Although the abdomen is widely referred to as the stomach, this is technically incorrect. The stomach is an organ that sits in the upper left region of the abdomen. When considering lower abdominal pain, which may be referred to as lower stomach pain, problems in the stomach are usually not one of the causes of pain in this region. Many of the causes of lower abdominal pain involve the bowels (small intestine and large intestine) with the pelvic organs (like the uterus in women and prostrate in men) sometimes contributing to pain in this area.
Where is the lower abdomen?
From an anatomical perspective, the abdomen can be divided into four quadrants or nine regions. When looking at the lower abdomen, it should be with the view of the four quadrants and specificall the right and left lower quadrants (also denoted as RLQ and LLQ). The area below the imaginary horizontal line running across the umbilicus (belly button or navel) would be the lower quadrants, or in common terms it will be referred to as the lower abdomen.
The RLQ and LLQ extends the areas of the lower abdomen into the pelvic region. However, it is important to note where the lower abdomen ends. The uppermost protruberances that can be felt at the front end of the hip (pelvic bone) is where the lower abdomen ends and the pelvic cavity begins. This is a rather simplistic anatomical description but serves the purpose of differentiating between lower abdominal pain and pelvic pain.
Organs in the Lower Abdomen
It is interesting to note that the stomach does not lie in the lower abdomen and usually does not even extend in part into this area of the abdomen. Stomach pain would refer to pain in the upper left quadrant where the majority of the stomach lies. Most of the stomach is tucked under the lower part of the left ribcage.
Read more on gastric pain for conditions that cause pain in the stomach.
The organs that lie in the lower abdominal area includes:
- Small intestine
- Large intestine
- Ureters (urinary tract)
Organs in the pelvic cavity lie next to the lower abdomen and should therefore also be considered:
- Prostate (men)
- Uterus, ovaries and fallopian tubes (women)
Enlarged organs like a pregnant uterus may extend into the lower abdomen and higher.
Causes of Lower Abdominal (Stomach) Pain
The causes of lower abdominal pain may be due to diseases and disorders of the organs that lie in this area. Sometimes pain originating from neighboring organs may refer or radiate to the lower abdomen, as is seen with pelvic problems such as bladder infection (cystitis). Depending on factors like abdominal obesity, sometimes a person may also mistaken upper abdominal pain as pain in the lower abdomen.
Abdominal Wall and Peritoneum
The abdominal wall is made up of the skin, muscles, fascia and other tissue that lie on the surface of the abdomen. It contains and protects the delicate abdominal organs. The peritoneum is a double layer membrane that lines some of the abdominal organs and inner surface of the abdominal wall.
- Muscle strain
- Abdominal hernia
- Strangulated hernia
Symptoms specific to these conditions may include pain with movement, abdominal tenderness and guarding.
The small intestin runs from the end of the stomach to the beginning of the large intestine. The small intestine is about 6 meters (approximately 20 feet) long. It is coiled up in the abdomen, and occupies most of the space in the lower abdomen. The small intestine is responsible for the final stages of digestion and most of the absorption of nutrients from food.
- Meckel’s diverticulum
- Celiac disease
- Lactose intolerance
- Small bowel obstruction
Symptoms specific to these conditions include constipation or diarrhea, abdominal cramping, nausea and vomiting (sometimes), loss of appetite and malnutrition.
The large intestine continues from the small intestine and ends at the anus. In contrast to the small intestine, it is only about 1.5 meters (approximately 5 feet) long. The large intestine starts at the lower left end of the abdomen (cecum), runs upwards (ascending colon), runs across the abdomen (transverse colon) and downwards (descending and sigmoid colon) to the rectum. Water is reabsorbed and stool is formed and stored in the large intestine.
- Chronic constipation
- Inflammatory bowel disease (IBD)
- Irritable bowel syndrome (IBS)
- Fecal impaction
- Colorectal cancer
Symptoms specific to conditions in this area include constipation or diarrhea, excessive flatulence, mucus or blood in the stool, persistent urge to defecate and fecal incontinence.
The urinary tract carries urine from the kidneys to the environment. The ureters run from the kidneys to the bladder where urine is stored. The ureters run along the flanks from the kidneys in the upper abdomen to the bladder in the middle of the pelvic cavity. Although the bladder is in the pelvis, pain in the area may also be described as lower abdominal pain.
- Urinary tract infection (UTI) – urerteritis and cystitis
- Kidney stones in the ureter and bladder stones in the bladder
- Ureteral strictures (narrowing)
- Ureteral or bladder cancer
Symptoms specific to conditions in this area include frequent urination, increased or decreased urine production, pain or burning when urinating, pus or blood in the urine, weak urine stream, straining to urinate, dribbling and urinary incontinence.
As mentioned, the proximity of the pelvic cavity to the lower abdomen may mean that pelvic pain radiates or is referred to the lower abdomen. Furthermore pelvic pain may be mistaken for lower abdominal pain. Therefore the following pelvic conditions, in addition to the bladder problems discussed above, need to be considered in lower abdominal pain:
- Cancer – cervical, uterus, ovaries or fallopian tube (women) or prostate (men)
- Pelvic inflammatory disease (women)
- Endometriosis (women)
- Polycystic ovarian syndrome (women)
- Uterine fibroids (women)
- Ectopic pregnancy (women)
- Prostatitis (men)
There may also be pain due to pregnancy despite there being no problem present. This may occur with expanding uterus and associated structures like in round ligament pain. Similarly period pain arises from the uterus and may affect girls and women during menstruation. It may be a normal feature of menstruation for some women but severe pain (dysmenorrhea) should be investigated.