The Quarterly Consult is a quarterly supplement to the Bulletin highlighting pediatric clinical expertise. If you have an item of interest to include in the Quarterly Consult, contact Dr. Steve Dassel at 206-625-7373, mailbox 8588.

By Steve Dassel, MD

It has been a long time since I have talked to a general surgeon about the acute abdomen, and I thought it might be interesting to visit this topic again.

I discussed it with Dr. Dan Ledbetter , who is an attending pediatric surgeon at Seattle Children's Hospital and an associate professor in the Department of Surgery at the University of Washington.

Ledbetter grew up in Florida and received his undergraduate and medical degrees from the University of Florida. He completed a general surgery residency at the University of Washington and then spent two years working in the lab with Dr. David Tapper, and another year as a trauma surgeon at Harborview Medical Center before doing a fellowship in pediatric surgery at Seattle Children's.

He was an attending pediatric surgeon at the University of Chicago and the University of Florida before returning to Seattle Children's Hospital in 2000.

We talked about three conditions in the differential diagnosis of the acute abdomen - intussusception, midgut volvulus and, to a lesser extent, appendicitis - that are surgical emergencies because of their potential to perforate, bleed or cause bowel ischemia and necrosis.

Q: Let's start with appendicitis. What is the setting?

A: Usually, it's a school-age child or adolescent with persistent abdominal pain. Classically, the pain is initially periumbilical and then localizes to the right lower quadrant, and the pain usually begins before vomiting.

This differs from gastroenteritis, where the vomiting (and often diarrhea) starts before the abdominal pain. Also, the pain of appendicitis is usually constant and progressively more severe.

Again, this contrasts with gastroenteritis, where the crampy, periumbilical or hypogastric pain waxes and wanes in severity, and usually improves after 8 to 12 hours.

Q: How long can we wait before perforation may occur?

A: In the older child, you usually have 24 hours or longer, but the younger child (4 to 6 years old) can perforate in less than 24 hours.

Q: This is an age in which it is more difficult to pick up appendicitis. Any tips?

A: Yes, younger patients often have more subtle signs and symptoms, especially early in the course of their illness. But abdominal pain that is worse with movement - especially walking and walking bent over - are indicative at any age.

Again, the persistence of pain that does not wax and wane is a tip-off to appendicitis. Finally, there is persistent, marked tenderness in the right lower quadrant. All these features distinguish appendicitis from gastroenteritis.

Q: Discuss imaging. Are there advantages to a CT versus ultrasound?

A: Although we still consider appendicitis to be a diagnosis that can usually be made by history, physical examination and a few lab tests, we do use imaging studies when the situation isn't clear.

Whether you choose ultrasound or CT depends on the skill and experience of the ultrasonographer and the radiologist. Here at Children's, they are reliable in getting a good ultrasound in kids. So, we start with an ultrasound at any age and then go on to CT if the ultrasound isn't informative.

This also saves many kids from the radiation exposure that comes with a CT scan. CT is preferable for demonstrating an abscess, so we may start with a CT if we suspect perforation and abscess formation, such as when the patient has been sick for several days.

Q: A recent pediatric board examination asked if a CT scan was indicated whenever appendicitis was suspected. The acceptable answer was yes, and many of us disagreed with this. What is your feeling?

A: One always has to ask oneself: If you have a patient presenting with classical history and physical findings of appendicitis, would a negative CT scan dissuade you from operating?

If it would not, then I think a CT scan is not indicated. If you think perforation is a possibility, a CT scan showing an abscess might lead you to delay surgery.

Q: Tell us more about that.

A: Many surgeons would prefer not to operate on an appendicitis that has ruptured and led to abscess formation because morbidity of the procedure is greater (longer hospital stays and a more difficult course).

In this situation, many of us would stabilize the patient, start him on antibiotics and remove the appendix through a much smaller operative site in six weeks.

Q: A 10% normal appendix removal rate was always considered necessary to avoid missing a hot appendix. With better diagnostic techniques, is this still true?

A: I think the goal now is less than 5%.

Q: What mistakes do you see primary care physicians making in the diagnosis of appendicitis?

A: Actually, delay of diagnosis that is iatrogenic is quite unusual. Delayed diagnoses usually result from parents sitting on the problem. As a rule, primary care providers get patients to us in a timely manner.

One thing we do see occasionally is a partially treated appendicitis when antibiotics have been given for a suspected urinary tract infection. This suspicion usually has been based on a poor urine specimen with a few white cells in a non-clean catch.

Q: You mean like partially treated meningitis?

A: Yes.

Q: Any other mistakes?

A: Trying to rule out appendicitis on the basis of a white count. History and physical examination always trump laboratory tests, especially the white count.

Q: Let's turn to intussusception. This is a narrower and younger age range?

A: Yes, this is a toddler problem. As a rule, the age range is usually 6 months to 3 years.

Q: And its presentation?

A: This is a bowel obstruction, so initially there is vomiting and abdominal pain, then later abdominal distention, bloody stools and lethargy.

The abdominal pain is usually intermittent and can be quite severe, but there is often no tenderness until there is complete bowel obstruction or intestinal necrosis.

Q: Yes, and this is lethargy like CNS infection lethargy. It is impressive. What causes it?

A: We still don't know. The patients are not septic, although there may be a low-grade fever.

Q: Every now and then, lethargy is the predominating feature, and that can get really confusing. Any tips on how to sort that out?

A: Fortunately, there will usually be some GI sign or symptom along with the profound lethargy. Although, I agree, it can be confusing in the absence of vomiting, and often the lethargy occurs before abdominal distention and bloody stools.

Usually, upon close questioning, there will be some vomiting or abdominal pain.

Q: What kind of imaging would be used for diagnostic purposes?

A: Initially, just a plain X-ray looking for signs of bowel obstruction: a dilated bowel followed by air fluid levels. You may see a soft tissue mass demonstrating the intussusception itself, but you can't count on it.

Q: How do you decide whether you are going to call for the radiologist to reduce the intussusception or go in surgically?

A: If there is peritonitis on clinical examination or the X-ray shows free air, we would go straight to operation; otherwise, we would have the radiologist do a contrast enema to make the diagnosis and possibly reduce the intussusception.

Q: What is the differential diagnosis of intussusception?

A: The differential diagnosis depends upon the predominant clinical features. With abdominal pain and vomiting, gastroenteritis is common. If there are bloody stools, then infectious colitis and hemolytic uremic syndrome must be considered.

As you know, colitis can be profound in this syndrome. This distinction is important - researchers from Children's tell us to avoid antibiotics in patients with hemolytic uremic syndrome.

Q: Again, what mistakes are made by primary care doctors?

A: Well, we touched on missing the sometimes-subtle GI symptomatology in the ill-looking, lethargic patient with intussusception.

Like so many things in medicine, it's a problem of not considering the diagnosis of intussusception in this particular patient, because as soon as you consider it, you will specifically ask about subtle symptoms of anorexia, nausea, vomiting and abdominal pain and look for subtle signs of abdominal distention.

Q: Finally, let's discuss midgut volvulus. Is there a specific age range for this?

A: Midgut volvulus is most common in newborns and infants, but can occur at any age. Primary care providers often think of it in their differential diagnosis of pyloric stenosis but not in the differential diagnosis of vomiting in the adolescent.

If the history of vomiting comes by telephone and you don't think to ask whether it is bilious (green or yellow) or not, you may miss that diagnosis.

Q: Any other tips on how not to miss this diagnosis?

A: Bilious vomiting is the key. When that red flag comes out in the history, we start looking for other signs and symptoms of bowel obstruction (abdominal distention, obstipation) and visceral ischemia (unexpectedly severe pain, fever, peritonitis, bloody stools).

We strive to make the diagnosis when it is a simple bowel obstruction before there is bowel ischemia.

Q: What about imaging in this condition?

A: When you are worried about midgut volvulus, you need to get an upper GI. In newborns and infants, bilious vomiting alone may be enough to warrant the study.

It's an urgent matter, because once the volvulus leads to bowel ischemia, there are only a few hours before necrosis occurs - and that is at any age.

Q: Thanks, Dan, this has been great.