| disease | Intra-abdominal Abscess |
Intra-abdominal abscess refers to a localized collection of pus in a specific space or area within the abdominal cavity, formed by the encapsulation of necrotic and liquefied tissue by intestinal loops, viscera, abdominal wall, omentum, or mesentery. It includes subphrenic abscess, pelvic abscess, and interloop abscess. This condition can result from various diseases that cause secondary peritonitis, as well as after abdominal surgery or trauma.
bubble_chart Etiology
Subphrenic abscess often occurs secondary to perforation and inflammation of intra-abdominal organs, such as perforation of acute {|###|}appendicitis{|###|}, perforation of gastroduodenal {|###|}ulcer{|###|}, or rupture of liver abscess, which commonly causes right subphrenic abscess. In contrast, postoperative infections following gastrectomy or splenectomy, as well as hemorrhagic necrotizing pancreatitis, often lead to left subphrenic abscess. The pathogenic bacteria mostly originate from the gastrointestinal tract, typically involving mixed infections with {|###|}large intestine{|###|} bacilli, streptococci, Klebsiella, and anaerobes. When the abscess spreads from suppurative diseases in the thoracic cavity, the infection is primarily caused by staphylococci, streptococci, or pneumococci.
Inflammatory exudates or pus in the abdominal cavity tend to form an {|###|}abdominal mass{|###|} in the pelvic region, leading to abscess formation. The most common causes include perforation of {|###|}appendicitis{|###|} and pelvic peritonitis resulting from infections in the female reproductive tract.
bubble_chart Clinical Manifestations
Subphrenic abscess: After treatment of inflammatory lesions in the abdominal organs, or in patients who have undergone gastrectomy or splenectomy, if the body temperature rises again after initially decreasing with warm purgation, the possibility of subphrenic infection should be considered. Patients often present with remittent fever as the main symptom, around 39°C, accompanied by profuse sweating, poor appetite, lack of strength, systemic malaise, and other toxic symptoms. Persistent dull pain in the upper abdomen on the affected side may radiate to the shoulder and back, worsening with deep breathing or cough, and sometimes accompanied by hiccup. Physical examination reveals deep tenderness or percussion pain in the upper abdomen or back on the affected side, and in severe cases, localized pitting edema may appear. Due to reactive inflammation and effusion in the pleural cavity, breath sounds at the base of the affected lung may weaken or disappear, and even moist rales may be heard. The white blood cell count and neutrophil ratio are increased.
Pelvic abscess: The pelvic peritoneum has a smaller surface area and a weaker ability to absorb toxins, so the systemic symptoms of pelvic abscess are milder while the local symptoms are relatively more pronounced. During the course of peritonitis or after pelvic surgery, if remittent fever persists or recurs after subsiding, accompanied by rectal and bladder irritation signs, the formation of a pelvic abscess should be considered. Symptoms include lower abdominal discomfort, tenesmus, frequent urge to defecate, and stools with mucus; urinary frequency, urgency, and even dysuria. Digital rectal examination may reveal relaxation of the anal sphincter, bulging, and tenderness of the anterior rectal wall.
Interintestinal abscess: After peritonitis, pus may become encapsulated by the intestines, mesentery, or omentum, forming single or multiple abscesses of varying sizes. Symptoms include low-grade fever and abdominal dull pain. Larger abscesses may present as palpable painful masses and may be accompanied by systemic toxic symptoms. Due to inflammatory adhesions, symptoms of incomplete intestinal obstruction, such as borborygmi, abdominal pain, and abdominal distension and fullness, may sometimes occur.
1. Diagnosis of subphrenic abscess: In addition to clinical manifestations, auxiliary examination techniques are often required for confirmation. B-mode ultrasonography is the most commonly used method, with a diagnostic accuracy rate of approximately 90%.
Upper abdominal X-ray and gastrointestinal barium meal examinations help determine the location of the abscess. Since 10–25% of abscess cavities contain gas, air-fluid levels may be observed. Other X-ray signs include gastrointestinal displacement, extrinsic indentation, elevated diaphragm, blurred costophrenic angle, and reactive pleural effusion.
Diagnostic puncture guided by B-mode ultrasonography is the simplest diagnostic method for subphrenic abscess. If necessary, catheter drainage can also be performed.
2. Pelvic abscess: For married women, a pelvic examination via the vagina can be performed to differentiate between an inflammatory pelvic mass and an abscess. Pelvic B-mode ultrasonography aids in diagnosis. Aspiration of pus via the rectum or posterior vaginal fornix after emptying the bladder confirms the diagnosis.
3. Interintestinal abscess: Abdominal X-ray may reveal widened spacing between intestinal walls and localized intestinal loop gas accumulation. B-mode ultrasonography, especially computed tomography (CT) scanning, can determine the location and extent of the abscess.
bubble_chart Treatment Measures
1. Treatment of Subphrenic Abscess: When treating peritonitis, adopting a semi-recumbent position, rationally selecting antibiotics, carefully achieving hemostasis after gastrosplenectomy, and placing drainage can effectively prevent the formation of subphrenic abscess. Even in the early stage of subphrenic abscess formation, inflammation may subside and be absorbed through antibiotic and supportive therapy. However, if fever persists after several weeks of treatment and the patient's physical condition is significantly weakened, timely drainage is still advisable.
Ultrasound-guided percutaneous drainage is a simple and effective treatment method for subphrenic abscesses that are deeply located, have small cavities, or contain thin pus. The key to success lies in selecting the appropriate puncture route and the need for catheter placement for irrigation and drainage.
1.1 Anterior Abdominal Approach: The most commonly used method. The procedure involves making an oblique incision along the costal margin, layer-by-layer dissection, and pushing aside the peritoneum once exposed, allowing drainage of abscesses in the right suprahepatic and left suprahepatic spaces. Due to the presence of adhesions around most abscesses, the peritoneum can also be incised to drain abscesses in the right subhepatic and left subhepatic spaces. After incising the abscess cavity, the pus is completely aspirated, and a silicone tube or double-lumen catheter is placed for drainage.
1.2 Posterior Lumbar Approach: An incision is made along the 12th rib, exposing and resecting the 12th rib, followed by a transverse incision of the rib bed at the level of the first lumbar vertebra. Care must be taken not to incise along the rib bed to avoid damaging the pleura. After incising the rib bed, the retroperitoneum is entered, and the kidney is pushed downward to drain subphrenic abscesses located posteriorly in the right subhepatic and left subphrenic spaces, as well as in the extraperitoneal space.
1.3 Thoracic Wall Approach: This should be performed in two stages. The initial stage [first stage] involves making an incision at the 8th or 9th rib on the lateral chest wall, resecting part of the rib, and reaching the extrapleural space. The wound is packed with iodophor gauze to induce adhesion formation between the pleura and diaphragm. Approximately 5–7 days later, the intermediate stage [second stage] surgery is performed. Through the original incision, the adhered pleura and diaphragm are punctured, and after aspirating the pus, the pleura and diaphragm are incised along the puncture needle direction to place drainage. This approach is suitable for draining high-position abscesses in the right suprahepatic space.
2. Treatment of Pelvic Abscess: Incision through the anterior rectal wall or posterior vaginal fornix is performed to place a soft silicone tube for drainage, which is removed 3–4 days postoperatively. Continued use of antibiotics, sitz baths, and perineal physiotherapy promotes the resolution and absorption of inflammation.
3. Interintestinal Abscess: Multiple small abscesses often resolve spontaneously with antibiotic treatment. Larger abscesses require laparotomy to aspirate pus, remove the abscess wall, and irrigate with copious saline or antibiotic solution, usually without the need for drainage.
