OPINION HOW CAN WE REDUCE THE RISK OF MOTHER-TO-CHILD TRANSMISSION OF HIV DURING INVASIVE OBSTETRIC PROCEDURES ?

Antenatal invasive obstetric procedures may be diagnostic or therapeutic, and are performed at different stages of pregnancy for various indications. The most common indication for an invasive procedure during pregnancy is for fetal karyotyping when a chromosomal abnormality or a genetic defect is suspected, either from the couple’s history or from ultrasound assessment of the fetus. Other less common but equally important indications may be diagnostic (fetoscopy, fetal tissue sampling, estimation of fetal haemoglobin) or therapeutic (aspiration of various fetal cavities, fetal blood transfusion and embryo reductions). In a high HIV prevalence setting like South Africa, a significant proportion of pregnant women in need of invasive procedures will be HIV-infected.


TIMING OF INVASIVE PROCEDURES IN PREGNANCY
Below is a list of commonly performed antenatal invasive obstetric procedures and the gestational age at which each procedure can, or should, be performed.n Amniocentesis: from 16 weeks n Chorionic villus sampling: from 11 to 14 weeks n Cordocentesis: from 20 weeks n Fetoscopy: usually in the 2nd and 3rd trimesters n Fetal tissue sampling (biopsies of organs, muscle, etc.): usually in the 2nd and 3rd trimesters n Aspiration of various fetal cavities, shunt insertion: any gestational age -usually from 16 weeks n Embryo reductions: from 11 weeks.
Several complications may occur with invasive procedures, and as part of pre-procedure counselling the woman/couple should be made aware of the risk of procedure-related complications.These include injury to maternal bowel, fetal injury, failure to obtain a sample, chorio-amnionitis, and most significantly fetal loss. 4The Royal College of Obstetricians and Gynaecologists guideline on amniocentesis and chorionic villus sampling advises that patients should be informed of an additional 1% risk of fetal loss following an amniocentesis, and a slightly higher risk following chorionic villus sampling. 5A 2003 Cochrane Review advises that, for second-trimester testing, amniocentesis is the safer procedure -safer than early amniocentesis or transcervical chorionic villus sampling. 6For testing before 15 weeks of pregnancy, transabdominal chorionic villus sampling is the safer procedure. 6There is no literature to suggest that the risk of procedurerelated complications is higher in HIV-infected women.

RISK OF MTCT WITH ANTENATAL INVASIVE PROCEDURES
There is limited literature on invasive obstetric procedures in the context of maternal HIV infection.Few studies have been published on the topic, most with a small number of patients.Important risk factors for MTCT such as maternal HIV viral load and CD4 + cell count are not always controlled for, and it may be difficult to infer causality in the reported cases of transmission after an invasive procedure.Without any maternal antiretroviral therapy initiated before an invasive procedure the risk of MTCT with invasive obstetric procedures is high, with rates of over 30% reported in some studies. 7In one study evaluating the effect of various factors on the risk on MTCT, third-trimester amniocentesis without any antiretroviral cover was associated with a fourfold increase in the risk of MTCT. 8tenatal invasive obstetric procedures may be diagnostic or therapeutic, and are performed at different stages of pregnancy for various indications.The most common indication for an invasive procedure during pregnancy is for fetal karyotyping when a chromosomal abnormality or a genetic defect is suspected, either from the couple's history or from ultrasound assessment of the fetus.Other less common but equally important indications may be diagnostic (fetoscopy, fetal tissue sampling, estimation of fetal haemoglobin) or therapeutic (aspiration of various fetal cavities, fetal blood transfusion and embryo reductions).In a high HIV prevalence setting like South Africa, a significant proportion of pregnant women in need of invasive procedures will be HIV-infected.
0][11] In studies reporting no MTCT with combination antiretroviral therapy, a significant number of women were initiated on therapy before conception, and the majority were virally suppressed at the time of the procedure. 9Despite the decrease in HIV transmission with antiretroviral cover, procedures that require more technical skills -such as chorionic villus sampling and cordocentesis -should still be avoided in the HIV-infected woman, as the risk of transmission to the fetus may be considerably increased.
Guidelines on the techniques of performing invasive procedures should be adhered to, and where possible the transplacental route should be avoided owing to the higher risk of transmission. 12

RECOMMENDATIONS ON ANTIRETROVIRAL PROPHYLAXIS PRIOR TO INVASIVE PROCEDURES
There is now general consensus that any HIV-infected pregnant woman who needs to undergo an invasive obstetric procedure should have combination antiretroviral therapy initiated before the procedure, regardless of maternal CD4 + cell count. 12,13Ideally, antiretroviral therapy should be initiated at least 4 -6 weeks prior to the procedure to achieve a significant level of maternal HIV viral suppression. 14If the gestational age precludes waiting for the period of 4 -6 weeks, the clinician can still go ahead with the procedure as continuation of combination antiretroviral therapy after the procedure should provide post-exposure prophylaxis.There is, however, no evidence on the role of post-procedure combination antiretroviral therapy as post-exposure prophylaxis, but an analogy between needling procedures and needlestick injuries has been made.
There are no data available to suggest a viral load at which HIV transmission is unlikely to occur with an antenatal invasive procedure, and data from general MTCT studies cannot be extrapolated to cases with invasive procedures.However, both the Royal College of Obstetricians and Gynaecologists and the British HIV Association recommend an undetectable maternal viral load at the time of the invasive procedure. 12,13If resources allow and there is sufficient time to wait before the invasive procedure, the maternal viral load should be determined as part of pre-procedure counselling.
In a high HIV prevalence setting like South Africa, it is advisable that a repeat HIV test be offered immediately before the invasive procedure if a woman has initially tested HIV-negative early in pregnancy.
Although there are no well-established approaches for managing HIV-infected women undergoing invasive procedures, international guidelines and literature published on the topic do offer guidance for the clinician.Local guidelines that are in line with international best practices, but also account for the nature of HIV/AIDS and obstetric practice in South Africa, are required to guide local clinicians.