Screening Guidelines for Sexually Transmitted Diseases.

Essential Features

Most sexually transmitted diseases (STDs) are asymptomatic. Persons with asymptomatic STDs are at risk for complications and transmission of infection to others.

 

In some cases, screening is the only means to detect and treat infection to prevent adverse outcomes.

 

The judicious use of screening tests relies on appreciation of disease epidemiology and accurate assessment of a patient's sexual risk behavior.

General Considerations

Most sexually transmitted diseases are asymptomatic. Patients often acquire infection from sex partners who exhibit no symptoms. Persons with asymptomatic infection may develop complications or sequelae without knowledge of being infected. The epidemiology of STDs—how those diseases are distributed within a population—is not random; risk factors that include age, gender, and sexual activity dictate who is likely to be infected. Screening and timely treatment have been shown to reduce the consequences of infection. National organizations, including the US Preventive Services Task Force and the Centers for Disease Control and Prevention (CDC), as well as professional medical societies, regularly review the current scientific literature and make evidence-based recommendations for STD and HIV screening. Individuals are advised to undergo STD testing not only to identify and treat asymptomatic infection (screening) but to monitor trends in the population (surveillance) and confirm a diagnosis. Table 1–1 summarizes current STD and HIV screening recommendations.

Nonpregnant Women

Routine screening for Chlamydia trachomatis has been shown to reduce the incidence of pelvic inflammatory disease (PID) and, on a population level, such screening may be associated with reductions in PID and ectopic pregnancy. All sexually active women aged 25 years and younger should be screened annually for C trachomatis, as should older women whose behaviors may place them at risk (ie, those with multiple or new sex partners). Recently some experts have suggested that the age range for C trachomatis screening should be expanded to encompass all sexually active women up to age 30 years. In addition to routine screening, new CDC guidelines recommend that women who test positive for chlamydia should be retested at 3 months to rule out reinfection.

Currently the most sensitive diagnostic assays are nucleic acid amplification tests (NAATs). Each available NAAT uses slightly different technology: polymerase chain reaction, strand displacement amplification, and transcription-mediated amplification. Overall these NAATs are significantly more sensitive than culture and more sensitive than nonamplified DNA probe assays. Specificity of these assays is very high (>99%). An additional advantage of these tests for screening is their simplified method of specimen collection. Obviating the need for pelvic examination, all currently available NAATs can be used on first-void urine specimens, and transcription-mediated amplification (APTIMA assays, GenProbe, Inc) is cleared by the Food and Drug Administration (FDA) for use on self-collected vaginal swabs.

In 2005 the US Preventive Services Task Force issued guidelines for gonorrhea screening in young women with select risk factors (eg, women with multiple partners, prior history of an STD, and black race). In areas where gonorrhea is relatively common, screening is likely to be beneficial and can be readily accomplished, because the same specimen collected for nucleic acid amplification testing for C trachomatis can also be used to test for Neisseria gonorrhoeae.

Beginning at age 21 or no later than 3 years after the onset of sexual activity, nonpregnant women should be screened annually for cervical disease using Papanicolaou (Pap) smears. The use of type-specific human papillomavirus testing remains under consideration as a screening tool. In women older than 30 years of age who have a history of normal results on three recent Pap smears, the frequency of screening can be reduced to every 2 or 3 years.

Syphilis screening using serologic tests for syphilis (rapid plasma reagin [RPR] or Venereal Disease Research Laboratories [VDRL] test) is not routinely recommended in nonpregnant women, nor is serologic screening for herpes simplex virus (HSV) infection. However, in women with select risk factors (eg, those who have multiple partners, exchange money or drugs for sex, have partners with other partners, have partners with an STD, or are at increased risk for HIV infection), some expert groups recommend syphilis testing and testing for HSV type 2 (HSV-2) antibody.

Routine screening in asymptomatic women is not recommended for trichomoniasis, bacterial vaginosis, or vaginal yeast infection.

Pregnant Women

Pregnant women are screened more aggressively for STDs than nonpregnant women because of the increased risk for adverse outcomes, including preterm delivery (resulting in low-birth-weight infants) and premature rupture of membranes (resulting in increased risk for chorioamnionitis). At the first prenatal visit all women should be screened for chlamydia and gonorrhea with an NAAT, and blood should be tested for syphilis (RPR or VDRL). Although HSV-2 antibody screening is not routinely recommended, a thorough history assessing risk for genital herpes—including prior episodes of genital ulcer disease, vesicular lesions, or recurrent urogenital symptoms of burning, pain, or erythema—is strongly recommended. If a current or prior sex partner has or had genital herpes, HSV-2 antibody screening is recommended. In most states, pregnant women must be offered HIV testing with the option to decline ("opt-out" testing). In asymptomatic pregnant women, evaluation of vaginal fluid for the presence of trichomoniasis or bacterial vaginosis is recommended in women who are at increased risk for an adverse pregnancy outcome, primarily defined as women with a history of preterm delivery. Two studies have demonstrated no benefit and perhaps harm in asymptomatic low-risk pregnant women who were screened and treated for bacterial vaginosis or trichomoniasis.

Heterosexual Men

There are no guidelines recommending routine STD screening of sexually active asymptomatic men. Although numerous studies have demonstrated high rates (5–15%) of asymptomatic chlamydial infections in select men (age younger than 25 years, incarcerated, urban residents), no national organization currently recommends routine chlamydia screening. In specific settings (eg, detention facilities and STD clinics), however, screening of asymptomatic men younger than 25 years of age is useful and has been associated with decreased rates of infection in the local community. Screening in that regard serves as a public health disease control strategy rather than a medical strategy to prevent the consequences of infection in an individual. Given the current low rates of asymptomatic gonococcal and syphilitic infections in much of the United States in men without specific risk factors (eg, men who have sex with men), screening for those infections is not routinely recommended. The prevalence of HSV-2 infection in some segments of the general adult population exceeds 20%; however, no recommendation currently exists for routine HSV-2 screening in persons without symptoms or known exposure to a partner with genital herpes. Screening for human papillomavirus infection is also not recommended.

New evidence suggests that screening for HIV infection should be routine in all sexually active adults, and the CDC recommends HIV screening for populations in which the prevalence is greater than 1%. The frequency of routine screening, however, remains unclear.

Men Who Have Sex with Men

Men who have sex with men (MSM) with multiple partners are at increased risk for STDs and HIV infection. Several organizations recommend routine screening for rectal chlamydia, rectal and pharyngeal gonorrhea, syphilis, HIV infection, and HSV-2 infection in MSM as a public health measure to decrease the continued community-level transmission of those infections. Ample evidence also exists to support routine STD screening and treatment as an individual measure to reduce the risk of HIV acquisition and transmission. The optimal frequency of screening is unclear, and recommendations range from every 3–6 months in men with "many" partners to annually in those with "few" partners. Unfortunately, data are limited on which to form strong evidence-based guidelines about the frequency of screening.

STD Screening in HIV-Infected Persons

In HIV care settings, it has been recommended that syphilis tests be conducted every 3 months, with routine immunologic and virologic monitoring and gonorrhea and chlamydia screening every 6 months. It is important to recognize that gonorrhea and chlamydia screening should be performed at each potentially exposed anatomic site where infection can occur. Thus, gonorrhea and chlamydia screening of the throat and rectum is recommended. NAATs have been proven to have superior sensitivity and comparable specificity to traditional culture of the throat and rectum. Nucleic acid amplification testing with strand displacement amplification or transcription-mediated amplification of specimens from those sites is also easier for the clinician and less laborious and time consuming for the laboratory. Although routine screening for cervical cancer caused by human papillomavirus infection is strongly recommended in HIV-infected women, the data are less robust in men and there are no national recommendations for anal cancer screening. The rates of anal cancer in men are similar to the rates of cervical cancer in women before the advent of routine cervical cancer screening (40–50 cases per 100,000 population); for this reason, some HIV care experts recommend routine anal cancer screening in HIV-infected men with annual or biannual anal Pap smears.

Practice Points

 Obviating the need for pelvic examination, all currently available NAATs can be used on first-void urine specimens, and transcription-mediated amplification is cleared by the FDA for use on self-obtained vaginal swabs.

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