Appearance is probably the best way to tell.
If there is still a significant remnant of the foreskin
, then the circumcision
was probably incomplete. If the sutures
were not placed correctly, there could be strictures causing too much tension on the head of the penis. Don't be too quick to judge however if the circumcision is very recent; the skin will need time to heal properly.
Answer assisted by David Escobar, Medical Student