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Trial registered on ANZCTR


Registration number
ACTRN12625000752460p
Ethics application status
Submitted, not yet approved
Date submitted
29/06/2025
Date registered
16/07/2025
Date last updated
16/07/2025
Date data sharing statement initially provided
16/07/2025
Type of registration
Prospectively registered

Titles & IDs
Public title
Can a nerve block during surgery reduce pelvic pain and opioid use in women with endometriosis?
Scientific title
Efficacy of Intraoperative Superior Hypogastric Plexus (SHP) Block for Persistent Pelvic Pain Management in Endometriosis Patients
Secondary ID [1] 314772 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Endometriosis 338004 0
Persistent Pelvic Pain 338005 0
Condition category
Condition code
Reproductive Health and Childbirth 334318 334318 0 0
Other reproductive health and childbirth disorders
Anaesthesiology 334513 334513 0 0
Pain management

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Intervention Name:
Arm 1 – SHP Block: Intraoperative Superior Hypogastric Plexus (SHP) block with local anaesthetic
Arm 2 – Placebo Control: Intraoperative sham injection with normal saline

Intervention Description (Arm 1 – SHP Block)
Brief name:
Intraoperative Superior Hypogastric Plexus (SHP) block with 0.25% bupivacaine

Materials:
Standard surgical supplies, including 10–20 mL of 0.25% bupivacaine, 22G spinal needle, and syringes. No additional patient-facing materials are used.

Procedures:
After induction of general anaesthesia, participants randomised to the intervention group will receive an SHP block performed under direct laparoscopic visualisation. Using a 22G spinal needle, the surgeon will inject 10–20 mL of 0.25% bupivacaine into the retroperitoneal space at the location of the superior hypogastric plexus, typically just inferior to the aortic bifurcation, anterior to the L5 vertebral body.

Provider and expertise:
Administered by a consultant gynaecological laparoscopic surgeon or a trained fellow with experience in pelvic nerve blocks under supervision.

Mode of delivery:
Face-to-face during surgery under general anaesthesia. Delivered individually to each participant.

Timing and dose:
A single dose of bupivacaine (10–20 mL of 0.25%) is administered once intraoperatively.

Location:
Operating theatres at Mater Mothers Hospital, Brisbane, within the Advanced Laparoscopy Gynaecological Unit.

Adaptation:
The intervention is not titrated or adapted. Standard volume and technique are used in all patients.

Fidelity and adherence:
Fidelity will be assessed by surgical documentation, intraoperative photography, and adherence to the standardised SHP block protocol. Fidelity checks will be conducted periodically by the principal investigator.
Intervention code [1] 331373 0
Treatment: Surgery
Comparator / control treatment
Comparator Description (Arm 2 – Placebo Control)
Brief name:
Intraoperative placebo injection

Procedures:
The control group receives a sham injection using the same approach and volume of sterile saline (0.9% NaCl) instead of bupivacaine, under laparoscopic visualisation.

Other details:
All other procedures and perioperative care are identical between groups. Participants and postoperative assessors are blinded to group allocation.
Control group
Placebo

Outcomes
Primary outcome [1] 341978 0
Postoperative pain intensity
Timepoint [1] 341978 0
Measured at 2, 6, 12, and 24 hours after surgery
Secondary outcome [1] 449216 0
Total opioid consumption in first 24 hours postoperatively
Timepoint [1] 449216 0
Hourly record over the intiial 24 hours after surgery
Secondary outcome [2] 449217 0
Total NSAID consumption in first 24 hours postoperatively
Timepoint [2] 449217 0
Hourly record over the intiial 24 hours after surgery
Secondary outcome [3] 449218 0
Central sensitisation severity
Timepoint [3] 449218 0
Assessed preoperatively, and at 3 and 6 months postoperatively
Secondary outcome [4] 449219 0
Pelvic pain-related functional impairment
Timepoint [4] 449219 0
Assessed preoperatively, and at 3 and 6 months postoperatively
Secondary outcome [5] 449220 0
Incidence of adverse events related to SHP block
Timepoint [5] 449220 0
monitored continuously Intraoperatively and hourly for first 6 hours and 4-hourly until 24 hours postoperatively

Eligibility
Key inclusion criteria
Female patients aged 18 to 50 years

Undergoing operative laparoscopy for confirmed or suspected endometriosis

History of chronic pelvic pain (greater than or equal to 6 months duration)

ASA physical status classification I–II

Willing and able to provide written informed consent

Fluent in English or able to complete questionnaires with assistance
Minimum age
18 Years
Maximum age
50 Years
Sex
Females
Can healthy volunteers participate?
No
Key exclusion criteria
Known allergy or hypersensitivity to local anaesthetics (e.g. bupivacaine)

Previous pelvic nerve block or pelvic surgery within the last 6 months

Coagulopathy or current use of anticoagulant medications

Severe pelvic adhesions precluding safe SHP block administration

Pregnancy or breastfeeding at time of surgery

Inability or unwillingness to provide informed consent

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation will be concealed using a centralised, computer-generated randomisation schedule managed by an independent administrator not involved in participant recruitment or clinical care. Group allocation will be revealed intraoperatively only after induction of anaesthesia by opening a sealed opaque envelope corresponding to the participant’s study ID. This ensures that eligibility assessment and consent occur prior to knowledge of group assignment.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
A computerised randomisation sequence will be generated using a secure, web-based software program. The sequence will use permuted block randomisation with variable block sizes to ensure allocation balance between the intervention (SHP block) and control (placebo) groups.

Stratification will be performed based on surgical indication (diagnostic vs therapeutic laparoscopy), to control for variability in operative extent and pain response.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Safety/efficacy
Statistical methods / analysis
Sample size justification and statistical analysis plan:

This is a pilot randomised controlled trial designed primarily to assess feasibility (e.g. recruitment, adherence, data completeness) and estimate preliminary effect sizes to inform a future, fully powered trial.

Based on prior literature and feasibility recommendations:

A total of 30 participants (15 per group) will be recruited.

This sample size is not powered for definitive statistical significance but is sufficient to:

Assess recruitment and retention capability

Evaluate protocol adherence

Estimate variability in primary outcomes (VAS pain scores and opioid use)

Detect trends in group differences for planning future sample size calculations

Statistical analysis plan:

VAS pain scores at 2, 6, 12, and 24 hours: Descriptive statistics and between-group comparisons using independent t-tests or Mann-Whitney U tests.

Opioid and NSAID use: Analysed using t-tests or non-parametric equivalents; reported in morphine milligram equivalents (MME).

Time to first analgesia: Analysed using Kaplan-Meier curves and log-rank test.

CSI and PPIQ scores: Assessed pre-op, 3, and 6 months; analysed using paired and independent t-tests or non-parametric tests.

Adverse events: Reported descriptively, including frequency and severity.

All statistical tests will be two-tailed, with p < 0.05 considered noteworthy, though results will be interpreted with caution given the pilot nature and small sample size.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/08/2025
Actual
Date of last participant enrolment
Anticipated
1/03/2026
Actual
Date of last data collection
Anticipated
29/09/2026
Actual
Sample size
Target
30
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
QLD
Recruitment hospital [1] 28154 0
Mater Mother's Hospital - South Brisbane
Recruitment postcode(s) [1] 44363 0
4101 - South Brisbane

Funding & Sponsors
Funding source category [1] 319327 0
Hospital
Name [1] 319327 0
Mater Mothers Hospital - in kind
Country [1] 319327 0
Australia
Primary sponsor type
Hospital
Name
Mater Mothers Hospital - in kind
Address
Country
Australia
Secondary sponsor category [1] 321812 0
None
Name [1] 321812 0
Address [1] 321812 0
Country [1] 321812 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 317909 0
Mater Misericordiae Ltd Human Research Ethics Committee
Ethics committee address [1] 317909 0
Ethics committee country [1] 317909 0
Australia
Date submitted for ethics approval [1] 317909 0
03/07/2025
Approval date [1] 317909 0
Ethics approval number [1] 317909 0

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 142522 0
Dr Thomas Yeung
Address 142522 0
Mater Mothers Hospital/ Mater Misericordiae Ltd Raymond Terrace South Brisbane QLD 4101 Australia
Country 142522 0
Australia
Phone 142522 0
+61 478419302
Fax 142522 0
Email 142522 0
[email protected]
Contact person for public queries
Name 142523 0
Thomas Yeung
Address 142523 0
Mater Mothers Hospital/ Mater Misericordiae Ltd Raymond Terrace South Brisbane QLD 4101 Australia
Country 142523 0
Australia
Phone 142523 0
+61 478419302
Fax 142523 0
Email 142523 0
[email protected]
Contact person for scientific queries
Name 142524 0
Thomas Yeung
Address 142524 0
Mater Mothers Hospital/ Mater Misericordiae Ltd Raymond Terrace South Brisbane QLD 4101 Australia
Country 142524 0
Australia
Phone 142524 0
+61 478419302
Fax 142524 0
Email 142524 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
• Requires a scientifically sound proposal or protocol
• Requires approval by an ethics committee
• Requires a data sharing agreement between data requester and trial custodian or sponsor
What individual participant data might be shared?
• All de-identified individual participant data
What types of analyses could be done with individual participant data?
• Any type of analysis (i.e. no restrictions on data re-use)
When can requests for individual participant data be made (start and end dates)?
From:
At the end of the study
To:
Not yet decided
Where can requests to access individual participant data be made, or data be obtained directly?
• Email of trial custodian, sponsor or committee: [email protected]

Are there extra considerations when requesting access to individual participant data?
No


What supporting documents are/will be available?

No Supporting Document Provided


Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.