Abdominal Emergencies

Types of abdominal pain — the key differentiator

The character of a patient's abdominal pain is the single most useful clue to where it is coming from, because the different structures of the abdomen are supplied by different kinds of nerves. The organs themselves have few nerve endings, so pain that arises in an organ is poorly defined. The parietal peritoneum that lines the abdominal cavity has a rich nerve supply, so pain that arises there is sharp and easy to point to. The table below sets out the four types of abdominal pain, where each originates and how each presents.

Table 26.1Types of abdominal pain — the key differentiator

Two of these types deserve a particular note. Tearing pain can be produced by only two structures, the aorta and the stomach, so a patient who describes a tearing pain should make you think of an abdominal aortic aneurysm, which classically produces tearing back pain, or of a perforating stomach ulcer. Referred pain is felt away from its actual source because the affected organ shares a nerve pathway with a distant part of the body; the classic examples are gallbladder pain felt in the right shoulder and the pain of an injured spleen felt in the left shoulder.

Key abdominal conditions

A handful of conditions account for most of the serious abdominal pain you will see, and each has a presentation you should be able to recognize. Appendicitis classically begins with nausea, followed by pain that starts around the umbilicus and then migrates to become persistent pain in the right lower quadrant (RLQ). If the appendix ruptures, the patient experiences a sudden, severe spike in pain as the lining of the abdomen becomes inflamed. That inflammation is peritonitis, which is extremely painful and produces a rigid abdomen with involuntary guarding. Peritonitis is life-threatening and often requires surgery.

Cholecystitis, inflammation of the gallbladder that is usually caused by gallstones, produces severe pain in the right upper quadrant (RUQ) or the epigastrium that is often referred to the right shoulder. Because of where it is felt, it is frequently confused with cardiac pain. Pancreatitis is common in patients with chronic alcohol use and produces epigastric pain that radiates to the back or the shoulders.

Gastrointestinal (GI) bleeding differs from the conditions above in that it often occurs without any pain at all. Its signs are dark, tarry stools or frank blood from the rectum and, when the bleeding is in the upper GI tract, vomit that looks like coffee grounds. Esophageal varices, which develop with chronic alcohol use, can bleed massively and compromise the airway.

An abdominal aortic aneurysm (AAA) presents in one of two ways. A slow leak produces a gradual onset of sharp or tearing pain that radiates to the back. A sudden rupture produces excruciating pain together with shock, and the pulses may be unequal between the limbs.

A hernia is a hole in the abdominal wall through which tissue protrudes. It becomes life-threatening only when the protruding tissue causes an obstruction or becomes strangulated, and because you cannot tell that from the outside, every painful hernia is transported. Renal colic, the pain of a kidney stone, is severe flank pain that radiates to the groin. These patients are classically described as writhing, unable to find a comfortable position, which sets them apart from the patient with peritonitis, who lies perfectly still.

Finally, two of the most dangerous causes are the easiest to miss. A myocardial infarction (MI) can present as epigastric pain that the patient describes as indigestion, so treat all epigastric pain as possibly cardiac until proven otherwise. Ectopic pregnancy is the most serious female-specific cause of abdominal pain. Assume that any woman of childbearing age with lower abdominal pain has an ectopic pregnancy until proven otherwise; she will not look pregnant.

Assessment sequence

Assessment of the patient with abdominal pain follows the standard sequence, beginning with the scene size-up. Because these patients frequently vomit, take steps to protect yourself before you approach. In the primary assessment, look for the early signs of shock before you take a single vital sign: altered mental status (AMS), anxiety, and skin that is pale, cool and moist, together with a rapid pulse and rapid respirations. Then obtain a history using OPQRST and SAMPLE, perform the physical exam, and take vital signs every 5 minutes.

For a female patient, the history must include questions that many patients will not volunteer, so ask them directly and in private. Find out where she is in her menstrual cycle, whether her period is late, whether she has had any bleeding outside her period, and whether there is any possibility that she is pregnant. Ask about pregnancy outright rather than leaving it to the patient to raise. A "yes" to any of these questions should make you suspect an ectopic pregnancy, but a set of "no" answers does not rule one out.

Physical exam & geriatric considerations

The physical exam of the abdomen consists of inspection followed by palpation, and the order in which you palpate matters. Palpate the painful area last, because pressing on it first can mask the patient's response when you examine the other quadrants. Once you have found pain or another abnormality, stop palpating that area. Watch for guarding, which the patient may show by drawing the arms across the abdomen or by tensing the abdominal muscles before you have even touched them.

Older patients call for particular caution. Decreased pain perception in the elderly makes the history harder to take, and mortality for the same abdominal condition can be up to 9 times higher than in a younger patient. Many older patients take beta blockers, which can mask the tachycardia that normally accompanies shock, so a pulse that appears normal might actually mean shock.

Care

Care for the patient with abdominal pain is supportive, and it begins with the airway. An altered mental status can compromise the airway, and vomiting is common, so keep suction ready. Give oxygen if the patient is hypoxic or in distress, or if the pulse oximeter reading is unreliable, with a target saturation of at least 94%. Allow the patient to assume a position of comfort unless shock or an airway problem overrides that choice, in which case place the patient in the left lateral recumbent position.

Never give an abdominal pain patient anything by mouth. Transport promptly, and do not let a lack of findings reassure you: the absence of abnormal findings does not mean the condition is not serious.