Risk factors for the prognostic effects of patients with pelvic abscesses: a clinical retrospective study.

This retrospective cohort study screened 165 patients diagnosed with pelvic abscesses at Ningde Municipal Hospital between August 2016 and October 2021. Data collection encompassed demographic and obstetric history, gynecological and reproductive health status, clinical presentation, laboratory parameters, and microbiological testing. Inclusion criteria were: (1) Meeting clinical diagnostic criteria for pelvic abscesses; (2) Availability of complete pre-treatment ultrasound, laboratory, and treatment response data. Exclusion criteria included: (1) Non-infectious pelvic masses (e.g., ovarian malignancies, endometriomas; n  = 3); (2) Incomplete medical records ( n  = 25). After applying these criteria, 127 patients were included in the final analysis. Baseline characteristics of the included and excluded patients are presented in Supplementary Table S1 . Ethical approval was obtained through the Research Ethics Board of Ningde Municipal Hospital (Approval No: NSYKYLL-2024-105), and the study was conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived by the aforementioned ethics committee due to the retrospective nature of the study, which involved anonymized analysis of existing medical records without additional interventions. All data were handled in compliance with patient confidentiality guidelines. The sample size was determined using the chi-square test for contingency tables in PASS 2021 software (NCSS LLC). Calculations were based on the following parameters: therapeutic effectiveness rate [ 8 ]: 65% (non-surgical group), 100% (laparoscopic group), and 100% (open surgery group); type I error rate (α): 0.05 (two-tailed); statistical power (1– β): 0.80. The sample size formula was applied as: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N = \frac{\lambda }{{{W^2}}}$$\end{document} where N is the total sample size, λ is the non-centrality parameter derived from the chi-square distribution, and W is the effect size calculated by: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$W = \sqrt {\sum\limits_{i = 1}^k {\frac{{{{({p_i} - \bar p)}^2}}}{{\bar p(1 - \bar p)}}} } $$\end{document} with p i representing the proportion of each group and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar p$$\end{document} the weighted average proportion. For the specified proportions (65%, 100%, 100%), the weighted average proportion \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\bar p$$\end{document} was 0.887 (assuming equal group sizes). Substituting these values yielded an effect size W  = 0.514. The required total sample size was N  = 111, corresponding to 37 patients per group. Clinical diagnosis of pelvic abscesses remains challenging under current PID management guidelines [ 9 , 10 ], with delayed treatment increasing risks of long-term sequelae. A three-tiered diagnostic framework was implemented: (1) Minimum diagnostic criteria: uterine or adnexal tenderness, cervical motion tenderness, or lower genital tract infection. (2) Additional criteria: high fever (oral temperature exceeding 38.3 °C); mucopurulent cervical or vaginal discharge; elevated white blood cells (WBC) in vaginal secretions; increased erythrocyte sedimentation rate; elevated C-reactive protein (CRP) levels; positive laboratory tests for Neisseria gonorrhoeae or Chlamydia. (3) Specific criteria: transvaginal ultrasound or MRI showing fallopian tube wall thickening, luminal effusion, pelvic free fluid, or tubo-ovarian mass; laparoscopic evidence of tubal surface congestion, tubal edema, fimbrial or serosal purulent exudate, or other inflammatory changes. Final diagnoses required histological confirmation from surgical specimens or intraoperative findings. Data extraction followed standardized protocols: (1) Two independent researchers blinded to outcomes reviewed electronic medical records (EMRs) to identify documented signs, laboratory results, and imaging/pathology reports. (2) Discrepancies underwent third-party adjudication by a multidisciplinary panel using raw imaging/pathology data. (3) Cases with incomplete records or ambiguous imaging descriptions were excluded to mitigate recall and documentation bias. This approach aligns with RECORD guidelines [ 11 ] for retrospective observational studies, balancing diagnostic specificity with methodological transparency. Cervical secretion cultures and blood cultures (for febrile patients with high fever) were obtained at admission. Third-generation cephalosporins were administered intravenously initially [ 12 ]. For patients with cephalosporin allergies, quinolone antibiotics were substituted, and medications were adjusted based on culture results [ 13 ]. Persistent fever, lack of improvement in symptoms, or an increase in the mass after 48–72 h of therapy indicated ineffective treatment [ 14 ]. Patients unresponsive to medical treatment or experiencing abscess rupture underwent surgical intervention (laparoscopic or open approach). Clinical signs of abscess rupture included sudden exacerbation of abdominal pain, distension, chills, high fever, nausea, vomiting, guarding during examination, or symptoms of infectious toxic shock. The decision to perform laparoscopy or open surgery was based on comprehensive preoperative and intraoperative evaluations. (1) Surgical history and adhesion severity: Patients with dense pelvic adhesions (particularly bowel-uterine adhesions) from prior surgeries underwent open procedures; (2) Lesion characteristics: Complex abscesses (> 10 cm diameter, bilateral involvement, or proximity to critical structures) favored open approaches; (3) Systemic status: Severe cardiopulmonary dysfunction or coagulopathy contraindicated laparoscopy. Intraoperatively, conversion to open surgery occurred for uncontrolled bleeding, unanticipated extensive adhesions, or suspected malignancy. A laparoscopy-first strategy was prioritized in most cases, with successful completion in > 80% of patients. Patient-specific factors including age, fertility preservation needs (conservative cystectomy for younger patients), and menopausal status (definitive hysterectomy with bilateral salpingo-oophorectomy for older/recurrent cases) further guided surgical planning. This tiered decision-making framework balanced minimally invasive advantages with anatomical safety, maintaining a 5–8% conversion rate to open surgery while optimizing outcomes (Supplementary Figure S1 ). In the laparoscopic group, patients underwent laparoscopic exploration under general anesthesia in the lithotomy position. A 10-mm vertical umbilical incision was made to insert an insufflation needle for establishing pneumoperitoneum (intra-abdominal pressure maintained at 12–14 mmHg). The operating table was then adjusted to the Trendelenburg position (head-down tilt) to optimize pelvic exposure. A laparoscope was introduced through the infraumbilical port, followed by placement of four additional trocars: two 5-mm ports at the left lower quadrant and left McBurney’s point, and two 10-mm ports at the right McBurney’s point and suprapubic region. Pelvic and abdominal exploration was performed using an ultrasonic scalpel or irrigator to dissect adhesions among the pelvic wall, intestines, ovaries, omentum, uterus, and fallopian tubes. Abscesses were exposed, and purulent material was aspirated via needle puncture or electrocoagulation-induced capsulotomy. Surgical interventions, including unilateral salpingo-oophorectomy or salpingectomy (unilateral or bilateral), were selected based on fertility requirements and lesion characteristics. The table was subsequently repositioned to the reverse Trendelenburg position (head-up tilt) for thorough saline irrigation, followed by routine drainage tube placement. Intraoperatively collected pus was sent for pathological culture and antibiotic sensitivity testing. In the open surgery group, patients underwent traditional laparotomy under general anesthesia with supine positioning. A 6–10 cm midline vertical incision was created two fingerbreadths above the pubic symphysis. Adhesions were manually dissected to expose abscesses, which were drained using aspiration or electrocoagulation. Similar to the laparoscopic group, unilateral adnexectomy or salpingectomy was performed as indicated. The abdominal cavity was irrigated with saline, and a drainage tube was routinely placed before layered closure of the abdominal wall. Ultrasound parameters included: unilateral/bilateral abscess, internal echo characteristics (mixed/ hypoechoic), maximum mass diameter (mm), mass boundary (clear/unclear), mass morphology (regular/irregular), Color Doppler flow imaging (CDFI, categorized as no significant flow, spot-like, short bar-like, or rich flow), and contents (dense punctate/other). Surgical metrics comprised operative time, intraoperative blood loss, and surgery-related complications. Postoperative factors encompassed abdominal pain relief duration (the duration until abdominal pain completely resolved), time for WBC normalization (the period required for the postoperative WBC count to recover to the normal range), antibiotic use duration (the total time period from the beginning of antibiotic use to the end of use), and length of hospital stay (the total postoperative hospitalization time of the patients). Patients were stratified into three treatment groups: non-surgical, laparoscopic, and open surgery. Continuous variables were presented as mean ± standard deviation and compared between two groups using independent samples t-tests after verifying normality and homogeneity of variances. For non-normally distributed data or unequal variances, Welch’s t-test or Mann-Whitney U test were applied. Categorical variables, expressed as counts (percentages), were analyzed with chi-squared tests when expected frequencies ≥ 5; otherwise, Fisher’s exact test was employed. For intergroup comparisons across three groups (non-surgical, laparoscopic, open surgery), one-way analysis of variance (ANOVA) with Tukey’s HSD post hoc test was used for normally distributed data, Kruskal-Wallis test with Dunn’s correction for non-parametric data, and Benjamini-Hochberg correction for categorical data. Cohen’s d was computed to quantify the standardized mean difference between groups. Effect sizes were interpreted as small (0.2 ≤| d| < 0.5), medium (0.5 ≤| d| < 0.8), or large (| d| ≥ 0.8) based on Cohen’s criteria. Multivariate linear regression was used to analyze risk factors of abdominal pain relief time, the duration of antibiotic use, and length of hospital stay. All statistical analyses were performed using SAS software version 9.4 (SAS Institute Inc., Cary, NC, USA). Two-tailed P  value < 0.05 was considered as statistical significance.

Among 127 patients, the duration from onset to admission was longest in the laparoscopic group and shortest in the non-surgical group ( P  = 0.0003). Significant differences were observed in WBC count ( P  < 0.0001), NEUT count ( P  < 0.0001), and CRP levels ( P  = 0.0150), with the open surgery group demonstrating the highest NEUT and PCT values, while the laparoscopic group exhibited the lowest. No significant differences occurred in platelet (PLT) count ( P  = 0.3817) or medical histories, including intrauterine device use, abortion, endometriosis, previous PID, cesarean section, or cervical secretion culture results (all P  > 0.05). Pre-admission temperature was highest in the open surgery group ( P  < 0.0001; Table  1 ). The Cohen’s d values for between-group differences in these metrics are presented in Supplementary Table S2 . With the exception of PLT, most Cohen’s d values for the remaining metrics exceeded 0.5, indicating medium to large effect sizes. Table 1 Baseline characteristics of 127 patients in hospital admission Non-surgical group ( N  = 51) Laparoscopic group ( N  = 44) Open surgery group ( N  = 32) P Age (years) 37.51 ± 3.54 37.47 ± 1.81 38.80 ± 4.27 0.3766 Number of deliveries ( n ) 1.38 ± 0.36 1.40 ± 0.50 1.29 ± 0.24 0.4611 Duration from onset to hospital admission (Days) 3.32 ± 4.18 7.70 ± 4.97 * 5.51 ± 6.46 #^ 0.0003 WBC (×10 9 /L) 9.86 ± 0.62 14.09 ± 4.80 * 10.56 ± 5.87 # < 0.0001 NEUT (%) 85.08 ± 2.65 82.83 ± 1.76 86.21 ± 1.40 ^ < 0.0001 CRP (mg/L) 164.43 ± 45.53 165.83 ± 39.14 141.03 ± 30.41 #^ 0.0150 PLT (×10 9 /L) 299.86 ± 113.09 332.40 ± 130.16 296.69 ± 154.31 0.3817 CA125 (U/mL) 67.08 ± 13.52 73.01 ± 13.99 * 85.20 ± 16.77 #^ < 0.0001 PCT (ng/mL) 0.27 ± 0.07 0.25 ± 0.06 0.35 ± 0.08 #^ < 0.0001 Pre-admission temperature (℃) 38.69 ± 0.40 38.23 ± 0.21 * 38.93 ± 0.32 #^ < 0.0001 Intrauterine device ( n , %) 0.1863  Yes 10 (19.61) 3 (6.82) 3 (9.38)  No 41 (80.39) 41 (93.18) 29 (90.63) History of abortion ( n , %) 0.0994  Yes 43 (84.31) 29 (65.91) 26 (81.25)  No 8 (15.69) 15 (34.09) 6 (18.75) History of endometriosis ( n , %) 1.0000  Yes 3 (5.88) 3 (6.82) 2 (6.25)  No 48 (94.12) 41 (93.18) 30 (93.75) History of pelvic inflammatory disease. ( n , %) 0.8389  Yes 8 (15.69) 9 (20.45) 6 (18.75)  No 43 (84.31) 35 (79.55) 26 (81.25) History of cesarean section. ( n , %) 0.8094  Yes 4 (7.84) 5 (11.36) 4 (12.50)  No 47 (92.16) 39 (88.64) 28 (87.50) Cervical secretions culture ( n , %) 0.8638  Positive 5 (9.80) 5 (11.36) 2 (6.25)  Negative 46 (90.20) 39 (88.64) 30 (93.75) Continuous variables were described as mean ± standard deviation, and categorical variables were expressed as number (percentage). WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin * P  < 0.05, significantly different from the non-surgical group; # P  < 0.05, significantly different from the non-surgical group; ^ P  < 0.05, significantly different from the laparoscopic group Baseline characteristics of 127 patients in hospital admission Continuous variables were described as mean ± standard deviation, and categorical variables were expressed as number (percentage). WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin * P  < 0.05, significantly different from the non-surgical group; # P  < 0.05, significantly different from the non-surgical group; ^ P  < 0.05, significantly different from the laparoscopic group Initial ultrasound assessments revealed non-surgical patients had higher rates of unilateral abscesses ( P  = 0.0464), smaller maximum mass diameters ( P  = 0.0008), and more frequent intact capsules ( P  = 0.0087). Regular mass morphology predominated in non-surgical cases ( P  = 0.0252). Internal echo patterns, mass boundary clarity, CDFI, and internal contents showed no intergroup differences (all P  > 0.05; Table  2 ). Table 2 The ultrasound and prognostic factors of abscesses in three groups Non-surgical group ( N  = 51) Laparoscopic group ( N  = 44) Open surgery group ( N  = 32) P Ultrasound  Location of abscesses ( n , %) 0.0464   Unilateral 29 (56.86) 15 (34.09) * 11 (34.38) #   Bilateral 22 (43.14) 29 (65.91) 21 (65.63)  Internal echo ( n , %) 0.7893   Mixed 17 (33.33) 13 (29.55) 12 (37.50)   Hypoechoic 34 (66.67) 31 (70.45) 20 (62.50)  Maximum diameter of mass (mm) 71.17 ± 31.05 91.51 ± 30.68 * 93.98 ± 29.72 # 0.0008  Boundary ( n , %) 0.1644   Clear 31 (60.78) 19 (43.18) 14 (43.75)   Unclear 20 (39.22) 25 (56.82) 18 (56.25)  Morphology ( n , %) 0.0252   Regular 34 (66.67) 19 (43.18) * 13 (40.63) #   Irregular 17 (33.33) 25 (56.82) 19 (59.38)  Integrity of the mass’s capsule ( n , %) 0.0087   Complete 32 (62.75) 17 (38.64) * 10 (31.25) #   Incomplete 19 (37.25) 27 (61.36) 22 (68.75)  CDFI ( n , %) 0.4993   No significant blood flow 26 (50.98) 17 (38.64) 14 (43.75)   Spot-like, short bar-like, or rich blood flow 25 (49.02) 27 (61.36) 18 (56.25)  Contents ( n , %) 0.0562   Dense punctate 22 (43.14) 23 (52.27) 8 (25.00)   Other 29 (56.86) 21 (47.73) 24 (75.00) Prognostic factors  Abdominal pain relief time (Days) 6.48 ± 1.30 2.24 ± 0.96 * 3.97 ± 2.44 #^ < 0.0001  Time for WBC normalization (Days) 3.65 ± 1.11 2.91 ± 1.94 3.55 ± 1.62 0.0600  The duration of antibiotic use (Days) 10.45 ± 2.28 6.85 ± 1.17 * 7.75 ± 1.65 #^ < 0.0001  Length of hospital stay (Days) 14.38 ± 3.56 7.87 ± 3.04 * 10.67 ± 4.62 #^ < 0.0001 Continuous variables were described as mean ± standard deviation, and categorical variables were expressed as number (percentage). CDFI = Color Doppler Flow Imaging * P  < 0.05, significantly different from the non-surgical group; # P  < 0.05, significantly different from the non-surgical group The ultrasound and prognostic factors of abscesses in three groups Continuous variables were described as mean ± standard deviation, and categorical variables were expressed as number (percentage). CDFI = Color Doppler Flow Imaging * P  < 0.05, significantly different from the non-surgical group; # P  < 0.05, significantly different from the non-surgical group Laparoscopic procedures demonstrated superior surgical outcomes compared to open surgery, with significantly shorter operative times (85.58 ± 10.48 vs. 126.74 ± 12.71 min; P  < 0.0001) and reduced intraoperative blood loss (62.52 ± 9.41 vs. 88.94 ± 13.97 mL; P  < 0.0001). The incidence of surgical complications showed no significant intergroup difference (0.00% vs. 9.38%; P  = 0.0706). Open surgery cases included one ureteral injury and two intestinal injuries (Table  3 ). Table 3 Comparison of surgical parameters between laparoscopic and open surgery groups Laparoscopic group ( N  = 44) Open surgery group ( N  = 32) P Operative time (min) 85.58 ± 10.48 126.74 ± 12.71 < 0.0001 Intraoperative blood loss (mL) 62.52 ± 9.41 88.94 ± 13.97 < 0.0001 Surgery-related complications ( n , %) 0 (0.00) 3 (9.38) 0.0706 Comparison of surgical parameters between laparoscopic and open surgery groups Results of prognostic outcome indicators demonstrated that the non-surgical group exhibited significantly prolonged time to relieve abdominal pain compared to both the laparoscopic and open surgery groups ( P  < 0.0001). No significant intergroup difference was observed in the time for WBC normalization ( P  = 0.0600). The non-surgical group also had longer duration of antibiotic use compared to both the open surgery and laparoscopic groups ( P  < 0.0001), and a longer length of hospital stay compared to the laparoscopic group ( P  < 0.0001) (Table  2 ). The Cohen’s d values for between-group differences in these metrics are presented in Supplementary Table S2 . With the exception of time for WBC normalization, all Cohen’s d values for the remaining metrics exceeded 0.5, indicating medium to large effect sizes. Thus, multivariable linear regression analyses were conducted on prognostic indicators in abdominal pain relief time, the duration of antibiotic use, and length of hospital stay. The analysis of abdominal pain relief time indicated that it increased with a longer duration from onset to admission ( β  = 0.090, P  = 0.0194), higher serum CA125 levels ( β  = 0.035, P  = 0.0036), elevated pre-admission temperature ( β  = 1.392, p  = 0.0062), and larger maximum mass diameter ( β  = 0.008, P  = 0.0431). Patients with regular abscess morphology experienced shorter pain relief times compared to those with irregular shapes ( P  = 0.0109). Abdominal pain relief time was 4.349 days shorter in the laparoscopic group and 2.370 days shorter in the open surgery group than in the non-surgical group (both P  < 0.0001; Table  4 ). Table 4 Analysis of risk factors for the abdominal pain relief time β Standard error t P Intercept -49.469 0 -2.62 0.0101 Age (years) 0.033 0.044 0.55 0.5837 Duration from onset to hospital admission (Days) 0.090 0.201 2.37 0.0194 WBC (×10 9 /L) -0.075 -0.139 -1.71 0.0908 NEUT (%) 0.036 0.037 0.41 0.6832 CRP (mg/L) 0.003 0.057 0.71 0.4787 CA125 (U/mL) 0.035 0.236 2.97 0.0036 PCT (ng/mL) 2.026 0.066 0.76 0.4477 Pre-admission temperature (℃) 1.392 0.245 2.79 0.0062 Location of abscesses  Unilateral 0.000  Bilateral 0.674 0.138 1.77 0.0797 Maximum diameter of mass (mm) 0.008 0.019 1.99 0.0431 Morphology of mass  Regular 0.000  Irregular 0.980 0.203 2.59 0.0109 Integrity of the mass’s capsule  Complete 0.000  Incomplete 0.714 0.148 1.86 0.0657 Treatment modality  Non-surgical 0.000  Laparoscopic -4.349 -0.857 -8.70 < 0.0001  Open surgery -2.370 -0.426 -4.50 < 0.0001 WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin Analysis of risk factors for the abdominal pain relief time WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin The analysis of antibiotic use duration revealed that it increased with a longer duration from onset to admission ( β  = 0.072, P  = 0.0377), elevated WBC levels ( β  = 0.131, P  = 0.0046), higher serum CA125 levels ( β  = 0.035, P  = 0.0047), elevated pre-admission temperature ( β  = 1.097, P  = 0.0408), and larger maximum mass diameter ( β  = 0.010, P  = 0.0364). Antibiotic use time was 3.160 days shorter in the laparoscopic group and 3.258 days shorter in the open surgery group than in the non-surgical group (both P  < 0.0001; Table  5 ). Table 5 Analysis of risk factors for the duration of antibiotic use β Standard error t P Intercept -26.830 0 -1.37 0.1720 Age (years) -0.052 -0.070 -0.84 0.4003 Duration from onset to hospital admission (Days) 0.072 0.162 2.12 0.0377 WBC (×10 9 /L) 0.133 0.247 2.94 0.0040 NEUT (%) 0.025 0.026 0.28 0.7820 CRP (mg/L) 0.004 0.075 0.90 0.3722 CA125 (U/mL) 0.035 0.234 2.87 0.0047 PCT (ng/mL) 2.296 0.075 0.84 0.4046 Pre-admission temperature (℃) 1.097 0.172 2.07 0.0408 Location of abscesses  Unilateral 0.000  Bilateral 0.431 0.089 1.10 0.2753 Maximum diameter of mass (mm) 0.010 0.019 2.01 0.0364 Morphology of mass  Regular 0.000  Irregular 0.680 0.141 1.74 0.0846 Integrity of the mass’s capsule  Complete 0.000  Incomplete 0.502 0.104 1.27 0.2080 Treatment modality  Non-surgical 0.000  Laparoscopic -3.160 -0.626 -5.59 < 0.0001  Open surgery -3.258 -0.589 -5.47 < 0.0001 WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin Analysis of risk factors for the duration of antibiotic use WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin The analysis of length of hospital stay showed that it increased with a longer duration from onset to admission ( β  = 0.157, P  = 0.0428), higher serum CA125 levels ( β  = 0.072, P  = 0.0034), elevated pre-admission temperature ( β  = 3.028, P  = 0.0032), and larger maximum mass diameter ( β  = 0.022, P  = 0.0241). Length of hospital stays were 6.572 days shorter in the laparoscopic group and 3.250 days shorter in the open surgery group than in the non-surgical group ( P  < 0.0001 and P  = 0.0091, respectively; Table  6 ). Table 6 Analysis of risk factors for the length of hospital stay β Standard error t P Intercept -104.824 0 -2.75 0.0069 Age (years) 0.150 0.106 1.24 0.2163 Duration from onset to hospital admission (Days) 0.157 0.183 2.05 0.0428 WBC (×10 9 /L) -0.122 -0.118 -1.38 0.1697 NEUT (%) -0.031 -0.016 -0.17 0.8649 CRP (mg/L) 0.011 0.094 1.12 0.2672 CA125 (U/mL) 0.072 0.250 2.99 0.0034 PCT (ng/mL) 3.457 0.059 0.64 0.5203 Pre-admission temperature (℃) 3.028 0.279 3.01 0.0032 Location of abscesses  Unilateral 0.000  Bilateral 0.886 0.095 1.15 0.2516 Maximum diameter of mass (mm) 0.022 -0.046 2.35 0.0241 Morphology of mass  Regular 0.000  Irregular 1.361 0.147 1.78 0.0774 Integrity of the mass’s capsule  Complete 0.000  Incomplete -0.090 -0.010 -0.12 0.9073 Treatment modality  Non-surgical 0.000  Laparoscopic -6.572 -0.678 -5.66 < 0.0001  Open surgery -3.250 -0.306 -2.66 0.0091 WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin Analysis of risk factors for the length of hospital stay WBC = White blood cell, NEUT = Neutrophils, CRP = C-Reactive Protein, PLT = Platelets, CA125 = Cancer Antigen 125, PCT = Procalcitonin

Our study highlighted critical differences in clinical outcomes among laparoscopic, open surgery, and non-surgical groups for pelvic abscess management. Notably, the laparoscopic group demonstrated superior outcomes, including reduced surgical time, blood loss, and shorter recovery times compared to non-surgical approaches. Prognostic factors such as admission interval, CA125 levels, and mass diameter further emphasized the importance of timely surgical intervention in severe cases. Pelvic abscess pathogenesis primarily originates from reproductive tract infections, iatrogenic surgical complications, and immunocompromised states [ 1 ]. High-risk factors for postoperative pelvic abscesses are classified into three categories, included preoperative (e.g., hydrosalpinx, endometriosis), intraoperative (e.g., blood loss > 500 mL, operative time > 140 min), and postoperative (e.g., prolonged pelvic/abdominal lavage, inadequate antibiotic prophylaxis) [ 15 ]. In this study, the laparoscopic group demonstrated significantly shorter operative time and reduced intraoperative blood loss compared to the open surgery group, which may be attributed to variations in surgical timing, technique complexity, and operator expertise — consistent with prior studies [ 16 , 17 ]. Although no significant intergroup difference emerged in overall incidence of surgery-related complications, all three complications occurred in the open surgery group, potentially due to severe pelvic adhesions or surgeon experience. Nonetheless, the safety profiles of both laparoscopic and open surgery procedures were acceptable. Laparoscopic approach achieves rapid inflammatory control, alleviates pain, shortens the disease course, and reduces pelvic inflammatory sequelae, thereby improving fertility outcomes [ 16 ]. Compared to open surgery, laparoscopy provides superior operative field visualization, minimized blood loss, reduced bowel injury risk, and lower surgical site infection rates. The laparoscopic procedure demonstrates minimally invasive advantages, involving small incisions, minimal surgical trauma, rapid recovery, short length of hospital stay, and rare instances of secondary surgeries, complications, or in-hospital deaths, establishing it is now widely preferred by clinicians [ 7 ]. In laboratory tests, WBC, NEUT, CRP, PLT, CA125, and PCT were elevated across all groups, with significant intergroup differences, indicating systemic inflammatory response. These findings suggested that most patients were in acute infection phase at admission, with elevated WBC, PLT, CRP, and CA125 levels aligning with previous study [ 18 ]. Intergroup variations likely reflect greater disease severity in surgical group [ 19 ]. CRP, produced by hepatocytes, indicates tissue and cell damage following bacterial infection. Its levels increase in response to infections but are less sensitive than PCT [ 20 ]. PCT, a precursor of calcitonin, serves as a marker for early bacterial infections [ 21 ]. CRP levels were elevated in the conservative and laparoscopic groups but reduced in the open surgery group, supporting its diagnostic utility in early stages of disease but not advanced pelvic abscesses. PCT was highest in the laparoscopic group, suggesting its value in diagnosing infections at specific stages. CA125, a glycoprotein originally used as a tumor marker for ovarian cancer, also increases in inflammatory conditions [ 22 ]. This study observed CA125 elevation proportional to inflammatory severity, potentially reflecting preoperative peritoneal involvement extent [ 23 ]. The prognosis for patients with pelvic abscess depends on disease severity, prompt treatment, and response to initial therapy. Spontaneous rupture into the rectum may relieve symptoms, whereas rupture into the abdominal cavity can lead to life-threatening peritonitis, requiring urgent surgical intervention and intensive monitoring [ 24 ]. Prognostic factors (abscess size, treatment modality, and serum CA125 levels) guide risk-stratified management: abscesses ≥ 5.5 cm exhibit a 5.7-fold higher surgical requirement versus smaller lesions (OR = 5.742, 95% CI: 2.025–16.182) [ 25 ], while elevated CA125 correlates with abscess severity and peritoneal inflammation but requires MRI-DWI integration to enhance diagnostic specificity [ 26 ]. Surgery timing critically affects outcomes—early intervention (within 48–72 h of failed antibiotics) facilitates adhesion separation and reduces surgical risks [ 27 ], whereas delayed cases correlate with dense adhesions, increasing hemorrhage and iatrogenic injury risks that impair fertility [ 28 ]. This study observed no intergroup difference in WBC normalization time, confirming all modalities’ efficacy for appropriately selected cases. However, laparoscopy achieved the shortest abdominal pain relief duration, antibiotic use, and hospital stay, underscoring its role as the preferred approach when surgically timed. Current guidelines advocate laparoscopic drainage for large/complex abscesses and conservative management for low-risk cases, optimizing fertility preservation and clinical outcomes [ 29 ]. The current study highlights critical prognostic factors and treatment outcomes in pelvic abscess management, yet further investigations could refine therapeutic strategies by exploring the following directions. (1) Biomarker-driven prognostic models: While serum CA125 and inflammatory cytokines are established biomarkers for pelvic abscess severity and malignancy risk, their combined use requires validation in diverse populations [ 30 ]. Future studies should explore multi-marker panels (e.g., CA125 + inflammatory cytokines) to improve diagnostic accuracy. (2) Timing of surgical intervention: Although laparoscopic surgery offers advantages in reduced operative time and blood loss compared to open procedures, the therapeutic window remains unclear. Current evidence suggests early intervention (< 7 days post-antibiotic initiation) improves outcomes, while delayed surgery may benefit patients with persistent inflammation [ 31 ]. Randomized trials comparing “early” versus “delayed” strategies, guided by biomarkers like CA125, are warranted. (3) Cost-effectiveness of minimally invasive techniques: Despite robotic-assisted laparoscopy reduces recovery time [ 32 ], its economic viability in resource-limited settings remains unproven. Comparative studies evaluating laparoscopy versus open surgery in terms of long-term recurrence rates and healthcare costs are critical. This study has three principal limitations that warrant careful interpretation. First, study design limitations. The retrospective nature introduces information bias, particularly regarding surgical technique documentation (e.g., adhesion severity grading inconsistencies). This may underestimate non-surgical failure rates and overestimate laparoscopic advantages compared to open surgery. Future prospective studies should implement standardized intraoperative documentation protocols. Second, data-related limitations. (a) Unmeasured confounders, including surgeon experience and socioeconomic factors (insurance type unavailable) may bias results, particularly as open surgery cases likely involved higher-risk patients (e.g., severe adhesions), inflating perceived laparoscopic advantages. (b) The lack of subgroup analyses due to sample size constraints limits our ability to explore heterogeneous treatment responses across clinically relevant patient subgroups. Multi-center collaborations could address these through standardized data collection. Third, generalizability constraints. (a) Over the 5-year study period, advancements in surgical instrumentation, perioperative care, and surgeon expertise disproportionately benefited later patients, obscuring the true prognostic impact of surgical methods. (b) The extended study period and advancements in gynecologic surgical techniques complicate the standardization of surgical methods, impeding a thorough assessment of their impact on prognosis between the laparoscopic and open surgery groups. (c) The study’s follow-up period was insufficient, which undermines the evidence for estimating pelvic abscess prognosis. Therefore, prospective studies with larger sample sizes or alternative study designs could provide more definitive evidence to supplement and validate these findings.

The treatment modality is the primary factor influencing the prognosis of pelvic abscesses, with surgical intervention demonstrating superior outcomes to non-surgical management, and laparoscopic approaches outperforms the open surgery. Key prognostic indicators include the duration from onset to admission, maximum mass diameter, WBC, CA125 levels, and pre-admission temperature. These findings underscore the prognostic value of early intervention, biomarker-guided decision-making, and minimally invasive approaches in pelvic abscess management. By identifying these factors, healthcare providers could effectively stratify patients based on their risk profiles, facilitating more personalized treatment strategies and improved prognostic outcomes.

Pelvic abscess, a severe complication of pelvic inflammatory disease (PID), poses significant challenges in clinical management due to its heterogeneous manifestations and variable treatment outcomes [ 1 ]. Current guidelines recommend antibiotic therapy as the first-line treatment, yet the reported efficacy of conservative treatment ranges widely from 16 to 95% [ 2 ], reflecting substantial variability in patient responses. This disparity is partly attributed to inconsistent selection criteria for invasive interventions. For instance, the 2016 European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) highlighted that abscess diameter > 5 cm often necessitates surgical intervention [ 3 ], while the 2020 updated French PID guidelines suggested initiating drainage for abscesses exceeding 3–4 cm [ 4 ]. Such discrepancies underscore the critical need for evidence-based prognostic indicators to guide individualized therapeutic strategies. Treatments for pelvic abscesses exhibit considerable individual variability. Conservative measures are appropriate for patients with mild symptoms, whereas surgical intervention is indicated for severe cases or treatment failures. Notable variability exists in inflammatory markers among patients with differing infection severities [ 5 ]. However, no consensus currently delineates an optimal treatment strategy to minimize complications. Early diagnosis and intervention are critical, as the timing and success of conservative and surgical treatments are closely correlated with individual patient factors [ 6 ]. The evolving landscape of pelvic abscess management reveals two unresolved controversies. First, while imaging-guided drainage demonstrates comparable efficacy to traditional surgery with lower complication rates [ 7 ], its adoption remains limited by the absence of standardized criteria for procedure selection. Second, inflammatory biomarkers such as C-reactive protein (CRP) and procalcitonin (PCT) show promise in predicting treatment failure [ 5 ]. However, these markers are not systematically integrated into current decision-making algorithms. This study aims to identify key prognostic factors, including abscess morphology, inflammatory dynamics, and intervention timing, that influence treatment outcomes in patients with pelvic abscesses. We hypothesize that: (1) irregular abscess morphology increases abdominal pain resolution time, (2) elevated CA125 predicts extended antibiotic requirement, and (3) delayed intervention correlates with prolonged hospitalization. Through retrospective analysis of pretreatment characteristics and therapeutic outcomes, these findings will provide actionable insights into personalized decision-making, potentially reducing unnecessary procedures in antibiotic-responsive cases while prioritizing early invasive approaches for high-risk populations.

Below is the link to the electronic supplementary material. Supplementary Material 1 Supplementary Material 1