Perforated Appendicitis
Emmanuel Abiola Babington1*
1University Hospitals of Leicester NHS Trust, Leicester, UK
*Correspondence to: Emmanuel Abiola Babington, Masters of Science, Sonographer, University Hospitals of Leicester NHS Trust, Infirmary Square, Leicester, Leicestershire LE1 5WW, UK; Email: Emmanuel.babington@uhl-tr.nhs.uk
Abstract
Background: Globally, nearly 100 in 100,000 adults develop appendicitis every year. When the wall of the inflamed appendix gets compromised, this leads to perforation, abscess, and peritonitis, which if left unmanaged can cause sepsis and potentially death.
The Case: This is a case of a 51-year old male that presented to the Surgical Triage Unit with right lower quadrant pain ongoing for four days, and some intermittent sharp pain. Ultrasound revealed an inflamed appendix in the right iliac fossa measuring 18mm in AP dimension with an irregular wall outline, loss of wall stratification, and a heterogeneous luminal content. Furthermore, a small amount of fluid was seen close to the compromised wall of the appendix near its fundal tip in keeping with complicated appendicitis with possible perforation. Computed tomography (CT) revealed a dilated and fluid-filled appendix measuring 17mm in AP dimension with a tiny appendicolith at the tip of the appendix. However, there was no evidence of free gas or periappendiceal abscess seen on CT to suggest perforation. The patient underwent laparoscopic appendectomy the following day and this revealed perforated appendicitis (PAp) with four quadrants peritonitis. Histopathology revealed a transmural acute inflammation with an overlying serosal reaction, ulcerated epithelium, and loss of the muscularis propria layer.
Conclusion: This case report highlights the features of PAp seen on ultrasound imaging and also discusses the role of ultrasound, CT, and haematology in the diagnosis of PAp based on recent works of literature.
Keywords: appendicolith, bowel ultrasound, complicated appendicitis, gangrenous appendicitis, gastrointestinal imaging
1 INTRODUCTION
Globally, nearly 100 in 100,000 adults develop appendicitis every year[1]. Appendicitis is the inflammation of the appendix, which usually presents as an acute onset of periumbilical pain that gradually migrates to the right iliac fossa (RIF)[1]. The aetiology of appendicitis can be due to lymphoid hyperplasia or obstruction of the lumen by an aggregated calcified faecal material (appendicolith) or an appendiceal mass, this leads to lymphoid and venous congestion within the appendix, hence the inflammation, which spreads through the layers of the appendiceal wall, hence appendicitis[2]. There is a raised clinical suspicion of appendicitis when a patient presents with a combination of an acute onset of RIF pain/tenderness with an elevated white cell count (WCC) above 11 and C-reactive protein (CRP) above 10, the suspicion is usually confirmed or ruled out by imaging[2].
Appendicitis is categorised into uncomplicated and complicated, which are now known to be two separate entities, meaning that one does not lead to another[3]. While uncomplicated appendicitis can sometimes be treated using antibiotic therapy since the wall of the appendix is not compromised, complicated appendicitis on the other hand requires immediate surgical intervention[4]. When the wall of the inflamed appendix gets compromised, this leads to perforation, abscess, and peritonitis, which if left unmanaged can cause sepsis and potentially death[5]. This case report aims to present some of the ultrasound appearances seen in perforated appendicitis (PAp) and to review some of the relevant literature available on the imaging of PAp and its accompanying complications.
2 THE CASE
This is a case of a 51-year-old male that presented to the Surgical Triage Unit with right lower quadrant pain ongoing for four days, and some intermittent sharp pain. His symptoms started in the RIF and over time became periumbilical; he was very tender on physical examination with some evidence of guarding. Blood results revealed a CRP of 27mg/L (normal=0-10) and WCC of 11×109/L (normal=4.0-11). Ultrasound was requested to rule out appendicitis, with a possible contrast computed tomography (CT) if ultrasound findings are equivocal.
Using a GE Logiq E10s ultrasound equipment, the entire abdomen and pelvis was examined, first with a C1-6 curvilinear multi-frequency transducer initially at a frequency of 4.5MHz, then 3MHz to examine the deeper abdominal structures. The transducer frequency was later increased to 6MHz for the bowel examination, done by gradual sweeping in a ‘lawn mowing’ fashion from the LIF in the region of the sigmoid colon to the RIF at the point of the appendix. Afterwards, the transducer was switched to a 9L (9MHz) linear array transducer for a more detailed assessment of the bowel structures and to further interrogate the abnormal appendix that was visualised using the curvilinear transducer (Figure 1A).
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Figure 1. Ultrasound images. A: Longitudinal sonogram of the inflamed appendix in the RIF obtained using a 6.5MHz curvilinear transducer; B: Longitudinal sonogram of the inflamed appendix with measurement callipers at the outer walls (from serosa to serosa) of the appendix, measuring 18mm in AP dimension. The image was obtained using a 9MHz linear transducer; C: Longitudinal sonogram of the inflamed appendix with a small area of fluid (FF) tracking from the posterior surface of the appendix (arrows), close to its fundal tip; D: Sonogram showing the body and base of the inflamed appendix in longitudinal orientation.
Ultrasound revealed an inflamed appendix in the RIF measuring 18mm in AP dimension with an irregular wall outline, loss of wall stratification and heterogeneous luminal content. Other findings on ultrasound include a significant amount of mesenteric oedema in the adjacent RIF, evidence of increased vascularity around the appendix, and a mildly thick-walled adjacent bowel loop likely secondary to the inflamed appendix. Furthermore, a small amount of fluid was seen close to the compromised wall of the appendix near its fundal tip. The sonographer concluded that the ultrasound appearances are in keeping with complicated appendicitis with possible perforation.
Due to the suspicion of perforation raised on ultrasound, a CT examination was requested for better imaging assessment. Eight hours after the ultrasound examination, a volumetric CT acquisition of the abdomen and pelvis was performed with the administration of an intravenous contrast agent. This revealed a dilated and fluid-filled appendix measuring 17mm in AP dimension with a tiny appendicolith at the tip of the appendix. Also, a significant peri-appendiceal inflammatory stranding was seen as well as some free fluid within the RIF. However, there was no evidence of free gas or peri-appendiceal abscess seen on CT to suggest perforation. Moreover, there was mural thickening of the terminal ileum on CT which was reported to be likely reactive and secondary to the inflamed appendix.
The patient underwent a laparoscopic appendectomy the following day and this revealed PAp with four quadrants peritonitis. The surgically removed appendix appeared distorted and necrotic. Microscopic histopathological assessment of the excised appendix revealed a transmural acute inflammation with an overlying serosal reaction, ulcerated epithelium, and loss of the muscularis propria layer. The appearances were concluded to be that of acute gangrenous appendicitis with features in keeping with perforation.
During recovery, the patient developed rising CRP levels at 297mg/L (normal=0-10) one-day post-op and it slowly dropped over the next three days of recovery. The patient also developed acute kidney injury with an abnormal Creatinine result of 51umol/L (normal=60-120) during the time of recovery. These all soon settled after treatment and the patient was discharged with further uneventful recovery.
3 DISCUSSION
The complete preoperative diagnosis of PAp is of significant clinical importance as its management differs from that of uncomplicated appendicitis[5]. While patients that had surgery for uncomplicated appendicitis tend to attain quick recovery, usually within one or two days post-op, with limited chances of complications, particularly after having a laparoscopic appendectomy, some studies have shown that most PAp patients will have longer hospital stay and increased possibility of post-op complications[6]. Age has been reported to be directly linked to the severity of appendicitis complications[7], as one study[8] showed that patients above 50 years old have higher risks of appendicitis complications, including perforation, abscess formation, and malignancy. In another retrospective study[4] of 1316 patients that underwent appendectomy, 83 of the 193 patients that had PAp were above 50 years old. This is in agreement with this case, as our patient was 51 years old and therefore considered to fall within the high-risk group for PAp.
Haematologically, WCC and CRP levels are the two most important parameters considered when there is a raised clinical suspicion of PAp[9]. In 2019, Withers et al.[10] conducted a retrospective study using the records of 763 patients that underwent appendectomy; they found that elevated CRP alone has a high sensitivity of 95.4% and low specificity of 24.5% than WCC with a sensitivity of 69.6% and specificity of 43.1% in the detection of PAp, furthermore, a combination of an elevated CRP and WCC in a patient raised the sensitivity to 97.47%. These findings were in agreement with a retrospective study by Worm et al.[11] where it was found that CRP has a higher supremacy over WCC in the clinical detection of PAp. Most studies put the cut-off point for CRP evidence of PAp at ≥100mg/L[11], in this case report, though the WCC value was only 11×109/L, the CRP was elevated at 27mg/L then progressed to 297mg/L one day post-op. This further highlights the importance of imaging in obtaining an accurate diagnosis, as the CRP value obtained before the ultrasound was only slightly raised.
CT is known to be the gold standard in the diagnosis of appendicitis with high sensitivity and specificity of 91-94% and 90-94% respectively, and is mostly accessible to emergency departments, particularly in the UK and many western countries, however, the use of ionising radiation and contrast administration are its major drawbacks[12]. Ultrasound does not use ionising radiation but high-frequency sound waves and is readily available, therefore has gained popularity as the first line of imaging in patients with clinically suspected appendicitis[12,13]. Although, Ultrasound has a lower sensitivity (69-83%) and specificity (81-93%) compared to CT and is very dependent on the skill and experience of its operator, due to the increased training and significant technological advancement, the diagnostic capability of ultrasound has greatly improved over the years and many patients are now able to have a more precise diagnosis on ultrasound with detailed appearances of the disease and possible complications[13].
On ultrasound, the normal appendix, like the rest of the bowel has five concentric layers, called wall stratification/layering, with alternating hyper-hypo echogenicity, namely the outer serosa, muscularis propria, submucosa, mucosa, and the inner mucosa interface, which can all be visible using a high-frequency linear transducer[14]. In this case report, the appendix was seen on ultrasound to have lost its normal wall stratification (Figure 1A-D) with a lack of distinction of the expected individual wall layers. This feature was congruent with the findings on histology which revealed evidence of transmural inflammation with overlying serosal reaction and loss of the muscularis propria layer (seen in The Case section). There also appears to be a small area of fluid seen in communication with the posterior surface of the appendix adjacent to the fundal tip (Figure 1C), this appearance on ultrasound significantly raised the suspicion of perforation as the said fluid appears to be tracking from the posterior surface of the appendix. Unfortunately, at the time of writing this case report, the exact location of the perforation on the excised appendix could not be confirmed in the available information compiled in this report. Another important feature visualised on this patient’s ultrasound images was the presence of significant oedema in the adjacent mesentery within the RIF, this appears as the areas of increased/bright echogenicity (hyperechoic) surrounding the inflamed hypoechoic appendix (Figure 2A), with evidence of increased vascularity around the appendix (Figure 2B), and CT evidence of as peri-appendiceal inflammatory stranding (Figure 3A-C).
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Figure 2. Transverse sonogram. A: Transverse sonogram of the inflamed appendix (arrow), also showing the echogenic areas of mesenteric oedema (marked stars) around it; B: Transverse sonogram of the inflamed appendix with colour Doppler showing evidence of increased vascularity in the inflamed appendix.
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Figure 3. CT scan. A: Axial CT slice of the inflamed appendix; B: Coronal CT slice of the inflamed appendix (three arrows) showing the tiny appendicolith at its fundal tip; C: Sagittal CT slice of the inflamed appendix (arrow).
A normal appendix on ultrasound is expected to be a blind-ending, tubular, non-peristaltic bowel structure mostly seen in the RIF adjacent to the caecum and terminal ileum, measuring <6mm in AP dimension with almost no signal evidence on colour Doppler interrogation i.e. limited ultrasound evidence of vascularity[14]. In this case report however, the appendix measured 18mm in AP dimension (Figure 1B) with some vascularity evidently seen around it, and it contained heterogeneous cystic components within its lumen which were seen as fluid on CT. A tiny appendicolith was visualised on CT (Figure 3B) but not on ultrasound where it could have been obscured by the heterogeneous cystic luminal component. The presence of an appendicolith within the appendix on imaging does not denote inflammation, as appendicoliths have been reported in normal appendices[15]. Nonetheless, appendicoliths triggering an obstruction of the appendix lumen have been reported to cause increased failure rates of non-operative management of appendicitis[1]. However, in this case, the appendicolith seen on CT is tiny and therefore unlikely to have caused the luminal obstruction and inflammation.
PAp is suspected on CT when there is a combination of an inflamed appendix measuring ≥7mm in AP dimension, with the presence of appendiceal wall defect, periappendiceal fluid, intra- or extraluminal appendicolith, extraluminal gas, inflammatory response in the adjacent bowel, and peritoneal thickening/hyperenhancement (peritonitis)[16]. However, the absence of some of these signs have been reported to not be completely reliable, as there have been cases of CT-diagnosed uncomplicated appendicitis that turned out to be PAp at the time of surgery[1,2]. For instance, in one study[17] of 837 patients with preoperative CT diagnosis of uncomplicated appendicitis, at surgery, 187 (22.3%) of the patients had evidence of perforation and/or abscess formation. In addition, delays from the presentation of symptoms to the time of surgery have a progressive increasing impact on the possibility of perforation of an inflamed appendix to occur, thus of detrimental effect on patient care[2,17]. Therefore, a multi-imaging approach to the diagnosis of PAp is not always advisable, particularly when the first line of imaging, in this case, ultrasound provided useful diagnostic information.
4 CONCLUSION
This is a case report of a 51-year old male with a four-day history of RIF pain, ultrasound done suggested the evidence of complicated appendicitis with possible perforation owing to the loss of the appendiceal wall stratification and some periappendiceal fluid seen tracking from its posterior surface. PAp was later confirmed in surgery and microscopic histopathology. Although the preoperative CT done in this case did not reveal evidence of perforation on the significantly inflamed appendix, CT remains the gold standard in the evaluation of appendicitis due to its higher sensitivity and specificity over ultrasound. This case report highlights the features of PAp seen on ultrasound imaging and also discusses some of the roles of ultrasound, CT, and haematology in the diagnosis of PAp based on recent works of literature.
All relevant permissions were granted prior to the usage of these anonymised images. Author has no relevant conflict of interest to declare.
Acknowledgements
The author thanks D.L Sander for their useful support. The author also thanks the publisher and their editorial team for their useful feedback on this manuscript.
Conflicts of Interest
The author declared no conflict of interest.
Author Contribution
Babington EA contributed to the manuscript and approved the final version.
Supplementary Data and Availability of Data
All relevant permissions were granted prior to the usage of these anonymised images. This is in line with our hospital protocol and the Royal College of Radiologists (RCR) ‘Guidance on the use of patient images obtained as part of standard care for teaching, training and research’.
Abbreviation List
RIF, Right iliac fossa
CRP, C-reactive protein
WCC, White cell count
PAp, Perforated appendicitis
CT, Computed tomography
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