Ultrasonic assessment of rhinostomy size following external dacryocystorhinostomy.

AIM To assess the dimensions and patency of the surgical epithelial fistula after external dacryocystorhinostomy, using B mode ultrasonography to define the postoperative soft tissue anastomosis. METHODS 12 patients undergoing 16 external dacryocystorhinostomies, with the creation of large osteotomies, were included in a prospective study. The horizontal and vertical dimensions of the bone ostium was recorded during surgery and compared with the ultrasonographic dimensions of the soft tissue anastomosis at 1 day, 2 weeks, and 6 months after surgery. Functional patency was confirmed with dye testing and irrigation. RESULTS Compared with an osteotomy of between 100 and 380 mm2 (mean 235 mm2), the soft tissue anastomosis on the day after surgery was, in all cases, markedly smaller (72-252 mm2; mean 144 mm2, or 61% of the bone window). The soft tissue anastomosis decreased to between 8 and 208 mm2 (mean 98 mm2; 68% of immediate postoperative value) at 2 weeks and 3-208 mm2 (mean 71 mm2; 49% of immediate postoperative value) at 6 months. 14 of the 16 (88%) dacryocystorhinostomies were functional at the end of the study, the two failures being associated with marked contracture of the soft tissue anastomosis; the outcome of surgery correlated significantly with the area of the anastomosis at 2 weeks (chi 2 = 16.3; p < 0.01) and at 6 months (chi 2 = 16.0, p = 0.01). CONCLUSIONS B mode ultrasonography provides a simple and effective method for assessing the size of the soft tissue anastomosis after external dacryocystorhinostomy and there is a significant reduction in size after surgery, to which the functional outcome of surgery appears related. As the initial soft tissue anastomosis cannot be larger than (and is, on average, about 60% of) the area of the osteotomy, this emphasises the paramount importance of a large rhinostomy to the success of lacrimal surgery.