A CT scan of the abdomen and pelvis with oral and IV contrast was obtained. Figure 1 demonstrates a blind-ending structure dilated to 13 mm in diameter in the expected location of the appendix, extending to the surgical clips in the pelvis. The 1.8 cm tubular structure has enhancing, thickened walls with adjacent fatty inflammatory changes. Thickening of the cecal wall is also present and there is a normal appearance to the terminal ileum. These findings are diagnostic of stump appendicitis.
Appendectomy is one of the most commonly performed surgeries in the United States, with >250,000 performed annually. Stump appendicitis is acute inflammation of the residual appendix, and is an under-reported complication that can occur after open or laparoscopic appendectomy.1 Stump appendicitis results from obstruction of the lumen of the remaining appendix, usually by a fecalith. This increases intraluminal pressure, impairing venous drainage and allowing subsequent bacterial infection. Clinically, it presents similar to initial appendicitis with right lower quadrant pain, nausea, fever, anorexia, and/or emesis. Abdominal tenderness and guarding are usually present, and a positive psoas sign, obturator sign, or Rovsing sign may be elicited. The WBC is usually elevated. Liang et al.found the mean WBC in a review of 36 cases of stump appendicitis to be 14,900.1
The diagnosis of stump appendicitis is usually not considered as the etiology for right lower quadrant pain in patients with prior appendectomy. This creates a delay in making the correct diagnosis, and explains why the rate of perforation for stump appendicitis approaches 70%.1 In this case, the patient was taken to the operating room after her CT scan. The cecum was mobilized and the base of the grossly inflamed appendiceal stump was identified and resected. A pathology report confirmed acute stump appendicitis with rupture and periappendiceal abscess formation (Figure 3).
Identifying the base of the appendix with complete removal of the appendix precludes the potential complication of stump appendicitis. Some reports have suggested that laparoscopic appendectomy is associated with an increased incidence of stump appendicitis when compared with open appendectomy. However, the most recent comprehensive review of the literature examining 36 cases of stump appendicitis by Liang et al. revealed that only 34% of cases were initially performed laparoscopically, and 66% were initially performed as open surgeries.1 The error common to either technique is not adequately identifying the base of the appendix and failing to completely amputate the entire appendix. Methods of identifying the base that decrease the likelihood of leaving residual appendix include: Tracing the taenia coli of the cecum to the appendix, or dissecting and ligating the recurrent branch of the appendiceal artery, which marks the true base of the appendix.1
Regarding the imaging findings, many of the same principles used to diagnose acute appendicitis can be applied to diagnose stump appendicitis. To make the diagnosis, an appendiceal stump must be confidently identified in a patient with a known history of appendectomy. Plain films, ultrasound (USD) and CT may all play a role in diagnosis.
Plain films of the abdomen will demonstrate a fecalith in approximately 14% of patients with acute appendicitis.2 Localized ileus and dilated ileum may be evident. Barium enema exam is frequently nonspecific, and while complete filling of the appendix is strong evidence against appendicitis, non-filling of the appendix has no diagnostic value on its own.2
Using the graded compression technique, USD can be quite accurate in providing a definitive diagnosis for acute appendicitis.2 It is commonly the diagnostic test of choice in women of child-bearing age and in children.2 The slow-graded compression technique includes using a near-focus transducer at the region of maximum tenderness.3 On USD, the normal appendix has a diameter of <6 mm when compressed. USD signs of acute appendicitis are a noncompressible appendix >6 mm in diameter measured from outer wall to outer wall, and visualization of a shadowing appendicolith.2 Sonography has been used to diagnose stump appendicitis preoperatively. In this single case, Baldisserotto et al. found an increased thickness of the residual appendix (8 mm), 2 enlarged lymph nodes, and a small amount of fluid in the right iliac fossa.4
In men, older patients, and when periappendiceal abscess is suspected, CT is the imaging method of choice for diagnosis of acute appendicitis.2 Definitive CT diagnosis of acute appendicitis is based on finding: 1) an abnormally dilated (>6 mm) enhancing appendix; 2) enhancing appendix surrounded by inflammatory stranding or abscess; or 3) pericecal abscess or inflammatory mass with a calcified appendicolith.2
Similarly, a CT scan with oral and IV contrast can diagnose stump appendicitis. If an appendiceal stump is identified, the findings are similar to that of acute appendicitis. They include an abnormally dilated (>6 mm) enhancing and thickened stump, and adjacent fat stranding or abscess. Pericecal inflammatory changes and cecal wall thickening may create the arrowhead sign of appendicitis. Fluid in the right paracolic gutter, abscess formation (a liquefied mass of <20 HU on CT), or an inflammatory mass (indurated soft tissue of >20 HU on CT) with a calcified fecalith may be seen. Upon diagnosis, the patient should proceed to the operating room for complete appendectomy.
Clinicians and radiologists should have a high index of suspicion for stump appendicitis in patients with a history of appendectomy who present with an acute appendicitis-like picture. This case illustrates the clinical and radiological findings of stump appendicitis. Early recognition of this complication may decrease the increased morbidity and high rate of perforation associated with delayed diagnosis.