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Frequently asked questions
Clinical questions
Technical questions
Patients are not eligible if they meet one or more exclusion criteria defined by the protocol, including:
age under 18 years;
known or suspected pregnancy;
acute cholecystitis not compatible with the study inclusion criteria;
clinical presentation not compatible with mild–moderate acute calculous cholecystitis;
Israeli score ≥2;
POSSUM Physiological Score ≥25;
poorly controlled or decompensated diabetes mellitus, defined as HbA1c ≥8.0% or clinically relevant acute metabolic decompensation;
known or strongly suspected clinically significant immunodeficiency;
transplant recipient status;
ongoing immunosuppressive therapy;
clinically relevant chronic corticosteroid therapy;
any other condition that, in the investigator’s clinical judgment, makes the patient unsuitable for study participation.
Yes. If the patient has already received antibiotic treatment for the current episode of acute cholecystitis before enrolment/randomization, the patient cannot be included in the study.
It is therefore important to inform Emergency Department colleagues and involved wards that, in patients with suspected acute calculous cholecystitis who may be eligible for PANEL ChIMMACC, antibiotic administration before surgical evaluation may make the patient non-enrollable.
If the patient has an urgent clinical indication for antibiotic treatment, antibiotics must be administered according to good clinical practice, and the patient will not be included in the study.
No. The protocol does not impose an identical standardized imaging pathway for all centres.
Imaging should be performed according to local clinical practice and the judgment of the treating team. Abdominal ultrasound is generally the first-line reference examination. Additional imaging, such as CT or other investigations, may be performed when clinically indicated, for example in suspected complicated cholecystitis, uncertain diagnosis or the need to exclude other conditions.
The examinations performed and the main relevant findings must be reported in the CRF.
The 72-hour limit is calculated from hospital admission, not from symptom onset.
The protocol requires early laparoscopic cholecystectomy within 72 hours from hospital admission. If the patient presents to hospital late after symptom onset, this alone does not automatically exclude the patient. However, the patient must still meet all inclusion criteria, have no exclusion criteria and be considered clinically suitable for early surgery within the required timeframe.
A previous ERCP is not, by itself, an automatic exclusion criterion.
The patient may be considered eligible if, at the time of study assessment, the inclusion criteria are met, no exclusion criteria are present and early laparoscopic cholecystectomy can be performed within 72 hours from hospital admission.
However, if the patient received antibiotics for the current episode, has cholangitis, complications or a clinical picture not compatible with the study target population, the patient may not be eligible.
Any ERCP must be recorded in the CRF.
Preoperative antibiotic prophylaxis must not be administered outside the assigned study arm.
The study compares two strategies:
experimental arm: no preoperative antibiotic treatment;
control arm: amoxicillin/clavulanic acid according to the protocol until surgery.
Therefore, in the “no antibiotics” arm, routine preoperative antibiotic prophylaxis must not be administered, because this would modify the assigned study intervention.
If a true clinical indication for antibiotic treatment arises, the patient must receive the most appropriate treatment according to clinical judgment. The event must be recorded and managed according to the protocol.
No. To ensure consistency across participating centres, the antibiotic arm uses a standardized regimen with amoxicillin/clavulanic acid, as defined in the study protocol.
Although the study is open-label and the assigned treatment is known to the clinical team, the antibiotic choice in the control arm is not left to local discretion.
If, during the clinical course, rescue antibiotic treatment becomes necessary, the choice of antibiotic is left to the treating clinician according to the patient’s condition, local practice and microbiological considerations, when available.
Any modification of antibiotic treatment, escalation, additional antibiotics or rescue therapy must be clinically justified and recorded in the CRF.
If rescue antibiotics are administered because a clinically significant infectious complication is diagnosed, the event must be recorded as part of the primary outcome, according to the protocol definitions.
No. Intraoperative gallbladder perforation or bile spillage does not automatically lead to drop-out.
These events may occur during routine surgical practice and are relevant for the interpretation of study results. They should be managed according to good surgical practice, including aspiration, lavage and surgical field cleaning according to the surgeon’s judgment.
The event must be recorded in the CRF. In these cases, bile culture is advisable if technically feasible.
No. Drain placement is not a reason for drop-out.
The use of a drain remains at the surgeon’s discretion, according to local clinical practice and intraoperative findings. This information must be recorded in the CRF, as it may be useful for the analysis and interpretation of postoperative outcomes.
Bile culture should be performed according to local microbiology procedures.
In general, the sample may be obtained intraoperatively by sterile aspiration of bile from the gallbladder, preferably after removal or under conditions that reduce the risk of contamination. The sample should then be sent to the laboratory according to local procedures.
In case of gallbladder perforation, bile spillage or stone spillage, bile culture is particularly recommended if technically feasible.
No. The primary outcome does not necessarily require microbiological confirmation.
The primary outcome is 30-day infectious morbidity, defined according to standardized clinical criteria. This includes CDC criteria for surgical site infections and the clinical diagnosis of other relevant infections, such as pneumonia, urinary tract infection, intra-abdominal infections or other clinically significant infections.
Microbiological cultures, when available, will be recorded and may help characterize infectious events, but they are not required to define the primary outcome.
Yes. There is no automatic exclusion based only on the time elapsed from symptom onset.
However, the patient must still fit the study target population: mild–moderate acute calculous cholecystitis, no exclusion criteria, POSSUM Physiological Score <25, Israeli score 0–1 and the possibility of performing laparoscopic cholecystectomy within 72 hours from hospital admission.
In practice, a patient presenting very late may be more likely to have complicated or more severe disease and may therefore be non-eligible.
No. In the current version of the protocol, placebo is not used.
The study is open-label. Placebo use was considered but was not maintained for organizational feasibility, safety and practical reasons in an international multicentre setting. The open-label design makes the protocol simpler, closer to real-world clinical practice and more easily applicable across centres.
Bail-out procedures, such as conversion to open surgery or subtotal cholecystectomy, must be performed when clinically indicated, according to the surgeon’s judgment and patient safety.
According to the protocol, these procedures must be accurately recorded. Their handling for analysis will follow the statistical protocol and the final CRF.
The protocol modifies only the preoperative antibiotic strategy assigned by randomization.
All other clinical, surgical and care decisions must follow usual clinical practice, the patient’s condition and the judgment of the treating team. Patient safety always takes priority over study participation.
Frequently asked questions
Clinical questions
Technical questions
Patients are not eligible if they meet one or more exclusion criteria defined by the protocol, including:
age under 18 years;
known or suspected pregnancy;
acute cholecystitis not compatible with the study inclusion criteria;
clinical presentation not compatible with mild–moderate acute calculous cholecystitis;
Israeli score ≥2;
POSSUM Physiological Score ≥25;
poorly controlled or decompensated diabetes mellitus, defined as HbA1c ≥8.0% or clinically relevant acute metabolic decompensation;
known or strongly suspected clinically significant immunodeficiency;
transplant recipient status;
ongoing immunosuppressive therapy;
clinically relevant chronic corticosteroid therapy;
any other condition that, in the investigator’s clinical judgment, makes the patient unsuitable for study participation.
Yes. If the patient has already received antibiotic treatment for the current episode of acute cholecystitis before enrolment/randomization, the patient cannot be included in the study.
It is therefore important to inform Emergency Department colleagues and involved wards that, in patients with suspected acute calculous cholecystitis who may be eligible for PANEL ChIMMACC, antibiotic administration before surgical evaluation may make the patient non-enrollable.
If the patient has an urgent clinical indication for antibiotic treatment, antibiotics must be administered according to good clinical practice, and the patient will not be included in the study.
No. The protocol does not impose an identical standardized imaging pathway for all centres.
Imaging should be performed according to local clinical practice and the judgment of the treating team. Abdominal ultrasound is generally the first-line reference examination. Additional imaging, such as CT or other investigations, may be performed when clinically indicated, for example in suspected complicated cholecystitis, uncertain diagnosis or the need to exclude other conditions.
The examinations performed and the main relevant findings must be reported in the CRF.
The 72-hour limit is calculated from hospital admission, not from symptom onset.
The protocol requires early laparoscopic cholecystectomy within 72 hours from hospital admission. If the patient presents to hospital late after symptom onset, this alone does not automatically exclude the patient. However, the patient must still meet all inclusion criteria, have no exclusion criteria and be considered clinically suitable for early surgery within the required timeframe.
A previous ERCP is not, by itself, an automatic exclusion criterion.
The patient may be considered eligible if, at the time of study assessment, the inclusion criteria are met, no exclusion criteria are present and early laparoscopic cholecystectomy can be performed within 72 hours from hospital admission.
However, if the patient received antibiotics for the current episode, has cholangitis, complications or a clinical picture not compatible with the study target population, the patient may not be eligible.
Any ERCP must be recorded in the CRF.
Preoperative antibiotic prophylaxis must not be administered outside the assigned study arm.
The study compares two strategies:
experimental arm: no preoperative antibiotic treatment;
control arm: amoxicillin/clavulanic acid according to the protocol until surgery.
Therefore, in the “no antibiotics” arm, routine preoperative antibiotic prophylaxis must not be administered, because this would modify the assigned study intervention.
If a true clinical indication for antibiotic treatment arises, the patient must receive the most appropriate treatment according to clinical judgment. The event must be recorded and managed according to the protocol.
No. To ensure consistency across participating centres, the antibiotic arm uses a standardized regimen with amoxicillin/clavulanic acid, as defined in the study protocol.
Although the study is open-label and the assigned treatment is known to the clinical team, the antibiotic choice in the control arm is not left to local discretion.
If, during the clinical course, rescue antibiotic treatment becomes necessary, the choice of antibiotic is left to the treating clinician according to the patient’s condition, local practice and microbiological considerations, when available.
Any modification of antibiotic treatment, escalation, additional antibiotics or rescue therapy must be clinically justified and recorded in the CRF.
If rescue antibiotics are administered because a clinically significant infectious complication is diagnosed, the event must be recorded as part of the primary outcome, according to the protocol definitions.
No. Intraoperative gallbladder perforation or bile spillage does not automatically lead to drop-out.
These events may occur during routine surgical practice and are relevant for the interpretation of study results. They should be managed according to good surgical practice, including aspiration, lavage and surgical field cleaning according to the surgeon’s judgment.
The event must be recorded in the CRF. In these cases, bile culture is advisable if technically feasible.
No. Drain placement is not a reason for drop-out.
The use of a drain remains at the surgeon’s discretion, according to local clinical practice and intraoperative findings. This information must be recorded in the CRF, as it may be useful for the analysis and interpretation of postoperative outcomes.
Bile culture should be performed according to local microbiology procedures.
In general, the sample may be obtained intraoperatively by sterile aspiration of bile from the gallbladder, preferably after removal or under conditions that reduce the risk of contamination. The sample should then be sent to the laboratory according to local procedures.
In case of gallbladder perforation, bile spillage or stone spillage, bile culture is particularly recommended if technically feasible.
No. The primary outcome does not necessarily require microbiological confirmation.
The primary outcome is 30-day infectious morbidity, defined according to standardized clinical criteria. This includes CDC criteria for surgical site infections and the clinical diagnosis of other relevant infections, such as pneumonia, urinary tract infection, intra-abdominal infections or other clinically significant infections.
Microbiological cultures, when available, will be recorded and may help characterize infectious events, but they are not required to define the primary outcome.
Yes. There is no automatic exclusion based only on the time elapsed from symptom onset.
However, the patient must still fit the study target population: mild–moderate acute calculous cholecystitis, no exclusion criteria, POSSUM Physiological Score <25, Israeli score 0–1 and the possibility of performing laparoscopic cholecystectomy within 72 hours from hospital admission.
In practice, a patient presenting very late may be more likely to have complicated or more severe disease and may therefore be non-eligible.
No. In the current version of the protocol, placebo is not used.
The study is open-label. Placebo use was considered but was not maintained for organizational feasibility, safety and practical reasons in an international multicentre setting. The open-label design makes the protocol simpler, closer to real-world clinical practice and more easily applicable across centres.
Bail-out procedures, such as conversion to open surgery or subtotal cholecystectomy, must be performed when clinically indicated, according to the surgeon’s judgment and patient safety.
According to the protocol, these procedures must be accurately recorded. Their handling for analysis will follow the statistical protocol and the final CRF.
The protocol modifies only the preoperative antibiotic strategy assigned by randomization.
All other clinical, surgical and care decisions must follow usual clinical practice, the patient’s condition and the judgment of the treating team. Patient safety always takes priority over study participation.
Frequently asked questions
Clinical questions
Technical questions
Patients are not eligible if they meet one or more exclusion criteria defined by the protocol, including:
age under 18 years;
known or suspected pregnancy;
acute cholecystitis not compatible with the study inclusion criteria;
clinical presentation not compatible with mild–moderate acute calculous cholecystitis;
Israeli score ≥2;
POSSUM Physiological Score ≥25;
poorly controlled or decompensated diabetes mellitus, defined as HbA1c ≥8.0% or clinically relevant acute metabolic decompensation;
known or strongly suspected clinically significant immunodeficiency;
transplant recipient status;
ongoing immunosuppressive therapy;
clinically relevant chronic corticosteroid therapy;
any other condition that, in the investigator’s clinical judgment, makes the patient unsuitable for study participation.
Yes. If the patient has already received antibiotic treatment for the current episode of acute cholecystitis before enrolment/randomization, the patient cannot be included in the study.
It is therefore important to inform Emergency Department colleagues and involved wards that, in patients with suspected acute calculous cholecystitis who may be eligible for PANEL ChIMMACC, antibiotic administration before surgical evaluation may make the patient non-enrollable.
If the patient has an urgent clinical indication for antibiotic treatment, antibiotics must be administered according to good clinical practice, and the patient will not be included in the study.
No. The protocol does not impose an identical standardized imaging pathway for all centres.
Imaging should be performed according to local clinical practice and the judgment of the treating team. Abdominal ultrasound is generally the first-line reference examination. Additional imaging, such as CT or other investigations, may be performed when clinically indicated, for example in suspected complicated cholecystitis, uncertain diagnosis or the need to exclude other conditions.
The examinations performed and the main relevant findings must be reported in the CRF.
The 72-hour limit is calculated from hospital admission, not from symptom onset.
The protocol requires early laparoscopic cholecystectomy within 72 hours from hospital admission. If the patient presents to hospital late after symptom onset, this alone does not automatically exclude the patient. However, the patient must still meet all inclusion criteria, have no exclusion criteria and be considered clinically suitable for early surgery within the required timeframe.
A previous ERCP is not, by itself, an automatic exclusion criterion.
The patient may be considered eligible if, at the time of study assessment, the inclusion criteria are met, no exclusion criteria are present and early laparoscopic cholecystectomy can be performed within 72 hours from hospital admission.
However, if the patient received antibiotics for the current episode, has cholangitis, complications or a clinical picture not compatible with the study target population, the patient may not be eligible.
Any ERCP must be recorded in the CRF.
Preoperative antibiotic prophylaxis must not be administered outside the assigned study arm.
The study compares two strategies:
experimental arm: no preoperative antibiotic treatment;
control arm: amoxicillin/clavulanic acid according to the protocol until surgery.
Therefore, in the “no antibiotics” arm, routine preoperative antibiotic prophylaxis must not be administered, because this would modify the assigned study intervention.
If a true clinical indication for antibiotic treatment arises, the patient must receive the most appropriate treatment according to clinical judgment. The event must be recorded and managed according to the protocol.
No. To ensure consistency across participating centres, the antibiotic arm uses a standardized regimen with amoxicillin/clavulanic acid, as defined in the study protocol.
Although the study is open-label and the assigned treatment is known to the clinical team, the antibiotic choice in the control arm is not left to local discretion.
If, during the clinical course, rescue antibiotic treatment becomes necessary, the choice of antibiotic is left to the treating clinician according to the patient’s condition, local practice and microbiological considerations, when available.
Any modification of antibiotic treatment, escalation, additional antibiotics or rescue therapy must be clinically justified and recorded in the CRF.
If rescue antibiotics are administered because a clinically significant infectious complication is diagnosed, the event must be recorded as part of the primary outcome, according to the protocol definitions.
No. Intraoperative gallbladder perforation or bile spillage does not automatically lead to drop-out.
These events may occur during routine surgical practice and are relevant for the interpretation of study results. They should be managed according to good surgical practice, including aspiration, lavage and surgical field cleaning according to the surgeon’s judgment.
The event must be recorded in the CRF. In these cases, bile culture is advisable if technically feasible.
No. Drain placement is not a reason for drop-out.
The use of a drain remains at the surgeon’s discretion, according to local clinical practice and intraoperative findings. This information must be recorded in the CRF, as it may be useful for the analysis and interpretation of postoperative outcomes.
Bile culture should be performed according to local microbiology procedures.
In general, the sample may be obtained intraoperatively by sterile aspiration of bile from the gallbladder, preferably after removal or under conditions that reduce the risk of contamination. The sample should then be sent to the laboratory according to local procedures.
In case of gallbladder perforation, bile spillage or stone spillage, bile culture is particularly recommended if technically feasible.
No. The primary outcome does not necessarily require microbiological confirmation.
The primary outcome is 30-day infectious morbidity, defined according to standardized clinical criteria. This includes CDC criteria for surgical site infections and the clinical diagnosis of other relevant infections, such as pneumonia, urinary tract infection, intra-abdominal infections or other clinically significant infections.
Microbiological cultures, when available, will be recorded and may help characterize infectious events, but they are not required to define the primary outcome.
Yes. There is no automatic exclusion based only on the time elapsed from symptom onset.
However, the patient must still fit the study target population: mild–moderate acute calculous cholecystitis, no exclusion criteria, POSSUM Physiological Score <25, Israeli score 0–1 and the possibility of performing laparoscopic cholecystectomy within 72 hours from hospital admission.
In practice, a patient presenting very late may be more likely to have complicated or more severe disease and may therefore be non-eligible.
No. In the current version of the protocol, placebo is not used.
The study is open-label. Placebo use was considered but was not maintained for organizational feasibility, safety and practical reasons in an international multicentre setting. The open-label design makes the protocol simpler, closer to real-world clinical practice and more easily applicable across centres.
Bail-out procedures, such as conversion to open surgery or subtotal cholecystectomy, must be performed when clinically indicated, according to the surgeon’s judgment and patient safety.
According to the protocol, these procedures must be accurately recorded. Their handling for analysis will follow the statistical protocol and the final CRF.
The protocol modifies only the preoperative antibiotic strategy assigned by randomization.
All other clinical, surgical and care decisions must follow usual clinical practice, the patient’s condition and the judgment of the treating team. Patient safety always takes priority over study participation.
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