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Undifferentiated abdominal pain 393
in patients with UAP. Expert opinion, based upon a wealth of available
evidence and anecdotal experience, and published in the world’s leading
journals in general medicine, surgery, and emergency medicine, is near
unanimous: it is inappropriate to allow patient suffering on the pretext of
preserving the physical examination. 2–5 The literature clearly demonstrates
that neither proximal endpoints (e.g. specific examination findings such as
Murphy’s sign) nor downstream outcomes are significantly adversely
impacted by administration of analgesics. 3,6–8 Rather than being caused
by relief of pain, errors in diagnosis of UAP are more likely to be caused by
premature cessation of the diagnostic process, or even from poor history owing
to pain-clouded consciousness (particularly in the elderly). This issue’slevelof
certainty has progressed to the point where it would be unethical to randomize
to placebo the necessary number of UAP patients (i.e. thousands) needed to
detect any outcomes detriment. 2
Opioids remain the most commonly used, and most commonly recommended,
treatment for acute UAP (including that which may be a result of
surgical disease). 2,3,8 Other than the abovementioned issues with respect to
opioids’ effect on the physical examination, there have been questions about
the effects of mu receptor agonists on the Oddi sphincter. The relevant
evidence is addressed in detail in the biliary colic chapter (p. 111); the
conclusions are that there is no relevant difference between the pure opioid
agonists, and that if Oddi sphincter tone is a particular concern buprenorphine
(0.3 mg IV) is a good choice. In the setting of UAP, there is no evidence
supporting clinical practice of administering meperidine (pethidine) (over
morphine) in case the pain is related to biliary tract spasm. 9–11
There are a number of RCTs (with placebo controls) addressing morphine
use for UAP, including pain suspected to be from appendicitis. The evidence
clearly and consistently demonstrates safety and efficacy from morphine use
in the UAP population. 3,6,8,12–16 Other opioids have also been studied and
found effective, although evidence for other agents is generally less rigorous
than that supporting morphine use. 3,6,12,15–24
The use of fentanyl is theoretically attractive, since this agent has a short
duration of action and is therefore easier to titrate. One study assessing IV
fentanyl use for UAP found this approach safe and effective, but the data have