Thank you for your query.
has a failure rate of 2 - 10 per 1000 women ligated.
Which means, it is not 100 % effective, though highly effective.
Hence, yes, there could be a chance of pregnancy in your case.
Other causes of irregular cycles are endometriosis
, stress, anxiety, metropathic cycles, weight fluctuations rapidly, polycystic ovaries
, endometrial hyperplasia
, hormonal medications etc.
Also, a word of caution, erratic spotting could herald an ectopic pregnancy, and after tubal ligation, chances of ectopic pregnancy are much higher compared to chances of an intra uterine pregnancy.
Please consult a gynecologist at the earliest for the diagnosis.