Upper Abdomen: Anatomy and Causes of Pain
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Introduction
Although abdominal pain is common, the many different causes can make it difficult to determine the exact etiology.
Fortunately, the following can help distinguish and prioritize the underlying process:
Location of the pain (right sided, left sided, upper, lower, etc)
Type of pain (crampy, sharp, dull, stabbing, burning, etc)
Associated symptoms (diarrhea, bloating, nausea, vomiting, etc)
Associated factors (after eating, exercise induced, during pregnancy, etc)
The abdomen is a large area, so this EZmed post will focus on the upper abdomen only.
We will walk through the different quadrants and anatomy of the upper abdomen, as well as discuss common causes of upper abdominal pain such as gallstones, gallbladder inflammation, stomach ulcers, pancreatitis, hepatitis, acid reflux, etc.
If you prefer a comprehensive overview of the entire abdomen, including the anatomy and causes of pain to the mid and lower stomach as well, then check out the following EZmed post! “Abdominal Pain Causes by Location: The Stomach Grid”.
Lastly, for a simple mnemonic to remember the main causes of upper abdominal pain, check out the following EZmed post! “The UPPER STOMACH Mnemonic”!
Let’s get started!
Upper Abdominal Quadrants
As mentioned above, there are many different causes of abdominal pain which can make it challenging to determine the underlying process.
The location of the pain is important to consider as this can help distinguish potential causes.
The simplest way to determine the location is to divide the abdomen into 9 different regions using a 3 x 3 grid as demonstrated below.
We will focus on the upper regions in this post.
Superior Row
The right upper section is the right upper quadrant (RUQ) - also referred to as the right hypochondriac region.
The central upper section is the epigastric region.
Lastly, the left upper section is the left upper quadrant (LUQ) - also known as the left hypochondriac region.
Image: The upper abdomen can be divided into the following regions: The right upper quadrant (RUQ), epigastric region, and left upper quadrant (LUQ).
Upper Abdominal Anatomy
Now that we have divided the upper abdomen into different regions, let’s discuss the anatomy of each section.
The below image can be used as a reference.
**We will focus on the main organs and not every single micro-structure. Also note that portions of structures can extend into other regions as well.
Right Upper Quadrant
The right upper quadrant primarily contains the liver, gallbladder, and biliary system.
Portions of the right kidney, small intestine, and ascending/transverse colon can also extend into the RUQ.
Epigastric
The epigastric region contains the stomach (as well as the lower part of the esophagus and first part of the duodenum/small intestine) and part of the pancreas.
The liver and biliary system can also extend into the epigastric region.
The descending aorta travels posteriorly through the epigastric region as well.
Left Upper Quadrant
In addition to the spleen being located in the left upper quadrant, part of the stomach and pancreas usually extend into this region too.
Portions of the left kidney, small intestine, and transverse/descending colon can also extend into the LUQ.
Image: The main structures of the RUQ include the liver, gallbladder, and biliary system.
The main structures of the epigastric region include the stomach, and part of the liver/biliary system and pancreas.
The main structures of the LUQ include the spleen, pancreas, and part of the stomach.
Upper Abdominal Pain
Now that we have discussed the main structures in each region of the upper abdomen, let’s discuss potential causes of abdominal pain by location.
**Below focuses on the main pathology for each quadrant and is not an extensive list of all abdominal pathology that can occur.
As mentioned above, for a simple mnemonic to remember the main causes of upper abdominal pain check out the following EZmed post! “Approach to Upper Abdominal Pain: The UPPER STOMACH Mnemonic”
Right Upper Quadrant
The primary structures in the right upper quadrant include the liver, gallbladder, and biliary system.
Therefore, problems with any of these structures may cause right upper quadrant pain.
Liver pathology may include hepatitis (inflammation and/or infection of the liver), hepatic abscess (abscess of the liver), cirrhosis (chronic degeneration, inflammation, and scarring of the liver).
Biliary pathology may include cholangitis - inflammation and/or infection of the biliary system usually caused by an obstruction of the common bile duct such as a gallstone.
Gallbladder pathology may include gallstones, also known as cholelithiasis, which may cause biliary colic.
If a gallstone leads to obstruction of the cystic duct, then cholecystitis may develop - inflammation and/or infection of the gallbladder.
Epigastric Region
As previously mentioned, part of the liver/biliary system can extend into the epigastric region.
Therefore, the hepatobiliary pathology discussed above may also present as epigastric discomfort.
Since the stomach and part of the pancreas are also located in the epigastric region, problems to these structures can lead to epigastric discomfort as well.
This may include pancreatitis (inflammation of the pancreas), gastritis (inflammation of the stomach), GERD (gastroesophageal reflux), peptic ulcer disease (PUD/stomach ulcers), gastroparesis (a complication usually of diabetes), or gastric perforation (hole in the stomach).
Left Upper Quadrant
The primary structures in the left upper quadrant include the rest of the pancreas, part of the stomach, and the spleen.
Therefore, pancreatitis can cause both epigastric and left upper quadrant pain.
Similarly, the stomach pathology discussed above can cause left upper quadrant pain as well.
Lastly, given the spleen is located in the left upper quadrant, any pathology to the spleen could present as pain to this region.
Spleen pathology may include splenic rupture, splenic abscess, or splenic infarct.
Image: Potential causes of upper abdominal pain based on location to the right upper quadrant, epigastric region, and left upper quadrant.
Referred Pain - From the Abdomen
While the source of abdominal pain may come from the organs and structures within that region, referred pain may also be present.
Referred pain is defined as pain that is perceived at a location different from where the stimulus is.
Pain may also radiate - pain that originates in one area and spreads to another in a fairly continual pattern.
Here are a couple intra-abdominal examples in which pain can be referred or radiate elsewhere.
Referred Pain
While hepatobiliary pathology commonly causes right upper quadrant abdominal pain as discussed above, the pain may also be referred to the right shoulder and patients might complain of right shoulder discomfort instead.
Radiating Pain
Pancreatitis often causes epigastric and/or left upper quadrant pain. However, this pain can also radiate to the back.
In fact, the patient complaint of “epigastric/LUQ pain radiating to the back” is a common buzzword phrase that shows up on medical examinations.
Image: Upper abdominal pain may radiate (pancreatitis: epigastric/left upper quadrant pain radiating to the back) or even be referred to other locations in the body (hepatobiliary pathology causing right shoulder pain).
Referred Pain - To the Abdomen
Similar to how intra-abdominal pathology can cause referred pain outside the abdomen, pathology outside the abdomen can cause referred pain in the abdomen.
Let’s take a look at some examples.
Upper Abdomen
When pain is referred to the upper abdomen, it is usually caused by pathology in the thorax.
Therefore, problems in the chest can present as upper abdominal pain.
One important consideration is acute coronary syndrome - a range of conditions to describe reduced blood flow to the heart.
For example, a myocardial infarction (heart attack) may cause epigastric discomfort instead of/in addition to chest pain.
Therefore, it is important to consider acute coronary syndrome and obtain an EKG (electrocardiogram) in individuals who have risk factors for cardiac pathology and are presenting with epigastric discomfort.
Lung pathology can also cause upper abdominal pain.
For example, a right lower lobe pneumonia may cause right upper quadrant pain, and a left lower lobe pneumonia may cause left upper quadrant pain.
Similarly, a pulmonary embolism, pleural effusion, or pneumothorax may cause right and/or left upper quadrant pain. There is usually a component of shortness of breath present as well.
Image: Sometimes pathology outside the abdomen (pneumonia, pulmonary embolism, cardiac causes, etc) may cause referred pain to the upper abdomen.
Conclusion
Hopefully this was a good overview of the upper abdomen including the anatomy and causes of pain.
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