A Single-Center Experience: The Diagnostic Role of Peritoneoscopy in Patients with Exudative Ascites

Introduction

Ascites is an accumulation of fluid in the abdominal cavity. Effective treatment of ascites is largely dependent on accurate identification of underlying factors. There are many classifications of ascites: due to their fluid content, ascites are categorized as being exudative or transudative types. Along with ethnicity and geographic factors, the most common cause of transudative ascites is portal hypertension. The main causes of exudative ascites are tuberculosis and malignancy.

Nowadays, causes of exudative and transudative ascites may be readily identified by noninvasive methods. In previous years, peritoneoscopy was used successfully for diagnostic purposes in exudative ascites with uncertain etiology. Peritoneoscopy procedure is similar to laparoscopy, but easier than laparoscopy. This procedure is performed in endoscopy unit with sedation anesthesia. Mortality, morbidity, and complications of the procedure are less than laparoscopy. The need for peritoneoscopy has decreased nowadays but, due to its high diagnostic value, is still regarded as the “gold standard” method for diagnosis of exudative ascites with unknown etiology.^1,2

In this study, we aimed to present the peritoneal biopsy results of patients with exudative ascites in our clinic between January 2012 and December 2015.

Materials and Methods

The study included a total of 86 patients. Patient data for this retrospective study were obtained from hospital records. All the patients showed abnormalities of the peritoneum or greater omentum, as determined by abdominal ultrasonography, and underwent peritoneoscopy between January 2012 and December 2015. The study conformed to the ethical guidelines of the 1975 Declaration of Helsinki.

Results

Demographic characteristics of the 86 patients (male: 22; 25.6%, mean age ± SD: 57.97 ± 15.97) are presented in Table 1. Among the diagnosed patients: 43 (50%) were peritonitis carcinomatosa, 21 (24.4%) were tuberculous peritonitis, 14 (16.3%) were mesothelioma, 4 (4.7%) were chronical inflammation, and 1 (1.2%) was lymphoma. Three (3.5%) patients had normal peritoneal biopsy findings (Table 2).

Among 43 patients with peritonitis carcinomatosa, the primary focus was ovary in 18 patients (20.9%), pancreas in 7 (8.1%) patients, stomach in 6 (7%) patients, colon in 4 (4.7%) patients, and hepatocellular cancer in 2 (2.3%) patients. Six (7%) patients had an unclear primary focus (Table 3).

Adenosine deaminase (ADA) and Ca-125 levels in patients with tuberculous peritonitis were detected to be high, but no statistically significant difference was identified between groups.

Discussion

The most frequent cause of ascites is hepatic cirrhosis, followed by neoplasms and, to a lesser extent, congestive heart failure and tuberculous peritonitis. These account for more than 90% of ascites. Ascites of unknown etiology is defined as ascites in which the cause cannot be determined after conventional laboratory tests and further radiologic imaging methods. This is a major diagnostic problem for clinicians. Causes of ascites of unknown etiology vary considerably with the geographic area and ethnic origin. Peritoneal tuberculous and peritoneal carcinomatosis constitute a high percentage of these patients.^3,4

The primary functions of the peritoneum are to limit diffusion of inflammation and to protect abdominal organs. Due to their proximity, tumors and infections of abdominal organs may spread to the peritoneum in the initial stages. Previously, diagnosis of peritoneal diseases relied on surgical methods. Nowadays, by using advanced radiologic methods such as computerized tomography (CT) and magnetic resonance imaging, these lesions may be readily diagnosed, while the rest are identifiable with peritoneoscopy. Peritoneoscopy is a less invasive method and has low risk compared to surgery; however, undesired injuries may occur sometimes. Generally, it is a reliable method when performed by experienced specialists. Nowadays, peritoneal biopsies guided by ultrasound and CT have become quite frequent. These methods demonstrate less complications compared with peritoneoscopy, and they have quite successful outcomes.^5–9

Tuberculosis is a worldwide pandemic caused by Mycobacterium tuberculosis. Tuberculosis can affect all tissues and organs with a large spectrum. Most tuberculosis foci are pulmonary; however, extrapulmonary tuberculosis accounts for ∼20% of all cases. Most patients with tuberculosis are from Asia (59%) and Africa (26%). The abdominal form of tuberculosis is the sixth most common type of extrapulmonary tuberculosis, after lymphatic, genitourinary, osteoarticular, miliary and meningeal tuberculosis. Abdominal tuberculosis may affect any part of the gastrointestinal tract, including the peritoneum and pancreatobiliary system. ¹⁰

In recent years, tuberculosis frequency in our community has increased. Twenty-five percent of pulmonary tuberculosis cases account for peritoneal tuberculosis. Tuberculous peritonitis is characterized by nonspecific signs, weight loss, abdominal symptoms/findings, and ascites formation. Peritoneal tuberculosis, which affects 4% of all patients with tuberculosis, is difficult to diagnose due to its often-muted clinical presentation. Although the triad of fever, ascites, and abdominal pain is present in 70% of patients, diagnosis is more difficult in patients who have no typical symptoms or laboratory and radiologic findings.^10,11

Diagnosis of peritoneal tuberculosis can easily be delayed or even missed. The peritoneal tuberculosis mortality rate is very high (15%–30%). Delay in diagnosis is a major cause for the high mortality from peritoneal tuberculosis. Due to high protein concentrations, ascites in these patients is of the exudative type. Rivalta's test is positive with predominant lymphocytes. No specific biological marker is available for the diagnosis of tuberculous peritonitis. Slight increases in leukocytosis and increases in inflammation parameters are frequently seen, but these are generally insufficient in each case. Peritoneal and omental bulking and induration may be seen in carcinoma peritonitis and in lymphoma peritonitis, which makes differential diagnosis more difficult. The detection of Mycobacterium in ascites fluid is extremely insensitive and Mycobacterium detection is positive by smear testing in fewer than 3% of patients. A culture is positive in less than 20% of patients and takes ∼6–8 weeks.^11–13

An abnormal chest X-ray can be observed in ∼38% of patients; however, coexistent active pulmonary disease is uncommon. Radiological methods are highly useful, but unfortunately, all radiologic findings are nonspecific and cannot be confirmatory for diagnosis in every case. As in our study, ADA activity indicators in ascites fluid are determined to be valuable in these patients, however, this issue requires separate study. Peritonoscopic biopsy is usually considered as the gold standard for diagnosis.^12,13

In cases of tuberculous peritonitis, peritoneoscopy demonstrates hyperemic, indurated peritoneum, white–yellow nodules in the peritoneum, and multiple thickened adhesions. Peritoneoscopy with a combination of visual and histologic investigations has shown high sensitivity and specificity rates of 93% and 98%, respectively. In more than 90% of patients included in this study, such peritonoscopic findings were observed for tuberculous peritonitis.^14–16

All cases with peritonoscopic biopsies in this study concluded with certain diagnosis. Compatible with the literature, the most frequent diagnosis was carcinoma peritonitis, followed by tuberculous peritonitis, already frequently seen in this geographic location.

The retrospective nature of this study was the main limitation of the study. Because of the scarcity of epidemiological research, this study will positively contribute to the medical literature. This study demonstrated that the peritonoscopic biopsy is still efficient in selected exudative ascites patients with uncertain etiology.

Authors' Contribution

B.A., conception and design, provision of study material or patients collection and/or assembly of data, article writing, and final approval of article. G.G., conception and design, provision of study material or patients, article writing, and final approval of article.