Percutaneous vs surgical management of World Health Organization cystic echinococcosis 1 and 3a liver hydatid cysts

Abstract

BACKGROUND

Hydatid cyst disease of the liver remains a significant public health problem in endemic regions. While surgical treatment has traditionally been the mainstay of therapy, minimally invasive percutaneous approaches have emerged as safe and effective alternatives, especially for selected World Health Organization (WHO) cystic echinococcosis (CE) 1 and CE3a cysts. Comparative data on efficacy, complication rates, and clinical outcomes between the two methods are essential for guiding optimal treatment selection.

AIM

To compare and evaluate the efficacy, safety, complication rates, and clinical course of WHO CE1 and CE3a liver hydatid cysts treated with surgical and percutaneous methods.

METHODS

A total of 989 patients diagnosed with liver hydatid cyst and treated either surgically (n = 734) or percutaneously (n = 255) between 2005 and 2025 were included in the study. Demographic data, treatment process, complications, and recurrence rates of the retrospectively evaluated patients were recorded. Cyst volume, hospital stay duration, and catheter removal times were compared. Cases with and without fistula development were also analyzed separately.

RESULTS

There was no significant difference between the surgical (n = 734) and percutaneous (n = 255) groups in terms of gender (female: 76.0% vs 72.2%; P = 0.250) and age (38.4 ± 15.9 years vs 38.1 ± 16.1 years; P = 0.800), respectively. Operation time (85.6 ± 34.5 minutes vs 40.3 ± 15.7 minutes; P < 0.001), hospital stay duration (7.3 ± 6.2 days vs 3.1 ± 2.3 days; P < 0.001), catheter removal time (6.6 ± 5.3 days vs 5.5 ± 6.4 days; P = 0.014), and intraoperative organ injury rate (2.7% vs 0%; P = 0.002) were significantly longer/higher in the surgical group compared to the percutaneous group. Recollection was significantly more frequent in the percutaneous group (4.7% vs 1.2%; P = 0.001), as was anaphylaxis (1.6% vs 0.3%; P = 0.041). The rate of cysto-biliary fistula was similar in both groups [surgical 14.6% (n = 113), percutaneous 14.9% (n = 43); P = 0.902]. However, in patients with fistula, catheter removal time (surgical: 8.3 ± 4.9 days vs 5.9 ± 2.7 days and percutaneous: 17.8 ± 8.7 days vs 3.5 ± 2.9 days; P < 0.001) and initial cyst volumes (surgical: 774.8 ± 513.2 mL vs 356.7 ± 95.6 mL and percutaneous: 700.9 ± 288.2 mL vs 346.5 ± 279.2 mL; P < 0.001) were significantly higher compared to those without fistula.

CONCLUSION

For treatment of WHO CE1 and CE3a liver cysts, the percutaneous approach is a safe and effective method due to shorter hospital stays, minimal invasiveness, and negligible risk of intraoperative organ injury, whereas surgical methods appear marginally advantageous regarding recollection and anaphylaxis. In both groups, higher cyst volume increases the risk of fistula and may prolong the treatment process. Patient selection should consider these parameters.

Key Words: Hydatid cyst; Liver echinococcosis; Percutaneous drainage; Surgery; Biliary fistula; Recurrence; Complication; World Health Organization classification; Puncture, aspiration, injection, and re-aspiration; Endemic region

Core Tip: This large-scale, retrospective study compares percutaneous and surgical treatments for World Health Organization cystic echinococcosis (CE) 1 and CE3a liver hydatid cysts over a 20-year period. Based on real-world data from an endemic region, the study highlights the safety and efficacy of percutaneous approaches, while also showing slightly lower recollection rates with surgery. Notably, the findings suggest that higher cyst volume increases the risk of fistula formation and prolongs treatment, regardless of the method used. These insights can help guide personalized treatment decisions and emphasize the need for standardizing follow-up protocols and recurrence definitions in future studies.

INTRODUCTION

Hydatid disease is an endemic zoonotic infection caused by the larval stage of Echinococcus granulosus and remains a major public health problem in regions such as the Mediterranean basin, the Middle East, and South America[1]. Cystic echinococcosis (CE) is classified according to the World Health Organization (WHO) criteria, which distinguish active cysts requiring treatment from inactive ones (CE4 and CE5). Even asymptomatic viable cysts should be treated because of the risk of life-threatening complications[2,3]. Surgery has traditionally been the mainstay of treatment, but percutaneous techniques such as puncture, aspiration, injection, and re-aspiration (PAIR) and catheter drainage have emerged[4-7]. The growing adoption of minimally invasive management, studies directly comparing long-term outcomes of surgical and percutaneous treatment remain limited, and consensus on recurrence rates is lacking.

As part of the HERACLES project, which investigates the burden of CE in endemic regions, Sanliurfa in southeastern Turkey has been identified as an important data center[8]. In this study, we deliberately included only WHO CE1 and CE3a cysts, as these are the most commonly encountered types in daily clinical practice and are the most amenable to percutaneous interventions. Their predominantly unilocular, fluid-filled morphology facilitates safe puncture and complete evacuation during PAIR or catheter-based techniques. In contrast, CE2 and CE3b cysts often contain multiple daughter cysts or partially detached membranes, which complicate drainage, reduce procedural success, and increase the risk of recurrence or recollection. This study compares surgical and percutaneous management of CE1 and CE3a liver hydatid cysts in this high-prevalence region, evaluating complications, hospital stay, and recurrence to address a major evidence gap in the literature.

MATERIALS AND METHODS

Patient data

This retrospective study was conducted at the largest tertiary referral hospital in Sanliurfa, a province located in southeastern Türkiye, where hydatid cyst disease is endemic. The study included patients diagnosed with hepatic hydatid cysts between July 2005 and September 2025. Patients who had received only medical treatment were excluded, underwent surgery for CE2 or CE3b cysts, had ruptured cysts, lacked accessible medical records, or were younger 18 years of age. Only patients with CE1 or CE3a cysts who underwent surgical or percutaneous treatment and had available follow-up data were included in the analysis.

Demographic data (age and sex), cyst type and size, pre- and post-treatment cyst volumes, occurrence of major and minor complications, presence of cysto-biliary fistula, catheter removal time, length of hospital stay, recurrence or recollection status, and treatment modality were obtained from electronic medical records. Patients were categorized and compared based on the presence or absence of fistula formation and the type of treatment received (surgery vs percutaneous).

Percutaneous treatment technique

All patients received oral albendazole tablets (10 mg/kg/day) for at least two weeks prior to the procedure to prevent intraperitoneal dissemination and recurrence[9]. All procedures were performed under general anesthesia in an operating room environment due to the risk of anaphylactic shock. The standard catheterization technique described by Akhan et al[10] was used for percutaneous treatment. Procedures were performed using the Seldinger technique under ultrasound (US) and fluoroscopic guidance. To prevent intraperitoneal dissemination, a minimum of 1 cm of normal liver tissue was traversed[11]. Under US guidance, an 18-gauge needle was introduced into the cyst cavity, and approximately 10% of the cyst volume was aspirated. Then, 10-30 mL of contrast medium was injected for cystography, and a 0.035-inch Amplatz guidewire (Cook Medical, Bloomington, IN, United States) was inserted. Depending on the cyst content, an 8-12 French pigtail drainage catheter was placed. To exclude cystobiliary communication before scolicidal therapy, the aspirated fluid was first inspected macroscopically for bile. Cystography was repeated under fluoroscopy with 10-30 mL of contrast medium. Absence of bile in the fluid and no opacification of the biliary tree were considered indicative of no biliary communication, and 20% hypertonic saline followed by 95% ethanol (30%-40% of cyst volume) was instilled for at least 10 minutes before respiration. If bile was present macroscopically or contrast passed into the biliary tree, ethanol instillation was avoided to prevent sclerosing cholangitis, and the catheter was left in place for follow-up. Scolicidal therapy was applied only after closure of the bile fistula. The catheter was removed once daily drainage fell below 10 mL. Persistent bile leakage was managed with endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and biliary stenting[11].

Surgical technique

In open surgery, a laparotomy was performed via a subcostal incision to expose the cyst. In laparoscopic surgery, four ports were inserted one for the camera through the infraumbilical region and three others depending on the cyst location for optimal access around the liver. Surrounding tissues were protected using gauze soaked in a scolicidal agent. The cyst was punctured and drained with the help of a Veress needle. Hypertonic saline was injected into the cyst and left for 10 minutes before respiration. Next, a partial excision of the cyst wall closest to the liver capsule was performed, and the germinative membrane was removed intact. The cyst cavity was irrigated with scolicidal agent and inspected for bile leakage. In cases with visible bile leakage, intraoperative suturing or clipping was performed where feasible. A drainage catheter was placed into the cyst cavity before completing the operation.

Follow-up

All patients underwent US at 3-, 6-, and 12-months post-procedure and annually thereafter. On US evaluation, cyst volume, internal content, wall structure, calcification, and the presence of solid or semi-solid components were assessed. Recurrence was defined as the reappearance or interval enlargement of a cystic lesion with imaging features suggesting viable parasitic elements, such as newly formed or detached membranes, daughter cysts, or enhancing solid components, following an initial post-treatment reduction in size. Recollection, in contrast, referred to sterile fluid accumulation within the residual cavity without viable structures or parasitic membranes. This distinction is clinically important, as recollection reflects inflammatory or mechanical fluid reaccumulation, whereas recurrence indicates treatment failure or reactivation of the disease[12]. It should be noted that no parasitological or microbiological examination of aspirated cyst fluid was routinely performed; thus, recurrence and recollection were differentiated solely based on imaging characteristics and clinical evolution. US was the primary imaging modality for follow-up. Contrast-enhanced computed tomography was selectively performed in cases where US findings were inconclusive, when complications were suspected, or when cyst wall thickening, intracystic echogenic material, or interval volume increase raised concern for recurrence. Magnetic resonance imaging was not routinely used in this cohort. Successful treatment response was defined by the absence of cyst growth, lack of daughter cyst formation, progression to a solid or calcified appearance, and reduction in cyst volume.

Statistical analysis

All analyses were performed using SPSS software v. 22.0 (IBM SPSS Statistics Version 22.0. Armonk, NY, United States: IBM Corp.). The variables were divided into two groups as categorical or continuous. Categorical variables were expressed as n (%) and compared with the χ² test. Continuous variables were expressed as mean ± SD. The Kolmogorov Smirnov test was used to test normality and a P > 0.05 was considered to indicate normally distributed data. Continuous variables that showed normal distribution were compared using Student’s t test, whereas the Mann-Whitney U test was used for non-normally distributed samples. The statistical significance level was accepted as P < 0.05.

RESULTS

Patient and cyst characteristics by treatment groups

A total of 989 patients were included, with 74.2% (n = 734) undergoing surgical treatment and 25.8% (n = 255) receiving percutaneous treatment. As shown in Table 1, there were no significant differences between the surgical and percutaneous groups in terms of gender distribution (female: 76.0% vs 72.2%; P = 0.250) or age (38.4 ± 15.9 years vs 38.1 ± 16.1 years; P = 0.800). The majority of patients in both groups had a single cyst (74.7%, n = 548 vs 75.3%, n = 192; P = 0.850). The percutaneous group had a significantly higher proportion of cysts located in the right lobe (80.9% vs 70.6%; P = 0.042) and more peripheral cyst placement (73.6% vs 60.2%; P = 0.031) compared to the surgical group. Additionally, WHO CE1 cysts were more common in the percutaneous group (78.6% vs 65.3%; P = 0.048). Pre-treatment maximum cyst diameters (120.4 ± 47.8 mm vs 118.2 ± 46.9 mm; P = 0.620) and baseline cyst volumes (421.1 ± 266.0 mL vs 374.3 ± 295.2 mL; P = 0.537) did not differ significantly between groups.

Table 1 Demographic and clinical characteristics of surgical and percutaneous treatment groups, mean ± SD/n (%).

Variables	Surgical (n = 734)	Percutaneous (n = 255)	All patients	P value
Age (years)	38.4 ± 15.9	38.1 ± 16.1	38.3 ± 16.0	0.801
Gender
Male	176 (24.0)	71 (27.8)	247 (24.9)	0.250
Female	558 (76.0)	184 (72.2)	742 (75.1)
Number of cysts
Single	548 (74.7)	192 (75.3)	740 (74.8)	0.850
Two	153 (20.9)	49 (19.1)	202 (20.4)	0.450
Multiple	31 (4.2)	14 (5.6)	45 (4.6)	0.350
Location
Right lobe	518 (70.6)	206 (80.9)	724 (73.2)	0.042a
Left lobe	216 (29.4)	49 (19.1)	265 (26.8)
Position
Central	292 (39.8)	67 (26.4)	359 (36.3)	0.031a
Peripheral	442 (60.2)	188 (73.6)	630 (63.7)
Cyst type
WHO CE1	479 (65.3)	200 (78.6)	679 (68.7)	0.048a
WHO CE3a	255 (34.7)	55 (21.8)	310 (31.3)
Cyst longest diameter (mm)	120.4 ± 47.8	118.2 ± 46.9	119.9 ± 47.6	0.620
Initial volume (mL)	421.1 ± 266.0	374.3 ± 295.2	410.0 ± 274.3	0.537

^aP < 0.05.

WHO: World Health Organization; CE: Cystic echinococcosis.

Complications

Table 2 summarizes the rates of major and minor complications according to treatment modality. The incidence of cystobiliary fistula (CBF) was comparable between the surgical and percutaneous groups (15.4% vs 16.8%; P = 0.651). However, recollection was significantly more frequent in the percutaneous group (4.7% vs 1.2%; P = 0.001), as was anaphylaxis (1.6% vs 0.3%; P = 0.041) (Figures 1 and 2). In contrast, true recurrence rates were low in both groups and did not differ significantly [surgical: 8/734 (1.1%) vs percutaneous: 4/255 (1.6%); P = 0.550]. Intraoperative organ injuries (diaphragm, liver, intestine) occurred in 2.7% of surgical patients (n = 20), but none were observed in the percutaneous group (P = 0.002). Minor complication rates were comparable between groups (23.4% vs 18.4%; P = 0.092). Postoperative pain was significantly more frequent in the surgical group (19.5% vs 11.0%; P = 0.002). Other minor complications such as fever, pleural effusion, and urticaria showed no significant differences between groups. Incisional or umbilical hernia occurred in 1.2% (n = 9) of surgical patients, while no hernias were observed in the percutaneous group (P = 0.067).

Figure 1 Ultrasound images before and after secondary catheterization in a 21-year-old patient treated percutaneously for a cystic echinococcosis 1 cyst who developed recollection. The cyst volume decreased from 480.1 mL to 65.3 mL (86.4% reduction) two months after catheterization. The aspirated material was bilious, and the fistula closed spontaneously without endoscopic retrograde cholangiopancreatography. The cause of recollection was bile leakage into the cavity through small bile ducts (Paired-Samples T test, P < 0.001).

Figure 2 Symptomatic recurrent hydatid cyst in a patient previously treated percutaneously one year earlier. A: Ultrasound shows fluid accumulation (orange arrow) and a detached membrane (yellow arrow) in the treated cyst cavity in the right hepatic lobe; B: Cystography shows no cystobiliary communication; C: The aspirated material was dark yellow, and microscopic examination revealed Scolex parasites. The patient developed anaphylaxis during catheterization.

Table 2 Comparison of complications in surgical and percutaneous treatment groups, n (%).

Type of complication	Surgical (n = 734)	Percutaneous (n = 255)	P value
Major complication	155 (21.1)	63 (24.7)	0.234
Cystobiliary fistula	113 (15.4)	43 (16.8)	0.651
Isolated cystobiliary fistula	107 (14.6)	38 (14.9)	0.880
Fistula + infection	6 (0.8)	5 (2.1)	0.231
Isolated cavity infection	5 (0.7)	0 (0)	0.342
Recollection	9 (1.23)	12 (4.71)	0.001a
Recurrence	8 (1.09)	4 (1.57)	0.550
Anaphylaxis	2 (0.3)	4 (1.6)	0.041a
Intraoperative iatrogenic injury	20 (2.7)	0 (0)	0.002a
Diaphragm	6 (0.8)	0 (0)
Liver	12 (1.6)	0 (0)
Intestinal	2 (0.3)	0 (0)
Mortality	0 (0)	0 (0)
Minor complications	172 (23.4)	47 (18.4)	0.092
Pain	143 (19.5)	28 (11.0)	0.002a
Fever	27 (3.7)	9 (3.5)	0.891
Pleural effusion	27 (3.7)	8 (3.1)	0.690
Urticaria	2 (0.3)	2 (0.8)	0.262
Incisional/umbilical hernia	9 (1.2)	0 (0)	0.067

^aP < 0.05.

Cystobiliary communication

CBFs developed in 15.4% (n = 113/734) of surgically treated patients and 16.8% (n = 43/255) of percutaneously treated patients, with no statistically significant difference (P = 0.651) (Table 3 and Figure 3). Intraoperative bile leakage was identified in 83.2% (n = 94) of surgical patients, with primary suture or clipping performed. Such interventions were not applicable in the percutaneous group (Figure 4). Post-procedural bile drainage via drains or catheters occurred more frequently in the percutaneous group (100% vs 56.6%; P < 0.001). The rate of spontaneous closure of the fistula without intervention was similar in both groups (76.7% vs 73.4%; P = 0.825). The mean time to spontaneous closure was also comparable between the surgical and percutaneous groups (14.2 ± 7.3 days vs 11.7 ± 9.4 days, respectively; P = 0.110). The need for postoperative ERCP due to persistent fistula was significantly higher in the percutaneous group (21.8% vs 8.8%; P = 0.033) (Figure 5). There was no significant difference between the groups in terms of secondary surgical intervention (6.2% vs 4.6%, respectively; P = 1.000). In the surgical group, secondary surgery was required in 7 patients (6.2%) due to persistent fistulas. In the percutaneous group, two patients underwent secondary surgery by personal preference: One underwent left lobectomy and the other partial cystectomy.

Figure 3 Management of patients with cystobiliary fistulas. ERCP: Endoscopic retrograde cholangiopancreatography.

Figure 4 Fluoroscopy and cyst fluid findings during percutaneous treatment of a 29-year-old male with a giant cystic echinococcosis 1 liver cyst (volume: 2318 mL). A and B: Fluoroscopy showing catheter placement and drainage of cyst contents with germinative membrane; C and D: Fluid initially clear, later bilious due to opening of occult bile ducts.

Figure 5 Images of a 54-year-old female patient with cystobiliary fistula development. A: The cystography image of the patient with the presence of bile in drainage fluid on the second day after percutaneous treatment, shows that the contrast medium having passed into the biliary tract (arrow) and the presence of a cystobiliary fistula; B: Computed tomography image taken on the third day shows that opaque material has accumulated in the gallbladder (arrow); C: Due to increased fistula flow, papillotomy and common bile duct stenting (arrow) were performed.

Table 3 Comparison of clinical characteristics of surgical and percutaneous patients developing cystobiliary fistula, mean ± SD/n (%).

Variables	Surgical (n = 113)	Percutaneous (n = 43)	Total (n = 156)	P value
Cystobiliary fistula	113/734 (15.4)	43/255 (16.8)	156/989 (15.8)	0.651
Intraoperative detection	94/113 (83.2)	12/43 (27.9)	106/156 (67.9)	< 0.001a
Intraoperative primary suture	94/113 (83.2)	0/43 (0)	94/156 (60.3)
Postoperative bile drainage via catheter/drain	64/113 (56.6)	43/43 (100)	107/156 (68.6)	< 0.001a
Spontaneous closure	47/64 (73.4)	33/43 (76.7)	80/97 (82.4)	0.825
Secondary operation	7/113 (6.2)	2/43 (4.6)	9/156 (5.8)	1.000
Postoperative ERCP	10/113 (8.8)	10/43 (21.8)	20/156 (12.8)	0.033a
Spontaneous closure time (days)	14.2 ± 7.3	11.7 ± 9.4	13.0 ± 8.6	0.110

^aP < 0.05.

ERCP: Endoscopic retrograde cholangiopancreatography.

Association between fistula development and clinical parameters

When all patients were considered, those who developed a fistula had significantly longer hospital stays (9.9 ± 5.3 days vs 5.4 ± 4.6 days, respectively; P < 0.001), prolonged catheter removal times (13.0 ± 8.9 days vs 4.5 ± 3.2 days, respectively; P < 0.001), and larger initial cyst volumes (726.8 ± 397.6 mL vs 351.1 ± 226.4 mL, respectively; P < 0.001) compared to those without fistulas (Table 4). When each treatment group was evaluated separately, hospital stay duration was significantly longer in patients with fistulas in both the surgical group (10.3 ± 5.7 days vs 6.7 ± 6.0 days, respectively; P = 0.002) and the percutaneous group (9.4 ± 4.9 days vs 2.7 ± 1.5 days, respectively; P < 0.001). Similarly, catheter removal time was also significantly prolonged in patients with fistulas in both groups (surgical: 8.3 ± 4.9 days vs 5.9 ± 2.7 days, respectively; P = 0.018 and percutaneous: 17.8 ± 8.7 days vs 3.5 ± 2.9 days, respectively; P < 0.001). Additionally, initial cyst volumes were significantly higher in the groups that developed fistulas. In the surgical group, the initial volume was 774.8 ± 513.2 mL in patients with fistulas and 356.7 ± 95.6 mL in those without (P < 0.001). In the percutaneous group, these values were 700.9 ± 288.2 mL and 346.5 ± 279.2 mL (P < 0.001).

Table 4 Comparison of clinical parameters in patients with and without fistula development, mean ± SD.

Parameter	Treatment group	Cystobiliary fistula (+)	Cystobiliary fistula (-)	P value
Hospital stay (days)	Surgical	10.3 ± 5.7	6.7 ± 6.0	0.002a
	Percutaneous	9.4 ± 4.9	2.7 ± 1.5	< 0.001a
	All patients	9.9 ± 5.3	5.4 ± 4.6	< 0.001a
Catheter removal time (days)	Surgical	8.3 ± 4.9	5.9 ± 2.7	0.018a
	Percutaneous	17.8 ± 8.7	3.5 ± 2.9	< 0.001a
	All patients	13.0 ± 8.9	4.5 ± 3.2	< 0.001a
Initial volume (mL)	Surgical	774.8 ± 513.2	356.7 ± 95.6	< 0.001a
	Percutaneous	700.9 ± 288.2	346.5 ± 279.2	< 0.001a
	All patients	726.8 ± 397.6	351.1 ± 226.4	< 0.001a

^aP < 0.05.

Follow-up and clinical parameters

As shown in Table 5, during follow-up after treatment, the mean final cyst volume was significantly lower in the surgical group compared to the percutaneous group (46.9 ± 38.8 mL vs 63.3 ± 55.6 mL, respectively; P = 0.025), and the final volume reduction rate was statistically higher in the surgical group (88.9% vs 83.1%; P = 0.005) (Figure 6). The mean duration of follow-up imaging was significantly different between the groups, being 12.0 months (range: 3-60 months) in the surgical group and 18.6 months (range: 8-60 months) in the percutaneous group (P < 0.001). Hospital stay and catheter removal time were also significantly longer in the surgical group than in the percutaneous group (7.3 ± 6.2 days vs 3.1 ± 2.3 days, respectively; P < 0.001, and 6.6 ± 5.3 days vs 5.5 ± 6.4 days, respectively; P = 0.014). Among uncomplicated cases, the mean procedure duration was significantly longer in the surgical group [81.3 ± 27.6 minutes (range: 40-180 minutes) vs 40.4 ± 6.2 minutes (range: 30-60 minutes); P < 0.001]. In the surgical group, operation duration was considerably longer in patients who experienced complications (Table 5). Recurrence or recollection defined as symptomatic fluid accumulation in the cavity reaching initial volume levels was observed in 17 patients (2.3%) in the surgical group and 16 patients (6.3%) in the percutaneous group (P = 0.002). These patients underwent drainage or secondary surgery (Figure 7).

Figure 6 Radiological images of a 21-year-old male patient with a cystic echinococcosis 1 liver cyst. A: Abdominal computed tomography image shows an untreated cystic echinococcosis 1 cyst of 85 mm in diameter located in the right lobe of the liver; B: Ultrasound image at 30 months after percutaneous treatment shows that the cyst is inactive, solidified, and reduced in size (Paired-Samples T test, P < 0.001, volumetric reduction rate: 83.6%).

Figure 7 Pre- and postoperative computed tomography and fluoroscopy images of a 40-year-old female patient with a cystic echinococcosis 2 cyst. A and B: Coronal computed tomography (CT) images show preoperative cyst size in liver segment 8 and a common bile duct stent (arrow) placed due to persistent high-output bile drainage (300 mL/day) from the drain; C and D: One month after drain removal, CT and fluoroscopy images show fluid accumulation (arrow) in the cavity and percutaneous catheterization (arrow).

Table 5 Clinical parameters and operation times of surgical and percutaneous groups, mean ± SD.

Features	Surgical (n = 734)	Percutaneous (n = 255)	All patients	P value
Final volume of cyst (mL)	46.9 ± 38.8	63.3 ± 55.6	53.5 ± 45.9	0.025a
Final reduction rate (%)	88.9	83.1	86.6	0.005a
Follow-up imaging duration (months), median (IQR)	12.0 (3.0-60.0)	18.6 (8-60)	13.7 (3-60)	< 0.001a
Hospital stay (days)	7.3 ± 6.2	3.1 ± 2.3	6.3 ± 5.8	< 0.001a
Catheter removal time (days)	6.6 ± 5.3	5.5 ± 6.4	6.3 ± 5.6	0.014a
Operation time without complications (minutes)	81.3 ± 27.6	40.4 ± 6.2	70.6 ± 31.5	< 0.001a
Operation time in patients with complications (minutes)
Diaphragm injury (n = 6)	163.3 ± 81.4
Intestinal injury (n = 2)	187.8 ± 53.1
Liver injury (n = 12)	115.6 ± 62.1
Suturing and/or omentopexy in bile fistula	103.1 ± 35.6

^aP < 0.05.

IQR: Interquartile range.

DISCUSSION

This study represents, to our knowledge, the largest comparative series from an endemic region evaluating surgical and percutaneous treatments for WHO CE1 and CE3a liver hydatid cysts, covering a 20-year period. While surgery has traditionally been the standard approach, percutaneous therapy has gained popularity in recent decades due to its minimally invasive nature, shorter hospital stays, and lower morbidity. However, large-scale comparative studies remain scarce. Previous studies by Khuroo et al[13], Tan et al[14], Abdelraouf et al[15], and Shera et al[16] included relatively small cohorts ranging from 40 to 102 patients. In contrast, our study provides robust data from a large patient population managed over two decades in an endemic region, encompassing both treatment approaches. Importantly, our analysis is limited to WHO CE1 and CE3a cysts, allowing for a more focused and clinically homogeneous evaluation. Consistent with earlier studies[13-16], we found that surgically treated patients experienced longer hospital stays (mean: 7.3 days vs 3.1 days), prolonged operative durations, and extended catheterization times. Based on these findings, percutaneous treatment appears to be a preferable approach for CE1 and CE3a cysts, offering reduced morbidity, lower healthcare costs, and a faster return to normal activities. Although the overall rate of major complications was similar between the groups (21.1% vs 24.7%), intraoperative organ injury involving the diaphragm, liver, or intestines occurred in 2.7% of surgical cases, underscoring the potential risks associated with operative management. A 2003 meta-analysis by Smego et al[17] which included 21 studies comprising 769 percutaneously and 952 surgically treated patients, reported higher rates of major complications such as cyst infection, intra-abdominal abscess, and biliary fistula in the surgical group, while the incidence of anaphylaxis was comparable between groups. In our study, similarly, cavity infections were more frequent among surgically treated patients, while biliary fistula rates were comparable. Notably, anaphylaxis and fluid recollection were observed more frequently in the percutaneous group.

Anaphylaxis is a serious and potentially life-threatening complication that can occur during the treatment of CE. A systematic review of 5943 patients reported a fatal anaphylaxis rate of 0.03%, and a reversible anaphylactic reaction rate of 1.7%[18]. In another study focused exclusively on patients with giant cysts treated percutaneously, the rate of reversible anaphylaxis was 4.5%[19]. In our cohort, anaphylaxis occurred more frequently in percutaneous procedures (1.6% vs 0.3%), likely due to minimal leakage during tract dilation. This difference may be attributed to our institutional protocol, which involves performing all percutaneous interventions under general anesthesia with anesthesiologist supervision, careful and gradual tract dilation, slow and controlled instillation of scolicidal agents, and the availability of full resuscitation equipment throughout the procedure. These measures likely minimized systemic antigen exposure and ensured prompt management of any hypersensitivity reactions. Importantly, this approach ensured that no irreversible complications occurred in our series. This structured protocol may serve as a procedural standard in similar settings.

In recent years, a modified form of the PAIR technique referred to as drainage, puncture, alcohol injection (DPAI) has been introduced, in which the instilled ethanol is not re-aspirated. Shera et al[16] have reported its feasibility in selected cases. However, we intentionally adhered to the conventional PAIR method with re-aspiration in order to reduce the risk of systemic absorption of ethanol and sclerosing cholangitis, particularly in cysts with a potential but undetected cystobiliary communication. Further comparative studies are needed to determine whether DPAI offers similar safety and efficacy in WHO CE1 and CE3a cysts.

In our study, CBF was present in a considerable proportion of patients in both treatment groups, with comparable rates (surgical: 15.4%, percutaneous: 16.8%). Cystobiliary communication remains one of the most significant challenges in the management of hepatic hydatid cysts, as it is associated with prolonged hospitalization, extended catheterization duration, and an increased risk of cavity infection. Previous studies on percutaneous treatment have reported highly variable CBF rates, ranging from 5% to 37%[20-23]. For instance, Aribas et al[20] reported an incidence of 11.1% (10/90), Atli et al[22] reported 21% (24/116), Unalp et al[23] reported 25% (64/252), and Kayaalp et al[21] reported 37% (45/121). In a surgical cohort, Chopra et al[24] documented a CBF incidence of 39.0% among 41 patients, with intraoperative identification and suturing performed in 28.9%. Several factors may account for the variability in CBF rates, including cyst characteristics (type, size, and location), fistula tract diameter (> 5 mm considered major; < 5 mm minor), the presence of frank vs occult fistulae, and the timing of detection. Pre-treatment pressure gradients also play a role. While the biliary system typically has a lower baseline pressure (15-20 cm water) compared to the cyst cavity (30-80 cm water), favoring bile flow toward the bile ducts, this gradient may reverse following percutaneous intervention, leading to bile leakage into the cyst cavity and clinical manifestation of a fistula[23,25]. One major advantage of surgery is the opportunity for intraoperative identification and direct suturing or clipping of the fistula. In our surgical cohort, 83.4% of CBF cases were identified and sutured intraoperatively. Similarly, Chopra et al[24] reported that 68.8% (11/16) of cases were managed surgically at the time of operation, while 18.7% (3/16) required ERCP due to persistent postoperative leakage. These findings suggest that intraoperative management may reduce the need for postoperative ERCP. In our study, ERCP was required significantly less often in the surgical group compared to the percutaneous group (8.8% vs 21.8%, P = 0.033). However, previous reports have indicated that up to 72% of CBFs resolve spontaneously within two months without the need for ERCP[20]. Aribas et al[20] suggested that for patients with daily bile drainage less than 206 mL, observation for up to three months may be appropriate. In our cohort, the mean time to spontaneous closure was similar between groups: 14.2 days in the surgical group and 11.7 days in the percutaneous group. Consistent with the literature, patients with CBF in both treatment arms experienced longer hospital stays, extended catheter duration, and larger initial cyst volumes compared to those without fistulae.

The effectiveness of percutaneous treatment in WHO CE1 and CE3a cysts has been well demonstrated, with clinical success rates ranging between 97.1% and 100%[26-29]. In our study, when patients who developed recurrence or recollection were excluded, clinical success was achieved in 97.7% of surgical cases and 93.3% of those treated percutaneously. Previous research has demonstrated recurrence rates of 6% in a cohort of 100 surgically treated patients[30], and as low as 1.7% in a combined series of 60 laparoscopic and 253 open surgical cases[31]. In contrast, other studies have reported recurrence rates ranging between 1.1% and 24%[32,33] reflecting substantial variability in outcomes. In our cohort, true recurrence occurred in 1.1% of surgically treated patients (8/734) and 1.6% of those treated percutaneously (4/255), while sterile recollection was observed in 1.2% and 4.7% of the respective groups (P = 0.001 for recollection). These findings suggest that recollection was significantly more frequent following percutaneous procedures, whereas recurrence rates were comparable between groups. In patients with CE, clinical success is typically defined by symptom resolution, absence of viable parasites, and lack of recurrence. The considerable variability in reported recurrence rates may be attributed to differences in definitions, diagnostic criteria, and interpretation between radiologists and surgeons. Notably, while “recurrence” and “recollection” are often used interchangeably in the literature, they actually denote different phenomena: Recurrence refers to disease reappearance with viable parasites, whereas recollection describes fluid accumulation without parasitic activity[6,7,33]. In our study, microbiological analysis of aspirated cyst fluid for viable protoscolices was not performed; thus, differentiation between the two was primarily based on imaging characteristics and clinical evolution. In a comparative study by Abdelraouf et al[15], which compared both treatment methods, the recurrence rate in the percutaneous group (n = 8/23, 34.8%) was higher than in the surgical group (n = 2/14, 14.3%), likely because cases of recollection were misclassified as recurrence. A systematic review by Gomez I Gavara et al[34] emphasized the role of omentoplasty, when combined with conservative surgery, in preventing postoperative fluid collection. This aligns with our findings, where a higher rate of recollection was observed among patients treated percutaneously. Based on these data, surgical treatment appears more favorable in minimizing recurrence or recollection. Moreover, although both modalities significantly reduced cyst volume during follow-up, volume reduction was more pronounced in the surgical group. It is important to note, however, that this reflects anatomical rather than clinical outcomes, as calcified or solidified cysts may still indicate successful therapy. The removal of the germinative membrane during surgery, particularly in larger cysts, may contribute to the greater final volume reduction observed in this group. It should be noted that the mean follow-up duration was significantly longer in the percutaneous group. This discrepancy may have led to an underestimation of late recurrence or recollection in the surgical group, representing a potential source of bias when comparing long-term outcomes.

In recent years, radical surgical approaches such as total cysto-pericystectomy and hepatectomy have been increasingly advocated as the definitive treatment for hepatic hydatid disease, particularly in large or centrally located cysts. These methods allow complete removal of the cyst and pericystic tissue, resulting in very low recurrence rates and are considered by some authors to be the treatment of first choice in experienced centers[35,36]. Subadventitial (closed) total pericystectomy, in particular, is proposed as the standard technique where feasible, as it enables complete restoration of liver parenchyma while preserving hepatic function[37]. However, these radical procedures require advanced surgical expertise, adequate instrumentation and are associated with higher intraoperative risk, especially in cysts located near major vascular or biliary structures. In our center, the majority of patients presented with WHO CE1 and CE3a cysts, which are morphologically suitable for conservative surgery or percutaneous treatment. Radical procedures were not routinely performed due to cyst proximity to critical vasculobiliary structures, limited surgical resources in some instances, and an institutional preference for parenchyma-sparing surgery. Therefore, our study focuses on conservative surgery vs percutaneous therapy, which reflects real-world practice in many endemic regions. This also highlights the need for future studies comparing percutaneous treatment with radical surgical procedures such as total pericystectomy or hepatectomy.

In our cohort, CE3a cysts and centrally located lesions in the left hepatic lobe were significantly more likely to be treated surgically[13,19]. This may reflect operator preference rather than absolute clinical necessity. Central location is often associated with a higher likelihood of cystobiliary communication and greater technical difficulty for safe percutaneous access. Although there is no universal consensus in the literature that cyst location is a definitive determinant of treatment choice, WHO guidelines recommend percutaneous intervention only for CE1 and CE3a cysts without biliary communication, indirectly acknowledging the role of anatomical factors[38]. Furthermore, the Turkish Hepatopancreatobiliary Surgery Association recently noted that centrally located or exophytic cysts particularly those adjacent to major vascular or biliary structures may be more appropriately managed surgically due to the technical limitations of percutaneous drainage[39]. Some studies have also reported lower success rates for CE3a compared to CE1 cysts in percutaneous therapy, attributing this to thicker cyst walls and detached membranes that make complete evacuation more[13,19,40]. These factors may have contributed to the treatment distribution in our series and represent a potential selection bias driven by operator decision-making. In our cohort, CE3a cysts and centrally located lesions were more frequently managed surgically. This pattern likely reflects operator preference, influenced by the increased technical difficulty and higher risk of cystobiliary communication associated with these cysts. Consequently, this non-random treatment allocation may have introduced a potential selection bias, as patients with more complex cysts who may inherently have higher complication or recurrence risks were preferentially assigned to the surgical group. This factor should be considered when interpreting comparative outcomes between the two modalities. Future prospective studies adjusting for cyst type, size, and anatomical location would be valuable to mitigate this bias.

Study limitations and future directions

This study has several limitations. First, the retrospective evaluation of patient data based on medical records may have resulted in missing or incomplete information. Second, due to the inclusion of patients over a long time period, differences in operator experience, skills, techniques, and technological advancements may have influenced clinical outcomes and complication rates. Third, the study is limited to WHO CE1 and CE3a cyst types, which restricts the generalizability of the findings to other types such as CE2 and CE3b. Fourth, the absence of randomized patient allocation may have introduced selection bias. Fifth, the unequal follow-up durations between groups may have influenced recurrence estimates, potentially favoring the surgical group due to shorter observation time. Future studies should incorporate time-to-event analyses such as Kaplan-Meier curves to more accurately compare recurrence-free survival. Lastly, the lack of subgroup analysis for surgical techniques (laparoscopic vs open, or conventional vs radical) is also a limitation. Additionally, a potential selection bias may have occurred because CE3a and centrally located cysts, which are generally more complex and technically challenging, were more frequently treated surgically. This non-random allocation may have influenced the observed complication and recurrence rates between treatment groups. Additionally, no parasitological or microbiological examination of the cyst fluid was performed to confirm the presence of viable protoscoleces. Therefore, recurrence and recollection were defined solely based on imaging findings and clinical follow-up, which may limit the precision of recurrence classification. Furthermore, this study did not stratify surgical interventions into conservative (partial cystectomy, evacuation) vs radical procedures (total pericystectomy, subadventitial cystectomy, or hepatectomy). As radical surgery is considered the preferred curative option in eligible patients in many contemporary centers, the lack of subgroup analysis for these techniques limits the comparability of our results with current surgical standards.

From an internal validity perspective, the retrospective and non-randomized design, operator variability, and reliance on medical records may have introduced measurement and selection biases.

From an external validity perspective, the single-center nature, focus on only CE1 and CE3a cysts, and the endemic setting limit the generalizability of our results to other populations and cyst types.

To improve both internal and external validity, future studies should consider prospective, multicenter designs and randomized controlled trials including broader cyst types such as CE2 and CE3b. Additionally, standardized definitions of recurrence and recollection, along with uniform follow-up protocols, are essential for more accurate outcome comparisons.

CONCLUSION

Our study demonstrates that the percutaneous approach is a safe and effective treatment modality for WHO CE1 and CE3a hepatic cysts, offering advantages such as shorter hospital stay, minimal invasiveness, reduced operative time, and a very low risk of intraoperative organ injury. Both surgical and percutaneous methods achieve high clinical success rates; however, the surgical approach appears slightly more advantageous in terms of reducing the risks of recollection and anaphylaxis. A larger cyst volume is associated with an increased risk of fistula formation and prolonged treatment duration for both treatment modalities. Therefore, patient selection should be carefully guided by these parameters. However, it should be emphasized that radical surgery (e.g., total pericystectomy or hepatectomy) remains the gold standard in eligible patients, while percutaneous treatment offers a safe and practical alternative for selected CE1/CE3a cysts, particularly in resource-limited or high-risk surgical settings.