Tuberculosis (TB) is the number one cause of death from infectious diseases worldwide each year. In recent years, the incidence of TB has been on the rise. Tuberculous peritonitis is a chronic diffuse peritoneal infection caused by Mycobacterium tuberculosis. Tuberculous peritonitis has an insidious onset with nonspecific symptoms and signs, making early clinical diagnosis difficult and thus delaying the timing of treatment. We reviewed and analyzed the ultrasound image characteristics of 56 patients with tuberculous peritonitis, aiming to evaluate the diagnostic value of ultrasonography for tuberculous peritonitis.
1.Data and methods
1.1 Study population All 56 cases of tuberculous peritonitis were inpatients or outpatients of our hospital from June 2007 to March 2009, including 22 males and 34 females, aged 16-71 years. All cases in this group were diagnosed by ultrasound, cytology and bacteriological examination and cured by anti-TB treatment.
1, 2 Instruments used GE LOGIC500 ultrasonic diagnostic instrument with a probe frequency of 3.5 MHz.
1.3 Examination method: Routine lying position, if necessary in left or right lateral position, the probe was scanned in longitudinal, transverse, oblique and other multi-sections in the order of right upper abdomen, right lower abdomen, left upper abdomen and left lower abdomen. Observe whether there is thickening of wall peritoneum, plasma membrane layer of intestinal wall and greater omentum, whether there are abnormal lymph nodes in the abdominal cavity, whether there are adhesions in the intestinal canal, etc. If there is an anechoic zone of ascites in the peritoneal cavity, pay attention to the presence of strip or grid-like light band echo and ascites translucency in the anechoic zone of ascites.
2. Results
Among the 56 cases in this group, the ultrasound diagnosis was clear in 52 cases, and the correct diagnosis rate was 92.9%, while 4 cases were missed and misdiagnosed, accounting for 7.1%. The ultrasound detected ascites in all 56 patients in this group, including 48 cases (85.7%) with stripes or lattice-like light bands in ascites; 45 cases (80.4%) with wall peritoneal thickening; 37 cases (66.1%) with plasma layer thickening of intestinal wall; 44 cases (78.6%) with large omentum thickening; 39 cases (69.6%) with intestinal adhesions; and 48 cases (85.7%) with abnormal lymph nodes detected in the abdominal cavity. 48 cases (85.7%).
The ultrasound manifestations of tuberculous peritonitis are more complex and variable, and the cases in this group can be divided into the following types.
Simple ascites type: 20 cases (35.7%) with moderate to large amount of ascites, the ultrasound images showed that free echogenic areas could be detected in the abdominal cavity and diffused throughout the abdomen, and intestinal tubes could be seen floating therein, most of the patients had poor permeability of ascites, and small punctate hypoechoic floating was common, some patients could detect stripes or lattice-like light bands in the ascites.
Encapsulated effusion type: 4 cases, accounting for 7.14%. The ultrasound images showed single or multiple round or irregularly shaped non-echoic liquid dark areas in the abdominal cavity, surrounded by the intestinal canal or omentum, and strong echogenic light spots could be detected within the liquid dark areas.
Diffuse peritoneal thickening: 7 cases, accounting for 12.5%. The ultrasound images showed patchy irregular thickening of the wall peritoneum and dirty peritoneum, hypoechogenicity, markedly reduced intestinal gas reflexes and decreased peristalsis.
Adhesive obstruction type: 10 cases, accounting for 17.9%. A small amount of free liquid dark area was scattered in the abdominal cavity, and the intestinal adhesions showed mass-like hyperechoic, less fluid and gas accumulation in the intestine, and weakened peristalsis. The intestinal obstruction was characterized by incomplete obstruction of the small intestine, and the proximal intestine of the obstruction was dilated.
Mixed type: 15 cases, accounting for 26.8%. The ultrasound manifestation has the characteristics of the above-mentioned types at the same time.
3. Discussion
Tuberculous peritonitis is a chronic diffuse peritoneal infection caused by Mycobacterium tuberculosis, and its main pathological changes are inflammatory congestion and edema of the peritoneum, fibrin exudation causing peritoneal thickening, grossness, and intestinal adhesions, while fluid exudation forming ascites or pus accumulation is its main clinical feature [1]. Thickening of the greater omentum is mainly due to exudative, proliferative, and millicase-like lesions caused by Mycobacterium tuberculosis infection [2].
All cases in this group had varying degrees of ascites, and more than moderate amounts were predominant, with fine punctate hypoechoic floaters common within, and some patients could detect striated or lattice-like light bands within the ascites. This is mainly due to inflammatory material and fibrin exudation. This type is mainly distinguished from cirrhotic ascites, ascites due to cardiac and renal disease, and cancerous ascites. The ascites due to cirrhotic ascites and cardiac and renal diseases is a leaky fluid with good acoustic transmission, no fibrous bands in the ascites, floating intestines, and good morphology and peristalsis; it can also be scanned for sonographic changes in the liver, heart and kidney with corresponding lesions. Cancerous ascites is also poorly translucent, but cancerous ascites grows rapidly, and ascites is often massive and not easily absorbed, so finding the primary lesion is the key to differential diagnosis.
Diffusely thickened peritoneum with tuberculous peritonitis should be distinguished from peritoneal mesothelioma or peritoneal mucinous tumor. Both show ascites, patchy irregular thickening of the peritoneum, hypoechogenicity, and even enlarged lymph nodes around the mesentery, abdominal aorta and inferior vena cava on ultrasound images, but the latter rarely shows diffuse thickening of the intestinal canal wall, and cytologic examination of ascites and bacteriologic examination can effectively help us make the differential diagnosis. When tuberculous peritonitis is combined with intestinal tuberculosis, the thickened intestinal wall is easily misdiagnosed as an intestinal tumor with a “pseudonephritic” acoustic image, and intestinal tuberculosis tends to develop in the ileocecal region and can involve the ileum. In the case of intestinal tumors, colon cancer is more common, and most of them do not involve the ileum, while colon liver flexure and splenic flexure are more common.
Intraoperative changes of adhesive-obstructive tuberculous peritonitis are marked thickening of the peritoneum, contraction of the greater omentum in a mass, and mesenteric lymph nodes of varying sizes. The mesentery, omentum, small intestinal collaterals, lymph nodes and intestinal wall were adherent to each other in a mass, and caseous necrosis with a small amount of exudate was seen on incision [3]. In our group, two cases of adherent-obstructive tuberculous peritonitis were mistaken for abdominal tumors.
In addition, ultrasound can effectively observe the dynamic changes of intra-abdominal lesions during the course of tuberculosis treatment.
Therefore, the diagnosis of tuberculous peritonitis should be suggested when ascites is found in the abdominal cavity and ultrasound reveals peritoneal separation, turbidity of ascites, thickening of peritoneum, intestinal adhesions in the form of masses or with intestinal obstruction. At the same time, we should raise awareness of the diagnosis and differential diagnosis of tuberculous peritonitis, and it is essential to make a comprehensive analysis by closely combining clinical history, laboratory or other imaging data.
In conclusion, ultrasonography has an important value in the diagnosis of tuberculous peritonitis and is the preferred method for the examination of tuberculous peritonitis. It has the advantages of being easy to perform and non-invasive. Ultrasonography can not only detect the presence or absence of peritoneal fluid, its amount and the location of fibrosis and encapsulation, but also can be performed under ultrasound guidance to extract ascites for cytological and bacteriological examination to further clarify the etiology if necessary, which is helpful for early clinical diagnosis and selection of reasonable treatment plan.