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close this bookSexually Transmitted Diseases (STD) Syndromic Management (AIDSCAP/FHI, 1997, 54 p.)
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View the documentValidity Testing of a Flowchart: Sensitivity and Specificity


A team of public health specialists should design diagnostic and therapeutic flowcharts for use at the national level. Key people to involve in the design are the coordinators of national programs, including STD/AIDS control, primary health care, essential drug, family planning, and maternal and child health. In some situations, it is advisable to ask specialists, such as gynecologists, microbiologists, genito-urinary specialists and pharmacists, to participate. The involvement of these specialties can help to ensure their cooperation and increase the acceptance of the flowcharts.

In order to ensure that as many patients as possible receive correct diagnoses, background information on local etiologies of STD syndromes, including mixed etiologies, is essential in designing an STD management flowchart. Data on validity and cost-effectiveness can be obtained from the literature or from special studies. Decisions on the most cost-effective treatments must be based on local or regional antimicrobial susceptibility patterns, results of treatment trials, toxicity data and the cost of the drugs.

To ensure efficient management of STDs, flowcharts should be adapted to the level of development of the health services. Feasibility is determined by the presence of laboratory facilities; the infrastructure available for physical examination (availability of an examination room with privacy, examination table, adequate specula, gloves and light source, and facilities to disinfect specula regularly); the level of training of personnel (ability to perform a speculum examination); access to a higher-level health care facility for referrals; the drugs available in health care facilities; and the staff time available per patient.

Local and cultural perceptions about STDs and health-seeking behavior will, to a large extent, determine the usefulness of certain flowcharts. For example, when designing a flowchart, it is important to consider whether a genital examination by a health care worker of the opposite sex is culturally acceptable.


Described below are examples of syndromic case management protocols developed by a variety of countries in Latin America and the Caribbean.16 The original WHO flowcharts were developed for six syndromes: urethral discharge, vaginal discharge, pelvic inflammatory disease, genital ulcer disease, swollen scrotum, and neonatal conjunctivitis. The first four are discussed below.

Urethral Discharge Syndrome in Men

Gonorrhea is the main cause of urethritis among clinic attendees in most developing countries. In recent years, however, as diagnostic techniques for chlamydia have become more sensitive, the role of chlamydial and mixed infections in causing urethritis in developing countries is also becoming better defined. Some clinicians rely on the characteristics of urethral discharge to differentiate between gonococcal and non-gonococcal urethritis (NGU). Gonococcal urethritis tends to be more purulent and NGU more mucoid. However, these clinical signs are not sufficiently discriminatory to predict the etiology or cause of urethral discharge in a given patient.17 In addition, they can be confounded by prior, ineffective treatments patients may have taken before coming to the clinic.

Two examples of flowcharts for urethral discharge are shown in Figures 2 and 3. The first example (Figure 2) is a simple syndromic management, treating every man with a complaint of urethral discharge for gonorrhea and NGU. A sequential treatment (first, treatment for gonorrhea and if this fails, treatment for NGU) has been the policy in the past in some countries in order to limit unnecessary treatments. However, because of a large proportion of missed chlamydial infections, and because many patients fail to come back, this approach can no longer be recommended.

Figure 2 - Management of Urethral Discharge - HONDURAS

In the second flowchart (Figure 3), Gram stain is added to a syndromic approach. Depending on the result of the Gram stain, a syndromic treatment or a treatment for NGU will be given. This approach offers the advantage of reducing unnecessary treatments (including expensive gonorrhea drugs) for the patient and his partner by increasing the specificity of the flowchart.

Figure 3 - Management of Urethral Discharge - JAMAICA

A flowchart including Gram stain can only be considered when laboratory facilities are available. Results should be given within a reasonable time so patients do not have to return to the health facility for treatment the next day. This approach reduces the risk of serious complications, acute morbidity associated with either gonorrhea or chlamydia, and further transmission of the causative organism.

Vaginal Discharge Syndrome in Women

The symptoms of cervicitis and vaginitis overlap. Abnormal (in amount, color or odor) vaginal discharge is the symptom most commonly presented, but it is more predictive for vaginitis than for cervicitis.18,19 The sensitivity of the symptom vaginal discharge for cervicitis varies from 25 percent (prostitutes in Zaire) to 48 percent (STD patients in USA). Cervical mucopus and induced endocervical bleeding have a high specificity (83 to 99 percent) but a low sensitivity (1 to 43 percent) as clinical signs for cervicitis. Examples of flowcharts for vaginal discharge are shown in Figures 4 and 5.

Figure 4 is a flowchart for situations in which a speculum examination is not possible. The most probable cause of a woman complaining of vaginal discharge is vaginitis. Cervicitis is a less frequent cause of consultation for vaginal discharge, but the complications of untreated cervicitis are much more serious.

Figure 4 - Example of a Flowchart for the Management of Vaginal Discharge - HAITI (without speculum)

The accuracy and cost-effectiveness of syndromic diagnosis of vaginitis can be improved significantly in some settings by adding a risk assessment component to the case management protocols (for instance, determining whether an individual has had a new sexual partner or more than one sexual partner in the past three months). Using this approach, a woman with vaginal discharge and positive risk assessment for STDs would be treated for gonorrhea and chlamydia cervicitis as well as for vaginitis; a woman with no risk factors for STDs would be treated only for vaginitis, which requires a much less expensive treatment regimen. A recent analysis of data from pregnant women and sex workers in Zaire suggested that a simple case management protocol based on reported vaginal discharge and a risk assessment could be a useful tool for symptomatic women at high and low risk for STDs.20

In situations where a speculum examination is possible, the clinician can try to differentiate between various etiologies of vaginal discharge. The clinical sign mucopus, however, is not sensitive enough to be the only indication for cervicitis treatment. Figure 5 is an example of a flowchart utilizing a speculum exam and a risk assessment.

Figure 5 - Example of a Flowchart for the Management of Vaginal Discharge - JAMAICA (without speculum)

An alternative for differentiating etiologies for vaginitis can be offered by simple laboratory tests, if the infrastructure is available. Direct examination of a vaginal wet mount is useful for detecting trichomonads and yeast forms. Determination of the vaginal pH and amine odor with 10 percent potassium hydroxide solution can be helpful in the diagnosis of bacterial vaginosis. However, no simple laboratory test has been developed so far for detecting cervicitis. Adding Gram stain for the detection of intracellular gram-negative diplococci or leukocytes in the endocervix does not offer any advantage, as the sensitivity will drop dramatically. The leukocyte esterase dipstick, which has a good sensitivity for detecting male urethritis, had a sensitivity of only 47 percent for the detection of cervicitis.15

Pelvic Inflammatory Disease: The Management of Lower Abdominal Pain

Pelvic inflammatory disease (PID) is a common complication of untreated gonococcal and/or chlamydial cervicitis and results in tubal scarring and occlusion. This can lead to ectopic pregnancy — a serious, possibly life-threatening complication. Most infertility problems in the developing world are attributed to prior upper genital tract infections.21

An example of a clinical flowchart for detecting PID is shown in Figure 6. Because of the serious complications of PID, the flowchart should start with a very sensitive symptom. Lower abdominal pain is more sensitive for PID than fever. It is important that surgical and obstetrical emergencies, such as peritonitis and extra-uterine pregnancy, are immediately referred.

Figure - Example of a Flowchart for the Management of Abdominal Pain - DOMINICAN REPUBLIC

Genital Ulcer Disease

Many studies have tried to describe a "typical" clinical picture for the different etiological diagnoses of genital ulcer disease (GUD) but have failed. Descriptions, such as regular shape, smooth base, undermined edge, friability, tenderness and purulence, are not sufficiently discriminatory (even for experienced clinicians) to make an etiological diagnosis in most cases. In a study in South Africa of 210 patients with genital ulcers, clinical diagnosis was compared with a gold standard laboratory test. Clinical diagnosis had a positive predictive value of 89 percent for chancroid, 47 percent for syphilis, and 19 percent for genital herpes.13 Dual infections were common, making an etiological diagnosis even more difficult. Without sophisticated laboratory tests, an etiological diagnosis of GUD is impossible.

The relative frequencies of the different causes of GUD vary between geographical areas but can also vary in time. For example, two studies on the etiologies of GUD, in Rwanda in 1986 and 1992, found there was a shift in the relative frequencies of different etiologies. As the prevalence of HIV infection increased, herpes became more important as an etiology of GUD.22

In many developing countries, the etiologies of GUD most frequently found are syphilis and chancroid. Both are treated with simple antibiotics (erythromycin and benzathine penicillin, respectively).

An antiviral therapy for herpes is not available in most primary health care settings in developing worlds. It is important to treat for chancroid and syphilis, even if some of the genital ulcers treated are actually caused by herpes.

In Rwanda, three different approaches were compared for the management of syphilis and/or chancroid. The syndromic approach adopted by most developing countries, illustrated in Figure 7, resulted in 99 percent of the patients with syphilis and/or chancroid correctly managed. For the approach based on the result of a Rapid Plasma Reagin (RPR) test (if RPR positive, treat for syphilis; if RPR negative, treat for chancroid) and for a clinical etiological approach, the proportions of correctly managed patients were 82 percent and 38 percent, respectively.

Figure - Example of a Flowchart for the Management of Genital Ulcers - BRAZIL

Including an RPR test in a hierarchic model is not an improvement in genital ulcer case management because many chancroid cases are missed. However, based on the Rwanda data, including an RPR test in a syndromic approach (treating all RPR positive patients for both syphilis and chancroid, and all RPR negative patients for chancroid alone), leads to a reduction in unnecessary syphilis treatment of patients and their partners.

Validity Testing of a Flowchart: Sensitivity and Specificity

The sensitivity of a flowchart is the proportion of infections detected and treated when applying the flowchart to patient management. A high sensitivity implies a large proportion of the infections will be detected and treated, so the cure rate will be higher, and only a small proportion of infections will be missed. Missed cases place the infected person at a continued risk of more serious complications and result in further disease dissemination.

The specificity of a flowchart is the proportion of patients without infection that are not treated. A high specificity implies that patients without infection are not being told they have an infection and are not being treated. A low specificity means too many patients without infection are being treated. This has social, biological and financial implications. Socially, people without STDs are being told to have their partners treated; biologically, over use of antibiotics may lead to resistance strains; and financially expensive drugs are being wasted.

Work is ongoing on the identification, development, and use of simple tests that could improve the sensitivity and specificity of syndromic diagnosis, including simple, rapid tests to identify oxidase-producing organisms (e.g. gonococci) in urethral discharge and tests to detect leukocytes in cervical and urethral specimens which would be suggestive of chlamydial and/or gonococcal infections.

The study population for validity testing has to be as representative as possible of the population in which a flowchart will be used. As long as enough STD patients are consulted to reach the necessary sample size within a reasonable time and a reference laboratory is available for the gold standard tests, a primary health care setting is suitable. In general, sophisticated laboratory tests are needed for gold standard diagnosis. If some patients consulting at the primary health care level have already taken drugs, it is important not to exclude them from the validity study.

When testing the validity of flowcharts, it is preferable to have two examination rooms. In one room, a health care worker can follow the directives of the flowchart and make a therapeutic decision. Then the patient can be asked to enter a second room, where a more systematic examination can be done and where specimens will be taken for the gold standard laboratory tests. Since a speculum examination is sometimes not included in STD flowcharts, using such a setting will ensure that the therapeutic decision is not based on the findings of the speculum examination.

The likely outcomes of diagnoses made using a flowchart can be simulated retrospectively using data from history taking, physical examination and laboratory tests. This desk exercise can be very useful for evaluating modifications to flowcharts without repeating studies. For example, it could be used to assess what would happen to the specificity of a flowchart if the gram stain examination were omitted.