|Year : 2014 | Volume
| Issue : 2 | Page : 166-169
Intra-abdominal pressure: A simple, yet reliable indicator for the diagnosis and prognosis of appendicitis
Raghuveer Reddy, Gurjit Singh
Department of General Surgery, Padmashree Dr. D. Y. Patil Medical College, Hospital and Research Centre, Dr. D. Y. Patil Vidyapeeth, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||4-Feb-2014|
Department of Surgery, Padmashree Dr. D.Y. Patil Medical College, Sant Tukaram Nagar, Pimpri, Pune - 411 018, Maharashtra
Source of Support: None, Conflict of Interest: None
Introduction: Appendicitis is one of the more common surgical emergencies and it is one of the most common causes of an acute abdomen. Left untreated, appendicitis has the potential for severe complications. Despite initial optimism, it has become apparent that in most units the normal appendix rate remains 15-30%. In view of this scenario, this study was undertaken to assess the role of intra-abdominal pressure (IAP) in the diagnosis and prognosis of acute appendicitis. Materials and Methods: A total of 200 patients with initial diagnosis of appendicitis were evaluated. Patients were grouped according to the final diagnoses as appendicitis (acute and acute on chronic), perforated appendicitis and negative exploration for appendicitis. A simple fluid column manometry system through the Foley's catheter is used to measure the IAP. Results: Out of a total of 200 cases 104 were female and 96 were male in the age range of 7-74 years. A normal appendix was found in 18 patients and 124 patients had appendicitis. A total of 58 cases were of appendicular perforation. The mean pre-operative values of IAP for cases of normal appendix, appendicitis and appendicular perforation were 3 ± 0.4, 8.2 ± 0.4 and 9.6 ± 0.3 respectively (P < 0.001). Post-operative 1 st day and 2 nd day values of the IAP for appendicitis, perforated appendicitis and normal appendix groups were 3 ± 0.2 and 1.0 ± 0.1, 4.2 ± 0.1 and 1.5 ± 0.1, 0.8 ± 0.6 and 0.5 ± 0.6 cm H 2 O respectively. Conclusion: IAP increases among patients with appendicitis and a further increase is encountered among patients with perforated appendicitis. Therefore, addition of this parameter to support the clinical diagnosis of acute appendicitis and perforative appendicitis is advocated specially in a rural setting. However, randomized controlled trials are required to support our findings.
Keywords: Appendicitis, bladder pressure, intra-abdominal pressure
|How to cite this article:|
Reddy R, Singh G. Intra-abdominal pressure: A simple, yet reliable indicator for the diagnosis and prognosis of appendicitis. Med J DY Patil Univ 2014;7:166-9
| Introduction|| |
Appendicitis is one of the more common surgical emergencies and it is one of the most common causes of an acute abdomen. Sir Zachary Cope wrote "Diagnosis of appendicitis is usually easy, but, there are difficulties, which need to be discussed."  Despite diagnostic and therapeutic advancement in medicine, appendicitis remains a clinical emergency. Left untreated, appendicitis has the potential for severe complications, including perforation or sepsis and may even cause death.
The diagnosis of appendicitis is clinical and essentially is based on history and clinical examination findings. The classic form of appendicitis may be promptly diagnosed and treated. When appendicitis appears with atypical presentations, it remains a clinical challenge. The differential diagnosis of appendicitis is often a clinical challenge because appendicitis can mimic several abdominal conditions. Statistics report that 1 of 5 cases of appendicitis are misdiagnosed; however, a normal appendix is found in 15-40% of patients who have an emergency appendectomy. Over the years, various clinical scoring systems (some computer assisted) have been used and although their clinical benefit has varied, most reports describe some improvement in clinical performance with their use at least for the duration of the study. Despite initial optimism, it has become apparent that in most units the normal appendix rate remains 15-30%.  In view of this scenario, this study was undertaken to assess the role of intra-abdominal pressure (IAP) in the diagnosis and prognosis of acute appendicitis.
| Materials and Methods|| |
A total of 224 patients with initial diagnosis of appendicitis were evaluated. The Institutional Ethics Committee approval was taken before the commencement of the study and a written informed consent was taken from all patients. Patients with a modified Alvarado score of more than 7 were taken up for surgical intervention and the rest were treated conservatively and considered in a "suspected appendicitis group" (total of 24 patients), which was not further considered in this study. In addition to the routine pre-operative hematological and ultrasonographic (USG) work-up, IAP of each patient was determined pre-operatively and then on the post-operative 1 st , 2 nd and 3 rd days.
Patients were grouped according to the final diagnoses as appendicitis, perforated appendicitis or negative exploration for appendicitis. The pre-operative and post-operative IAPs of the patients were compared among the groups. Post-operative complications were recorded and IAPs of those patients were additionally compared with others in the same group.
A simple fluid column manometry system via the Foley's catheter is used to measure the IAP. The drainage tubing is marked with a silk tape along its length and the Foley's catheter is marked as '0', 5 mm proximal to the Y-junction, which serves as the zero reference point when it is at the level of the symphysis pubis. The drainage tubing is marked at an increment of 1 cm on the tape, starting from the mark on Foley's catheter as zero and then 50 ml of sterile saline is introduced into the bladder.
After reconnecting the Foley's catheter to the drainage tubing, the zero reference point is taken at the level of the symphysis pubis and the drainage tubing is raised vertically making sure that the transition from horizontal to vertical is at "0" mark and is not too abrupt. The distance the sterile saline raises vertically in the tubing is the intra-abdominal pressure in cm of H 2 O.
The normal range of bladder pressure is taken as 0 or slightly sub atmospheric. 
White blood cell (WBC) count >10,000/mm 3 was accepted as leukocytosis. Primary criterion for diagnosing appendicitis by USG was evidence of a non-compressible appendix and a measured diameter of greater than 7 mm. Other criteria were echogenic periappendiceal fat and periappendiceal fluid collection. Criteria of histological acute appendicitis were accepted as infiltration of the muscularis propria with polymorphonuclear cells. Pathology results as appendix vermicularis-without any additional finding were accepted as negative appendectomy.
All statistical analysis were performed using the Statistical Package for the Social Sciences (SPSS Inc., 233 South Wacker Drive, 11 th Floor, Chicago, IL60606-6412. Patent No. 7,023,453) for Windows (version 15·0). P values less than 0.05 were accepted as significant. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated. The receiver-operating characteristic (ROC) curve was prepared for the elevated total WBC count, elevated temperature and elevated IAP.
| Results|| |
On a total of 200 cases 104 were female and 96 were male in the age range of 7-74 years. A normal appendix was found in 18 patients and 124 patients had acute appendicitis. A total of 58 cases were of appendicular perforation. The mean pre-operative values of IAP for cases of normal appendix, acute appendicitis and appendicular perforation were 3 ± 0.4, 8.2 ± 0.4 and 9.6 ± 0.3 respectively (P < 0.001).
Post-operative 1 st day and 2 nd day values of the IAP for acute appendicitis, perforated appendicitis and normal appendix groups were 3 ± 0.2 and 1.0 ± 0.1, 4.2 ± 0.1 and 1.5 ± 0.1, 0.8 ± 0.6 and 0.5 ± 0.6 cm H 2 O, respectively.
The difference between acute and perforated appendicitis groups was significant (P < 0.05). Surgical site infection was noted in 15 of the 58 cases of appendicular perforation and 4 of the 124 cases of acute appendicitis.
The pre-operative and first post-operative day IAP values of patients with perforated appendicitis and acute appendicitis who experienced a wound infection were 12.8 ± 0.4 and 4.8 ± 0.2 and 9.6 ± 0.2 and 3.1 ± 0.3 cm H 2 O (P < 0.001).
In this study group of patients, a total WBC count >10,000 cells/mm 3 had a sensitivity of 74% and specificity of 51%. The PPV was 40% and the NPV was 78%.
A temperature >99.0°F had a sensitivity of 47% and specificity of 64%. The PPV was 37% and the NPV was 72%.
IAP <3 cm of H 2 O has excluded appendicitis with a 95% confidence interval.
The areas under the curve for ROC curve were 0.72 and 0.59 for an elevated total WBC count and an elevated temperature, respectively.
| Discussion|| |
Appendicitis is a very common disease with a lifetime occurrence of 7%.  Traditionally, appendicitis has been a clinical diagnosis with the adjuvant aid of leucocytosis and USG both to confirm and to rule out other abdominal pathologies. In spite of these adjuvant aids the negative appendicectomy rate is as high as 15-30%. 
In a study by Cardall, et al. of 293 patients presenting to the emergency department in whom the diagnosis of appendicitis was the attending physician's primary consideration a total WBC count >10,000 cells/mm 3 had a sensitivity of 76% and specificity of 52%.  In the same study, the PPV was 42% and the NPV was 82%.  These results are very similar to the results of our study.
In a study by Douglas, et al. the use of a diagnostic protocol incorporating both Alvarado score and graded compression USG failed to produce better outcome than unaided clinical diagnosis.  The proportion of patients in each group who had an adverse outcome (either a non-therapeutic operation or delayed treatment in patients with appendiceal perforation) was nearly identical - about 12%. Graded compression USG performed by experienced ultrasonographers still produced a 5% false negative result.  Despite new technology such as the use of USG, computed tomography, radionuclide scanning and C-reactive protein evaluation, the accuracy rate does not usually reach 95%. ,,,, Therefore, additional diagnostic modalities are required to reduce these high rates and to improve diagnostic accuracy of appendicitis.
The current study showed that mean pre-operative values of IAP of appendicitis, perforated appendicitis and negative laparotomy for appendicitis groups differ significantly. Mean IAP is elevated among patients with appendicitis. A further elevation has been encountered among patients with perforated appendicitis. Mean value of IAP has been normal among patients who were suspected initially to have appendicitis, but the symptoms subsequently subsided.
Our results suggest that IAP increases after the onset of appendicitis. The inflammatory reactions encountered during the onset of appendicitis, including the edema of the peritoneal surfaces, peritoneal transudation and exudation, may have contributed to the elevation of IAP. In addition, edema of the intestine caused by extensive intra-abdominal inflammation resulting in distension of the bowel segments and ileus may have contributed to the elevation of IAP in appendicitis. Progression of appendicitis, which results in perforation and subsequent abscess formation, further elevates IAP.
Among patients with negative exploration for appendicitis, the absence of gross peritonitis or inflammation suggests that inflammation either localized or generalized is the most important contributor to the elevation of IAP. Therefore, the elevation of IAP seems to show a diagnostic value that helps additionally to predict the patients in whom perforated appendicitis developed.
The mean pre-operative values of IAP in children for acute, perforated, or suspected appendicitis and negative exploration were 6.2 ± 0.4, 9 ± 0.3, 0.3 ± 0.4 and 3 ± 0.4 cm H 2O, respectively (P < 0.001) in a study conducted by Bingöl-Koloğlu et al. They concluded that IAP was found to be increased in appendicitis, but did not increase in conditions mimicking appendicitis. They also noticed further increase amongst children with perforated appendicitis. The values above are quite similar to the results of our study. In the same study, the pre-operative and first post-operative day IAP values of patients with perforated appendicitis who experienced a wound infection and who were without a wound infection have been 11.8 ± 0.4 and 4.8 ± 0.2 and 8.4 ± 0.2 and 3.1 ± 0.3 cm H 2 O (P < 0.001), which is also along the lines of the results of our study.
Although, there is a wide spectrum of diagnostic tools, an experienced physician almost always gives precedence to the clinical evaluation of the patient, which is tightly linked with the diagnosis of appendicitis. For standard evaluation of patients with appendicitis by emergency services, standardization of medical staff and equipment is necessary. A bladder pressure measurement may help the primary physician anywhere with limited laboratory and/or imaging choices or even in the absence of a specialist for the evaluation.
Elevated IAP solely cannot affect the final decision for establishing the diagnosis of appendicitis. However interpretation of elevated IAP, demonstrated through bladder pressure measurement, with history, physical examination findings, laboratory findings and/or imaging studies, may be helpful in supporting the diagnosis of appendicitis.
| Conclusion|| |
IAP increases among patients with appendicitis and a further increase is encountered among patients with perforated appendicitis. Complicated course is encountered among patients with highest IAP values.
Therefore, IAP may be used both as an adjuvant diagnostic parameter and a predictor of a complicated course of appendicitis.
An experienced surgeon still gives precedence to clinical evaluation for the diagnosis of appendicitis although there is a wide spectrum of diagnostic tools available for the same.
Bladder pressure measurement is a cost effective and a highly reliable adjuvant tool for the diagnosis and prognosis of appendicitis especially in settings with limited laboratory and/or imaging choices or even in the absence of a specialist for the evaluation. However, randomized controlled studies are needed to conclusively prove its efficacy so as to be included in the armamentarium of a surgeon especially in a rural setting.
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