Approach to upper abdominal pain: Clinical sciences

Abdominal pain is a symptom of many conditions, which can range from mild to serious ones that require surgical intervention. Based on the affected region of the abdomen, abdominal pain can be classified into a right upper quadrant, epigastric, left upper quadrant, periumbilical, right lower quadrant, and left lower quadrant pain.

The first step in evaluating a patient with abdominal pain is to assess their ABCDE to determine if they are stable or unstable. If the patient is unstable, start acute management before doing any diagnostic workup. This means that you might need to stabilize their airway, provide supplemental oxygen, establish IV access, and continuously monitor hemodynamics.

On the other hand, for stable patients, your first step is to obtain a focused history and physical exam, or H&P for short. On history, you should characterize the pain based on its location, severity, and chronicity, and determine aggravating and alleviating factors as well as other associated symptoms. Next, you should quickly assess for any signs of an acute abdomen. In this case, ask for history of recent abdominal or GI procedures such as EGD, colonoscopy, or surgery; as well abdominal aortic aneurysm.

On physical exam, acute abdomen presents with signs of diffuse peritoneal inflammation, including diffuse tenderness, rebound pain, rigidity, and guarding. Also, upright chest x-ray or abdominal x-ray series should be done to check for free air under the diaphragm, which suggests perforation of the viscera.

Now, acute abdomen is also known as a surgical abdomen, since emergency surgical intervention is required for most causes, such as perforated viscus, abdominal sepsis, or ruptured abdominal aortic aneurysm. In this case, exploratory laparotomy is considered both diagnostic and therapeutic, so call for an emergent surgical consult while you continue resuscitation and the diagnostic workup.

Now, once you have ruled out an acute abdomen, the next step is to assess for other causes of upper abdominal pain. The location of pain on history and physical examination can be your best initial guide to narrow your differential diagnoses based on your clinical suspicion.

First, let's start with right upper quadrant pain, which is associated with biliary and liver conditions.

If the patient reports right upper quadrant pain, in addition to H&P, you should order labs like CBC, CMP, lipase, and amylase. The classic presentation of biliary diseases is the acute onset of pain after eating a fatty meal associated with nausea, vomiting, and sometimes a fever. Important risk factors to look out for are biologically female sex, obesity, and age over 40. The exam might reveal upper right quadrant RUQ tenderness with a positive Murphy sign. Labs might show leukocytosis with a left shift, elevated LFTs, and normal lipase and amylase. Keep in mind that labs can be all normal, especially in biliary colic.

Next, order an ultrasound to visualize the gallbladder. The ultrasound usually shows signs of biliary disease like sludge or stones in the gallbladder, pericholecystic fluid, a thickened gallbladder wall, and sometimes, a dilated common bile duct. If this is the case you can make a diagnosis of biliary colic, acute cholecystitis, choledocholithiasis, or acute cholangitis.

Alright, let’s move on to liver disease. These patients typically report nausea, vomiting, and fever. History might also reveal risk factors like substance use disorder, immunosuppression, cancer, or hypercoagulable state. On exam, you might find RUQ tenderness, hepatomegaly, jaundice, or altered mental status in extreme cases. If you find leukocytosis with left shift, elevated LFTs with normal lipase and amylase on labs, the next step is to obtain a RUQ ultrasound to rule out gallbladder pathology.

If there are no signs of biliary disease, order a CT scan, which will help you make a diagnosis. If you see a peripheral rim enhancing liver lesion  in a patient with fever, then you can consider a liver abscess. On the flip side, if you see hepatomegaly and thrombosed hepatic veins, you can diagnose Budd-Chiari syndrome. Finally, if imaging shows a thrombus in the portal vein, we are talking about portal vein thrombosis.

Okay, let’s move on to another important cause of RUQ pain, which is acute hepatitis. Just like with other liver diseases these patients present with nausea, vomiting, and fever. However, an important risk factor to look out for is recent travel. As before, a physical exam might reveal RUQ tenderness, hepatomegaly, and jaundice, while labs are usually normal except for elevated LFTs, including fractionated bilirubin. Keep in mind that fractionated bilirubin is different in diseases where the liver isn't working, mainly leading to elevated indirect bilirubin, whereas diseases of the biliary system would mainly lead to elevated direct bilirubin.

Now, if you see these findings you should consider acute hepatitis. Next, order viral hepatitis serology like IgM antibodies for hepatitis A, or HBs antigen, and anti-HBc antibodies for hepatitis B.

Now that RUQ is complete, let’s move on to epigastric pain.