Pain in lower left abdomen: A review of internal organs
As a practicing physician, I have evaluated and treated many patients with pain in left lower abdomen. I think it will be helpful for you to review what internal organs you have inside your body that can cause pain in lower left abdomen. I will be explaining everything in plain English so that you can understand and use this information without any prior medical knowledge. I believe that everyone can learn medicine if taught in a language they understand.

Here is a picture that shows you what lies under your skin in your lower abdomen. Among organs in the abdomen, colon and rectum occupy a significant part of the lower left abdomen. Colon is a part of the digestive tract. Food from your stomach goes to small intestine where most of the nutrients is absorbed. The small intestine is about 20 feet long and lies curled up in your lower abdomen. It connects to the large intestine. Colon is the major part of the large intestine and it helps mostly with reabsorption of water and some remaining nutrients in the digestive tract. The part of the colon that runs horizontal in the picture is called the transverse colon and the part that goes downward on the left side is the descending colon. Similarly, the part that goes upwards on the right side is the ascending colon. Appendix is a small pouch located near the junction of the small and large intestine. The descending colon leads to rectum and opens outside to anus.

Kidneys and blood vessels are also important in evaluating pain in lower left side of abdomen. They lie behind the digestive tract and can be seen in the next picture. The major artery than runs along the back of the lower abdomen is called abdominal aorta and it eventually divides to supply blood to the legs.
Pain in lower left abdomen from diverticulitis
Diverticula are sac like protrusions that develop in the colon wall. They are more commonly formed on the left side of the colon than on the right. These sacs can get inflamed and cause significant pain in lower left side of abdomen. This type of pain is usually described as cramping, irritation but could also be sharp and relenting. The severity of pain may depend on the severity of inflammation. The pain in left side of abdomen from diverticulitis is usually constant for a few days, which may help to distinguish it from other conditions that deteriorate rapidly. In addition to left lower abdominal pain, patients may have occasional diarrhea. Presence of blood in stool can happen but is very rare. As in most digestive tract disease, you may have nausea and vomiting with diverticulitis.
When untreated, diverticulitis can get worse and may cause complications. It can form collection of pus called abscess and patient may have pain in upper left abdomen in addition to the pain in lower left side of abdomen.
One of the most feared complications is a rupture of colon wall at the protrusion. When it ruptures, the dirty fecal material may enter the sterile interior of the abdominal cavity and cause widespread inflammation and infection that can be life threatening. When this happens, the whole abdomen becomes painful and tender.
Pain in lower left abdomen from colitis
Colitis simply means inflammation of the colon. It is not a single disease but describes a condition that can result from a number of different disease processes. From the first picture, you can see that colon is present on the left, right and middle of the lower abdomen. Abdominal pain from colitis can occur in any of these places depending on the part of the colon that is involved. A mild inflammation of the right sided colon may cause dull pain lower right side while severe inflammation of the lower left colon may cause significant pain in lower left abdomen. Pain originating from the inflammation of colon can cause some feeling of irritation and constant need to evacuate your bowels. Diarrhea is common but not always present. The severity of pain may or may not correlate with the severity of inflammation because different patients have different levels of pain tolerance.
Pain gets worse if you develop complications from colitis. Just like diverticulitis, any form of colitis may end up with rupture of the colon wall. The resulting symptoms of widespread infection and inflammation can be identical to the rupture caused from diverticulitis.
Pain in lower abdomen: peritonitis
Peritonitis simply describes what I explained earlier: it is the widespread inflammation and infection of the internal lining of the abdominal cavity. Abdominal cavity is the space inside your abdomen where your internal organs live. This cavity is usually clean and sterile. The dirty part containing fecal material and undigested food is contained inside the digestive tract by the wall of the intestines. Whenever the contents of the bowel leak outside to this sterile area, it can cause catastrophic inflammation. You can feel the resulting pain almost all over your abdomen. This type of pain can be very sharp. When you have peritonitis, your abdomen is very tender. It hurts more when you touch or poke it.
If you have pain like this in any part of your abdomen, it is a medical emergency. Peritonitis can kill you within a few hours if not treated right away. If you are having abdominal pain of this nature, please stop reading this article and call 911 right away.
Pain in lower left abdomen from colon cancer
The pain and discomfort from colon cancer may be similar to that caused by colitis. Like colitis, it can happen on the left or right lower abdomen. You may only have dull pain in right side or left side of your abdomen. All the symptoms I described for colitis can happen with colon cancer. That is why it is important to screen for colon cancer after you recover from an episode of colitis. The only way to be sure about colon cancer is to get colonoscopy with biopsies.
Pain in lower left abdomen from acute appendicitis
As you can see in the first picture, appendix is normally located on the right lower side of your abdomen. Pain from acute inflammation of the appendix, called acute appendicitis, is also normally located on the right lower abdomen. However, it is important to know that acute appendicitis can occasionally cause pain in left side of abdomen. In the right setting, you cannot rule out acute appendicitis just because the pain is located on the wrong side of your abdomen.
Acute appendicitis can cause pain in lower left abdomen because of the individual variation in human anatomy. In a small percentage of people, the colon anatomy is reversed and organs switch sides. In those people, appendix can be found on the left side. In other people, the appendix can be very long; so long that the tip of the appendix actually crosses the midline and lies on the left. When the inflammation of appendicitis affects those people, the pain can be felt on the left side. Some people may even have pain in upper right abdomen.
Left lower abdominal pain from acute appendicitis shows how each individual is different and how there are exceptions to the rules in medical symptoms.
Pain in lower left abdomen from left kidney stones:
Kidney stones may cause pain in lower abdomen and back. Pain originating from the left kidney can be felt in the left lower abdomen. Because of the difference in the type of nerve that supplies kidneys and intestine, the nature of the pain is usually different. Pains originating in the kidneys are more localized and sharper. They also tend to occur more towards the sides of the abdomen. Some patient may also feel pain in upper left abdomen. These types of pain usually occur in waves with fluctuating intensity. As the stones move, the location of pain may move with it. Sharp pain in lower left side of abdomen that slowly moves downwards, could be the result of kidney stone passing downwards from the left kidney traveling towards the urinary bladder.
Pain in lower left abdomen from ruptured abdominal aortic aneurysm
As you can see in the second picture, a major artery runs down the middle behind the digestive tract. It carries blood that eventually goes to your legs. This part of the artery is called abdominal aorta and it can sometimes balloon up. When that happens, it is called an aneurysm. The aneurysms can develop slowly over many years without causing any symptom. However, they can suddenly rupture causing severe sharp pain in lower abdomen. The resulting pain is usually in the middle with radiation to the back but can also be felt in the left lower abdomen if the blood moves towards the left side.
A massive bleeding from the rupture can result in shock and death within a few hours. However, the bleeding may temporarily halt because of sequestering of the blood around tight places behind the abdominal membrane. This may allow enough time for surgical repair that can save the patient’s life.
Women specific left lower abdominal pain:

Diseases of the internal female reproductive organs can cause left lower abdominal pain specific to female patients. As you can see in the picture, female reproductive organs include two ovaries and fallopian tubes on two sides. The uterus or womb lies in the middle and connects to the cervix. The cervix opens into the vagina. The location of the women specific abdominal pain depends on which organ is affected. Women specific left lower abdominal pain can occur when the left ovary or the left fallopian tube is involved. It can also occur when the left side of the ureter has problems. The most feared women specific pain in left side of abdomen is caused by ectopic pregnancy in the left fallopian tube. It is called ectopic pregnancy because it happens outside the womb. Besides severe sharp pain in lower left side of abdomen, ectopic pregnancy can cause vaginal bleeding, dizziness, lightheadedness and occasionally fevers or chills.
Different kinds of cysts and tumors can form in the left ovary and left fallopian tubes. These normal or abnormal growths can cause different patterns of pain in lower left abdomen of female patient. Lower abdominal pain in women over 50 along with vaginal bleeding raises concern for gynecological cancers.
I hope this article about left lower abdominal pain will help answer some of your questions about this particular symptom. Please share this article with your friends and family and do not hesitate to post your questions and comments below. I cannot give you any specific medical advice but I can answer your general questions about what causes pain in the left lower abdomen.