Frequency of Extravasation on Pericatheter Retrograde Urethrogram in Patients Who Undergo Posterior Urethroplasty

Introduction

Urethroplasty is the gold standard treatment for urethral stricture disease resulting from pelvic fractures, urethral manipulation, and straddle injuries. Post-operative morbidity depends on the presence of urethral catheterization with or without a suprapubic catheter (SPC). Urethral healing at the anastomotic site can be easily assessed using retrograde pericatheter urethrography (RPU). Post-operative removal of the catheter is traditionally performed on the 21^st day following urethroplasty. However, some controversy still exists regarding the best feasible time of proper urethral healing and its assessment utilizing simple techniques. The duration of anastomotic healing differs depending on the type of procedure performed, but whether there is any significant difference in duration of healing at the anastomotic site according to the etiology of short‐segment stricture urethra is still a dilemma.

Materials and methods

This was a descriptive case-series conducted for a duration of six months from September 2019 to February 2020 at the urology department of a tertiary care hospital in Karachi, Pakistan. A sample population of 135 patients aged 20-50 years with posterior urethral stricture who underwent posterior urethroplasty with disease duration of >12 months was included in the study. All patients were put on the next operation theater (OT) list for urethroplasty. After surgery, the patients were catheterized and were kept in the ward under observation for 48 hours and discharged on the 2^nd post-operative day. All patients were followed weekly and RPU was performed on the 21^st day following urethroplasty to assess the presence of extravasation and the collected data was entered into the proforma by the investigators. All statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 23.0.

Results

The mean age of our participants was 32.8±6.02 years. The mean duration of the procedure was 26.3±7.14 months. Extravasation cases were observed in less than one-fifth (n=22 out of 135, 16.3%) of the posterior urethral stricture patients in our study.

Conclusions

It is to be concluded that extravasation is fairly common in patients who undergo posterior urethroplasty. The prevalence varies depending on the assessment method, likely reflecting the treatment of somatic symptoms.

The effect of nitrogen supplementation on the efficiency of colour and COD removal by Malaysian white-rot fungi in textile dyeing effluent

White-rot fungi, namely Coriolus versicolor and Schizophyllum commune, were studied for the biodecolorization of textile dyeing effluent in shaker-flask experiments. The results showed that C. versicolor was able to achieve 68% color removal after 5 days of treatment while that of S. commune was 88% in 9 days. Both fungi achieved the above results in non-sterile condition with diammonium hydrogen phosphate as the nutrient supplement. On the other hand, the best COD removal of 80% was obtained with C. versicolor in 9 days in sterile effluent with yeast extract as nutrient supplement, while S. commune was able to remove 85% COD within 8 days in non-sterile textile effluent supplemented with diammonium hydrogen phosphate.

Caustic merit function for optical design

The two caustic surfaces, which are in turn the loci of the image points, are formed in the image region by each element of the source of an optical system. Lens optimization is achieved herein by adjusting parameters so that the caustic surfaces formed by rays from selected points of the object coalesce and converge to the corresponding Gaussian image points. A merit function, specifying the sum of the distances between each caustic surface and the corresponding Gaussians image, is defined and minimized subject to the constraints that the system focal length and physical length are constant and that the third-order aberrations of the system are zero. An optimization procedure, based on minimizing the caustic merit function, is used to design a singlet, doublet, and triplet lens system.

Wave front equation, caustics, and wave aberration function of simple lenses and mirrors

Using the condition of constant optical path length for rays passing through an optical system, an equation for the wave front is presented in a simplified form. The wave front equation has been explicitly evaluated for a plane wave incident on a spherical reflector or a plano-convex lens. Then, the principal radii of curvature of the reflected or refracted wave front, evaluated directly from the wave front equation, are shown to locate the caustic surfaces of the optical system. From the wave front equation, a closed form expression for the wave aberration function for a plane wave reflected by a spherical mirror or a plano-corvex lens has been evaluated and compared to the results obtained from third-order aberration theory.