Ans. (a) UreterocoeleRef: SRB Manual of Surgery 4th ed. /1279The adder head /cobra head sign refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocoele. The presence of this cobra head appearance is an indicator of uncomplicated ureterocele.A ureterocele is a submucosal cystic dilation of the terminal segment of the ureter.It may be classified most easily as intravesical, defined by its presence entirely within the bladder, or extravesical, defined by the permanent presence of some portion of the ureterocele at the bladder neck or urethra.