Left Side Abdominal Pain (Upper and Lower Abdomen) Causes

Abdominal pain can be one of the most perplexing conditions to diagnose especially when it is not accompanied by any other symptoms. In these instances the approach is to isolate the region/quadrant where the pain appears to be originating. Broadly the abdomen can be divided into four quadrants – left upper, left lower, right upper and right lower quadrants. The right upper and lower quadrants have been discussed under right side abdominal pain.

Organs on the Left Side of the Abdomen

It is important to understand which organs are located on the left side of the abdomen when assessing left-sided abdominal pain. An abnormality or disease in one or more of these organs are the most likely source of the pain. However, it is possible that pain felt on the left side of the abdomen may be emanating elsewhere despite it being felt here and this is known as referred pain. Alternatively pain from one part of the body may radiate towards another unaffected part and this is termed as radiating pain.

The following organs lie on the left side:

  • Stomach
  • Esophagus (terminal portion)
  • Spleen
  • Liver (smaller portion than the right)
  • Descending colon, half of the transverse colon, sigmoid colon and rectum.
  • Kidney and ureter (left)
  • Part of the pancreas
  • Part of the small intestine

Organs like the ovary, fallopian tube and uterus are technically in the pelvic cavity. In addition, the overlying skin, abdominal wall (muscles and fascia), large blood vessels (aorta and inferior vena cava), nerves, lymphatics, fat tissue, deep muscles and sheets of tissue known as peritoneum are also part of the abdomen.

Causes of Abdominal Pain on the Left Side

Many of the causes of abdominal pain that can present on either the right or left side have already been discussed under right side abdominal pain. Therefore this article will cover specific causes of left side abdominal pain only despite some degree of overlap.

Gastritis and Peptic Ulcers

Gastritis and peptic ulcers are two of the most common causes of upper left abdominal pain. Gastritis is inflammation of the stomach wall often due to excessive use of NSAIDs and other drugs or due to H.pylori infection. Peptic ulcers are open sores that form in the walls of the stomach or duodenum. The pain is often felt underneath the lower left rib cage and may extend to the upper middle portion of the abdomen. It is accompanied by nausea, bloating and belching among other symptoms.

Kidney Stones and Infection

Kidney stones or a kidney infection (pyelonephritis) typically causes upper left flank pain. Stones are hard masses that form from the sedimentation of the components of urine and it can block the outlet of the kidney or ureter thereby causing an accumulation of urine. Pyelonephritis is an infection of the kidney that can arise as a complication of a lower urinary tract infection or if microbes like bacteria reach the kidney through the bloodstream. Blood in the urine, frequent urination, little or no urine production along with a fever and pain are some of the symptoms of these conditions.

Spleen Infection or Rupture

The spleen tucks around the left side of the stomach and sits in the upper left flank. It acts as a reservoir for blood and also plays a role in immune defenses. Inflammation of the spleen is also referred to as splenitis and may arise with trauma, infections or autoimmune conditions. Enlargement of the spleen without swelling (splenomegaly) usually does not cause pain. Severe trauma can also lead to a rupture of the spleen which presents with severe pain and requires immediate spleen removal.

Constipation and Fecal Impaction

Constipation can cause some degree of discomfort as pain especially as the stool and gas is trapped in the descending and sigmoid colon. This can lead to stretching of the colon wall. Sometimes it may complicate to fecal impaction where the stool becomes hard and cannot be evacuated even with the use of laxatives. Fecal impaction can lead to serious complications if not treated properly as the colon is excessively stretched.


Diverticula are outpouchings from the colon wall that occurs most commonly with advancing age. If these pouches become infected then it is known as diverticulitis. Since most diverticula occur in the sigmoid colon, diverticulitis often presents with lower left abdominal pain. Fever, nausea and vomiting, constipation and sometimes diarrhea are other symptoms that may also be present in diverticulitis.

Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a condition where there is inflammation of the bowel wall with the formation of open sores (ulcers) and other lesions. There are two types – ulcerative colitis and Crohn’s disease. Since ulcerative colitis mainly affects the lower colon (descending and sigmoid colon) and the rectum, pain is usually felt on the lower left abdomen. There are other symptoms such as alterations in bowel habit (usually diarrhea), mucus and/or blood in the stool.

Colorectal Cancer


Although colorectal cancer is one of the more common cancers it is overall an uncommon cause of abdominal pain. Even when it does occur, pain is usually not an early symptoms. It arises with abnormal cell growth and differentiation leading to malignant lesions that invade and destroy healthy tissue. Bleeding from the rectum or blood in the stool are more common symptoms and even weight loss or loss of appetite may precede the pain.

Abdominal Wall Pain

Abdominal wall pain refers to pain emanating from the skin, muscles or fat tissue that comprises the abdominal wall. It is one of the more common causes of abdominal pain but is often ignored as a possible cause. It may occur with a blow to the abdomen, penetrating injuries and with muscle strain often due to exertion. Usually the pain is felt more superficially and it is not uncommon for there to be no other symptoms particularly with muscle-related conditions.

Other Causes

  • Irritable bowel syndrome (IBS)
  • Peritonitis
  • Gynecological problems like polycystic ovarian syndrome (PCOS) or ectopic pregnancy
  • Pancreatitis and pancreatic cancer
  • Hiatal hernia
  • Esophageal ulcers
  • Functional dyspepsia
  • Gastric perforation
  • Kidney abscess
  • Adrenal gland bleeding or tumors

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