Abdominal pain is one of the most common presenting complaints
in the primary care physician’s office and often a diagnostic
dilemma for surgeons. Despite recent technologic advances, the diagnosis
and treatment of chronic, recurrent abdominal pain remain a challenge.
Pain is a subjective sensation that patients often find difficult
to describe. By contrast with other areas of the body, the abdominal
organs have poorly developed sensory systems that also may contribute
to the patient’s difficulty when trying to describe and
localize the pain. In the majority of clinical scenarios, no physical
course is apparent and symptoms are transient. The purpose of pain
is to protect the organ and the patient from injury. After the source
of the pain is found, every effort should be made to control or
eliminate it. In chronic pancreatitis or diffuse malignancy, for
example, pain control may become as much a challenge as in instances
where no underlying cause can be found.
For a patient to perceive pain, the autonomic nervous system
must be intact. The anatomy and physiology of pain have been described
in detail in previous chapters. Abdominal viscera are relatively
insensitive to many stimuli compared with a more sensitive organ
such as the epidermis. In addition to the relative paucity of sensory
nerve endings, the same group of nerves may innervate several viscera.
There are a few well-known nociceptive triggers in the abdominal
cavity. These include abnormal distention or contraction of hollow
organ walls, ischemia of the visceral musculature, direct action
of chemical substances on the mucosa, formation of allogenic mediators,
and traction or compression of ligaments, vessels, or mesentery.
Pain patterns are not well differentiated as to their location or
the cause. Nevertheless, there are some recognizable pain patterns,
and a careful history often can lead to the correct diagnosis. The
history and physical examination provide diagnosis in two thirds
of clinical presentations. Laboratory and radiologic tests are important
auxiliary tools for investigative workup. The invasiveness and cost-effectiveness
of the proposed tests should always be considered.
There is either a physical (organic) or psychogenic (nonorganic)
cause to pain, with one or more elements dominating. Abdominal pain
can be classified by the duration of the symptoms, etiology, primary
diagnosis, anatomic localization, and its response to treatment.
It can be either acute or chronic; chronic pain being arbitrary,
based on symptoms persisting for more then 6 months or after the
healing process is completed. Some clinicians divide pain into nociceptive
(somatic or visceral), neuropathic, psychogenic, or referred.
Visceral pain is transmitted from nociceptors found on the walls
of the abdominal viscera via sympathetic (thoracic branches and
lumbar splanchnic nerves synapsing in subsidiary plexuses: celiac,
splenic, hepatic, aorticorenal, superior mesenteric, adrenal) and
parasympathetic (vagus and nervi erigentes S2–4; motor
and sensory) pathways. This pain is nonspecific because of wide divergence
and relatively small number of afferent fibers innervating a large
area with extensive ramification. Patients usually have difficulty
localizing the source of pain ...