Opiates and Abdominal Pain

Make the Diagnosis: Opiates and Abdominal Pain

Background

The initial diagnosis of the patient with abdominal pain is rarely certain, and the first examining physician is often not the surgeon responsible for making an operative decision. Thus, the examining physician must decide whether to prescribe analgesics (usually opiates) while awaiting results from additional tests, surgical consultation, or both. Unlike most Rational Clinical Examination questions that focus on the likelihood ratio for symptoms and signs, the decision to use opiates must address the question of whether these analgesics alter the findings. By altering the findings, opiates could affect the differential diagnosis and, consequently, the decision to operate or pursue other diagnostic tests or therapies. For the changes in physical findings to be important, the changes must create management errors such as delayed or unnecessary surgery.

Effect of Opiates on the Physical Examination

The relative risk (RR) that opiates change the physical examination findings in adults with abdominal pain (RR, 1.51; 95% confidence interval [CI], 0.85-2.69) is similar to that for children (RR, 2.11; 95% CI, 0.60-7.35). Peritoneal findings may disappear in 5.6%-18.7% of patients in the group receiving opiates and in 2.6%-7.7% of those in the control group.

Effect of Opiates on Potential Management Errors

Despite the potential to alter the physical examination findings, there was no significant change in the rate of incorrect management decisions among adult patients who received opiates vs those who did not receive them (+0.3% absolute increase; 95% CI, –4.1% to +4.7%, Table 67-1). The findings in children are also not significant, showing an absolute decrease in incorrect management decisions when opiates were given (–0.8%; 95% CI, –8.6% to +6.9%). Across all studies (adult and pediatric), there was virtually no change in the management error rate for those who received opiates (+0.1% absolute increase; 95% CI, –3.6% to +3.8%), which translates to a number needed to harm (NNH) of 909. This NNH means that 909 patients would need to be treated with opiates for their abdominal pain to create 1 management error attributable to analgesia.

Reference Standards for Management Errors

Delivering optimal surgical care necessitates performing a certain number of operations in patients who do not ultimately have surgical pathology. For instance, to avoid perforated appendicitis due to delaying surgery, a certain percentage of patients will undergo laparotomy in which the ...