Hallow Dear, Pregnancy test done in the first week after missed period may be false negative, particularly performed on the random urine sample. Ideally this test should be performed on overnight morning first urine sample after 8-10 days of missed period. However, delayed period for one week with stabbing pain in left iliac fossa should not be taken lightly. Please report to the Gynaecologist. You have to rule out ectopic pregnancy. Ectopic pregnancy is a serious condition wherein the baby is implanted somewhere outside the uterine cavity - most commonly in the tubes. In this condition, the hCG hormone which gives pregnancy test positive is low and hence the pregnancy test may be negative or weak positive. There is always a risk of rupture of such pregnancy which causes threateningly alarming bleeding. Such accident usually needs lot of blood transfusion and surgical intervention. Ultrasonography will help you find out whether the pregnancy is located in the uterus or somewhere else. Also please repeat pregnancy test on overnight first morning urine sample after 4 days. Alternatively you may opt for Beta hCG test. This is very sensitive test. If it is positive and/or weak positive and the uterus is empty, it suggests ectopic pregnancy. Then Laparoscopy is advisable. If it reveals unruptured ectopic pregnancy, it can be managed through laparoscopic surgery and further catastrophic bleeding can be prevented. I hope this guides you for further steps. Please report to an Obstetrician ASAP. Dr. Nishikant Shrotri