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REctus Sheath Trial

Transverse Versus Longitudinal Approaches for Rectus Sheath Block: a Randomized Controlled Trial in Healthy Volunteers

Who can join

Ages 18 and older · All sexes · Healthy volunteers welcome

Inclusion criteria:

1. Ability to provide written informed consent
2. Ability and willingness to comply with the study procedures and duration requirements
3. ASA physical status 1 or 2
4. Age ≥ 18 years
5. Weight \> 60kg

Exclusion criteria:

1. BMI \> 40kg.m-2
2. Use of analgesics within 24 hours before the procedure
3. History of abdominal trauma or surgery
4. Abdominal deformities or abnormalities that may prevent proper block performance
5. Abdominal tattoos in the supraumbilical area
6. Systemic neuromuscular disease
7. Contraindications to regional anesthesia (e.g., infection, allergy)
8. Structures are unable to be visualized by ultrasound
9. Pregnancy
10. Other known health conditions that would affect the participant's ability to successfully complete the study

About the study

Regional anesthesia techniques (or nerve blocks) are used to provide sensory blockade over the abdominal wall. The most established technique is thoracic epidural. This provides bilateral spread but is also associated with neuraxial complications, which has led to a decrease in clinical usage. The rectus sheath block (RSB) is an established regional anesthesia technique used to provide somatic analgesia to the midline anterior abdominal wall by depositing local anesthetic in the posterior rectus sheath, thereby targeting the terminal anterior branches of the lower thoracic intercostal nerves. The conventional approach involves placing the ultrasound (US) probe transversely across the rectus abdominis muscle and advancing the needle in-plane either lateral-to-medial or medial-to-lateral. While this technique achieves spread within the sheath, the cephalocaudal distribution of local anesthetic may be suboptimal, potentially limiting the extent of dermatomal coverage. A longitudinal probe orientation, with needle insertion from cephalad to caudad, may theoretically facilitate a more extensive cranio-caudal spread by aligning the injection axis with the anatomical fascial plane of the posterior rectus sheath. However, the relative efficacy of these two approaches has not been investigated in a controlled, comparative setting. Thus, this randomized, single-blinded trial aims to evaluate the dermatomal sensory distribution and ultrasound-assessed local anesthetic spread achieved by the transverse versus longitudinal in-plane approaches to ultrasound-guided RSB in healthy adult volunteers. To compare the dermatomal sensory block distribution, investigators will use dermatomal mapping with pinprick, and cold.

What is being tested

• 1.0% lidocaine with epinephrine (1:100,000) (drug)

Sponsor: Duke University · Participants: 25 · Started: Oct 26, 2026

Contact the study team

• David MacLeod, MBBS · Phone: 9198123201
• Ashley Burke · Phone: 919-681-2849

Official record on ClinicalTrials.gov — NCT07068243

Locations in the U.S.

Conditions

• Acute Pain
• Pain After Surgery

From ClinicalTrials.gov, data retrieved Nov 15, 2026. Each study sets its own eligibility; the study team decides who can join.