The left lower side of your abdomen contains a section of your large intestine called the sigmoid colon, the left ureter (the tube connecting your left kidney to your bladder), and in women, the left ovary and fallopian tube. When you feel pain or pressure in this area, one of these structures is usually the source. Understanding what sits there helps you make sense of symptoms and communicate more clearly with a doctor if something feels off.
The Sigmoid Colon
The most prominent structure in your left lower abdomen is the sigmoid colon, an S-shaped segment of your large intestine that connects the descending colon to the rectum. This is where stool is stored before a bowel movement, which means it’s under regular pressure and prone to several conditions. Most left lower abdominal pain in adults traces back to something happening in or around the sigmoid colon.
Diverticulitis: The Most Common Culprit
Small pouches can form along the wall of the sigmoid colon over time, especially after age 40. These pouches are called diverticula, and they’re extremely common. When one or more of them becomes inflamed or infected, the result is diverticulitis, which causes a steady, aching pain in the left lower abdomen that can range from mild to severe. You might also notice bloating, nausea, fever, or a change in bowel habits.
Diverticulitis accounts for roughly half a percent of all emergency department visits in the United States, and that rate has been climbing, from 0.40% of ER visits in 2016 to 0.56% in 2023. About 30% of people diagnosed end up being admitted to the hospital, though that number has been declining as more mild cases are managed at home with antibiotics and a temporary change in diet. A CT scan of the abdomen and pelvis is the gold standard for confirming the diagnosis, with an accuracy rate of about 98%.
Ulcerative Colitis and the Left Side
Ulcerative colitis is a form of inflammatory bowel disease that often starts in the rectum and spreads upward. When inflammation reaches the sigmoid colon and beyond, it’s classified as left-sided colitis. Symptoms include bloody diarrhea, pain on the left side of the abdomen, loss of appetite, and weight loss. Unlike the sudden flare of diverticulitis, ulcerative colitis tends to develop gradually and cycle between flare-ups and periods of remission.
Reproductive Organs in Women
The left ovary and fallopian tube sit in the left lower abdomen, which means gynecological conditions can easily mimic or overlap with digestive problems in this area. Several conditions are worth knowing about:
- Ovarian cysts: Fluid-filled sacs that develop on or inside the ovary. Most are harmless and resolve on their own, but larger cysts can cause a dull ache or sharp pain, especially if they rupture or twist.
- Ovulation pain: A brief, one-sided pain that occurs mid-cycle when an egg is released. It typically lasts minutes to hours and alternates sides month to month.
- Ectopic pregnancy: A fertilized egg implants in the fallopian tube instead of the uterus. This causes sharp, worsening pain on one side and is a medical emergency.
- Endometriosis: Tissue similar to the uterine lining grows outside the uterus, sometimes on the ovary or surrounding structures. It causes chronic pelvic pain that often worsens during menstruation.
- Pelvic inflammatory disease (PID): An infection of the reproductive organs, usually caused by sexually transmitted bacteria. It produces lower abdominal pain, unusual discharge, and sometimes fever.
Because reproductive and digestive organs overlap in this region, doctors often include a pelvic exam and pregnancy test when evaluating left lower abdominal pain in women.
Kidney Stones in the Left Ureter
Your left ureter runs from your left kidney down through the lower abdomen to your bladder. When a kidney stone gets stuck in this tube, it causes intense, wave-like pain that starts in the back or side and radiates into the lower belly. The pain typically comes and goes in sharp bursts, which distinguishes it from the steadier ache of a bowel problem. You may also notice blood in your urine, painful urination, or a persistent urge to urinate.
Inguinal Hernias
An inguinal hernia occurs when tissue, usually a loop of intestine, pushes through a weak spot in the abdominal wall near the groin. The hallmark sign is a visible bulge on one side of the pubic bone that becomes more obvious when you stand up, cough, or strain. It often causes a burning or aching sensation at the site, along with groin pressure that worsens with bending or lifting.
Most inguinal hernias are not emergencies, but they can become one. If a hernia becomes strangulated, meaning the blood supply to the trapped tissue is cut off, you’ll experience sudden worsening pain, nausea or vomiting, fever, and the bulge may turn red or purple. That situation requires immediate surgical treatment.
How Doctors Evaluate Left Lower Abdominal Pain
A physical exam is the starting point. Your doctor will press on different areas of your abdomen to pinpoint where the tenderness is, which helps narrow down the likely cause. Blood tests can check for signs of infection or inflammation, and urine tests help rule out kidney stones or urinary tract infections.
For imaging, CT scans are the most useful tool for evaluating left lower quadrant pain. They’re accurate across different body types, can detect a wide range of conditions, and help determine whether a problem needs surgery or can be managed conservatively. Ultrasound is sometimes used as a first step, particularly in Europe and for gynecological concerns, but it’s less accurate in people with a larger body size and may miss complications that CT would catch. In one study, ultrasound misidentified up to 80% of patients with complicated diverticulitis.
Pain That Needs Urgent Attention
Some types of left lower abdominal pain can wait for a scheduled appointment. Others cannot. Seek emergency care if you have severe pain that makes it difficult to move, eat, or drink. The same applies to sudden onset pain, high fever, blood in your stool or vomit, or abdominal pain after any kind of trauma. Sudden, sharp pain on one side in a woman of childbearing age should always be evaluated promptly to rule out an ectopic pregnancy or ovarian torsion.