Pain characteristics to assess cause of abdominal pain

Abdominal pain is experienced between the chest and the groin, with the most common cause being digestive problems. However, any disruption in the normal functioning of the organs and other structures housed in the abdomen, including the heart artery and vein that pass through the abdomen, can also cause abdominal pain. Hence, it is challenging to assess the cause of the pain. 

A systematic approach that focuses on the pain characteristics, history taking, and physical examination is key to assess the causes of abdominal pain. The terms abdominal pain and gastric pain are often used interchangeably; however, they are not the same entity. The article entitled “Gastric pain vs abdominal pain: How do they differ?” clarifies the differences.

What are the causes?

Abdominal pain is a common problem and a wide range of conditions can be associated with it. 

Common causes of abdominal pain include:

• gas 
• acid reflux 
• vomiting
• food intolerance
• gastroenteritis
• irritable bowel syndrome (IBS)
• Gastroesophageal reflux disease (GERD)
• stomach or peptic ulcers
• Crohn’s disease
• celiac disease
• strained muscles
• endometriosis
• urinary tract infections (UTIs)

In children, the common causes also include constipation and lead poisoning.

Uncommon causes of abdominal pain that can be fatal are:

• stones in kidney or gall bladder
• infection of kidney or kidney disease
• hepatitis 
• parasitic infection
• food poisoning 
• some of the heart conditions 
• hiatal hernia
• cysts 
• stomach, pancreatic or bowel cancer

How to assess the cause of the pain?

Assessment of history and subsequent physical examinations are crucial for differential diagnosis. As part of this, six pain characteristics play an important role in evaluating the cause. These include onset, progression, migration, character, intensity and localization.

• Onset: – when and how the pain started?
• sudden, rapid or gradual onset 

Sudden-onset pain occurs within a second. It is possible for the person to tell when exactly the pain started. It can be caused by gastrointestinal (GI) problems such as perforation of the GI tract from a gastric or duodenal ulcer, a colonic diverticulum or presence of a foreign body. The other causes can include ruptured ectopic pregnancy, mesenteric infarction, ruptured aortic aneurysm and embolism of an abdominal vessel.

Rapid-onset pain begins within a few seconds and increases in severity over the ensuing minutes. It may be hard to tell precisely when the pain started. It can be caused by cholecystitis, pancreatitis, intestinal obstruction, diverticulitis, appendicitis, stone in ureter, and penetrating gastric or duodenal ulcer.

Gradual-onset pain progresses to more severe form over a few hours or even days. It is generally caused by neoplasms, chronic inflammatory processes and large bowel obstruction. However, other intra-abdominal problems can also cause this type of pain making it challenging to identify the exact cause.

• Progression: how has the pain changed over time?
• increasing, decreasing or intermittent pain

When the pain of sudden onset subsides on its own, the cause can be perforated ulcer in which the pain stops if the perforation seals without additional leaks.

When intermittent pain progresses to stable constant pain, it might indicate small bowel obstruction.

• Migration: where else the pain has shifted to or felt?
• change in site/location of the pain 

In the case of acute appendicitis, the initial periumbilical or epigastric pain moves to the right lower quadrant (somatic) later in the illness.

• Character: What kind of pain it is?
• cramping, dull, or aching and either constant or intermittent

Cramping pain is when the pain gradually increases in intensity, reaches maximum and then stops with complete absence over short interval but re-occurs. It can be caused by mechanical small bowel obstruction. 

Pain that is dull or aching but constant can be due to distention or edema of the wall of a hollow viscus.

• Intensity: how bad it is?
• Severe or mild

Although severe pain may raise more concerns, serious conditions cannot be ruled out in cases of mild pain. For example, one can have very severe abdominal pain caused by gas or stomach cramps due to viral infection. Contrary to this, fatal diseases like colon cancer may involve mild or no pain at all.

The perception of intensity of the pain varies from person to person and it can be assessed by monitoring how the person responds to the pain. 

For example, when the person prefers to lie still on one side with the hip and knees bent, without making much movement, it is likely to indicate a somatic pain (pain is in the muscles, bones or soft tissues). On the other hand, when the person keeps changing positions, the pain is likely a visceral pain (pain originating from the internal organs of the body).

• Localization: where is the pain felt?
• exact site of pain 

Visceral pain may be poorly localized, and the site can vary depending on the organ involved. For example, pain related to the stomach, pancreas, liver, biliary system and proximal duodenum is localized to the epigastric region. In contrast, pain related to the bladder, hind portion of the colon and pelvic genitourinary organs is localized in the suprapubic region.

Somatic pain is generally well localized.

Challenges

A wide range of etiologies such as GI and systemic disorders is associated with abdominal pain, making assessment of the cause difficult, especially in older persons and children.

The other challenge is, the severity of the abdominal pain may not be an indicator of the seriousness of the condition that is causing the pain. An experienced physicians can find the common causes of abdominal pain quickly, though in some instances extensive workup may be required.

Conclusions

Collecting or providing detailed history is crucial in shortlisting the causes of abdominal pain. This help to limit extensive investigations in a cost-effective manner.