Gonorrhea Workup

In women with symptoms and signs suggestive of pelvic inflammatory disease (PID) who are difficult to diagnose clinically, laparoscopy may be indicated to rule out (and, if need be, treat) appendicitis, ovarian torsion, ectopic pregnancy, or other surgical emergencies.

Imaging studies such as ultrasonography are obviously a less invasive means of obtaining diagnostic information, but potentially emergent cases may require a more definitive examination, which permits rapid intervention if required.

Perform lumbar puncture and joint aspiration, if indicated by clinical findings.

Culdocentesis, although rarely indicated, may demonstrate free purulent exudate and provide material for Gram stain and culture.

Culture is the most common diagnostic test for gonorrhea, followed by the DNA probe, and then polymerase chain reaction (PCR) and ligand chain reaction (LCR). The DNA probe is an antigen detection test that uses a probe to detect gonorrhea DNA in specimens.

Always obtain a pregnancy test for women of childbearing age who present with gonorrhea or any other sexually transmitted diseases (STD).

Culture and nonculture for N gonorrhoeae

Perform a culture or nonculture detection test for N gonorrhoeae on endocervical, urethral, pharyngeal, or rectal discharge. Because organisms are intracellular, attempt to obtain specimens in a manner that will contain mucosal cells and not merely discharge (similar to a Papanicolaou smear).

Nonculture tests are less accurate in the presence of blood or during menses. Use culture instead at these times.

Culture is performed on Thayer-Martin plates that must be stored refrigerated but warmed to room temperature before obtaining sample. The plate is then incubated in a carbon dioxide atmosphere. Poor technique drastically reduces test sensitivity.

Medicolegal cases (eg, child abuse, rape) require culture due to the possibility of false-positive results with nonculture methods. However, performing the more sensitive PCR-based tests to raise the likelihood of detecting an infection, and then following up with culture to produce admissible evidence, is appropriate.

Other STDs

Other tests that might be indicated are those for concurrent STDs. Patients in whom gonococcal disease is suspected should be evaluated for syphilis infection as well as infection with Chlamydia trachomatis (high rate of asymptomatic carriage), human immunodeficiency virus (HIV) (with counseling), hepatitis B virus (HBV), herpes simplex virus (HSV), and any STDs that are suggested by the history and physical examination findings. Administer HBV vaccination to these individuals unless they have received the full vaccine series.

Rapid HIV test technology makes testing in the emergency department (ED) and referral more practical than enzyme-linked immunosorbent assay (ELISA). The need for additional testing depends on the situation; they are often performed as a battery of tests in suspected rape and child abuse cases.

HIV testing in cases of rape or new-onset abuse does not acutely diagnose a new infection but does establish a baseline status of the patient such that subsequent seroconversion might be linked back to the event in question.

Gram stain

Gram stain is a rapid and inexpensive test available in many emergency departments (EDs). The positive predictive value (PPV) is high for urethral infection, but a negative Gram stain does not rule out infection in asymptomatic men.

Collect specimens from the urethra, endocervix, pharynx, rectum, conjunctiva, urine, or blood.

A Gram stain of urethral or cervical discharge may show gram-negative intracellular diplococci (diagnostic in the male) and polymorphonuclear cells. This is very useful if the physician has easy access to a microscope, because the diagnosis may be made without waiting for culture results.

Sensitivity and specificity of the Gram stain are lower for endocervical specimens and rectal specimens. Gram stains from these sites are not recommended for routine use in the ED. In addition, Gram staining is not useful for the diagnosis of pharyngeal infection, because the oropharynx may be colonized by other Neisseria species that can lead to false-positive results.

Culture

Specific culture of a swab from the site of infection is a criterion standard for diagnosis at all potential sites of infection and can potentially guide treatment by determining antibiotic susceptibility.

N gonorrhoeae is a fastidious organism that requires moist carbon dioxide-rich atmosphere and must be grown on enriched media, usually chocolate agar containing lysed blood. Empiric treatment is often necessary because culture results are not available for 24-48 hours.

Cultures are particularly useful when the clinical diagnosis is unclear, when a failure of treatment has occurred, when contact tracing is problematic, and when legal questions arise.

Suspected disseminated gonococcal infection

When disseminated gonococcal infection (DGI) is suspected, blood and joint effusions should be sent for Gram stain and culture, although negative Gram stain results and sterile cultures do not rule out disseminated disease. Cerebrospinal fluid should be stained and cultured if signs or symptoms of meningitis are present.

Gram stains, cultures, and/or nucleic acid amplification tests (NAATs) of genital, rectal, conjunctival, and pharyngeal secretions should also be obtained when disseminated gonococcal infection is suspected, even if the patient has no localized symptoms at any of those sites.

Nucleic acid amplification tests (NAATs) are designed to amplify sequences of DNA unique to a given pathogen, such as Neisseria gonorrhoeae. These tests are more sensitive and specific than nonamplification techniques.

Several US Food and Drug Administration (FDA)–approved NAATs are available for the detection of N gonorrhoeae in urethral swab specimens obtained from males; endocervical swabs; and urine specimens obtained from men and women. These tests are more rapid than culture, more specific than immunoassays, and do not require viable organisms.^[8]

NAATs may be of particular use when examination and mucosal swab are difficult (in children or extremely apprehensive patients), and urine specimens are more easily obtained. However, although these tests can be used on eye secretions, their performance is less well validated. In addition, NAATs are not all recommended for rectal and pharyngeal specimens at this time.

Clinicians should be familiar with specimen collection guidelines and performance parameters of the test available at their own hospitals.

Suspected disseminated gonococcal infection

NAATs of genital, rectal, conjunctival, and pharyngeal secretions should also be obtained when disseminated gonococcal infection is suspected, even if the patient has no localized symptoms at any of those sites.

Polymerase chain reaction (PCR) and ligand chain reaction (LCR) are gene amplification techniques that markedly increase the sensitivity of specimen testing. Both techniques amplify the genetic fingerprint of specimens with very few organisms present in order to more easily detect and identify the organisms. Although the sensitivity is significantly increased, these methods of diagnosis are many times more expensive than culture or DNA probe. In many settings, PCR and LCR are not readily available, because they may require a specialized laboratory facility. False positives are generally due to laboratory error (inadvertent contamination).

Ultrasonography may be indicated in women to investigate suspected pelvic inflammatory disease (PID) and to visualize the appendix and ovaries as other possible causes of the symptoms. Pelvic ultrasonography or computed tomography (CT) scanning may demonstrate thick, dilated fallopian tubes or abscess formation.

PID is uncommon in pregnancy when the cervical mucous plug may provide some protection to the upper tract. Ultrasonography should be used to rule out ectopic pregnancy whenever a pregnant patient has signs and symptoms of possible PID.