Under short dissociate anesthesia, another attempt was made to untie the knot and straighten the catheter with angiography wire through the catheter lumen. Failing this maneuver, the catheter was divided flush with the glans penis and the knotted catheter was gently manipulated out through a small perineal urethrostomy (Fig. ​(Fig.1).1). A percutaneous suprapubic tube was inserted and was left in place for a week. The child had been passing urine in good stream on follow up.

Case 2: A male newborn weighing 1.8 kg was operated for ileal atresia on day-1 of life; resection of atretic segment and end-to-back ileo-ascending colic anastomosis was done. The patient was re-operated after two weeks for anastomotic leak. Three days later, an attempt to remove the catheter (6 Fr IFT) was met with resistance. From the past clinical experience, catheter knotting was suspected. On this occasion, manipulation with angiography wire through the catheter lumen succeeded and the catheter removed. The child was discharged after a month of admission. Unfortunately, a week later he was brought moribund to the casualty where he succumbed to severe dehydration and refractory shock.

Although knotting of urethral catheters is rare, removal represents significant morbidity, such as general anesthesia, radiation exposure during fluoroscopy, and transient hematuria [1]. Potential for further complications such as stricture formation also needs to be considered. Knotted urinary catheters may also jeopardize delicate surgical reconstructions [3, 6]. Unfortunately, many doctor colleagues and nursing staff are unaware of this problem or its proper management. A telephone survey of 24 tertiary- care Emergency Departments in Canada revealed that none of them were aware of catheter knotting and 22 had no protocol established for safe catheterization [1].

Several hypothetical explanations have been offered for the knotting of catheters. The tendency of a catheter to knot probably depends on its flexibility, smaller diameter and redundancy within the bladder. The probable mechanism involves an extra length of catheter coiling around itself and then the catheter end looping through these coils [4]. The coils tighten cinching down in a knot when counter traction is applied to remove the catheter. If the diameter of this knot exceeds that of urethra the catheter gets stuck. Bladder spasm has been also been attributed as a risk factor [7]. Water-current generated by the flow of urine around the catheter may also play a role in the genesis of catheter knotting [2]. Raveenthiran suggested that the catheters slender than 10 Fr, over-distended bladder and insertion of excessive length (greater than 10 cm beyond bladder neck) of catheters must be considered as risk factors for catheter knotting [2].

Several techniques have been described to retrieve the knotted catheter. They include sustained traction under anesthesia, unraveling the knot using a guide-wire through the catheter under fluoroscopy, endoscopic retrieval and suprapubic cystotomy [4, 7, 8, 9]. Guide-wire manipulation is useful only at the early ‘open-loop stage’ of knot formation when the knot is not tight enough [8] and succeeded in one of our cases. Sustained traction also worked once, but such a manipulation with or without urethral dilatation carries the risk of urethral damage. Moreover, this technique is not useful when the knot is bulky or when two catheters knot together [2]. Suprapubic cystotomy has been known as a simple, safe and cost-effective method of retrieving knotted bladder catheters [10], though in the modern era, this could be replaced by vesicoscopy.