Posthysterectomy pelvic abscess

INTRODUCTION — Pelvic abscess occurs as an infectious complication of surgery (eg, hysterectomy, cesarean delivery, induced abortion) or the result of infectious processes (eg, pelvic inflammatory disease, inflammatory bowel disease, diverticulitis). This topic will review the diagnosis and management of pelvic abscess complicating hysterectomy.

In this topic, when discussing study results, we will use the gender terms as they are used in the studies presented. We encourage the reader to consider the specific counseling and treatment needs of transmasculine and gender-expansive individuals.

INCIDENCE — Less than 1 percent of patients undergoing obstetric or gynecologic surgery develop an abscess [1]. In a retrospective cohort study of 23,366 patients undergoing either laparoscopic or abdominal hysterectomy, 783 (3 percent) developed a surgical site infection [1]. Most of these were wound infections, but approximately one-quarter were infections of the organ space (or 0.7 percent of the entire cohort [210/23,366]).

RISK FACTORS — Risk factors for posthysterectomy pelvic abscess can be separated into pre-, intra-, and postoperative elements. Risk reduction is focused on eliminating as many factors as possible. Implementation of surgical site reduction bundles in gynecologic and gynecologic oncology surgeries have been associated with reduced postoperative surgical site infections [2-4]. (See "Overview of preoperative evaluation and preparation for gynecologic surgery", section on 'Surgical site infection prevention'.)

We counsel women with multiple nonmodifiable risk factors about their increased risk for postoperative infection and possible need for subsequent treatment.

●Preoperative risk factors for posthysterectomy abscess include untreated pelvic inflammatory disease (PID), bacterial vaginosis, endometrioma, hydrosalpinx, prior laparotomy, anatomic anomalies, renal comorbidities, and American Society of Anesthesiologists class ≥3 [1,5-8]. Bacterial vaginosis at surgery increases the risk of both posthysterectomy cuff cellulitis [9-11] and subsequent pelvic abscess formation [12]. (See "Bacterial vaginosis: Initial treatment", section on 'Individuals undergoing gynecologic procedures'.)  

●Intraoperative risk factors include perioperative blood transfusion and operative time >180 minutes for laparoscopic hysterectomy [1]. In addition, one retrospective review of 413 women undergoing hysterectomy at a single institution reported increased risk of postoperative pelvic abscess when gelatin-thrombin matrix was used during surgery [13].

●The main postoperative risk factor is postoperative hematoma.

An overview of risk factors for surgical site infection is discussed separately.

MICROBIOLOGY — Gynecologic surgical site infections are polymicrobial and commonly contain gram-negative bacilli, enterococci, streptococci, and anaerobes, similar to the microbiology of abdominal sepsis patients (table 1) [10,14]. While mixed aerobic/anaerobic infections are most common, case reports have also described pelvic abscesses caused by yeast, actinomyces, tuberculosis, and mycoplasma [15-18].

Discussion of microbiology for general intra-abdominal infections is presented in related content. (See "Antimicrobial approach to intra-abdominal infections in adults" and "Antimicrobial approach to intra-abdominal infections in adults", section on 'Microbiology'.)

PATHOGENESIS — Microbial contamination of the surgical site is a key step in the development of surgical site infection. Quantitatively, risk for infection increases markedly if the operating site is contaminated with >100,000 microorganisms per gram of tissue [19,20].

The intraabdominal abscess rat model demonstrates two phases for mixed aerobic-anaerobic infections of the abdomen and pelvis (figure 1) [21]. Peritonitis occurs initially. Some animals develop sepsis and die over approximately five days. The surviving animals wall off the infection to form an abscess due to anaerobic bacteria.

PREVENTION — Preoperative prevention and early identification strategies include:

●Treatment of bacterial vaginosis (BV)

•(See "Bacterial vaginosis: Clinical manifestations and diagnosis".)

•(See "Bacterial vaginosis: Initial treatment".)

●Short-term postoperative evaluation – We have patients return for an office check approximately two weeks following their hysterectomy. Many patients with vaginal cuff infections present more than two weeks following surgery, which suggests a late ascending spread of vaginal microorganisms. Postoperative blood and other secretions from the cuff may enhance the development of BV, in part by raising the vaginal pH. To prevent this, women with a history of BV or those noting a fishy vaginal odor undergo microscopy of the vaginal secretions and are treated for BV, if present. Using antibiotic therapy for postoperative BV does not give the patient a diagnosis of surgical site infection.

•(See "Vaginitis in adults: Initial evaluation".)

●Stabilization of preexisting medical illness, such as diabetes mellitus, when appropriate. (See "Susceptibility to infections in persons with diabetes mellitus".)

●Antibiotic prophylaxis (table 2) – (See "Overview of preoperative evaluation and preparation for gynecologic surgery", section on 'Antibiotic prophylaxis' and "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

●Treatment of vaginal cuff cellulitis – Prompt identification and treatment of postoperative vaginal cuff cellulitis is advised to diminish risk of pelvic abscess and/or cuff dehiscence, although supporting data are scarce.

PATIENT PRESENTATION — Posthysterectomy abscesses typically develop at the vaginal cuff but may form in the adnexa. The abscess usually presents in one, or in some cases, combinations, of the following ways:

●Typical presentation – The typical presentation is fever, tachycardia, tachypnea, and lower abdominal pain [22], days to weeks after hysterectomy. On physical examination, the pelvis is diffusely tender, and a fluctuant mass may be palpable in the pelvis or vaginal apex. Laboratory findings include leukocytosis with left shift, elevated erythrocyte sedimentation rate, and elevated C-reactive protein [22].

●Failed treatment for cellulitis – Patients may initially present with pelvic cellulitis [22]. Lack of improvement after 48 to 72 hours of appropriate antibiotic therapy suggests abscess.

●Sepsis or septic shock – Sepsis or septic shock suggests ruptured abscess. These patients may be disoriented or delirious. (See "Sepsis syndromes in adults: Epidemiology, definitions, clinical presentation, diagnosis, and prognosis" and "Evaluation and management of suspected sepsis and septic shock in adults".)

DIFFERENTIAL DIAGNOSIS — Causes of postoperative pain and fever can be infectious or noninfectious. Infectious causes include surgical site infection, vaginal cuff cellulitis, pelvic cellulitis, infected urinoma, infected hematoma, septic pelvic thrombophlebitis, and necrotizing cellulitis or fasciitis [23,24]:

●Vaginal cellulitis – Posthysterectomy pelvic and vaginal cellulitis have similar presentations to posthysterectomy abscess but are not associated with a pelvic fluid collection. (See "Cellulitis and skin abscess: Epidemiology, microbiology, clinical manifestations, and diagnosis".)

●Urinoma – Urinoma from a ureteral injury develops in the retroperitoneum; intraperitoneal urine collections are more commonly due to a bladder injury. The patient may become febrile and have pain due to an inflammatory response or because of infection. On imaging, the fluid collection has no debris or loculation, which are typical of an abscess. The patient's serum creatinine and urea nitrogen may be elevated from peritoneal reabsorption of the urine. Drainage and culture of the fluid is required to determine if the fluid is infected. (See "Urinary tract injury in gynecologic surgery: Identification and management".)

●Infected hematoma – An infected pelvic hematoma is difficult to distinguish from a frank abscess; however, treatment is the same. Drainage of the collection would confirm blood if the collection is a hematoma and pus if it is an abscess.

●Septic pelvic thrombophlebitis – Septic pelvic thrombophlebitis can occur in posthysterectomy patients, including after laparoscopic surgery. It is generally a diagnosis of exclusion, after the patient has failed to respond to broad spectrum antibiotic therapy. (See "Septic pelvic thrombophlebitis".)

●Necrotizing infection – Necrotizing cellulitis and fasciitis are rare but extremely dangerous infections. In a necrotizing cellulitis the affected area is usually erythematous (without sharp margins), swollen, warm, shiny, and exquisitely tender. Necrotizing fasciitis is associated with a thin, grey, dishwater-like wound drainage sometimes associated with gas formation. This infection involves the subcutaneous tissue and superficial fascia (Camper's and Scarpa's). It is rare for the deep fascia and muscles to be involved. Surgical exploration is the only way to definitively establish the diagnosis. Resection of all necrotic tissue is an essential element of treatment. (See "Necrotizing soft tissue infections".)

DIAGNOSTIC EVALUATION — The diagnostic evaluation includes history, physical examination, laboratory testing, and imaging studies.

●Physical examination and laboratory testing – Physical examination and laboratory evaluation should rule out other causes of postoperative fever and leukocytosis.

●Imaging – Patients with suspected pelvic abscess generally undergo imaging with computed tomography (CT).

•Computed tomography (CT) – Computed tomography (CT) is the diagnostic standard because it allows visualization of the entire abdominal/pelvic cavity with excellent spatial resolution and delineation of the adjacent anatomic structures (image 1) [25,26]. CT is not impaired in the setting of ileus, wound dressings, stomas, and the open abdomen [25]. The use of intravenous contrast increases the diagnostic accuracy. The images often demonstrate a hypodense collection (between 0 and 30 Hounsfield units) associated with a round or oval peripheral intensification [26]. CT may be more sensitive and specific than ultrasound for detecting tubo-ovarian abscess (TOA), one type of pelvic abscess [27-29]. In a review of three studies, sensitivity to detect TOA was 78 to 100 percent for CT versus 75 to 82 percent for ultrasound; specificity was 100 percent for CT versus 92 percent for ultrasound [27].

•Ultrasound – If CT is not available ultrasound imaging is a reasonable alternative. It is easy to perform, inexpensive, distinguishes between fluid and solid tissue without ionizing radiation, provides excellent imaging of the upper genital tract, and can be done at the bedside [26,27]. However, some areas of the pelvis can be difficult to visualize because of body habitus, postoperative air, or postsurgical changes [26]. An abscess appears as a multi-locular complex mass(es) with debris, septations, and irregular thick walls. In addition, open surgical wounds or abundant bowel gas may limit image quality.

•Magnetic resonance imaging (MRI) – Magnetic resonance imaging provides no additional information and therefore is not typically ordered in this setting [27,30].

DIAGNOSIS — The diagnosis of posthysterectomy pelvic abscess should be suspected in any posthysterectomy patient who presents with pain, fever, and leukocytosis. Palpation of a fluctuant mass supports the diagnosis, and imaging provides the definitive evidence of an intraabdominal abscess [25].

MANAGEMENT — The initial treatment of posthysterectomy pelvic abscess depends on several factors (algorithm 1):

●Hemodynamic stability

●Abscess size

●Abscess location

Hemodynamically unstable patients — Patients who are hemodynamically unstable are likely to have a ruptured abscess. Intraabdominal abscess rupture is a life-threatening emergency and requires prompt surgical intervention (see 'Surgical technique' below). Clinical findings suggestive of intraabdominal rupture include, but are not limited to, hypotension, tachycardia, tachypnea, acute peritoneal signs, or acidosis.

These patients require aggressive fluid resuscitation, infusion of broad-spectrum antibiotic therapy (see 'Antibiotic therapy' below), and prompt surgical intervention [12,27]. In our experience, most women who are acutely ill will not improve without surgical removal of the nidus of infection. A general or trauma surgeon should be consulted.

Even in the absence of evidence of abscess rupture, surgical exploration and treatment are advisable in any woman with overt signs of sepsis and a large abscess. In women who are treated surgically, antibiotics should be started as soon as possible, either before or during the urgent operative intervention. In an unstable patient with the presumptive diagnosis of abscess rupture, surgery should not be delayed for the administration of antibiotics.

Postoperative care in an intensive care unit should be arranged as the patient may develop septic inflammatory response syndrome. (See "Evaluation and management of suspected sepsis and septic shock in adults".)

Hemodynamically stable patients

Antibiotic therapy — Antibiotic selection is based, in part, on data from treatment of patients with intra-abdominal infections. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Empiric antimicrobial therapy'.)

Drug regimen — Patients are treated empirically with broad spectrum parenteral antibiotic regimens that have both aerobic and anaerobic activity. The suggested antibiotic regimens are based on the spectrum of coverage provided and not based on randomized studies. Multiple antibiotic combinations can provide such coverage for polymicrobial abscesses (table 3). (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Approach to empiric antibiotic selection'.)

We typically use:

●Piperacillin-tazobactam at a dose of 3.375 g intravenously every six hours.

or

●Alternative treatment regimens with ceftriaxone plus either clindamycin or metronidazole are also reasonable.

For patients with severe penicillin or cephalosporin allergy, therapy with aztreonam plus clindamycin or a carbapenem (eg, ertapenem, meropenem) may be appropriate, but depends on the details of the patient's allergy history (algorithm 2). Selection of antibiotics for patient with a history of penicillin allergy is presented in detail separately.

●(See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Approach to empiric antibiotic selection'.)

●(See "Choice of antibiotics in penicillin-allergic hospitalized patients".)

Initial antimicrobial regimens may need to be changed based on subsequent culture and sensitivity results, when available. If the patient does not respond to initial therapy in 48 to 72 hours, a consultation with an infectious disease specialist may be warranted. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Targeted antimicrobial therapy'.)

Drug duration — Parenteral antibiotics are continued until the patient is afebrile for 48 hours, and the abscess is shrinking, the elevated white blood count is resolving, and the patient is clinically improving [31]. At that point, the patient may be switched to an oral regimen to complete a 14-day course of therapy [22,27]. We suggest metronidazole 500 mg every 12 hours and trimethoprim-sulfamethoxazole 160/800 mg every 12 hours, or monotherapy with amoxicillin-clavulanate 875/125 mg every 12 hours because of the excellent oral absorption and polymicrobial coverage. The choice of oral antibiotic(s) should be tailored to the culture and sensitivity results, when available. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Duration of therapy'.)

Decision for percutaneous drainage — For hemodynamically stable patients, the optimal abscess size threshold for using antibiotics alone or combined with percutaneous drainage is unclear. In our practice, for patients with an abscess that is 7 cm or greater, we simultaneously start parenteral broad spectrum antibiotics and proceed with abscess drainage (algorithm 1). Although smaller abscesses less than 7 cm may respond to antibiotics alone [32], in our experience, percutaneous drainage combined with parenteral antibiotic therapy appears to hasten resolution [33]. Thus, for initial treatment of abscesses <7 cm but greater than 2 cm, we suggest empiric antibiotic and percutaneous drainage and reserve antibiotic therapy alone for patients with abscesses not accessible to drainage. Patients with abscesses 2 cm or smaller typically respond to antibiotic therapy only. However, if the patient does not improve after 48 to 72 hours of antibiotic therapy, then percutaneous drainage is performed.

Studies informing our approach commonly include tubo-ovarian abscess (TOA) patients or general surgical patients; data are extrapolated to posthysterectomy patients.

●A retrospective chart review of 122 TOA patients reported increasing likelihood of surgical or procedural treatment with increasing TOA size [34]. All patients with abscess size <2 cm responded to antibiotics alone. All patients with abscess size >10 cm required drainage. The mean abscess size was 4.3 cm for successfully medically treated patients and 7.3 cm for patients who subsequently required surgical intervention.

●In a case review of 135 patients with TOA, 69 percent responded to antibiotic-only therapy, and 31 percent required drainage or surgery [35]. The average abscess size for successful medical management was 6.3 cm as compared with 7.7 cm for patients who required intervention.

●In a retrospective cohort analysis of 240 patients with pelvic abscess, 84 percent of patients were successfully treated with antibiotics alone [36]. The patients who were successfully treated with antibiotics had smaller abscesses than the patients who required drainage (5.9 versus 8.5 cm).

Percutaneous drainage — Catheter drainage can be performed via ultrasound or computed tomography (CT) guidance with a transabdominal, transgluteal, transrectal, or transvaginal approach (image 1). The approach depends on operator experience and abscess location; a transabdominal approach is used for abscesses in the upper pelvis or abdomen, and a transvaginal approach is used for deeper pelvic abscesses [37]. CT guidance provides better spatial and contrast resolution for accurate localization of the collection and the detection of adjacent nerves and vessels [38]. Drained fluid should be sent for Gram stain, culture, and sensitivity. At the conclusion of the procedure, an indwelling catheter may be placed for continued drainage.

Indwelling catheters should be maintained on closed drainage systems [25]. There is no clear guideline regarding duration of catheter drainage [39]. There does not appear to be a benefit to the use of suction or irrigation of these catheters, although flushing once per day with saline ensures patency [25]. Patients should defervesce within 48 hours of catheter insertion. Repeat imaging is done at approximately five to seven days to ensure shrinkage of the abscess. Criteria for removal of the drain include clinical resolution of septic parameters, including patient well-being, normal temperature, and leukocyte count; minimal drainage from the catheter; and imaging evidence of abscess resolution.

Prior to the availability of modern imaging-guided drainage procedures, gynecologists drained pelvic abscesses transvaginally through a posterior colpotomy. Colpotomy is an appropriate option for posthysterectomy vaginal cuff abscesses that bulge into the vaginal space. However, reports have highlighted occasional onset of peritonitis and sepsis after use of this approach for drainage of a TOA [12]. Thus, in most women with abscess in the upper pelvis, this approach should be avoided.

Treatment failure — Failure of combination treatment (antibiotics and percutaneous drainage) can be defined by persistent fever, leukocytosis, and pain, and lack of resolution of the abscess on imaging.

Risk factors — Risk factors for treatment failure include residual fluid collection after initial drainage and increasing patient age. In a study of 81 general surgical patients, all of whom had postoperative abscesses treated with percutaneous drainage and antibiotics, 18 patients (22 percent) needed subsequent surgery [40]. Residual fluid collection after the attempted drainage was the single predictor of failure after univariate and multivariate analysis. In a retrospective review of 122 TOA patients, maximal leukocyte count, increasing age, and parity were associated with treatment failure [34].

Management approach — Culture and sensitivity results should be reviewed to ensure the patient is receiving appropriate antibiotic treatment; consultation with an infectious disease specialist may be helpful (see "Antimicrobial approach to intra-abdominal infections in adults", section on 'Introduction' and "Antimicrobial approach to intra-abdominal infections in adults"). A second percutaneous drainage procedure is reasonable for stable patients with a persistent fluid collection [41]. However, in hemodynamically unstable patients or those who have undergone two prior percutaneous drainage attempts, surgical drainage is warranted.

Surgical technique — Surgical abscess drainage is performed in hemodynamically unstable patients and those who fail antibiotic therapy or percutaneous drainage. Surgery is technically challenging because of anatomic distortion, extensive adhesions, necrosis, and inflammation, which may thicken the peritoneum [27]. In our practice, most of these patients are explored through a vertical midline incision in order to ensure adequate exposure. However, in select stable patients without abscess rupture, laparoscopy appears to be safe and, in such cases, may have improved outcomes compared with laparotomy [42].

Procedure — The importance of involvement of experienced gynecologic surgeons cannot be overstated. Regardless of approach, surgical cases involving pelvic abscesses are notoriously challenging because of the anatomical distortion and friable tissue planes that universally exist from the extensive inflammatory process. It is not uncommon to also require the assistance of a surgeon experienced with bowel surgery. Appropriate preoperative arrangements assuring availability of operators possessing these skills are prudent.

Laparotomy is the surgical route used by most gynecologic surgeons for treatment of pelvic abscess. The decision of which incision to employ is important given the need for complete pelvic visualization. In our practice we use a vertical midline incision to allow complete exposure of the pelvis and abdomen. A Maylard transverse incision may also be used. (See "Incisions for open abdominal surgery".)

The steps of surgical procedure for posthysterectomy pelvic abscess are the following:

●Confirm the diagnosis of an abscess (image 1) and arrange for appropriate surgical backup.

●Upon entry into the peritoneum, anaerobic and aerobic cultures are obtained of the peritoneal fluid and the abscess cavity itself.

●Surgically remove as much of the abscess cavity and associated infectious/inflammatory fluid and debris as possible. If an ovarian abscess is diagnosed at surgery, surgical removal (adnexectomy) is generally performed because the ovary is typically necrotic.

●Copiously irrigate the peritoneal cavity, thereby lessening the overall infectious/inflammatory burden to the patient.

●All removed tissues should be sent for pathologic evaluation and may be used for microbiologic evaluation as well.

Given the high rates of wound infection from contamination of the surgical field ("dirty wound") generated from abscess cavity disruption, we often use the following measures, when appropriate [43-47]:

●Close the fascia with monofilament nonabsorbable or delayed absorbable suture, leaving the skin and subcutaneous wound open for at least the early postoperative period (72 hours). The wound can then be managed with a delayed closure procedure or can heal by secondary intention. Many gynecologic surgeons will opt for primary skin closure in such patients, and this may also be a reasonable option for women with extensive abscess surgery, although no direct evidence suggests the superiority of either approach. (See "Complications of abdominal surgical incisions", section on 'Delayed closure' and "Overview of the evaluation and management of surgical site infection", section on 'Delayed primary closure and reconstruction'.)

●Leave in a closed suction drain (eg, Jackson-Pratt) postoperatively until the patient demonstrates clinical improvement and the output from the drain is minimal.

Laparoscopy — Some data suggest that a laparoscopic approach can be used successfully, primarily among patients with no evidence of a ruptured abscess [42,48]. In addition, a small case series has suggested improved outcomes while using a laparoscopic approach (compared with laparotomy), but definitive data are lacking. The choice between laparoscopy and laparotomy depends greatly upon the skill of the surgeon. Even in patients without evidence of rupture, a laparoscopic approach should be undertaken only by an experienced laparoscopic surgeon. Surgical treatment of posthysterectomy abscess is often a complex procedure given the extensive inflammatory changes impacting the tissues.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Gynecologic surgery".)

SUMMARY AND RECOMMENDATIONS

●Abscess risk reduction – Posthysterectomy abscess formation can be limited by optimizing preoperative medical management of patients, adhering to surgical guidelines for aseptic technique, and perioperative antibiotics. Bacterial vaginosis, if present, should be treated. (See 'Prevention' above.)

●Microbiology – Pelvic abscesses are polymicrobial, including both aerobes and anaerobes, as the organisms originate from the lower genital tract. (See 'Microbiology' above.)

●Clinical presentation – The typical presentation of posthysterectomy abscess is fever, tachycardia, tachypnea, and lower abdominal pain, days to weeks after hysterectomy. On physical examination, the pelvis is diffusely tender, and a fluctuant mass may be palpable in the pelvis or vaginal apex. Some patients initially present with sepsis or after failure to respond to treatment of pelvic cellulitis. (See 'Patient presentation' above.)

●Diagnostic evaluation and diagnosis –The diagnosis of posthysterectomy pelvic abscess is based on clinical suspicion, palpation of a fluctuant mass, and visualization on imaging studies. Computed tomography or ultrasound imaging provides the definitive evidence of an intraabdominal abscess. In the absence of these definitive findings, pelvic abscess should be suspected in any posthysterectomy patient who presents with pain, fever, and leukocytosis.

•(See 'Diagnostic evaluation' above.)

•(See 'Diagnosis' above.)

●Management – The initial treatment of posthysterectomy pelvic abscess depends on several factors, including hemodynamic stability, abscess size, and abscess location (algorithm 1).

•Hemodynamically unstable – Patients who are clinically unstable or have worsening clinical status may have a ruptured pelvic abscess and should have urgent surgical exploration in addition to parenteral antibiotics (algorithm 1). (See 'Hemodynamically unstable patients' above.)

•Hemodynamically stable – Treatment of posthysterectomy pelvic abscess is based, in part, on data from patients with intra-abdominal infection. Detailed discussion of this patient population is available separately. (See "Antimicrobial approach to intra-abdominal infections in adults", section on 'Duration of therapy'.)

-Initial treatment – Initial antibiotic treatment is empiric and includes a broad-spectrum parenteral antibiotic regimen (table 3). We suggest parenteral piperacillin-tazobactam (Grade 2C). In our practice we use 3.375 g intravenously every six hours. The antibiotic therapy is adjusted if abscess drainage is performed and culture results become available. The initial treatment may be changed to a different broad spectrum agent as long as the cultured organism is sensitive. (See 'Drug regimen' above.)

-Patients responding to parenteral antibiotic therapy are discharged on an oral broad-spectrum regimen (eg, trimethoprim-sulfamethoxazole 800/160 mg [double-strength] one tablet orally every 12 hours and metronidazole 500 mg orally every 12 hours), to complete a 14-day course of treatment. (See 'Drug duration' above.)

●Role of abscess drainage – Larger abscesses are less likely to resolve with antibiotic treatment alone than smaller abscesses, but the optimum threshold for abscess drainage, preferably via percutaneous technique, is unclear. (See 'Decision for percutaneous drainage' above.)

•For initial treatment of abscesses ≥7 cm, we suggest abscess drainage in addition to empiric antibiotic therapy (Grade 2C). (See 'Decision for percutaneous drainage' above.)

•For initial treatment of abscesses <7 cm but greater than 2 cm, we suggest empiric antibiotic and percutaneous drainage and reserve antibiotic therapy alone for patients with abscesses not accessible to drainage. (Grade 2C). If fever, leukocytosis, pain, and lack of abscess resolution on imaging persist despite 48 to 72 hours of antibiotic therapy, we proceed with drainage. (See 'Decision for percutaneous drainage' above.)

•For initial management of abscesses ≤2 cm, we suggest initial treatment with antibiotics only (Grade 2C). As above, if fever, leukocytosis, pain, and lack of abscess resolution on imaging persist despite 48 to 72 hours of antibiotic therapy, we proceed with drainage if technically feasible. (See 'Decision for percutaneous drainage' above.)

●Treatment failure – Patients who do not respond to appropriate antibiotic treatment (persistent fever and leukocytosis, lack of abscess resolution) require either percutaneous drainage, either primary or repeat, or surgery. (See 'Treatment failure' above.)