Episode 29 - Assessing Abdominal Pain in Adults: A Rational, Cost-Effective, and Evidence-Based Strategy

Show Notes Jeff: Welcome back to EMplify the podcast corollary to EB Medicine’s Emergency medicine Practice. I’m Jeff Nusbaum and I’m back with Nachi Gupta for your regularly scheduled monthly dose of evidence based medicine. This month, we are tackling an incredibly important topic – Assessing abdominal pain in adults, a rational, cost effective, and evidence-based strategy. Nachi: This incredibly important topic was chosen to mark the 20th anniversary of Emergency Medicine Practice. It is actually a revision of the first issue of Emergency Medicine Practice in 1999, now with updated evidence and recommendations. Thanks Robert Williford and Dr. Colucciello for getting this all started 2 decades ago! Jeff: Wow – 20 years – that’s amazing considering Emergency Medicine as a specialty hadn’t even been around all that long at the time and as Dr. Jagoda writes in his intro “evidence based education was still finding its footing.” Nachi: As a tribute to the man who started it all, EB Medicine again turned to Dr. Colucciello, who is no longer wearing his editor in chief hat, but instead is a professor at the University of North Carolina School of Medicine, to update his original article with the latest evidence. Jeff: Before we dive into the meat and potatoes of this month’s issue, let me also recognize Drs. Taylor and Shaukat of Emory and Coney Island Hospital respectively for their efforts in peer reviewing this huge topic. Show More v Nachi: For a number of reasons, this month is going to be a little different. You will notice that we will focus more on safe disposition instead of on diagnosis. Which is reasonable, as that is the crux of our job as emergency physicians. Jeff: Indeed. So for those of you who can’t wait, here’s a quick spoiler, The CBC isn’t all that useful. CT is good but you really should learn ultrasound, and lastly, sick patients need prompt consultation and resuscitation, not rapid trips to radiology. Nachi: All valid points, but let’s dive in too some actual detail. Jeff: Abdominal pain is the one of most frequent complaint in US emergency departments, representing 8% of all adult ED visits, with admission rates for all patients with abdominal pain ranging between 18-42% and reaching as high as 60% for the elderly. Nachi: With respect to the elderly, statistically speaking, 20% presenting with abdominal pain will undergo surgery, and 5% will die. Jeff: Often the etiology of the abdominal pain is never determined. This happens up to 40% of the time by the end of the ED visit. Nachi: I feel like that needs to be restated for emphasis – nearly half of patients who present to the ED with abdominal pain will have no determined etiology for their pain. Clearly, that doesn’t mean you are a bad ED physician – it’s just the way it goes. Jeff: Definitely still a win to be told you aren’t having an intra-abdominal catastrophe at the end of your visit! Nachi: Moving on to pathophysiology. Visceral pain results from distention or inflammation of the hollow organs or from ischemia from any internal organ, while the more localized, somatic pain is typically from irritation of the adjacent peritoneum. Jeff: And don’t forget about referred pain. Due to the movement of organs and stretching of nerve pathways during fetal development, pain may be referred to distant sites, like diaphragmatic irritation presenting as shoulder pain. Nachi: Let’s talk differential diagnosis. The differential for abdominal pain is tremendously broad and includes both intra-abdominal and extra abdominal pathologies. Check out table 2 for a very thorough list. Jeff: Table 1 is also worth reviewing while you’re on page 3 as it lists a few of the common dangerous mimics that often lead to misdiagnosis on initial presentation. To highlight a few – a AAA can masquerade as renal colic, diverticulitis, or a lumbar strain; an ectopic may present similar to PID, a UTI, or a corpus luteum cyst, and mesenteric ischemia may present shockingly similar to gastroenteritis, constipation, ileus, or an SBO. Nachi: Though misdiagnosis is certainly possible at any age, one must be particularly cautious with the elderly. Abdominal pain in the elderly is complicated by a number of factors, they often have no fever, no leukocytosis, or no localized tenderness despite surgical disease, surgical problems progress more rapidly, and lastly, they are at risk for vascular catastrophes, which don’t typically afflict the younger population Jeff: Dr. Colucciello closes the section on the elderly with a really thought-provoking point – we routinely admit 75 year old with chest pain and benign exams, yet we readily discharge a 75 year old with abdominal pain and a benign exam even though the morbidity and mortality of abdominal pain in this group exceeds that of the chest pain group. Nachi: That’s an interesting perspective, but we still have to think about this in the context of what an admission would offer in either of these cases. Most of the testing for abdominal pain can be done in the ED, CT being the workhorse. This point certainly merits more thought though. Jeff: Most clinicians have a low threshold to scan their elderly patients with abdominal pain, and the data behind this practice is quite compelling. In one study, CT altered the admission decision in 26%, need for surgery in 12%, the need for antibiotics in 21%, and changed the suspected diagnosis in 45%. Nachi: That latter figure, 45% change in suspected diagnosis, that was also confirmed in another study in which CT revealed a clinically unsuspected diagnosis in 43% of the elderly. Jeff: And it’s worth mentioning, that even though CT may be the go-to-tool - biliary tract disease, which we know is best visualized on ultrasound, is actually the most common cause of abdominal pain, especially sudden onset abdominal pain in the elderly. Nachi: The next higher risk group to discuss are patients with HIV. While anti retroviral therapy has certainly decreased the burden of opportunistic infections, don’t forget to keep a broader differential in this group including bacterial enterocolitis, drug-induced pancreatitis, or AIDS related cholangiopathy Jeff: Definitely make sure to check to see if the patient has a recent CD4 count to give you a sense of their disease and what they may be at risk for. At less than 200, cryptosporidium, isospora, cyclospora, and microsporidium all make their way onto the differential in addition to the standard players. Nachi: For more information on HIV and its management, check out the February 2016 issue of Emergency Medicine Practice, which covered this and more in depth. Jeff: The next high risk population we are going to discuss are women of childbearing age. Step one is always the same - diagnose pregnancy! Always get a pregnancy test for women between menarche and menopause. Nachi: The pregnancy test is important not only for diagnosing an intrauterine pregnancy, but it’s also a reminder, that we need to consider and rule out an ectopic. Jeff: Along similar lines, you also need to consider torsion, especially in your pregnant population, as 20% of cases of ovarian torsion occur during pregnancy. Nachi: Unfortunately, you cannot rely on the physical exam alone in this age group, as the pelvic exam may be misleading. Up to a quarter of women with appendicitis can exhibit cervical motion tenderness -- a finding typically associated with PID. Sadly, errors are common and ⅓ of women of childbearing age who ultimately were found to have appendicitis were initially misdiagnosed. Jeff: To help reduce your risk in the pregnant population, consider imaging, particularly with radiation reduction strategies, including using ultrasound and MRI, which is gaining favor in the diagnosis of appendicitis in pregnancy. Nachi: Diagnosis of appendicitis, in a pregnant patient, ultrasound vs. mri. Sounds familiar. Didn’t we just talk about this in Episode 24 back in January? Jeff: We sure did! Take another listen if that doesn’t ring a bell. Nachi: That was focused on first trimester only, but while we’re talking about appendicitis in pregnancy - keep in mind that during the second half of pregnancy, the appendix has moved out of the RLQ and is more likely to be found in the RUQ. Jeff: As yes, the classic RUQ appendix. As if our jobs weren’t hard enough, now anatomy is changing… Anyway, the last high risk group we are going to discuss here are those patients with prior abdominal surgery. Make sure to ALWAYS examine the patient's exposed skin to look for scars. Adhesions are the leading cause of SBOs in the industrialized world, followed by malignancy, IBS, and internal or external hernias. Nachi: Also keep a high index of suspicion for patients who have undergone bariatric surgery. They are especia...