Chorionic villus sampling is a procedure performed to biopsy placental tissue between 10 to 13 weeks gestation for prenatal genetic testing.

Indications According to the American College of Obstetrics and Gynecology, women of all ages should be offered prenatal assessment for aneuploidy by screening or diagnostic testing regardless of maternal age or other risk factors. Contraindications Caution is advised in patients receiving anticoagulation. Equipment The procedure is performed under continuous ultrasound guidance using an aseptic technique. Apart from an ultrasound machine, the following equipment is required: Transabdominal Approach Sterile drape.

Personnel The procedure requires a sonographer to scan in real-time. Preparation Prior to the Procedure Formal consult with a maternal-fetal medicine specialist. Informed consent after a thorough discussion of risks and benefits with opportunity for patients to ask questions.

Ultrasound to confirm fetal heart activity, gestational age assessment with crown-rump length measurement, site of cord insertion, and location of the placenta. Technique The route used to perform the procedure is based on provider preference, but the placental location may influence the decision. Complications The risks of chorionic villus sampling are similar to those of amniocentesis and include pregnancy loss, bleeding, infection, rupture of membranes, and uncertain results.

Clinical Significance Chorionic villus sampling is a safe and established option for early diagnostic prenatal genetic testing. Enhancing Healthcare Team Outcomes A maternal-fetal medicine specialist generally performs chorionic villus sampling. Review Questions Access free multiple choice questions on this topic.