Emergency Medicine Forum

My sister called one morning and told me Fred, my nephew, wasn’t feeling well.  As the only physician in my immediate family, these calls are not unusual.  She said he was complaining of a stomach ache, and didn’t want to eat breakfast.

Fred was 8 yrs old, and had no medical problems.  He had no vomiting or diarrhea, and had already had a normal bowl movement today.  He didn’t feel feverish (thermometer could not be found).

“Have him point to where it hurts.”  I asked.

“He points to his right lower side.”  She answered.

“Have him jump up and down three times.”

“Aunt Char said jump up and down 3 times!”  I heard her ask him.

“Ow, ow, ow!”  I heard in the background.

Questions:
 
1. What is the Rovsing sign?  The Obturator sign?  The Psoas sign?  How reliable are they?

Rovsing sign is RLQ pain on palpation of the LLQ, and suggests peritoneal irritation in the RLQ precipitated by palpation at a remote location.

The Obturator sign (RLQ pain with internal or external rotation of the flexed right hip) may suggest an inflamed appendix is located deep in the right hemi-pelvis.

The Psoas sign (RLQ pain with extension of the right hip) may suggest the inflamed appendix is located along the course of the right Psoas muscle. 

These signs are only present in a minority of patients, and their absence does not rule out appendicitis.  (1)

2. How often is appendicitis missed on the patients first health care provider visit?

Overall, about 10% of adult’s are initially misdiagnosed. (1) 

In pregnant women, diagnosing appendicitis is even more challenging.  During pregnancy, the appendix migrates towards the right kidney, and is located above the iliac crest at about 4.5 months of gestation.  In the latter half of pregnancy, right upper quadrant or right flank pain may represent appendicitis.  (1)

In non-pregnant women, appendicitis is initially misdiagnosed in 33% of women of childbearing age.  (1). 

In children, it is initially misdiagnosed in 25% of cases, and the misdiagnosis is inversely related to the age of the patient.  (1). Children are more likely than adults to have vomiting before the pain, concurrent diarrhea or constipation, or symptoms of upper respiratory infection.  (1)

3. On arrival in the ED, Fred’s temp was 99F.  He had not vomited (my sister had kept him NPO), but he still had no appetite.  He had no history of peri umbilical pain migrating to RLQ (“I just woke up and it hurt here!” pointing to the RLQ).  Exam revealed RLQ tenderness and localized rebound.  He also had voluntary guarding on palpation of the RLQ.  His Rovsing sign was positive (He noted RLQ pain on palpation of the LLQ). Otherwise exam was unremarkable.  Acute abdominal series showed a RLQ localized ileus (no appendicolith).  WBC was 18,000 with 90% PMN, and urine was negative.  Surgery was consulted and ordered a CT scan.  What do you think?
 
The role of imaging in patients with potential appendicitis has become very controversial.  The advantage is that it is very sensitive and specific (adults:  94% sensitivity, and 94% specific, children 94% sensitive and 93% specific) (2).  The positive likelihood ratio for CT is 16, and the negative likelihood ratio of CT is .06.  So if your pretest probability is high, based on the history and physical, then even if the CT is negative, your post test probability will still be over 50%.  

On the disadvantage side, there is considerable radiation with a CT.  

A 2004 evidence based review of CT exams and children’s lifetime cancer risk found that the lifetime cancer mortality risk attributable to the radiation exposure from a single abdominal CT in a 1-year old is about 1 in 550. (3) This means if you did abdominal CT scans on 550 children 1 year old, 1 of them would die later in life from cancer that developed because of the radiation of the CT you ordered.  (3)  This doesn’t mean we shouldn’t order CT scans, but we do need to be aware of the risk/benefit ratio…what information will you get vs. the small (but not zero) increased risk of cancer down the road.

Recently, efforts to decrease the radiation exposure and still diagnose appendicitis have been promising.  (4)  In a recent study from Korea, researchers did 2 CT scans (surprising they got this past the IRB!), one regular dose, and one low dose (actually Ѕ the dose of the usual CT) on patients with suspected appendicitis.  The low dose CT was able to successfully identify appendicitis, with a sensitivity of 99% and a specificity of 93-95%.  (4)

One last point about the elevated WBC count, in a best bets review of the usefulness of WBC counts in helping to diagnose appendicitis, they found that a single white blood cell count is neither sensitive nor specific in the diagnosis.  (5, 6).

Outcome:
Although the Surgical resident ordered the CT, the EM doc (I did not take care of Fred) actually called the pediatric surgeon himself. (This case occurred a few years ago, and I suspect the surgical resident today would not have ordered the CT scan in a patient with a very convincing exam.) The surgical attending came to evaluate Fred, cancelled the CT and took him to the OR where he did a laparoscopic removal of Fred’s inflamed and infected appendix. He was back in his hospital room by 6PM, and left before noon the next day!

References:
  
1. Craig S.  Acute Appendicitis.  Emedicine.  June 1, 2009.  Accessed at: http://emedicine.medscape.com/article/773895-overview

2. Meeks D, Kao LS. Controversies in Appendicitis.  Surgical Infections. 2008 9(6):  553-558.  Entire manuscript available at: http://www.liebertonline.com/doi/pdf/10.1089/sur.2008.9954?cookieSet=1
 
3. Drozdowski BJ, Frohna J, CT examinations in children possibly increase lifetime risk of cancer mortality.  University of Michigan Department of Pediatrics Evidence-Based reviews.  Accessed at: http://www.med.umich.edu/pediatrics/ebm/cats/catrad.htm
 
4. Seo H, Ho Lee K, Jung Kim H, Kim K, Bang SB, Kim SY, Kim YH.  Diagnosis of Acute appendicitis with sliding slab ray-sum interpretation of Low-Dose unenhanced CT and Standard-dose IV contrast-Enhanced CT scans.  Am J Rent July 2009; 193:96-105.  Accessed at: http://www.ajronline.org/cgi/content/abstract/193/1/96
 
5. Williams R, Mackway-Jones K. White cell count and diagnosing appendicitis in children.  Best BETS.  Sept 2002.  Accessed at: http://www.bestbets.org/bets/bet.php?id=131
 
6. Williams R, Herren K.  White cell count and diagnosing appendicitis in adults.  Best BETS.  May 2003.  Accessed at: http://www.bestbets.org/bets/bet.php?id=133