Case Of the Month 5 – Answer

One main finding to latch on to is the character of this patient’s abdominal pain.  This is a patient who is doubling over in pain and yet on exam although there is diffuse tenderness there doesn’t appear to be any peritoneal signs.  The patient has a history of abdominal surgery which is a red flag, but there is no obstruction on CT or really any particular finding.  The bloodwork is largely unimpressive aside from an elevated lactate and a +UTI.  All of these things are usually reassuring, as it appears that there may not be any emergent surgical issues driving this abdominal pain.  Perhaps this could be an insidious presentation of sepsis from a UTI.  But where is the pain coming from in that situation, why is she bent over in pain?   To diagnose this illness, you should latch on to her PMH as well: CVA and uncontrolled HTN, plus she is nonadherent to her medications.   What sort of illnesses is she prone to with a history of these medical problems?  Which of those would give her an elevated lactate aside from infection?  What if we phrase it as severe abdominal pain in a potential vasculopath with a nonspecific abd exam adn an elevated lactate on labs?

This is a case of mesenteric ischemia, a can’t-miss diagnosis.  Mesenteric ischemia can be divided into arterial and venous disease, and the arterial disease can be further subdivided into embolic, thrombotic, or nonocclusive.  This patient has many risk factors for thrombotic mesenteric ischemia including a history of CVA, uncontrolled HTN, and nonadherence to her meds (which should most likely include a statin and aspirin).  Visceral atherosclerotic disease develops in the same way as in coronary and cerebral arteries, and then either a plaque rupture or a low-flow state (such as post-MI or during a CHF exacerbation) can cause the ischemia.  Thrombotic ischemia usually requires at least 2 of the 3 arteries supplying blood to the intestines to be occluded in order to have significant bowel injury.  This is a high mortality illness ranging from 50-70% in part due to the difficulty in diagnosing the disease in a timely fashion.  Exam may reveal tenderness or nothing at all, despite the patient being in obvious distress.  Labwork may only reveal an elevated lactate, however as necrosis develops patient will frequently become septic.  CT A/P with contrast has a sensitivity in the 90% range but in the setting of an early presentation of AMI CT may not reveal bowel edema, stranding, or other nonspecific signs.  A CTA would be more likely to be diagnostic in these early stages and would allow prompt intervention, which is likely to be life-saving.  However, we cannot always rely on imaging when our clinical gestalt is that of a potentially deadly disease process and no clear alternative diagnosis can be found.

Aside from considering a CTA or MRA to make the diagnosis, early surgical consult is key.  Arterial thrombotic mesenteric ischemia has not been shown to be responsive to thrombolytic therapy, and currently angiocatheter-directed papaverine infusion is the pharmacologic mainstay, so IR consultation is also imperative.  Ultimately, a lot of these patients will require arterial reconstruction and bowel resection via laparotomy.  Therefore the best therapeutic measure we can do in the ED for these patients is to make a rapid diagnosis and get early help from our colleagues to help reduce the impending morbidity and mortality.  See the following attached algorithm for further details.