Emerg Radiol DOI 10.1007/s10140-014-1253-x
ORIGINAL ARTICLE
Stump appendicitis: surgical background, CT appearance, and imaging mimics Jennifer Johnston & Daniel T. Myers & Todd R. Williams
Received: 24 April 2014 / Accepted: 20 June 2014 # American Society of Emergency Radiology 2014
Abstract Stump appendicitis, also known as remnant appendicitis, is an uncommon entity with little radiologic literature. It is the result of unintentional incomplete appendectomy with subsequent inflammatory changes in the appendiceal remnant. A retrospective review of the radiology and pathology archives at our institution over an 8-year period yielded six surgically/pathologically confirmed cases. Imaging findings at presentation were evaluated, including appendiceal stump length, appendiceal stump diameter, presence or absence of surrounding stranding in the periappendiceal fat, and presence or absence of complication (perforation or abscess). The CT findings of the six cases had an average surgical specimen appendiceal stump length of 3.5 cm (range 2.0–5 cm) and an average appendiceal diameter of 12.3 mm (range 10–16 mm). All six cases demonstrated the presence of periappendiceal inflammatory fat stranding on the CT scan. Range of imaging presentation is reviewed with pictorial examples as well as examples of potential false-positive cases (mimics) including Crohn’s disease, residual surgical drain tract, and epiploic appendagitis. Familiarity with stump appendicitis as well as its imaging mimics may lead to earlier diagnosis and treatment and prevent unnecessary complications.
Keywords Stump appendicitis . Remnant appendicitis . Appendicitis . Appendectomy . Computed tomography
J. Johnston (*) : D. T. Myers : T. R. Williams Henry Ford Hospital, 2799 W. Grand Boulevard, Detroit, MI 48202, USA e-mail:
[email protected] D. T. Myers e-mail:
[email protected] T. R. Williams e-mail:
[email protected]
Purpose (introduction) Stump appendicitis, also known as remnant appendicitis, is an uncommon entity with little radiologic literature. The main purpose of this manuscript is to raise awareness of this rare, but clinically significant, entity to avoid missed or delayed diagnoses. In addition, this manuscript will review the surgical literature pertaining to stump appendicitis with an emphasis on factors that may predispose patients to the development of stump appendicitis. We will review the CT imaging findings of pathologically proven stump appendicitis as well as alternative diagnoses that may mimic the appearance of stump appendicitis. Greater education of physicians about the appearance of stump appendicitis and increased awareness will aid in avoiding delay in diagnosis and misdiagnosis and prevent both unnecessary workup and complications.
Background Stump or remnant appendicitis is a rare post-appendectomy complication first reported by TF Rose in 1945 [1]. In the USA, >25,000 appendectomies are performed each year, with the lifetime risk of appendicitis totaling 8.6 % in men and 6.7 % in women [2]. The incidence of stump appendicitis is approximately 1:50,000 cases of appendectomy with a reported range of clinical presentation ranging from 2 months to 50 years after appendectomy [3]. The clinical presentation is nonspecific with right lower quadrant pain seen in 77 % of patients and nausea and vomiting seen in 57 % of patients in one meta-analysis [2]. Clinically, there is often a delayed diagnosis leading to increased incidence of complications, including gangrene, abscess formation, and peritonitis with perforation in 59–70 % of reported cases versus 16–30 % in initial acute appendicitis [4, 5]. This results in the need for more extensive surgery including bowel resection.
Emerg Radiol Table 1 Characteristics of pathologically proven cases of stump appendicitis Months from original appendectomy
Original surgical appendectomy method
Surgical method of stump resection
Specimen stump length (cm)
CT stump diameter (mm)
Fat stranding present
Complication from remnant resection
37 7 3 17
Unknown Laparoscopic Laparoscopic Laparoscopic
Laparoscopic Laparoscopic Laparoscopic to open Laparoscopic
3.0 2.4 5.0 4.2
11 11 13 13
Yes Yes Yes Yes
None None None None
5 20
Laparoscopic Laparoscopic
Laparoscopic Laparoscopic
2.0 4.1
10 16
Yes Yes
None None
Methods and materials After approval by the Institutional Review Board (IRB), a retrospective review of radiology reports and images from the radiology archive for the prospective diagnosis of stump or remnant appendicitis was performed. This utilized a medical search engine (Softek Illuminate, Prairie Village, KS, USA) searching over an approximately 8-year time frame (October 2005–February 2014). Data search utilized the key words “stump” or “remnant” combined with “appendicitis.” In an effort to identify cases that the diagnosis may not have been prospectively identified by imaging, a retrospective review of the surgical pathology database was also performed using an internal search engine and key words “stump” or “remnant” and “appendicitis” over the same time frame. A total of 16 potential cases imaged with CT scans of the abdomen and pelvis were identified between the radiology and pathology database review. A 3rd-year radiology resident and two senior staff radiologists with 20 and 19 years of experience in abdominal imaging reviewed the CT scans and electronic medical record (EMR). Review of the clinical, surgical, and pathology notes was performed, with documentation of the presenting history, original appendectomy date, type of original appendectomy (laparoscopic vs. open), treatment course of stump appendicitis, and, if available, pathology diagnosis. Imaging findings at presentation were evaluated including appendiceal stump length of the pathology specimen, appendiceal stump diameter on CT, presence or absence of surrounding stranding in the periappendiceal fat on CT, and presence or absence of complication (perforation or abscess) identified on CT. The presence of imaging from the original presentation of appendicitis was also noted, if available. As the review encompassed a long span of time and several imaging sites, the equipment and technique varied. In the patients with confirmed stump appendicitis, 4- and 64-slice MDCT scanners were utilized (Philips, Amsterdam, Netherlands, and General Electric, Fairfield, CT). Axial slice thickness ranged from 3.75 to 5 mm. Iodinated intravenous contrast, iopamidol 61 %, was administered in four patients
(Isovue 300; Bracco Diagnostics, Princeton, NJ), and two patients were imaged without intravenous contrast due to renal insufficiency. All patients received positive oral contrast.
Results The initial radiologic and pathologic search revealed 16 potential cases of stump appendicitis at our institution. Review of the imaging and surgical and pathology notes narrowed this to six pathologically confirmed cases. The six pathologically confirmed cases were taken to surgery (five laparoscopic, one laparoscopic converted to open) with surgically identified and pathology-proven stump appendicitis. The ten remaining cases consisted of five clinically suspected cases of stump appendicitis that were treated medically and five cases that had alternative diagnoses ultimately established as, but initially both clinically and radiographically mimic, stump appendicitis. The five clinically suspected cases were treated successfully with antibiotic therapy in three patients and combination of antibiotic therapy and pericecal abscess drainage in
Fig. 1 Coronal CT of classic acute appendicitis with a dilated, fluid-filled appendix (arrow) and adjacent inflammatory stranding
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Fig. 2 Coronal CT of a non-inflamed appendiceal stump (arrow) in a post-appendectomy patient
Fig. 3 Non-inflamed appendiceal remnant (arrow) on axial (a) and coronal (b) images in a patient who was 9 days postappendectomy. The patient returned 2 months postappendectomy with stump appendicitis. In addition to appendiceal dilatation and inflammatory stranding, there were mass effect and edema on the adjacent cecum, the arrows seen on axial (c) and coronal (d) images
the two remaining patients. As there was no pathologic confirmation, these cases were not included in our data set. The alternative diagnoses of the five patients included surgical drain tract fluid collection, cecal adenocarcinoma, ileitis, ovarian and para-tubal endometriosis, and tubo-ovarian abscess. The six pathologically confirmed cases (Table 1) presented on average 14.8 months after original appendectomy (range 3–37 months) had an average surgical specimen appendiceal stump length of 3.5 cm (range 2.0–5 cm) and an average appendiceal diameter measured perpendicular to the long axis of the appendix on the CT scan of 12.3 mm (range 10– 16 mm). All six cases demonstrated the presence of periappendiceal inflammatory fat stranding on the CT scan. None of the pathologically confirmed cases had a significant pre- or post-surgical complication. Five of six pathologically proven cases underwent initial laparoscopic appendectomy at the time of the original presentation of acute appendicitis. One case had an unknown method of appendectomy at an outside institution. Only one case had a reported complicated initial appendectomy, with a post-surgical perirectal abscess requiring percutaneous drain placement.
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Fig. 4 Axial CT of a fluid-filled drain tract (arrow) mimics stump appendicitis. The appendiceal remnant was identified as a separate structure slightly inferior to this location
Discussion The appendix typically arises from the posterior-medial wall of the cecum 3 cm distal to the ileocecal valve. Surgically, the appendix is identified by tracking the convergence of three taenia coli. Alternatively, dissection and ligation of the recurrent branch of the appendiceal artery can be used to identify the appendix [3, 4]. There are anatomic and surgical technique factors which may lead to inadequate visualization of the base of the appendix. These include retrocecal location of the appendix, severe inflammation, difficult anatomic dissection, or surrounding phlegmon [2]. Surgical technique has not been definitively shown to be causative in the development of stump appendicitis; however, the literature leans toward a higher incidence of stump appendicitis following open rather than laparoscopic appendectomy. The majority of cases reviewed by Subramanian et al. demonstrated initial open appendectomies in almost 66 % of the reviewed cases [2]. Various surgical strategies of dealing with the appendiceal stump including stump ligation and stump inversion have not proven successful at eliminating stump appendicitis [6].
Fig. 5 Axial CT of a blind-ending inflamed sinus tract (arrow) in Crohn’s disease mimics an inflamed appendiceal remnant in this patient who has had prior appendectomy
Fig. 6 Axial CT of an oval inflamed epiploic appendage (arrow) appears similar to remnant appendicitis in this patient with epiploic appendagitis
Liang et al. [4] considered inadequate visualization of the appendiceal base as the strongest contributing factor in the development of stump appendicitis. This conclusion is supported in the available literature and, further in this study, with remnant appendiceal stump length >2 cm in our pathologically proven cases. The surgical literature generally recommends leaving a stump measuring 6 mm, presence of adjacent inflammatory fat stranding, appendiceal
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wall thickening, and additional findings of appendiceal inflammation such as edema or mass effect at the base of the cecum (“arrowhead sign”). Sonographic findings of stump appendicitis are limited to two patients from a case report and a patient series [11]. Both demonstrate a noncompressible right lower quadrant tubular structure with a luminal diameter >6 mm. A review of our radiology archives revealed cases with imaging findings suggestive of stump appendicitis, but following additional clinical evaluation, they were found to be radiologic mimics. Of the five alternative diagnoses, one case was somewhat unique and merits further discussion: surgical drain tract fluid collection. This patient underwent laparoscopic-guided appendectomy at an outside institution. Outside medical documents noted an immediate post-surgical complication of abscess requiring a percutaneous drain placement. Upon presentation to our institution, 5 months postappendectomy, the patient’s history was significant for 2-weeks of intermittent mild right-sided flank pain, fever, and tachycardia. CT with intravenous and oral contrast was interpreted as potential stump appendicitis given a fluid-filled structure arising off of the cecum (Fig. 4) in the setting of prior appendectomy. The clinical team, with the knowledge of prior drain placement, concluded that the findings were consistent with the prior drain tract. The patient was treated with antibiotics and symptoms resolved. A second review of the images did demonstrate findings that were not consistent with stump appendicitis. The tubular structure origin was approximately 5 cm (cranial) proximal to the appendectomy sutures. All cases of stump appendicitis should arise from the cecum, and the stump should terminate at the level of the sutures, if the sutures are visible on CT. Reviewing coronal and sagittal images can be a useful tool in evaluating the origin of the abnormality. The remaining cases in our review that had an imaging appearance suggestive of stump appendicitis ultimately had diagnoses of cecal adenocarcinoma, ileitis, ovarian and paratubal endometriosis, and tubo-ovarian abscess. Not surprisingly, these same diagnoses can cause diagnostic confusion in the diagnosis of conventional appendicitis at presentation. The shared findings of a right lower quadrant process that involves stranding in the fat may lead to misdiagnosis. In our experience, additional alternative diagnoses that potentially may appear similar to stump appendicitis are the typical causes of right lower quadrant pain that a radiologist may encounter on imaging performed for conventional appendicitis [13, 14]. We illustrate some of these more common mimics including Crohn’s disease (Fig. 5) and epiploic appendagitis (Fig. 6) but also include tubo-ovarian abscess, cecal diverticulitis, cecal neoplasm, and endometriosis as other diseases which share imaging features of our mimics and stump appendicitis.
While awareness should be heightened in the setting of right lower quadrant symptoms in a post-appendectomy patient, stump appendicitis is only one among many different diagnoses that can have overlapping CT findings. By utilizing the criteria of a blind-ending tubular structure arising off of the cecal tip that is greater than 6 mm in diameter with adjacent inflammatory changes in the periappendiceal fat, the majority of alternative diagnoses will not commonly cause a diagnostic dilemma.
Conclusion The clinician and radiologist should have a heightened sense of awareness of all potential diagnoses when they are presented with a post-appendectomy patient presenting with right lower quadrant pain. Stump appendicitis shares imaging characteristics with conventional appendicitis. The use of the criteria commonly used to diagnose typical appendicitis will successfully allow the radiologist to accurately diagnose stump appendicitis. Early recognition and treatment of stump appendicitis is critical to prevent delay in diagnosis and avoid complications.
Conflict of interest The authors declare that they have no conflict of interest.
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