Left-sided abdominal pain can occur due to many common and usually non-serious causes, and it is important to understand that normal tumor markers (CEA, CA-125, CA 15-3) are actually reassuring. These blood tests are not meant to find the cause of pain; they are mainly used to monitor known cancers or assess risk in specific clinical situations. If these markers are within normal limits, it strongly suggests that the pain is not due to cancer.
The most common causes of left-sided abdominal pain in a 30-year-old woman include gas, acidity, gastritis, irritable bowel syndrome (IBS), constipation, muscle strain, or colonic spasm. In women, gynecological causes such as ovulation pain, ovarian cysts, or hormonal fluctuations can also cause intermittent left-sided pain even when blood tests are normal. Sometimes pain can also be referred pain from the back or abdominal wall muscles.
Pain does not always show up in blood tests. Functional problems of the gut (like gas trapping or bowel spasm) and mild inflammation often cause significant discomfort but do not alter tumor markers or routine blood reports. Stress and anxiety can also amplify gut sensitivity and pain.
Next Steps
If ultrasound abdomen/pelvis, basic blood tests, and gynecological evaluation are normal, the pain is usually benign and treatable with dietary modification, gas-relieving or antispasmodic medicines, and lifestyle changes. However, if pain becomes persistent, severe, associated with fever, vomiting, weight loss, or abnormal bleeding, further evaluation may be required.
Good luck!! And do contact in case of any doubt.