My period is 3 weeks late and I have been having lower abdominal pain. Do you have any idea of what could it be?

Hello,

Welcome to icliniq.com.

If your menses have been delayed for over a week now and if it had been regular all this while, then the first thing which needs to be done is to rule out pregnancy. A urine pregnancy test will help you rule out pregnancy. If the pregnancy is ruled out, then the likely cause of sudden sharp shooting pain in the right iliac fossa could be:

1. Ovarian torsion - It is a gynecologic emergency in which the ovary gets rotated in such a way that the ovarian artery or vein is occluded.
2. Appendicitis - inflammation of the appendix.

Both shall require an ultrasound pelvis with Doppler studies to establish the diagnosis, and both are emergencies and would necessitate surgical intervention.

Another possibility is if the urine pregnancy test is positive, but no signs of pregnancy in the uterus, in that case, an ectopic pregnancy would have to be ruled out, and serum beta-hCG levels shall be required to confirm the viability of the pregnancy.

If all ultrasound reports and pregnancy tests are negative, then this lower abdominal cramps can be associated with premenstrual syndrome or PMS indicating that probably your menses shall ensue in the next few days.