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Amniocentesis is the aspiration of amniotic fluid from the amniotic cavity and is the most common invasive fetal testing procedure. Amniocentesis is an invasive technique. It is usually performed to diagnose or exclude fetal aneuploidy or other fetal genetic, biochemical or infectious risks. Prenatal diagnosis enables the diagnosis of a broad spectrum of chromosomal abnormalities, gene disorders, X-linked conditions, neural tube defects, and infections to be made before the birth of the fetus. The indications grow with progress in these fields. This activity outlines the procedure, reviews its complication rates, describes the complexity of obtaining truly informed consent, and examines the role of the healthcare team in improving care for high-risk patients who undergo this invasive procedure. Objectives: Identify the common indications and contraindications of performing amniocentesis. Describe the equipment required, the technique used, and the patient preparation needed for obtaining valid informed consent and performing an amniocentesis. Outline and review the possible complications associated with amniocentesis. Review interprofessional team strategies for obtaining informed consent, care coordination, and communication needed to improve clinical outcomes. Access free multiple choice questions on this topic.

Prenatal diagnosis enables the diagnosis of a broad spectrum of chromosomal abnormalities, gene disorders, X-linked conditions, neural tube defects, and infections to be made before the birth of the fetus. The various invasive prenatal diagnostic tests are amniocentesis, chorionic villus sampling, and fetal blood sampling or cordocentesis. Amniocentesis Amniocentesis is an invasive technique. This technique removes amniotic fluid from the uterine cavity using a needle. This procedure is performed transabdominally and under ultrasound guidance by a trained obstetrician. It was first performed for the diagnosis of genetic diseases (sex determination) of the fetus by Fuchs and Riis in 1956.[1] It is performed for diagnostic and therapeutic purposes, including for diagnostic evaluation in the form of chromosomal, biochemical, histopathological, and microbial assessments. When performed as a therapeutic procedure, it is done to reduce the volume of amniotic fluid in patients with polyhydramnios.[2][3][4] The amniotic fluid obtained consists of fetal exfoliated cells, transudates, fetal urine, and lung secretions. Amniocentesis can be performed from 15 weeks of gestation to delivery, with an attributable risk of loss in experienced hands of 0.13% in singletons. Earlier the attributable risk is greater than chorion villus sampling (CVS), which provides similar data from 11 to 15 weeks. There is an increased risk of amnionic fluid leakage of 1 to 2%, most of which corresponds to decreased activity in days and fetal demise, which is usually much rarer than the risk of demise attributable to the indication for the procedure, except in low-risk women with no maternal risks indicating the procedure, and talipes equinovarus, presumably from oligohydramnios.[5] Counseling of the couple is necessary regarding the procedure's indications, risks, benefits, and limitations.[6] This can be complex, as the individual circumstances leading to risk, including maternal age, parental family history, maternal serum screening, sonographic signs of chromosomal and other problems, and population history, can vary significantly. The benefit of possible pregnancy termination also varies depending on the patient's education, religious and ethical preferences, and, at present, state law. Chorionic Villus Sampling

Counseling of the couple is necessary regarding the procedure's indications, risks, benefits, and limitations.[6] This can be complex, as the individual circumstances leading to risk, including maternal age, parental family history, maternal serum screening, sonographic signs of chromosomal and other problems, and population history, can vary significantly. The benefit of possible pregnancy termination also varies depending on the patient's education, religious and ethical preferences, and, at present, state law. Chorionic Villus Sampling It is a prenatal invasive procedure and is done under ultrasound guidance. This procedure uses ultrasonography to guide the catheter or needle into the chorion frondosum. It is done abdominally and is followed by tissue aspiration (chorionic villi) for genetic or chromosomal analysis with a syringe containing tissue culture media. It is done in the first trimester for prenatal diagnosis between 10 to 14 weeks. Depending on the position of the uterus and bladder, the patient's gestational age, and placental localization, it can be performed transabdominally or transcervically. The safer and earlier termination of pregnancy is possible as karyotype results are available within 7 to 10 days, although placental mosaicism is a risk for a false diagnosis or reassurance. It is indicated in chromosomal and genetic disorders. The samples collected are sent for DNA analysis. It is not performed in vaginal bleeding, in cases of cervical abnormalities, and severe infections. The major complications involved in this procedure are limb reduction defects from earlier procedures, chromosomal abnormalities present in the extraembryonic tissue, which are not found in the fetal tissue, intrauterine infections, membrane rupture, and fetal loss. The attributable risk in trained hands is similar to amniocentesis. Both procedures assume direct ultrasound guidance for a safe procedure. Fetal Blood Sampling or Cordocentesis

The safer and earlier termination of pregnancy is possible as karyotype results are available within 7 to 10 days, although placental mosaicism is a risk for a false diagnosis or reassurance. It is indicated in chromosomal and genetic disorders. The samples collected are sent for DNA analysis. It is not performed in vaginal bleeding, in cases of cervical abnormalities, and severe infections. The major complications involved in this procedure are limb reduction defects from earlier procedures, chromosomal abnormalities present in the extraembryonic tissue, which are not found in the fetal tissue, intrauterine infections, membrane rupture, and fetal loss. The attributable risk in trained hands is similar to amniocentesis. Both procedures assume direct ultrasound guidance for a safe procedure. Fetal Blood Sampling or Cordocentesis It is the technique in which, under ultrasound guidance, fetal blood sampling is performed through the maternal abdomen. It is usually performed after 18 weeks after visualization of cord insertion. As the lumen of the cord at earlier weeks of gestation is narrow, it is considered safer to perform at 20 to 28 weeks of gestation. The blood sample is sent to the laboratory for hematological, immunological, and biochemical analysis. The results are obtained within 24 to 72 hours. There is an increased risk of fetal loss, which is comparatively higher (1 to 3% attributable risk) compared with other invasive procedures. The benefits include conversion to fetal transfusion, which can be life-saving. This is commonly indicated in maternal blood group sensitization from a transfusion or prior or current pregnancy sensitization to fetal cells from delivery or miscarriage of fetomaternal hemorrhage, suspected in the case of aplastic anemia from fetal Parvovirus B19 infection with the maternal acquisition of "Slapped face fever" - more common in teachers, parents, and childcare workers.[7]

Both maternal and fetal complications can occur with amniocentesis. Maternal Complications There is an estimated 2.6% risk of fetomaternal hemorrhage. Maternal isoimmunization in Rh-negative cases. There is minimal chance of introducing skin bacteria into the amniotic cavity. The risk of chorioamnionitis and uterine infections is less than 0.1%. The procedure increases the risk of preterm labor in the third-trimester amniocentesis. Preterm premature rupture of membrane and oligohydramnios are common complications encountered following amniocentesis. There is a 2% to 3% risk of vaginal bleeding. Post-procedure pain and maternal discomfort: Mean pain intensity described is 1.6+/-1.3 when noted on a scale of 0 to 7.[35] Amniotic fluid embolism, very rare There can be hematoma of maternal skin or intestinal or internal organ injuries. Fetal Complications On average, the fetal loss rate associated with amniocentesis is 0.11%. The loss is 0.56% within 28 days and 0.09% within 42 days.[29] The risk of fetal loss is higher in women who are otherwise at a higher risk of miscarriage, such as women carrying fetuses with structural malformations, fibroids, obese women, and women with vaginal infections at the time of the procedure. Amniocentesis in up to 86.0% of the patients is safe and free from complications.[36] The risk of fetal loss in case of multiple pregnancies is higher. Amniotic fluid leak: 1% to 2%, and usually associated with spontaneous sealing of membranes.[29] It may also result in: Fetal lung hypoplasia Respiratory distress Fetal injuries like bleeding from the cord, ocular injuries, and postural deformities like talipes equinovarus (clubfoot) might occur. The risk of complications is high when more than or equal to 3 pricks are used to obtain amniotic fluid. In ideal conditions, if an adequate fluid sample is not obtained in two pricks, the procedure should be abandoned for 24 hours, after which it can be re-attempted. The risk is less in experienced hands, i.e., people who perform more than 300 procedures/year.

The decision to perform amniocentesis and to convey the results to the couple requires communication between geneticists and fetal medicine experts operating as an interdisciplinary and interprofessional team. Geneticists must counsel the patient to know the possibility of the fetus being affected by a genetic disease. The genetic counselors should educate themselves and verify the availability of the required laboratory testing facilities prior to suggesting a prenatal diagnostic test to the patient. The operator should be aware of the type of samples required to be collected, the type of procedure to be performed, knowledge of the sample collection instrument, sample storage and handling instructions, and prescribed ways to transport the samples. Following the counseling session, the patient is referred for the procedure. While performing the procedure, coordination amongst the team is required. Once the needle is inside the amniotic cavity, the assistant should carefully and promptly withdraw the amniotic fluid so that the procedure is performed in the minimal time possible and with minimal risk of needle displacement. Following the test, the implications of the report should be conveyed to the patient and her family by the geneticists. Consultation with the pediatrician and disability center counselors can be arranged for the patient if required. Meetings with the diagnosed disability social support group and families dealing with a similar disability in a family member help the patient make a proper decision.