Introduction

Acute appendicitis represents one of the main causes of non-traumatic abdominal surgery worldwide, with an estimated prevalence of 8.6% in men and 6.7% in women [1, 2]. There are diagnostic systems such as the modified Alvarado scale or the scale The Raja Isteri Pengiran Anak Saleha appendicitis (RIPASA) that help assess the clinical risk of appendicitis, preoperatively identifying complicated acute appendicitis (CAA) can be challenging [3].

Various laboratory and imaging studies, such as leukocyte count, neutrophil-lymphocyte ratio, C-reactive protein (CRP) or radiological characteristics, have been investigated as predictors of AAC, giving rise to tools such as the «Clinical and Radiological Appendicitis Severity Index» (APSI) [4—7]. On the other hand, extensive use of computed axial tomography (CAT) has been reported, however, its use presents radiological exposure and in some places difficult accessibility.

Acute appendicitis varies in severity from mild inflammation to gangrene with perforation, mainly due to luminal obstructions of the appendix. CAA, which accounts for up to one-third of cases, is associated with a higher incidence of postoperative complications associated with perforation, which may lead to localized or generalized peritonitis [8].

The presence of right hydronephrosis, although rare, has been associated with complicated acute appendicitis, retrospective studies have shown a higher prevalence of hydronephrosis in this group of patients, suggesting its usefulness as a sign of complication [9—13].Ultrasonography could be a promising tool to identify hydronephrosis and therefore help predict the severity of acute appendicitis, offering advantages such as safety, accessibility and speed compared to CT [14, 15]. In this sense, it is evaluated whether hydronephrosis constitutes a predictor of complicated acute appendicitis.

Methods

Study design

An observational, cross-sectional, analytical study was conducted to determine the association between the presence of hydronephrosis and the severity of acute appendicitis. The study was conducted at the Trujillo Regional Teaching Hospital (HRDT), between June and December 2022.

Population and sample

A total of 145 patients were included. Inclusion criteria were patients with a pathological diagnosis of acute appendicitis, age over 18 years, with a complete abdominal ultrasound prior to surgery performed by a radiologist; exclusion criteria were patients with generalized peritonitis, appendicular masses or pregnant women.

Definitions — Measurements

Complicated acute appendicitis was defined as the Acute inflammatory appendiceal infection that may be perforated, gangrenous, or present with a peri-appendiceal abscess according to histopathological diagnosis [16]. Hydronephrosis was defined as the documented presence of dilatation of the renal collecting system in the ultrasound report. Clinical, laboratory and surgical variables were also collected.

Procedures

The study was approved by the Research and Ethics Committee of the Antenor Orrego Private University and the HRDT Research Committee. A prospective review of the medical records of patients with a histopathological diagnosis of acute appendicitis was performed during the study period. The data were collected on a data collection sheet designed for this purpose, and subsequently entered into a database for statistical analysis.

Data analysis

Data were analyzed using IBM SPSS Statistics Base 29.0 software. Descriptive statistics were used to summarize sample characteristics, and analytical statistics such as Student’s t-test and chi-square were used to compare quantitative and qualitative variables, respectively. Crude odds ratio was calculated to assess the association between hydronephrosis and complicated acute appendicitis, with a 95% confidence interval.

Ethical aspects

Authorization was obtained from the corresponding ethics committees and the Code of Ethics of the Medical College of Peru and the international ethical guidelines for research with human beings were followed. Given the observational design of the study, informed consent was not required from patients due to the absence of direct intervention and the zero associated risk for both participants and researchers.

Results

145 patients with a histopathological diagnosis of acute appendicitis were included, 95 (65.52%) with complicated acute appendicitis and 50 (34.48%) with uncomplicated acute appendicitis, who underwent complete abdominal ultrasound studies between June and December 2022. The mean age was 33.77 years, with a predominance of males in 85 patients (58.62%), with no significant differences observed between both groups.

Regarding the duration of the illness, an average of 56.83±48.27 hours was found in patients with complicated acute appendicitis and 43.06±41.39 hours in the group of uncomplicated acute appendicitis. The waiting time from the patient’s admission to the emergency room until appendectomy was 9.43±6.06 hours in the group of complicated acute appendicitis and 8.59±6.37 hours in the group of uncomplicated acute appendicitis.

Regarding the operating time, 71.34±32.20 minutes were recorded in patients with complicated acute appendicitis and 52.16±21.16 minutes in patients with uncomplicated acute appendicitis, this difference was statistically significant (p<0.05). Open appendectomy was the predominant surgical procedure in 93.79% of acute appendicitis cases. In the histopathological study of the complicated acute appendicitis group, 49 (51.58%) presented the gangrenous stage and 46 (48.42%) the perforated stage. While in the uncomplicated acute appendicitis group 3 (6%) had the catarrhal stage and 47 (94%) had the suppurative stage (Table 1).

Table 1. Distribution of patients with acute appendicitis according to general characteristics and complicated appendicitis

Note. HTA: High blood pressure; DM2: Type 2 diabetes mellitus.

The most frequent appendicular location was sub-cecal, observed in 48.42% (46 patients) of the group of acute complicated appendicitis, followed by pre-ileal with 21.05% (20 patients) and retrocecal with 9.47% (9 patients). Likewise, in the group of acute uncomplicated appendicitis, the sub-cecal location was the most frequent 40% (26 patients), followed by pre-ileal location 24% (12 cases) and retrocecal 12% (6 cases). (Figure).

Distribution of patients with acute appendicitis according to location of the appendix and complicated appendicitis.

Hydronephrosis was detected in 6.32% (6 patients) in the complicated acute appendicitis group, compared with 2% (1 patient) in the uncomplicated acute appendicitis group (Table 2). Of the total number of patients with hydronephrosis, 71.4% had perforated acute appendicitis. Regarding the location of the appendix in these cases, pre-ileal was the most common in 3 patients (42.8%), followed by pelvic in 2 patients (28.6%), and sub-cecal or post-ileal in 1 patient each (14.2% each).

Table 2. Distribution of patients with acute appendicitis according to hydronephrosis and complicated appendicitis

Note. Chi-square OR: 3.3 95% CI [0.39—28.23]

Discussion

Acute appendicitis is one of the main causes of acute abdominal pain and accounts for more than 50% of emergency surgeries in many hospitals nationally and internationally [17—19].It is crucial to distinguish between complicated and uncomplicated acute appendicitis to properly optimize the preoperative management of each patient. This study explored the role of hydronephrosis as a potential diagnostic marker for complicated acute appendicitis.

In this investigation, 6.8% of patients with complicated acute appendicitis had right sided hydronephrosis, compared with 2% in those with uncomplicated acute appendicitis; however, this difference did not reach statistical significance. Despite this finding, the high frequency of hydronephrosis in cases of complicated acute appendicitis suggests a possible clinical association that deserves further exploration. Our results are in agreement with previous studies, Lee et al. [15] reported a significantly higher prevalence of hydronephrosis in patients with complicated acute appendicitis compared to those with uncomplicated acute appendicitis. Furthermore, Goldberg et al. [14]. In a study in Israel, they found associations between the presence of hydronephrosis, peri-appendiceal abscesses and appendiceal perforation, although in smaller proportions than those observed in our study.

The exact mechanism by which hydronephrosis develops in acute appendicitis is not yet fully understood. It has been proposed that the anatomical proximity of the appendix to the right ureter could facilitate the spread of the inflammatory process, causing compression and urinary stasis [20]. In addition, right ureter obstruction could be caused by appendiceal abscesses, exacerbating the clinical picture in some patients [11, 21].

The anatomical location of the appendix could also influence urinary complication. In our study, the most common location associated with hydronephrosis was pre-ileal (42.8%), followed by pelvic (28.6%). This pattern differs from other reports where retrocecal location was predominant, suggesting geographic and ethnic variability in the clinical presentation of appendicitis [14, 15]. Further research is needed to clarify these discrepancies.

Illness time and operative time were variables of interest in our analysis. Although we found a non-significant difference in illness time between the complicated and uncomplicated acute appendicitis groups, the duration of surgery was significantly longer in complicated cases. These findings are consistent with previous studies that have shown that prolonged operative time may be associated with increased postoperative complications and prolonged hospital stays [22—26].

This study has several limitations, including its cross-sectional design that limits the determination of temporal relationships between variables. Furthermore, the use of non-probability sampling could affect the generalizability of our findings. The reliance on physician-dependent ultrasound results reports and data collection limited to a single hospital center could also introduce biases in our results.

Conclusion

Although right hydronephrosis was not statistically associated with complicated acute appendicitis in our study, the findings suggest a possible clinical association that warrants further investigation. Further exploration of the underlying mechanisms and prospective studies with more representative samples are crucial to confirm these preliminary findings.

Ethical aspects: All authors certify that they meet the current criteria for authorship of the International Committee of Medical Journal Editors (ICMJE).

Conflict of interest statement: The authors have no conflict of interest to declare.

Sources of funding: The authors declare that this work has not received funding.