The prevalence of human immunodeficiency virus (HIV) has been found on population screening to be about 0.15% of pregnant women in England, with the highest prevalence in those born in sub-Saharan Africa (where an estimated ~26 million of the ~37 million people currently living with HIV infection are located). In the UK, the prevalence of the disease in the general population is ~0.16%, compared with 0.4-0.9% in the USA. In parts of central and east Africa, the incidence may reach 20-30% in the larger cities.
The natural course of infection is an acute viral-type illness, followed approximately 3 months later by seroconversion when the patient becomes ‘HIV-positive’; progression to the acquired immunodeficiency syndrome (AIDS; characterised by lymphadenopathy and conditions indicating reduced cell-mediated immunity, e.g. chronic opportunistic/invasive infections, chronic diarrhoea, malignancies, neurological involvement) occurs in about two-thirds of cases over the next 10 years, although up to 20% of people who are HIVpositive survive for 20 years without progression to AIDS. Median survival once AIDS is diagnosed is about 3-4 years; in Africa, survival is shorter, with about one-third of infected people progressing to death without developing AIDS itself.
HIV infection has altered the way in which contaminated materials are handled on the labour ward, and the way in which blood and blood products are administered. It is now recommended that all pregnant women undergo routine antenatal HIV testing, as neonatal transmission occurs in 25-30% of cases, with a further 14% infected if the mother breastfeeds; with appropriate medical management of known cases (see below), neonatal transmission can be reduced to under 3%. Since this recommendation by the Department of Health in 1999, the proportion of HIV-infected women diagnosed before delivery in the UK has risen to over 90%.
Human T-cell leukaemia/lymphoma virus (HTLV) types I and II have been found to have a similar prevalence to that of HIV in pregnancy, and screening of blood donations and/or pregnant women is performed in some countries.
Since the target of infection is primarily the lymphocyte, plasma counts of CD4-positive cells (mainly helper T-lymphocytes) have been used to monitor the course of infection and guide treatment. The CD4:CD8 ratio and plasma viral load (amount of viral RNA measurable in the plasma, representing degree of viral replication) are also used.
Problems and special considerations
Problems may be related to the acute viral illness of initial HIV infection.
Problems may also arise from impaired organ function and immunodepression of AIDS. All systems may be affected, either by primary HIV infection or by secondary infection, for example with fungi or other atypical organisms. Co-infection with tuberculosis, hepatitis B or hepatitis C may exist in some patients, and substance abuse is not uncommon. Of particular importance to anaesthetists are neurological manifestations, which may include neuropathy, encephalopathy, meningitis, focal brain lesions, dementia, myelopathy and myopathy, cardiovascular disease such as HIV-associated cardiomyopathy, and haemostatic abnormalities such as thrombocytopenia or platelet function disorders. HIV-positive patients, particularly those with low CD4+ counts, have an increased risk of venous thromboembolism, which may be related to a deficiency in protein C or S or to the use of protease inhibitors.
The effects on organ systems of prophylactic highly active antiretroviral therapy (HAART) must also be considered. These may include blood dyscrasias, gastrointestinal disturbances, neurological and hepatic impairment and increased drug metabolism via hepatic enzyme indication.
There is a risk of transmission of HIV to the neonate. There is also a risk of transmission to medical and midwifery staff, and to other patients.
Management options
All units should offer counselling and testing for at-risk women prenatally or even prepregnancy, and this should continue during pregnancy. Many units have protocols in place for joint management of HIV-positive women by obstetricians and HIV specialists.
Acute HIV infection is rarely a known problem on labour ward and in general is managed as for any acute viral illness. For those with acute organ dysfunction, supportive management is directed at the organ system affected. Patients with chronic HIV infection must be assessed carefully before any anaesthetic intervention and managed according to their degree of organ impairment, which in most cases presenting to labour ward will not be severe.
In general, patients with HIV infection are managed as for any obstetric patient, unless specific contraindications exist. Particular care with invasive techniques has been suggested, to reduce the risk of introducing infection, but standard aseptic methods should be adequate if they are followed. The use of epidural or spinal anaesthesia has been questioned for fear of seeding the virus into the cerebrospinal fluid (CSF), thus accelerating the central nervous system (CNS) progression of the infection; because of a theoretical risk of seeding opportunistic infective organisms into the CNS; and because there may be complications related to underlying and undiagnosed CNS pathology. Since CSF involvement occurs very early in HIV infection, however, no further risk is generally felt to exist, and this is supported by clinical experience, albeit limited. Epidural blood patching has also been performed in HIVpositive patients without apparent adverse consequences. There has been no report of secondary CNS infection introduced during administration of regional anaesthesia in the HIV-infected mother, and this risk is generally felt to be theoretical only. Further, if no evidence of CNS involvement exists then most authorities recommend regional anaesthesia as routine. If CNS abnormalities do exist, then management depends on their severity and other considerations such as the presence of other complications.
Most units now treat HIV-positive mothers with antiviral drugs such as zidovudine, which has been shown to reduce transmission to the neonate by up to two-thirds. Combination with elective caesarean section reduces the risk further, to about 1%, although if the mother is well controlled on HAART and the viral load is under 400 copies/ml, vaginal delivery is associated with a similar risk of vertical transmission. There is wide consensus that breastfeeding should be discouraged.
Owing to the implications of testing for HIV, most health authorities advocate the approach of ‘universal precautions’ to potentially at-risk patients; thus routine management of all women on labour ward should involve the use of protective clothing where appropriate (gloves, goggles, etc., according to individual choice), use of disposable equipment and/or appropriate sterilisation techniques and careful handling and disposal of contaminated sharps. If these practices are routinely followed, the known HIV-positive patient should need no extra measures. Units that have policies such as this have accepted the cost implications of such all-inclusive guidelines, especially given the high cost and high profile of legal proceedings against establishments where cross-infection has occurred.
If an accidental needlestick injury or similar event occurs, local protocols and specialists should be consulted for guidance about prophylactic zidovudine therapy, since this is a controversial area. The risk of seroconversion after needlestick is about 0.3%.
Key points
• HIV-positive mothers may have many systems affected and may be taking several drugs.
• General anaesthetic management is according to standard criteria for indications and contraindications.
• Universal precautions should apply to all patients to reduce contamination of staff.
• Regional anaesthesia is not contraindicated in the HIV-positive parturient.
Further reading
Bull L, Khan AW, Barton S. Management of HIV infection in pregnancy. Obstet Gynaecol Reprod Med 2015; 25: 273-8.
Hignett R, Fernando R. Anesthesia for the pregnant HIV patient. Anesthesiol Clin 2008; 26: 127-43.
de Ruiter A, Taylor GP, Clayden P, et al.; British HIV Association. British HIV Association guidelines for the management of HIV in pregnant women. HIV Med 2014; 15 (Suppl 4): 1-77.