Research Analysis: A Prospective Evaluation of Point-of-Care Ultrasonographic Diagnosis of Diverticulitis in the Emergency Department

INTRODUCTION

Diverticulitis is a common diagnosis in the emergency department (ED), resulting from inflammation of colonic diverticula. It often presents with a constellation of non-specific symptoms, including diarrhea, fever, and abdominal pain, making it challenging to diagnose.

The authors believed that this study was important since approximately one third of patients with acute diverticulitis receive misdiagnoses on initial clinical presentation. Currently, computed tomography (CT) is the imaging modality of choice for patients with suspected diverticulitis because of its high sensitivity and specificity. CT, however, is associated with radiation exposure as well as increased length of stay in the ED. Therefore, point-of-care ultrasonography, which is commonly performed in the ED to evaluate patients presenting with undifferentiated abdominal pain, is a very attractive imaging modality which could be used to evaluate for diverticulitis.

MATERIALS AND METHODS

This was a prospective study in a University Hospital with an ED census of approximately 90,000 patients per year. It is an American College of Surgeons–verified Level I trauma center with an established emergency medicine residency program and an emergency ultrasonographic fellowship training program.

The authors enrolled a convenience sample of patients in this study. Study personnel included ultrasound fellowship–trained faculty members and fellows. After screening of the ED dashboard, they approached the treating physicians and asked whether they were considering diverticulitis in their differential diagnosis as the cause of the patient’s symptoms and whether they were planning to order an abdominal CT scan to confirm the diagnosis.

Patients were eligible for study participation if they presented with abdominal pain associated with suspicion for diverticulitis and the emergency physician planned to order an abdominal CT scan.

Exclusion criteria included clinical instability (at the discretion of the treating physician), pregnancy, younger than 18 years, abdominal surgery within the previous 2 weeks, a pre-confirmed diagnosis of diverticulitis, unable to consent, or no CT scan during the ED visit.

DATA COLLECTION AND PROCESSING

The ultrasonographic protocol consisted of scanning a supine patient using a curvilinear transducer. The scan was initiated at the patient’s point of maximum tenderness. Graded compression was used to enhance visualization of the bowel. The entire abdomen was scanned with the “lawn mower” technique, which consisted of starting at the point of maximum tenderness and moving the ultrasonographic transducer, using grading compression, in a vertical pattern across the abdomen to evaluate the entire bowel.

Diverticulitis was determined to be present if all of the following were observed on the point-of-care ultrasonographic examination: bowel wall edema greater than 5 mm and surrounding a diverticula, enhancement of the surrounding pericolonic fat (indicating associated inflammatory changes), and sonographic tenderness to palpation. All 3 findings on the same location were required to make the diagnosis.

OUTCOME MEASURES

The primary outcome measures of this study were the sensitivity, specificity, positive predictive value, and negative predictive value of point-of-care ultrasonography in diagnosing diverticulitis, using CT as the criterion standard for comparison.

RESULTS

The final analytic sample was composed of 452 patients who received both a point-of care ultrasonographic examination and a CT scan.
Compared with CT, point-of-care ultrasonography had a sensitivity of 92%, specificity of 97%, positive predictive value of 94% and negative predictive value of 96% in the diagnosis of diverticulitis. The mean time to complete the point-of-care ultrasonographic examination was 4.9 minutes.

CONCLUSIONS

The author concluded that point-of-care ultrasonography can be used as an imaging modality for patients with suspected acute diverticulitis. They also commented on the fact that ultrasonography may have a role in the diagnostic evaluation of younger patients with suspected diverticulitis. Finally, they think that with limited additional training, emergency physicians with advanced ultrasonographic experience can reliably identify diverticulitis with point-of-care ultrasonography.