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Journal of Medical Cases

Case Report

Volume 6, Number 9, September 2015, pages 430-432

Retroperitoneal, Abdominal, and Pelvic Abscess in Appendicitis: The Limitation of Diagnostic Modalities

Acute appendicitis with an underlying presentation of peritonitis and abscess can result in prolonged hospital stay and duration of treatment. Such complications need to be reinforced in order to prevent further adverse effects. Intra-abdominal abscesses have been shown to complicate many illnesses, some of which include appendicitis, pancreatitis, diverticulitis, and may even present during a postoperative time period. However, retroperitoneal abscess can also develop and as it is uncommon, it may be missed both during imaging and surgery. The mortality associated with undiagnosed and untreated abscesses is relatively high and thus must be taken into consideration when treating appendicitis, especially when associated with peritonitis. Although physicians can diagnose abscesses with the use of ultrasonography or computed tomography (CT) scan, as seen in this case report, this is not always the case and thus needs to remain within a physician’s differential when managing appendicitis. At times, it can also be associated with retroperitoneal and pelvic abscesses which may go overlooked and worsen a patient’s clinical outcome especially when not diagnosed preoperatively.

A 62-year-old female with no significant past medical history other than morbid obesity presented to the emergency department with complaints of abdominal pain. The patient stated that the abdominal pain was of sudden onset and began 4 days prior. She did not initially see a physician until the pain got progressively worse leading to several episodes of non-bloody, non-bilious vomiting. The pain started in the right lower quadrant and subsequently turned into diffuse abdominal pain. Patient denied any symptoms of fevers, chills, diarrhea, constipation, or any other associated aggravating or alleviating symptoms.

Vital signs on presentation showed a blood pressure of 128/60 mm Hg, pulse of 90/min, respiratory rate of 18/min, and temperature of 99.8 °F. Pertinent findings on physical examination showed a diffuse mild abdominal tenderness with a localized point of significant tenderness in the right lower quadrant. Bowel sounds were present and there were no signs of abdominal distention. Initial laboratory data demonstrated a white blood cell count of 17.1 × 10³/μL, hemoglobin of 14.8 g/dL, hematocrit of 45%, and platelets of 363 × 10³/μL. Na was 129 mmol/L, potassium was 3.5 mmol/L, chloride was 87 mmol/L, bicarbonate was 27 mmol/L, blood urea nitrogen was 39 mg/dL, creatinine was 1.3 mg/dL, and glucose was 153 mg/dL. Other findings showed an amylase of 12 U/L, lipase of 10 U/L, alkaline phosphatase of 137 U/L, aspartate transaminase of 19 U/L, alanine transaminase of 28 U/L, and total bilirubin of 0.8 mg/dL.

CT urogram (Fig. 1) demonstrated an appendix measuring 1.5 cm in caliber with demonstration of a 7-mm appendicolith. There was subtle associated pericecal and periappendiceal mesenteric stranding. The findings were most compatible with acute appendicitis. Additionally there was approximately a 10-cm rounded structure within the pelvis compressing the bladder. As origin of this structure could not be delineated, a CT scan with contrast was performed. Abdomen-pelvis CT with contrast was significant for similar findings (Fig. 2) compatible with acute appendicitis. Additionally there were scattered areas of ascites throughout the mesenteric leaflets with adjacent mesenteric stranding suggestive of peritonitis. There was an area of loculated ascites within the pelvis with the largest area of loculation measuring 7.6 × 4.5 cm causing a mass effect on the bladder.

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Figure 1. CT urogram demonstrating signs of appendicitis.

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Figure 2. CT abdomen showing dilated signs of significant ascites.

Patient was evaluated and taken to the operating room by surgery. Initially laparoscopic techniques were attempted which revealed multiple areas of abdominal abscesses including retroperitoneal abscesses and as the small intestine was grossly distended from an obvious ileus from the peritonitis, exploratory laparotomy was initiated. The patient’s abdominal cavity revealed small intestinal loops, which were grossly attached to each other from peritonitis. There was additionally the presence of two separate large pelvic abscesses, which required irrigation and drainage. The grossly necrotic appendix was gradually dissected using a Harmonic scalpel and appeared to be gangrenous and was clearly perforated at the time. Fecalith was also found to be within the appendix. The abdominal cavity was heavily irrigated with 10 L of sterile normal saline. Fibrinous peal was removed from the patient’s intestine. A flat 10 French Jackson-Pratt drain was left in place in order to prevent further abscess formations.

Postoperatively, the patient experienced some respiratory distress and was monitored in the intensive care unit on BiPap. She improved over the course of several days with the use of zosyn and flagyl which was later adjusted to ceftriaxone as peritoneal cultures grew Escherichia coli.

Diagnostic imaging as described above is not always a reliable method in demonstrating underlying complications associated with appendicitis. Through this discussion we will analyze the importance for a physician to be aware of these findings including but not limited to the various locations of abscesses, peritonitis, and the risks that may be associated with these complications if they go overlooked. Acute appendicitis is a relatively common condition and carries a low morbidity and mortality rate through the use of effective diagnosis and management [1, 2]. In most cases of appendicitis which are non-perforated, they can be treated with urgent appendectomy. However, in cases where there is perforated appendicitis, there may be a formation of abscess, commonly in the right iliac fossa or in the pelvic cavity, which is either treated by early appendectomy or appendectomy followed by percutaneous drainage [3, 4].

Development of retroperitoneal abscess is of the rarer and serious complications associated with the perforation of retrocecal appendix, normally due to its delayed diagnosis and treatment [3, 5, 6]. In our case, the patient was found to have several sites of both abdominal including retroperitoneal and pelvic abscesses. Due to the urgent laparotomy, fortunately complication of the retroperitoneal abscesses was limited as it was evidently discovered. However few reports in the literature have demonstrated cases of appendicitis complicated by retroperitoneal abscesses resulting in emphysema in psoas and thigh which can be highly detrimental to a patient’s condition [3, 5-7].

CT scan is the most common used imaging modality for the diagnosis of appendicitis. In the literature, it has been shown to be highly effective in demonstrating the formation of abscesses in patients with appendicitis. However, in our case abdominal abscesses were not noted on CT, as they may have been hidden by overlying signs of ascites and peritonitis. CT scan normally helps in the diagnosis and can help with surgical planning. If abscess is demonstrated, the plan for drainage can be determined and thus conducted either percutaneously via a retroperitoneal approach or by laparotomy. Moreover, our case illustrates that CT imaging can have its limitations which can impact a patient’s outcome and surgical approach.

Only about 2-7% of patients with appendicitis manifest with complex features such as abscesses; however, if not managed appropriately it can result in potential septic shock [8]. Progression of a retroperitoneal abscess from a perforated appendicitis is unusual and difficult to diagnose as it may lack classical symptoms of acute appendicitis at the onset of the condition and normally may not be associated with peritonitis, thus final diagnosis may only be achieved during surgery [9]. Our patient, although was discovered to have retroperitoneal abscesses also had co-presentation of peritonitis associated with abdominal and pelvic abscesses. Ultrasound has been used previously as it is highly available and inexpensive but it requires a high level of technical expertise. CT scan on the other hand is very accurate and also non-invasive. Imaging modalities such as a multidetector CT (MDCT) may be found to be more efficient in determining underlying complications of appendicitis. In a retrospective study of 244 patients with MDCT scan analysis demonstrated that abscess (99%), extraluminal gas (98%), and ileus (93%) had the high specificities; however, their sensitivities were low (34%, 35%, and 53%) and thus relying on these features may result in missed perforation in half of these patients [9]. In another study of 94 patients, the presence of either extraluminal gas, abscess, phlegmon, extraluminal appendiculolith, or appendicular wall enhancement defect was 96.4% sensitive and 100% specific for perforated appendicitis [9]. Although, these findings suggest perforated appendicitis, the reverse rationale may not apply. Appendicitis often seen on CT scan may or may not be associated with various locations of abscess formations.

Research and retrospective studies have yet to demonstrate the sensitivity and specificity of CT imaging in locating retroperitoneal and abdominal abscesses found in patients during surgical exploration but not via diagnostic imaging. Thus, physicians need to be aware that although CT imaging may not demonstrate these findings, during appendectomy especially of a perforated appendix, a proper examination needs to be conducted to rule out underlying abscess collections.

Grant Support

None.

Financial Disclosures

None.

Conflict of Interest

This is to state that there has been no activity or involvements that will raise the question of bias in this case report or any of the conclusions or opinions that it stands for.

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Journal of Medical Cases is published by Elmer Press Inc.