Umbilical cord puncture

The umbilical puncture or Chordozentese is a method of prenatal diagnostics , in which blood from the umbilical cord of a fetus (English sample fetal blood, FBS ) is removed. The examination is possible from around the 20th week of pregnancy.

An umbilical cord puncture is not a routine examination and is only carried out if it is expressly requested by the pregnant woman or the parents. The attending physician is obliged to advise the pregnant woman in detail before the examination and to discuss the advantages, disadvantages and risks in an understandable manner.

If the examination reveals something unusual, the parents-to-be shouldn't rush into anything, but rather get up- to- date information on the diagnosis. Discussions with affected parents (e.g. in the context of self-help groups), medical specialists, employees of (genetic) counseling centers, etc. can be very helpful, as well as visiting information pages on the Internet.

Investigation procedure

A needle is inserted through the abdominal wall (= transabdominal) of the pregnant woman under ultrasound control into the umbilical vein of the unborn child ( puncture ), and 1 to 2 ml of blood are taken.

This examination is usually done when you want to know something about the composition of the blood of the unborn child. This is particularly important if, based on abnormal blood values ​​in the mother or abnormal ultrasound findings, there is a suspicion that the unborn child may have anemia or an infection .

The blood test can also include tests such as B. to determine blood groups and antibodies , to diagnose blood group intolerance, metabolic disorders, rubella and toxoplasmosis .

If it is particularly urgent in individual cases, an umbilical cord puncture can also be done to obtain cell material for a chromosome examination. The samples taken from the umbilical cord are examined in the laboratory.

The result of a chromosome examination (often also carried out to confirm the results of the amniocentesis , chorionic villus sampling or the FISH test ) is obtained after about a week, the results of the blood test for infections, anemia, etc. are usually faster.

When it comes to determining chromosomal peculiarities, the consultation that the attending physician has to hold with the pregnant woman or the parents before the examination also includes the express reference to the fact that there is no therapy for causal healing for chromosomal peculiarities in the child , and thus, in the event of a positive examination result, ultimately only the acceptance of the child with its particularity, the postnatal release of the child for adoption or the postnatal transfer of the child to a foster family / a home or the termination of pregnancy are alternatives.

If it is necessary to administer medication to the unborn child, this is usually done via the umbilical cord.

Application Risks

Risks involved in the examination should be weighed up by the pregnant woman or the parents before they consent to an amniocentesis. Due to the increased risk, invasive examinations are usually carried out if, in particular, the risk of miscarriage as a result of the procedure is lower than the statistically expected probability of the presence of a chromosomal peculiarity or a hereditary disease .

The following events can occur during or after the procedure:

• Amniotic fluid loss
• Bleeding in the womb
• Injuries to the uterus
• Violations of the mother cake
• Infections
• Injury to the unborn child from the needle (especially if the child moves a lot and / or unexpectedly)
• Uterine contractions (often noticeable as a kind of "pulling" in the abdomen, which in most cases subsides)
• Miscarriage
• If the embryo receives a blood transfusion during chordocentesis , this can lead to an incorrect transfusion into the surrounding tissue (umbilical cord tamponade). In this case, the child must be delivered immediately by caesarean section due to the threat of undersupply (emergency).

After the procedure, the pregnant woman should consistently take it easy for a while, as it is in principle still possible for days after the procedure that, e.g. B. comes to amniotic fluid loss.

Miscarriage

The numbers for miscarriages after an umbilical cord puncture are given as around 1%, sometimes with up to 7%.

With regard to these very contradicting figures, the figures from the amniocentesis (removal of amniotic fluid) also help . This procedure is understandably a little less risky and invasive, as there is no additional blood vessel to be punctured.

There, on the one hand, the numbers in two studies were 1% to 1.7%. In another study, in which 1,006 amniocenteses were retrospectively evaluated, the miscarriage rate at an examination in the 16th or 17th week of pregnancy was 2.5% in women aged 20 to 34 years, and increased in the women age group from 35 up to 39 years to 3.4% up to 5.1% for women over 40 years. In addition to age, vaginal bleeding during pregnancy was an important risk factor that increased the incidence of miscarriages to 6.5% (= 2.4 times higher risk); Women with a spontaneous miscarriage in earlier stages of pregnancy or an abortion had an incidence of 8% (= 3-fold increased risk).

In another study, the complication rate (miscarriage, intrauterine fetal death ) within 14 days of amniocentesis was 1.5% for training assistants and 0.6% for specialist doctors.

Antibody formation in case of rhesus incompatibility

Since small amounts of the child's blood usually get into the maternal amniotic fluid when the umbilical cord is punctured, the amniotic sac and uterus are also injured during the procedure, this can lead to the child’s blood being introduced into the maternal bloodstream . If there is a blood group incompatibility ( Rhesus incompatibility ) to the Rhesus factor - antigen "D", i. H. between Rh-negative (Rh−, rh, genotype dd) mother and Rh-positive (Rh +, Rh, genotype Dd, dD, DD) child, antibody formation by the mother (called "anti-D") against the child's blood would be likely . This process can also be initiated by other invasive interventions on the child or in the case of pregnancy in the uterus (e.g. induced abortion or termination of pregnancy ; amniocentesis ; chorionic villus sampling ). "Anti-D" is an irregular erythrocyte antibody that Rhesus negative people can produce if they are immunized by Rhesus positive erythrocytes . The drug ("anti-D prophylaxis", such as RHOPHYLAC from CSL Behring and RHESONATIV from Octapharma), which is usually administered prophylactically against this process and its consequences in children (see Rhesus incompatibility # pathogenesis ) is also called this.

See also

• Screening , double test , triple test , first trimester screening , fine ultrasound , 3D ultrasound

Individual evidence

1. ↑ Diedrich among others: Gynecology and Obstetrics. Berlin / Heidelberg 2000, p. 330.
2. ↑ Diedrich among others: Gynecology and Obstetrics. Berlin / Heidelberg 2007.
3. ↑ Diedrich among others: Gynecology and Obstetrics. Berlin / Heidelberg 2000.
4. ^ NE Papantoniou, GJ Daskalakis, JG Tziotis, SJ Kitmirides, SA Mesogitis, AJ Antsaklis: Risk factors predisposing to fetal loss following a second trimester amniocentesis. In: BJOG - An International Journal of Obstetrics and Gynaecology . 108, 2001, pp. 1053-1056. doi: 10.1111 / j.1471-0528.2001.00246.x ; PMID 11702837 .
5. ↑ D. Bettelheim, B. Kolinek, A. Schaller, G. Bernaschek: On the complication rate in invasive, intrauterine interventions in a prenatal diagnostic department . In: Ultrasound in Med. 23 (2), 2002, pp. 119-122, doi: 10.1055 / s-2002-25191 PMID 11961726 .

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !