This post is the second in a series detailing the differential diagnosis process. The first article reviewed the basics of differential diagnosis and this and subsequent posts will look at the process for specific complaints which frequently present to EMS. This post is the first of two detailing the construction of a differential diagnosis for abdominal pain. This article is also posted at my site: 510medic.com
You are dispatched to a private residence 30 minutes before the end of your shift for abdominal pain. What goes through your mind en route? Aside from the obvious frustrations of course. What symptoms do you think about on the way? What possible diagnoses do you consider? What concerns do have about the patient?
Abdominal pain represents one of our frequent calls in EMS. It is also one of the hardest complaints to diagnose. The abdomen houses many organs, any of which could cause pain, and abdominal pain can be a symptom of serious conditions including cardiac disease and pneumonia.
DIFFERENTIAL DIAGNOSIS REVIEW
As discussed in the first article in this series, differential diagnosis is the method of evaluating data from examination and assessment to construct causes for presenting complaints. An initial list is constructed based on the complaint or body system involved. This list is narrowed down by findings that move the index of suspicion to the point that you are comfortable either treating or discarding that cause. The usefulness of a test is quantified by specificity and sensitivity. A positive result in a highly specific test means it is likely a patient has a certain disease. A negative result in a highly sensitive test means it is likely that the patient does not have a certain disease. Tests and assessments continue until your index of suspicion crosses the threshold to treat or ignore and you move to the next potential cause.
CONSTRUCTING A DIFFERENTIAL FOR ABDOMINAL PAIN
In building a list of causes for abdominal pain, the provider considers three important aspects: the specifics of the pain, the patient’s history and the findings during the physical examination. When reviewing the patient’s pain, the PQRST mnemonic (P – Provoke/Palliate, Q – Quality, R – Radiation, S – Severity, T – Time) can help to ensure than nothing is missed. These findings, along with the location of the pain, can help construct a list of causes. For instance, upper abdominal, or epigastric pain can be caused by the organs in that area: the pancreas, gall bladder and stomach; though sometimes epigastric pain can result from a heart attack. Knowing which organs are where is important because, for instance, pain from an appendicitis is likely to occur in the right lower quadrant so choosing that as a differential diagnosis for left upper quadrant pain could be a dangerous mistake.
Along with information about the patient’s pain, you should take a detailed history from the patient. Knowledge of associated symptoms can aid in the construction of a differential diagnosis. Some historical findings include:
- Change in oral intake
- Blood in the stool/urine
By asking these questions, you are able to know the time frame of the symptoms and the organs or body systems affected.
In addition to symptoms associated with abdominal pain, it is vital to ask about the remainder of their medical history. Particular attention is paid to respiratory symptoms and any cardiac history as abdominal pain may be a presenting symptom in both an acute myocardial infarction and pneumonia. Lastly, the patient’s sexual/reproductive/menstrual history should be noted and any alcohol or drug usage.
The next step in the diagnosis of abdominal pain is the physical exam beginning with vital signs. In addition to the standard set of vitals, consider checking for positive orthostatic changes (a drop in blood pressure and an increase in heart rate when moving from lying to sitting and sitting to standing). Positive orthostatic findings include a systolic blood pressure drop of 20 mmHg or a heart rate increase of 20 BPM. Care must be taken with patients on heart rate control medications (like Atenolol) because their heart rates cannot increase during times of shock.
Continuing the physical examination, the practitioner performs a cardiac and respiratory exam including 12 lead ECG, lung sounds and heart tones. Since life threatening conditions like acute MI and pneumonia can present as pain referred to the upper abdomen or epigastric region, it is important to rule out the presence of these conditions early in the construction of a diagnosis.
Finally, the physical exam proceeds to the actual hands on assessment. The patient is assessed through visual inspection of the abdomen, auscultation to check for the presence or absence of bowel sounds and palpation using first light pressure then deeper pressure. During the palpation phase, it is important to talk to the patient to distract him and to work towards the region where the complaint of pain exists.
Based upon specific findings during the history and physical examination, the practitioner should be able to determine the underlying cause of the patient’s complaint. In tomorrow’s post, we will present a review of some of the common causes of abdominal pain and which specific findings may indicate an underlying cause. Stay tuned!