EM Didactic: Is Acute Appendicitis always a CLINICAL DIAGNOSIS?

RLQ pain is quite a common presentation in the ED. We always think and rule out appendicitis first. So this week, let's go through a few questions that popped into my mind while evaluating a RLQ/RIF pain. To begin with, I was always taught that appendix is a vestigial organ but recent literature on biofilms suggests that appendix may act as a storehouse for commensal microorganisms that defend us against pathogens.

So what actually causes Appendicitis?

Mostly, appendicitis is caused as a result of an acute obstruction of the appendiceal lumen due to an appendicolith, calculus, tumor, parasite, or an enlarged lymph node. This leads to a rise in intraluminal pressures and accumulation of mucosal secretions. The resulting distention stimulates visceral afferent pathways perceived as a dull, poorly localized pain. Ulceration and ischemia develop as the intraluminal pressure exceeds the venous pressure. Gradually, the appendix becomes swollen, and factors elaborated in the pathologic process begin to irritate surrounding structures, including the peritoneal wall leading to more localized pain. If swelling does not terminate, gangrene or perforation occurs.

What causes this migration of pain from peri-umblical area to RIF?

Afferent fibers, which conduct visceral pain from the appendix, accompany the sympathetic nerves and enter the spinal cord at T10 segment. This causes an early referred of pain to the umbilical area that later migrates to RIF.

The classic appendicitis – a clinical diagnosis

Vague onset of dull periumbilical pain with low-grade fever, anorexia, nausea, and vomiting. Pain then migrates to the RIF. This presentation does not require imaging which is why we were taught that "Appendicitis is a clinical diagnosis." It can be hard to distinguish OBGYN pathology from Appendicitis in females, so have a low threshold to obtain imaging for them.

Atypical symptoms: Increased urinary frequency and the desire to defecate.

Retrocecal or Retroiliac Appendix: Pain may be dulled by overlying bowel. Isolated rectal tenderness rarely may be the only site of localized pain in patients with a low-lying or retrocecal appendix.
Elongated Appendix: Pain may be referred to the flank, pelvis, or RUQ.

Physical Exam: Localized RLQ abdominal tenderness. The pain may be noted over McBurney’s point (but not always). Abdominal guarding and Rigidity to palpation (may not be seen in elderly due to less muscle mass). Rebound tenderness is a late finding which may be absent early in the course. (Elicit this only once, this can be extremely painful)

Rovsing sign - Tenderness is referred to the RLQ with palpation of the LLQ.
Psoas sign – Increased pain on hip extension (due to stretching of Psoas)
Obturator sign - Pain on hip flexion external rotation

In addition, pain on coughing suggests acute peritonitis and a lack of worsening pain with cough make appendicitis less likely.

Here is a table with mimics of appendicitis:

Do they always have a low-grade fever?

No. Vitals can be normal in the beginning. However, a low-grade fever is present only in about 15% of patients with uncomplicated appendicitis; and in up to 40% if perforation has occurred.

Who is at the risk of perforation?

Patients may be more prone to earlier perforation because of anatomic changes in the appendix associated with aging, such as a narrowed appendiceal lumen, thinner mucosal lining, decreased lymphoid tissue, and atherosclerosis. It usually occurs within 24 to 36 hours. Perforation is more commonly seen at the extremes of ages.

How do we evaluate a pregnant female with suspected appendicitis?

Diagnosing appendicitis in females is a challenge regardless of the conception status. Therefore, use of imaging should be strongly considered in any female with RLQ pain. Nausea and vomiting occur normally in a pregnancy, and the accuracy of the physical exam is compromised because of altered anatomy. Lab values are not useful, because leukocytosis is common during pregnancy.

Maternal death from appendicitis is extremely rare, spontaneous fetal abortion occurs in up to 15-37% cases. Start with a USG, then MRI if USG is indeterminate. A shielded CT should only be the last resort. If there are potential delays in obtaining imaging, admit them for serial abdominal exams.

ED Management

NPO
Analgesia: There is robust literature that proves that opioids do not mask physical exam findings or interfere with surgical decision making. If your surgical colleagues like to examine patients prior to that then give them a call the moment you suspect appendicitis and make sure that they put their hand on the patient’s belly within the next few minutes.
IVF
Antiemetics
Antibiotics

Equivocal Imaging. Can we send them home with red flags?

Educate your patients about worsening signs of appendicitis, along with arrangements for immediate re-evaluation if their symptoms worsen, or call them for an abdominal re-examination in 12-24 hours. Document this discussion in the patient’s record.
Consider admission for those who require significant doses of opiates to control their pain, who cannot follow-up, if patient or family reliability is in question.

Is it possible to have acute appendicitis with a NORMAL Leukocyte Count

Yes, it is certainly possible to have appendicitis despite having a normal WCC although many surgeons believe otherwise. Approximately 80 to 90% of patients with acute appendicitis will have an elevated white blood cell (WBC) count above 10,000/mm. Unfortunately, the leukocyte count is nonspecific and often is elevated with other causes of abdominal pain.
Other labs: Mild sterile pyuria may be seen if the appendix is irritating the ureter but significant pyuria (i.e. > 20 WBCs/ HPF) is highly suggestive of urinary tract pathology.
Use scoring systems such as “MANTRELS score” cautiously especially with female patients.

Imaging Appendicitis - USG or CT scan?

USG: On ultrasound, a non-compressible appendix with a diameter greater than 6 to 7 mm is considered diagnostic for appendicitis. Ultrasonography is inexpensive, requires no exposure to radiation, adds no extra time for contrast administration, and is also useful in diagnosing OBGYN pathology in women.

A negative ultrasound scan with a concerning story and symptomatic patient warrants either in-hospital observation or a CT scan. i.e. a negative USG cannot rule out appendicitis in a patient with concerning history and physical exam.

CT scan: Even if you start with a CT scan, let me tell you that a CT is not 100% accurate as well. Care should be taken not to label minor changes in appendix as “negative,” because 1/3 of patients with such equivocal findings eventually have histologic confirmation of appendicitis.

Having a final word with them is crucial: If the CT appears truly negative, still you need to explain them explicitly about when to return for reevaluation if symptoms worsen or do not resolve in the next 24hrs. Such information and follow-up is important in patients evaluated within the first few hours of symptoms, as early appendicitis may be missed on the CT scan.

Do all of them require surgery?

The Appendicitis Acuta (APPAC) trial compared "antibiotic therapy" with "appendectomy" in the treatment of 530 patients with uncomplicated acute appendicitis confirmed by CT. The trial did not demonstrate noninferiority of antimicrobial management versus surgery.

However, currenlty nonsurgical treatment can be considered only when appendectomy is not accessible. Anecdotal reports describe the success of IV antibiotics in treating acute appendicitis in patients without access to surgical intervention. About 1/3 of non surgically treated patients are likely to have a recurrent episode of appendicitis within 14 months.

Take Home:

Pain Relief always comes first.
A normal white cell count, a negative USG or even a negative CT cannot rule out appendicitis in a patient with concerning story and physical exam. Therefore, whenever sending them home, discuss reg flags and document that in the patient's chart.
Pregnancy with RLQ pain, start with USG and then MRI scan if needed. A shielded CT should only be your last option here.
Have a low threshold to obtain imaging in every female with RLQ pain because appendicitis is "not always" a clinical diagnosis.