Month two

All about the am­nio

Your Pregnancy - - Contents - YP

WHAT IS IT?

Am­nio­cen­te­sis is a pre­na­tal test where a sam­ple of the am­ni­otic fluid sur­round­ing the baby is with­drawn. It’s mostly used for test­ing of ge­netic con­di­tions, but can also be used to check if a baby’s lungs are ready in case you need to have a preterm de­liv­ery for any rea­son. WHEN AND HOW IS IT DONE FOR GE­NETIC CON­DI­TIONS? Am­nio­cen­te­sis is usu­ally done be­tween 16 and 22 weeks of preg­nancy. Af­ter the ab­domen is cleaned with ster­ile fluid, and us­ing a sonar as a guide, a nee­dle is in­serted through the ab­dom­i­nal wall into the uterus, and be­tween 10 to 20ml (less than four tea­spoons) of am­ni­otic fluid is drawn up. When done for lung ma­tu­rity, it is per­formed in the late third trimester.

HOW DOES IT WORK?

Our bod­ies are made up of thou­sands of cells which con­tain the ge­netic ma­te­rial. This is made up of 23 pairs of chro­mo­somes which hold the genes re­spon­si­ble for ev­ery­thing about us – not only how we look, but ev­ery­thing about us, in­clud­ing how our bod­ies func­tion. We nat­u­rally lose skin cells ev­ery­day (no­tice the ring around the bath and basin, or dry skin flak­ing off) and so does the un­born baby. A sam­ple of the am­ni­otic fluid con­tains the baby’s cells, and th­ese are ex­tracted and an­a­lysed in the lab­o­ra­tory.

WHO DOES THE AM­NIO­CEN­TE­SIS?

A skilled ob­ste­tri­cian, foetal medicine spe­cial­ist, or an ex­pe­ri­enced ra­di­ol­o­gist.

DOES IT HURT? DO I HAVE A LO­CAL ANAES­THETIC?

A lo­cal anaes­thetic is not used, be­cause the am­nio­cen­te­sis is rel­a­tively quick. You will feel the nee­dle be­ing in­serted, and if the ab­dom­i­nal mus­cles are re­laxed, it tends to be less painful. Women have de­scribed the sen­sa­tion as “strange” when the fluid is pulled back into a sy­ringe. Af­ter the pro­ce­dure, you may feel lower ab­dom­i­nal pain sim­i­lar to pe­riod pain, but this will pass. You can take parac­eta­mol for any pain you may feel if you need to.

WHY IS TEST­ING DONE?

Am­nio­cen­te­sis is of­fered to women for the fol­low­ing rea­sons: • If the mother is over the age of 35 years, she has a higher chance of hav­ing a baby with a chro­mo­some ab­nor­mal­ity like Down syn­drome or other chro­mo­some ab­nor­mal­i­ties. • If ab­nor­mal­i­ties have been seen on any of her sonars. • If the par­ents are known “car­ri­ers” of a ge­netic con­di­tion where they have a chance to have an af­fected baby, like cys­tic fi­bro­sis, sickle cell anaemia (com­mon in peo­ple from cen­tral Africa) or tha­las­saemia (com­mon in Greek and In­dian com­mu­ni­ties).

• If one of the par­ents car­ries a “bal­anced” chro­mo­so­mal re­arrange­ment (the right amount of chro­mo­somes, and the right amount of ge­netic ma­te­rial) but there is a risk to have a baby with an “un­bal­anced” re­arrange­ment of chro­mo­somes. • If the mom has had a pos­i­tive first trimester screen, or pos­i­tive sec­ond trimester screen. Re­mem­ber that a pos­i­tive screen does not mean that the baby has Down syn­drome, it just means that the risk has been in­creased from the age re­lated risk. This nat­u­rally raises the anx­i­ety lev­els and an am­nio­cen­te­sis is the only way of know­ing 100 per­cent if the baby is at all af­fected.

WHAT ARE THE RISKS?

As there is a nee­dle in­serted through the uterine wall and mem­branes there is a small risk of in­fec­tion. The main risk is that of mis­car­riage and is the re­gion of 0.7-1 per­cent. Although some doc­tors are more con­ser­va­tive than oth­ers, and some say you can carry on as nor­mal, it is ad­vis­able to take pre­cau­tions af­ter the pro­ce­dure to min­imise this risk. So you should rest, not do any stren­u­ous ex­er­cise and avoid sex­ual in­ter­course for a few days af­ter the pro­ce­dure. Be sure to have your am­nio­cen­te­sis per­formed by a qual­i­fied per­son to re­duce risks. Although there is not ex­ten­sive re­search on this, by in­sert­ing a nee­dle into the womb, there may be a small chance of HIV pos­i­tive blood mix­ing with baby’s.

WHAT SHOULD YOU LOOK OUT FOR?

If you have any se­vere cramp­ing, or loss of fluid or blood, you need to go to your hos­pi­tal or clinic im­me­di­ately. Although this is very rare, com­pli­ca­tions and mis­car­riage as­so­ci­ated with an am­nio­cen­te­sis usu­ally oc­cur within two weeks af­ter the pro­ce­dure.

HOW MUCH DOES IT COST?

In the state sys­tem, preg­nant women are free pa­tients, and the costs are cov­ered by the hos­pi­tal. In the pri­vate sec­tor, there is a cost for the scan and pro­ce­dure of ap­prox­i­mately R2 600, the anal­y­sis of the chro­mo­somes is R4 000 and the PCR is R2 000. If you dis­cuss it with your med­i­cal aid, they should cover some of the costs, de­pend­ing on your spe­cific med­i­cal scheme.

IS THE TEST­ING AC­CU­RATE?

The lab­o­ra­to­ries are very care­ful in their sort­ing and test­ing of sam­ples, and there should be no chance of an er­ror. It is very im­por­tant to note that although the baby may not have a chro­mo­so­mal ab­nor­mal­ity, or other ge­netic con­di­tions, there is no way of know­ing for sure whether or not the baby may have a vis­ual or hear­ing im­pair­ment or in­tel­lec­tual de­lay. It’s im­por­tant that the mid­wife, doc­tor or ge­netic coun­sel­lor take a thor­ough ge­netic his­tory to make sure, as best as they can.

PLEASE TAKE NOTE:

If you’re Rh-neg­a­tive, it’s im­per­a­tive that you have an anti-D in­jec­tion af­ter an am­nio­cen­te­sis – this will help pre­vent a build-up of Rh-pos­i­tive an­ti­bod­ies which could af­fect your baby in fu­ture preg­nan­cies. If you’re HIV pos­tive and want an am­nio­cen­te­sis done, you must be on ARV treat­ment for at least two weeks prior to the test – please dis­cuss the tak­ing of ARVs with your doc­tor or mid­wife.

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