#MiniTeach: Don't Be A Dipstick!
"A 74-year-old white male is referred by his GP for ?pyelonephritis."
He is normally fit and well, but taking medication for high blood pressure. He developed severe left sided loin pain this morning and felt faint while he was urinating. His urine is weakly positive for blood and protein.
His observations are: P95, BP 110/82, RR20, Temp 36.8, Pain score 8/10.
1. What’s the differential diagnosis?
Always think of the ‘big five’ when confronted by an older person with atraumatic abdominal pain: AAA, Ischaemic bowel, Intra-abdominal sepsis, Pancreatitis and Obstruction.
Once these have been ruled out, you can consider the legion of other differential diagnoses, which include renal colic, pneumonia, diverticular disease……urinary tract infection would be very unusual in a well man of this age and should be way down your list.
2. What should happen at initial assessment?
Obtain a full set of obs.
Insert a wide-bore cannula (grey or bigger) and take blood for FBC, U+E, LFT, Bone, Amylase, G+S, COAG.
Give IV analgesia and get a stat assessment.
This patient needs an urgent bedside aortic ultrasound.
3. A CT scan is done. What does it show?
The scan shows a ruptured abdominal aortic aneurysm.
4. How useful is clinical examination for diagnosing this condition?
Diagnosing an abdominal aortic aneurysm clinically depends on the size of the patient, the size of the aneurysm and the experience of the assessor. Abdominal examination can miss up to 80% of aneurysms. The pick up rate is a bit better if the aneurysm has ruptured – only 40% are missed!
Ultrasound on the other hand has a sensitivity and specificity approaching 100% for diagnosing an aneurysm, but it won’t tell you whether it has ruptured.
5. What is your immediate management?
Move the patient to Resus. Follow the vascular emergencies pathway. (See attached). Key points are:
Take care with fluid/blood resuscitation. If the patient is shocked, aim for a systolic BP no higher than 90 mmHg
Get an immediate CT aortogram
Communicate the results to the vascular registrar (based at GGH)
If accepted, transfer urgently and let blood bank know.
6. What is the evidence behind the definitive management options?
The two definitive management options are: EVAR = endovascular aneurysm repair and OSR = open surgical repair. A recent Cochrane review showed that both have similar outcomes in terms of LOS and 30 day mortality.
http://www.cochrane.org/CD005261/PVD_endovascular-treatment-ruptured-abdominal-aortic-aneurysm
NOTE OF CAUTION!
Some people get confused between aortic dissection and aortic aneurysm. The two conditions are different and present differently. Both require a high level of clinical suspicion.
Don’t treat people for a UTI based on a dipstick alone. Lots of conditions can cause a ‘positive urine dipstick’, some of these conditions may even have associated with urinary tract symptoms (diverticular disease, intra-abdominal malignancy, appendicitis). Treat the patient, not the test.
