[Year:2022] [Month:July-August] [Volume:14] [Number:4] [Pages:5] [Pages No:453 - 457]
Aims and objectives: To analyze the indications of fetal blood sampling, the advantages, and disadvantages of different routes employed to obtain the fetal blood, the complications due to gestational age vs procedure-related failures, and their incidences in fetal blood sampling. Also to study the outcomes of the pregnancies after fetal blood sampling and the association between placental position, and its effects on fetal blood sampling.
Materials and methods: This is a prospective study done on patients coming from all over South India to Bhagwan Mahaveer Jain Hospital and the Bangalore Prenatal Diagnosis and Therapy Associates, Bengaluru. The study was carried out on pregnant women with at least one indication for fetal blood sampling. A total number of patients in the study period of 12 months will be enrolled irrespective of age, parity, period of gestation, and type of indication.
Inclusion criteria: Previous offspring with chromosomal anomalies or other birth defects; Maternal age 35 years or more at first pregnancy; Recurrent pregnancy loss (or both paternal translocation and inversion); Suggestive fetal ultrasonographic findings; Positive maternal screening test findings; Pregnant woman/spouse has a family history of mental retardation/physical deformities/genetic disease/inborn errors of metabolism; Mother having a disease or being exposed to drugs, medications, or infections known to be associated with congenital malformations in the fetus; Any indication for fetal therapy.
Exclusion criteria: Any patient with a history of bleeding diathesis or hematological disorders; Intrauterine death of the fetus.
Procedure: All eligible patients who have signed the informed consent form are taken for the procedure. The patient had to sign Form G and Form F as per the PC and PNDT Act 2003. History and investigations were done. Under aseptic precautions, the procedure was performed under ultrasound guidance with continuous needle-tip visualization. About 2 mL of fetal blood was obtained and sent for chromosomal, DNA, or biochemical analysis. If indicated, fetal therapy was performed. Following the procedure, further, follow-up was done until the outcome of pregnancy. Post-procedure antibiotics were given and the patient was referred back to her primary obstetrician. The patients were followed up to the end of pregnancy. The outcome of pregnancy and its relation to indication, complications, and results were analyzed.
Results: The pregnancy termination rate in this study was 3.85% (n = 2), and indications for termination were Turner’s syndrome and malascended right kidney with cystic dysplasia of left kidney with delayed fetal nasal bone ossification and single umbilical artery. Out of 96.15% (n = 50) who continued their pregnancy, 65.4% (n = 34) had normal live and healthy babies. Of the six patients who had stillbirth, the various causes were – 2 patients with Down’s syndrome, one patient with Glucose-6-phosphate dehydrogenase deficiency who underwent cardiocentesis, one patient with early hydrops fetalis with IUGR, esophageal fistula, and polyhydramnios, and one patient with soft + major marker, 46, add(15)(q25). One patient who underwent intrahepatic vein portion of umbilical vein sampling for the fetus with porencephaly, intraventricular hemorrhage, left vitreal hemorrhage with retinal detachment, delivered a congenitally malformed baby and the baby died 6 hours after birth. One patient who had left-sided congenital diaphragmatic hernia and liver up position had preterm delivery and the baby died after 2 hours of birth. Of the eight intrauterine deaths, the causes were Klinefelter’s syndrome, Down’s syndrome, 45,-14,-15t(14;15)(q10;q10) apparently balanced Robertsonian translocation, 46,inv(2)(p12;q21), 46,inv(9)(p11;q13), fetal hepatomegaly, bladder outlet obstruction with B/L hydroureter, and duodenal atresia, and one patient with severe IUGR, lissencephaly, and cerebellar hypoplasia. One patient with omphalocele, continued pregnancy till term, and later the baby was operated. In one patient with Fallot’s Tetralogy with a single umbilical artery and fetal thymic hyperplasia, cord blood was sent for FISH 22q deletion, which was normal, had term delivery but the baby was admitted to higher center, treated conservatively and baby recovered.
Conclusion: Fetal blood sampling is a safe and effective prenatal diagnostic procedure in experienced hands, mostly performed at 21–24 weeks of gestation. Cordocentesis can be done as an alternative to amniocentesis after 18 weeks of pregnancy as results of karyotype can be obtained earlier. In such cases, FISH can be avoided to cut down the cost. The risk of culture failure and fetal loss is also acceptable. Methods like fetal blood sampling, which makes karyotyping possible within a short time, should be preferred to amniocentesis and FISH analysis because FISH does not detect chromosomal mosaicism and structural aberrations. Triple test screening is on an increase, but it requires an external quality control program and standardization of the variables. Soft markers of ultrasound are a reliable screening test. Major anomalies on ultrasound are likely to be associated with cytogenetic abnormality. Hence, these fetuses need a cytogenetic study preferably before termination. This would aid in counseling for future pregnancies. Cardiocentesis or intrahepatic portion of umbilical vein sampling may be used as alternate method when cordocentesis is difficult to perform. Complications were similar in both fundo-anterior and fundo-posterior placental locations. Although this study consists of 54 patients on whom fetal blood sampling was done, larger studies are needed to validate the conclusions of this study.