Why is my left lower abdomen swollen?

The left lower part of your belly houses parts of your colon, and conditions that affect this area can cause it to swell. One common cause is diverticular disease or diverticulitis. Diverticular disease occurs when small pouches form in the colon wall, and if these pouches become inflamed or infected (diverticulitis), this can lead to pain, swelling, and discomfort in that region. Another possibility is bloating due to gas or fluid buildup from your diet or digestive problems. When gas or fluid gets trapped in your intestines, it can make your abdomen feel swollen. Even constipation can cause swelling, due to back up of stool. Additionally, other factors such as minor trauma or changes in the soft tissues might contribute to the swelling. If your swelling is accompanied by pain, fever, or other discomforts, you can use a free symptom checker to help identify possible causes, and then consult a healthcare provider who can perform a physical exam and suggest tests like imaging studies to find out exactly why you're experiencing swelling and how to treat it.