Cordocentesis is a method of fetal blood sampling which is usually carried out under ultrasound guidance.
It may be performed for various reasons which include:
- establish the degree of a fetal anaemia
- further investigation of an underlying chromosomal anomaly
- further investigation of an in utero infection
Usually, a 20-gauge spinal needle is inserted under direct sonographic guidance towards the umbilical vein. A typical sampling site would be where the segment of the umbilical cord is closest to the placenta where the cord is relatively fixed. The presence of a posterior placenta increases the difficulty of the procedure and in such cases, a muscle relaxant may be required prior to the procedure to immobilise the intervening fetus.
There is a higher complication rate if performed prior to 20 weeks. An associated fetal loss rate as high as 4% has been reported 2.
Recognised complications include:
- 1. A Cameron et.al Fetal Medicine for the MRCOG and Beyond. RCOG Press. ISBN:1906985367. Read it at Google Books - Find it at Amazon
- 2. Maulik D. Doppler ultrasound in obstetrics and gynecology. Springer Verlag. (2005) ISBN:3540230882. Read it at Google Books - Find it at Amazon
- 3. Srisupundit K, Wanapirak C, Piyamongkol W et-al. Comparisons of outcomes after cordocentesis at mid-pregnancy between singleton and twin pregnancies. 2011;doi:10.1002/pd.2834 - Pubmed citation
- 4. Tangshewinsirikul C, Wanapirak C, Piyamongkol W et-al. Effect of cord puncture site in cordocentesis at mid-pregnancy on pregnancy outcomes. 2011;doi:10.1002/pd.2790 - Pubmed citation
- 5. Tongsong T, Wanapirak C, Kunavikatikul C et-al. Cordocentesis at 16-24 weeks of gestation: experience of 1,320 cases. Prenat. Diagn. 2000;20 (3): 224-8. Prenat. Diagn. (link) - Pubmed citation