While data most likely underestimate the true incidence of HIV-1 infection, roughly half of the 40 million individuals living with HIV worldwide are women (1). Of the industrialized countries, the United States is the most heavily affected, with an estimated 56,000 new cases annually (2). In 2006, more than 1.2 million individuals were living with HIV in the United States (3), and women comprised an estimated one-third of those infected. Of note, approximately one-quarter of these infected individuals are unaware of their HIV-positive status (4).

Both African American and Hispanic men, as well as women of ethnic and racial minority groups, are affected disproportionately in the U.S. epidemic. Indeed, the rate of new HIV and acquired immunodeficiency syndrome (AIDS) diagnoses in 2005 was 21 times higher among African American women than among white women (5). More recent statistics estimate that Blacks/African Americans account for 52% of all diagnoses of HIV infection in the United States and 44% of all persons living with an AIDS diagnosis (2). The rate of infection among Hispanics is roughly 3 times higher than that of the white population. From 2007 to 2010, males accounted for 79% of all diagnoses of infection among adults and adolescents, while the rate of HIV infection among women decreased slightly to 8/100,000 (6). Unprotected heterosexual intercourse and, secondarily, intravenous (IV) drug use with contaminated needles are the two main sources of HIV infection among female minority subgroups. Among all women, heterosexual intercourse is the primary source of infection.

In Western Europe, HIV infection is also becoming endemic, with both heterosexual transmission and cases imported from Africa accounting for a large proportion of new infections. In Eastern Europe and Asia the incidence of HIV infection is burgeoning, in large part due to IV drug use, the sex-trade industry, and subsequent secondary transmission to stable partners. In the Russian Federation and the Ukraine, women accounted for roughly 40% of the new infections in 2005, most likely acquired during heterosexual intercourse. Sub-Saharan Africa, however, carries the greatest burden of HIV infection worldwide, with 70% of HIV-infected individuals; 68% of new infections; and more than 90% of the world’s HIV-infected children and AIDS orphans (7). Statistics from the late 1990s indicate that more than 80% of the women infected with HIV worldwide were African. HIV infection rates among pregnant women in some urban centers in southern and eastern Africa reach an astounding 25% (8).

HIV-1 is a single-stranded RNA virus that is related genetically, morphologically, and biologically to the lentivirus subfamily of retroviruses. Like other lentiviruses, HIV-1 has a complex viral genome and characteristically causes indolent infections with extensive central nervous system (CNS) involvement and long periods of clinical latency. HIV-1 infection begins when glycoproteins on the HIV lipid envelope interact with CD4 receptors and a variety of co-receptors, such as CCR5 and CXCR4, on host cells. The CD4 antigen complex was first detected on helper T cells, and was subsequently identified on B cells, macrophages, and monocytes. It is also located on placental cells, thereby providing a route for vertical transmission to the fetus in early pregnancy. Once the virus enters the cell it is copied by a reverse transcriptase enzyme into a double-stranded DNA, which can be inserted into the infected host’s cells. Mutations during the process and the rapid rate of viral replication contribute to viral resistance and complicate drug therapy. The human immunodeficiency virus type 2 (HIV-2) is similar to HIV-1, but is more commonly encountered in West Africa and has a longer asymptomatic stage, lower transmission rate, and less pathogenic course than HIV-1 (9).

The most common mode of HIV-1 infection is via sexual transmission through the genital mucosa, although transmission also occurs by exposure to infected blood or blood products and by perinatal transfer from mother to child. In the United States, high-risk heterosexual transmission of HIV comprises the principal source of infection of women of all races and ethnicities, and accounts for at least 80% of new infections among women (10). Perinatal transmission can occur in utero, during labor and delivery, and postnatally from breastfeeding, although the majority occurs in the intrapartum period (11). Regardless of the mode of transmission, within 2 days the virus can be detected in peripheral lymphoid tissues and it can be cultured from the plasma within a week. Thereafter there is a rapid rise in plasma viremia, as the virus spreads to lymphoid organs and to the brain.

CD4+ T cells are infected early in the course of the disease, and play a key role in propagating the infection. The number of CD4+ cells declines sharply during initial infection and slowly rebounds as the immune system combats viral replication. An
asymptomatic period marked by a balance between CD4+ cell production and destruction ensues, ending once viral replication outpaces the immune system’s defenses. In general, the decline in CD4+ cells marks HIV progression from the initial infection and accounts for the profound immunodeficiency of advanced AIDS (12). Plasma viral load also serves as a marker for disease progression, and is extremely high during the acute infection and subsides during the latent stage. Patients tend to be highly infectious during the early stages of infection as a result of the high viral load. Acute infection manifests with transient flu-like symptoms of fever, fatigue, rash, headache, lymphadenopathy, pharyngitis, myalgia, arthralgia, and nausea, vomiting, and diarrhea.

Since the mid-1990s, diagnosed cases of perinatally acquired HIV infection have declined by an estimated 90% in the United States (13). This sharp decline is attributed in part to routine HIV screening during pregnancy and the widespread availability of therapeutic drugs that prevent transmission. Preconceptual counseling for known carriers of HIV or early detection of HIV infection during pregnancy in patients whose HIV status is unknown, with subsequent counseling, are cornerstones of the prevention of mother-to-child transmission of HIV.

Currently, the Centers for Disease Control and Prevention (CDC), U.S. Public Health Service (USPHS), and the American College of Obstetricians and Gynecologists (ACOG) recommend HIV screening for all pregnant women. The so-called “opt-out” approach to prenatal HIV testing encourages health care providers to test routinely for HIV infection unless the woman specifically refuses. Under universal opt-out screening, all parturients are notified that they will receive an HIV test as part of the routine prenatal tests unless they decline. Additional written documentation of informed consent beyond that required for routine tests is not necessary. The HIV test should be performed early in pregnancy and should be repeated in the third trimester in particular “at-risk” populations, such as IV drug users, women whose partners are infected, women who themselves or whose partners have more than one sexual partner during pregnancy, women who exchange sex for money or drugs, or women who receive healthcare in areas with an elevated incidence of HIV/AIDS (14). A repeat test in the third trimester for all pregnant women, regardless of risk factors, is also considered cost-effective. If testing has not been performed prior to term gestation or if the HIV status remains unknown at the onset of labor, rapid HIV testing is recommended at the time of presentation to the labor and delivery unit, unless the patient declines. If maternal HIV status is still unknown postpartum, a rapid test is recommended. Newborns whose maternal HIV status is unknown should be tested as soon as possible after birth.

Several diagnostic tests, with varying degrees of sensitivity and specificity, are available to determine HIV status. The enzyme-linked immunosorbent assay (ELISA) detects antibodies to HIV in the patient’s serum and is often the initial screening test for HIV. Rapid enzyme-linked immunoassay (EIA) blood and oral secretion tests are also available and are recommended during labor and delivery for women of unknown HIV status. Obstetrician–gynecologists may also choose to use rapid testing as their standard outpatient test (15). Currently, four rapid HIV antibody tests are available in the United States, two of which are approved for point-of-care. Results are interpreted visually; when HIV antibodies in a positive specimen bind to HIV antigens affixed to the test strip, a color change occurs. Positive EIA tests are confirmed by a more specific test, such as a Western blot, immunofluorescence assay (IFA), or HIV RNA polymerase chain reaction (HIV RNA-PCR). In the event that a parturient of previous unknown HIV status presents in labor and has a positive rapid HIV test by the opt-out approach, delaying treatment for confirmatory tests is not feasible. The expectant mother should be counseled that her preliminary test is positive and that the newborn may be exposed to HIV. Immediate initiation of antiretroviral (ARV) prophylaxis should be recommended. Antiretroviral therapy (ART) for both the mother and child will be discontinued if the confirmatory test result is negative (16).

False-positive and false-negative results, as well as indeterminate confirmatory testing, occasionally occur. Both the EIA test and the Western blot test rely on the detection of antibodies to HIV antigens, yet there may be a period after initial infection during which adequate antibody levels have not yet formed or remain undetectable. During this “window period,” a patient may be highly contagious despite negative test results. Immunosuppressive therapy may also account for false-negative results. False-positive EIA tests can be caused by autoimmune disease, hepatitis B immunization, and high parity, among other things. Indeterminate test results occur when a positive EIA test is followed by a Western blot result that is insufficient to make a definitive diagnosis. Causes of indeterminate results include partial seroconversion, organ transplantation, autoimmune disease, blood transfusions, and advanced AIDS. Repeat testing can be delayed if indeterminate test results occur early in pregnancy, as initiation of ARV prophylaxis in the absence of maternal indications is suggested after the first trimester (but no later than 28 weeks’ gestation).

For patients with confirmed HIV disease, preconception counseling is highly advised. Counseling provides the opportunity to discuss modes of mother-to-child transmission, methods to avoid transmission, safe sex practices during pregnancy, means of optimizing maternal health and nutrition, when to initiate ART, and concerns about potential adverse effects of ARV therapy for both mother and fetus. Birth control options to prevent future pregnancies, smoking cessation initiatives, referrals for drug counseling, delivery options, and alternatives to breastfeeding might also be discussed. For women whose HIV-positive status is discovered during prenatal testing, similar subjects should be broached during that or subsequent prenatal visits.

It is estimated that up to 25% of HIV-1-infected people will require surgery at some stage during the course of their illness (17). Further, given the rising rate of infection among women of childbearing years, anesthesiologists will encounter infected patients in the labor and delivery suites with increasing frequency. HIV infection affects multiple organs, and the provision of care may be further complicated by opportunistic infections, substance abuse, social and domestic issues, therapeutic drugs, tumors, and the risk of viral transmission to the health care worker. The following sections review the multiple organ systems affected by HIV.