Usually there will not be any connection or relation between umbilicus
and sexual organs.Your condition may not interfere with intercourse,but a discharging sinus
may cause discomfort and sometimes increased intra abdominal pressure(as occurs during sexual intercourse) may delay healing process.It all depend on the cause,complexity and stage of healing.Your surgeon is the best person to asses this.I suggest you to discuss with him without any hesitation and most probably you will get a positive answer.
In summary, You can have sex without any fear but get a nod from your surgeon before doing so.
Wish you all the best