Deep Neuromuscular Blockade and a Low-Residue Diet for the Surgical Field in vNOTES Hysterectomy

Official title

Effect of Deep Neuromuscular Blockade and a Preoperative Low-Residue Diet on Intra-operative Surgical Field Conditions During Vaginal Natural Orifice Transluminal Endoscopic Surgery (vNOTES) Hysterectomy: A 2×2 Factorial, Assessor-Blinded Randomized Controlled Trial

Overview

vNOTES (vaginal natural orifice transluminal endoscopic surgery) hysterectomy is performed entirely through the vagina, with no abdominal incision. A clear surgical view is essential, and the main obstacle to the view is bowel falling into the pelvis. This randomized trial tests whether two simple measures improve the surgical field, individually or in combination: a preoperative low-residue diet for three days, and deeper intra-operative muscle relaxation (deep neuromuscular blockade). No group receives mechanical bowel preparation. Using a 2×2 factorial design, participants are allocated equally (1:1:1:1) to one of four groups: (1) no diet with standard relaxation; (2) diet with standard relaxation; (3) no diet with deep relaxation; (4) diet with deep relaxation (the "bundle"). The surgical field is measured objectively: during a standardized window the carbon-dioxide insufflation pressure is lowered step by step, and 2-3 blinded assessors score the field from de-identified video. The primary outcome is the lowest pressure at which the field remains adequate; a lower pressure indicates an intrinsically better field. The trial hypothesis is an interaction - that the combination achieves an adequate field at a meaningfully lower pressure than either measure alone. The final sample size is determined from an internal pilot. Secondary outcomes include the continuous field score, the need for an additional instrument to clear the field, postoperative nausea and vomiting, and routine operative outcomes.

Detailed description

The field is scored with the vNOTES-OVI, a 3-point index (0 = inadequate, 1 = adequate only with instrument bowel-retraction, 2 = optimal/clear), adapted for vNOTES from the team's prior objective visualisation index in conventional laparoscopy. At each 1 mmHg step a 3-second clip is recorded with a fixed scanning choreography (right adnexa → midline/cephalic boundary → left adnexa); the consensus (median) of the blinded assessors defines, per participant, the lowest pressure at which the field is adequate (OVI ≥ 1; primary) and at which it is optimal (OVI = 2; secondary).

Deep relaxation is rocuronium by continuous infusion to a post-tetanic count of 1-2 (no train-of-four twitches); standard relaxation is rocuronium by intermittent bolus to a train-of-four count of 1-2. Relaxation depth is monitored quantitatively and fully reversed (train-of-four ratio ≥ 0.9 confirmed) before extubation in every participant; the reversal agent is sugammadex in all four groups (neostigmine is not used), and because sugammadex dosing follows block depth (≈ 2 mg/kg moderate, ≈ 4 mg/kg deep) the dose differs by the NMB factor by necessity, so it is recorded per participant and reported by arm (collinear with NMB depth, it is examined only in a sensitivity analysis, not added as a covariate to the factorial nausea model). The step-down field measurement descends from 12 mmHg to 6 mmHg in 1 mmHg steps with a 60-second equilibration at each step. The preoperative low-residue diet (diet arms) restricts daily intake to less than 10 g of dietary fibre for the three days before surgery - permitting refined grains, well-cooked or canned skinless and seedless vegetables, peeled or canned fruit, tender meat, fish, eggs, and moderate dairy, while avoiding whole grains, raw fruits and vegetables, legumes, nuts, seeds, and dried fruit - and participants receive a written diet information sheet; no group receives mechanical bowel preparation. The primary outcome is assessor-blinded (assessors score de-identified video with pressure and group removed); the operating surgeon is blinded to allocation and the data analyst analyses with groups coded; the anaesthesia team is necessarily unblinded to relaxation depth but does not score the outcome. The internal pilot (≈ 10-15 per group) is used for blinded sample-size re-estimation; detecting an interaction typically requires several times the sample size of a main effect.

Interventions

• Drug Deep Neuromuscular Blockade (NMB)
  Rocuronium by continuous infusion to maintain profound relaxation (no train-of-four twitches; post-tetanic count 1-2) until the end of the field measurement and surgery; reversed with sugammadex and confirmation of full recovery (train-of-four ratio ≥ 0.9) before extubation. Cross-reference to arms: Arms 3, 4
• Drug Standard (moderate) neuromuscular blockade
  Rocuronium by intermittent bolus to maintain a train-of-four count of 1-2 (usual care); reversed with sugammadex and confirmation of full recovery (train-of-four ratio ≥ 0.9) before extubation. Cross-reference to arms: Arms 1, 2
• Other Preoperative low-residue diet
  A low-residue diet (less than 10 g dietary fibre per day) for the three days before surgery, with standardised food lists and a patient information sheet. This is a dietary measure, not a laxative; no mechanical bowel preparation is used. Cross-reference to arms: Arms 2, 4

Primary outcome measures

• Lowest CO₂ insufflation pressure at which the surgical field is adequate (blinded Transvaginal Natural Orifice Endoluminal Surgery - Objectiveisual Index: vNOTES-OVI ≥ 1) [Time frame: Intra-operative (single measurement window)]

Secondary outcome measures (10)

• Continuous surgical-field score (vNOTES-OVI) [Time frame: Intra-operative]
• Lowest pressure at the strict threshold (vNOTES-OVI = 2) [Time frame: Intra-operative]
• Requirement for a third working instrument [Time frame: Intra-operative]
• Postoperative nausea and vomiting - complete response [Time frame: 0-24 hours postoperative]
• Nausea severity [Time frame: 0-24 hours postoperative]
• Vomiting episodes [Time frame: 0-24 hours postoperative]
• Operative time [Time frame: Through surgery completion]
• Estimated blood loss [Time frame: Through surgery completion]
• Conversion to another approach [Time frame: Intra-operative]
• Intra-operative and early postoperative complications [Time frame: hrough 24 hours postoperative]

Eligibility criteria

Inclusion criteria

• Adult women (aged 18 years or older) scheduled for hysterectomy for a benign (non-cancer) indication.
• Judged suitable for the vNOTES approach by the operating surgeon.
• Able to understand the study and provide written informed consent.

Exclusion criteria

• Suspected or known gynaecological malignancy.
• Conditions expected to make the approach or the field assessment non-standard (e.g., anticipated dense pelvic adhesions or severe endometriosis, a contraindication to vNOTES, or an obliterated cul-de-sac).
• Any medical reason why deep neuromuscular blockade or sugammadex would be unsafe (defined with the anaesthesia team).
• Any medical reason why a low-residue diet would be unsuitable.
• Inability to give informed consent.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Factorial

Masking

Double blind

Primary purpose

Treatment

Study locations

Turkey (Türkiye) · 3 centers

• Kartal Dr. Lütfi Kırdar Şehir Hastanesi — Istanbul
• Acibadem Kartal Hospital — Istanbul
• Kütahya Şehir Hastanesi — Kütahya

Publications

• Yassa M, Karadeniz O, Kaya C, Doğan O, Şentürk B, Çalışkan E. Vaginal Natural Orifice Transluminal Endoscopic Surgery (vNOTES) Hysterectomy in Benign Gynecologic Indications: Evidence-Based Recommendations of the Pelvic Floor and Cosmetic Gynecology (PETKOZ) Association, Combined with Expert Consensus - A National Guideline. Anat J Obstet Gynecol Res. 2026 May 13;3(1):1-20. doi: 10.4274/anajog.gal
• Yassa M, Kaya C, Kalafat E, Tekin AB, Karakas S, Mutlu MA, Birol P, Tug N. The Comparison of Transvaginal Natural Orifice Transluminal Endoscopic Surgery and Conventional Laparoscopy in Opportunistic Bilateral Salpingectomy for Permanent Female Sterilization. J Minim Invasive Gynecol. 2022 Feb;29(2):257-264.e1. doi: 10.1016/j.jmig.2021.08.009. Epub 2021 Aug 16. PMID 34411729

Identifiers

NCT: NCT07730970 · ATADEK 2026/12, 2026-12/513

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗