A number of diagnostic aids may be helpful in confirming or making the diagnosis of rhinosinusitis. An evidenced-based report by the Agency for Health Care Policy and Research suggested that ancillary tests and radiographs are not cost-effective in making the diagnosis, and are typically unnecessary in uncomplicated ABRS.

Rather, a clinical diagnosis is preferred. In CRS, however, it is recommended that unless the diagnosis is clear from history and physical examination, confirmation should be obtained either through nasal endoscopy, CT scanning, or plain sinus X-rays.

The various tools that have been used to aid in the diagnosis and assessing the response to treatment will be discussed.

Transillumination

Transillumination of the frontal or maxillary sinus may suggest the presence of fluid; however, it cannot differentiate between fluid opacification, tumor, and agenesis of the sinus.

Also, evaluation of ethmoid and sphenoid sinuses is not feasible. The utility of transillumination in the diagnosis of rhinosinusitis is questionable and would not likely facilitate the diagnosis or treatment.

Transillumination may have some value in confirming the diagnosis or assessing the response to treatment, if it were positive at the onset of treatment and negative later. Since clinical response may be a better measure, transillumination has little value.

Rigid or Flexible Endoscopy

Rigid or flexible endoscopy gives the diagnostician unparalleled access to the nose for the evaluation of the lateral nasal wall, which may otherwise not be possible on anterior rhinoscopy.

The anatomy of the middle meatus can be carefully evaluated. The presence of accessory ostia may be confused for the natural os. Small polyps or purulence within the middle meatus may be seen.

Evaluation of the sphenoethmoidal recess is possible by directing a fiber-optic scope along the floor of the nose and then directing the tip 90 degrees cephalad (toward the top of the head).

In children, evaluation of the nasopharynx may demonstrate chronic adenoiditis. Cultures may be taken from the middle meatus during rigid nasal endoscopy.

Although culture of the sinus cavity itself is not obtained, a strong correlation between endoscopic culture of the middle meatus and antral puncture with culture has been reported.

Endoscopically obtained cultures demonstrate a sensitivity of 85.7%, and a specificity of 90.6% when compared to sinus puncture. Culture of the nasal cavity in the absence of frank purulence will likely yield nasal flora, and thus would not be useful.

Although culture-directed therapy is ideal, treatment of uncomplicated cases of rhinosinusitis is presumptive, and is directed at S. pneumoniae, H. influenzae, and Moraxella catarrhalis.

However, cultures should be considered in patients who have failed previous therapy, have a history of immunodeficiency, or have poorly controlled diabetes mellitus.

Although the concordance between cultures obtained from antral puncture and those endoscopically obtained from the middle meatus appear promising, not enough evidence currently exists to recommend this technique over antral puncture.

Sinus Aspiration and Culture

Although sinus aspiration and culture are considered the gold standard for the diagnosis of rhinosinusitis, they are rarely indicated in uncomplicated cases. The cost, need for specialty referral, and discomfort experienced by the patient need to be considered.

Although generally safe, sinus puncture has been associated with rare but serious complications, including tissue emphysema, air embolism of venous channels, vasovagal reactions, and soft tissue or bony infection.

Although adult patients readily tolerate the procedure in an outpatient setting, children often require a general anesthetic. As previously stated, initial treatment of ABRS is presumptive, directed at the most commonly identified organisms (S. pneumoniae, H.Influenzae, M. catarrhalis).

The majority of cases of rhinosinusitis would likely resolve even without antibiotics. Positive cultures are recovered in only 50% to 60% of patients diagnosed with rhinosinusitis. The maxillary sinus is readily accessible through a canine fossa approach or via the inferior meatus.

In children, an inferior meatal approach is preferred since it carries less risk to the dentition and orbit. This is performed under general anesthesia and often in conjunction with adenoidectomy. A sublabial, canine fossa sinus puncture is well tolerated, and can be performed in the office setting with minimal morbidity.

Commercial kits are readily available. A specialist finds the procedure simple to perform and accurate results can be obtained as long as proper steps are taken to prevent contamination. The aspirated fluid should be noted for its gross appearance.

Aerobic and anaerobic cultures as well as gram stain should be obtained. Fungal cultures can be obtained if the index of suspicion is high. Individuals with rhinosinusitis who have failed multiple courses of antibiotics and those with immune suppression should be considered for sinus aspiration and culture.

Those individuals with infection extending to the orbit or threatened intracranial extension should be scheduled for emergency surgery. However, critically ill patients who are not operative candidates may tolerate sinus aspiration quite well. This procedure may prove to be therapeutic as well as diagnostic.

Quantitative cultures may assist in identification of the pathogenic organism from nasal flora. The recovery of bacteria in a density of at least 104 colony-forming units (CFU)/mL is considered representative of a true infection.

Also, the finding of at least one organism per high power field on gram stain is significant, and correlates with the recovery of bacteria in a density of 105CFU/mL.

Limitations of sinus aspiration include the inability to sample the sphenoid and ethmoid sinuses. Frontal sinus sampling would engender risk to the brain and would be inadvisable. Contamination by oral or nasal flora may result in misleading results; however, quantitative cultures may prove more reliable.

Imaging

The role of imaging is discussed in detail in another chapter, and will only be briefly described here. Plain sinus radiographs have long been used to aid in the diagnosis of rhinosinusitis.

Given the poor sensitivity and specificity and the likelihood of abnormal findings even with a viral URTI, plain sinus radiographs have little value in ABRS. They have not been shown to be cost-effective.

They may be helpful in confirming the diagnosis of CRS in patients who have appropriate signs and symptoms for a sufficient duration of time, but cannot be confirmed by a nasal examination, particularly where endoscopy is not available.

Ultrasound has also been used, particularly in Europe, but has similar if not greater limitations compared to plain sinus films. CT scanning is considered the radiographic modality of choice.

Although limited in differentiating ABRS from a viral URTI, CT scans are very useful in CRS or in assessing the suspected complications of either ABRS or CRS. MRI scan is generally considered to be of limited value in the evaluation of rhinosinusitis at this time.

Ancillary Tests

There are a number of ancillary tests thatmay be helpful in assessing the severity of disease or the response to treatment.

These include measures of smell (such as the University of Pennsylvania Smell Identification Test or UPSIT), measures of nasal airflow or resistance by acoustic rhinometry or rhinomanometry, the Electronic Nose, or various blood tests.

As mentioned previously, allergy testing may be useful, particularly in those with a strong allergic history or family history, or who have had a poor response to directed therapy.

Outcome Evaluations

An area of great recent interest in many diseases and disorders over the last few years are the methods to evaluate quality of life (QOL) and outcomes. Rhinosinusitis has been well studied in relationship to QOL and outcomes, and a few tools or instruments have been specifically designed to evaluate this specific entity.

Three commonly used instruments are the Rhinosinusitis Disability Index (RSDI), the Sino–Nasal Outcomes Test (SNOT), and the Chronic Sinusitis Survey (CSS). The RSDI was specifically developed to assess rhinosinusitis, although it has more recently been validated for other nasal and sinus disorders, including allergic and non-allergic rhinitis.

Although there are some differences between these instruments, they all serve to establish a level of function for rhinosinusitis patients and may be used to evaluate the response to treatment.