Ultrasonic detection of middle ear effusion: a preliminary study.

Objective: To assess the ability to detect and characterize middle ear effusion in children using A-mode ultrasonography.

Design: Prospective nonblinded comparison study.

Setting: Tertiary children's hospital.

Patients: Forty children (74 ears) scheduled to undergo bilateral myringotomy with pressure equalization tube placement.

Interventions: Before myringotomy, ultrasound examination of the tympanic membrane and middle ear space was performed on each ear. Afterward, myringotomy was performed and the type of effusion (serous, mucoid, or purulent) was recorded. Pressure equalization tubes were then placed.

Main Outcome Measure: Comparison of ultrasound findings with the visual assessment of the type of middle ear effusion present.

Results: Of the 74 ears tested, 45 (61%) had effusion on direct inspection. The effusion was purulent in 8 ears (18%), serous in 9 ears (20%), and mucoid in 28 ears (62%). Ultrasound identified the presence or absence of effusion in 71 cases (96%) (P = .04). Ultrasound distinguished between serous and mucoid effusion with 100% accuracy (P = .04). The probe did not distinguish between mucoid and purulent effusion.

Conclusions: Ultrasonography is an accurate method of diagnosing middle ear effusion in children. Moreover, it can distinguish thin from mucoid fluid. Further refinements in probe design may further improve the sensitivity of fluid detection and allow differentiation of sterile vs infectious effusion.