COVID-19 is an emerging, rapidly evolving situation.
Get the latest public health information from CDC:

Get the latest research information from NIH: Menu

Transversus Abdominis Plane (TAP) Block for Cesarean Section (CLOTAP)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01015807
Recruitment Status : Completed
First Posted : November 18, 2009
Results First Posted : May 30, 2017
Last Update Posted : October 23, 2017
Information provided by (Responsible Party):
Laurent Bollag, University of Washington

Brief Summary:
The purpose of this study is to determine whether a transversus abdominis plane (TAP) block with Clonidine added to the injectate (Clo-TAP) performed approximately 2hrs after the cesarean section (CS) will decrease the amount of postoperative hyperalgesia and ultimately reduce post-CS chronic pain.

Condition or disease Intervention/treatment Phase
Hyperalgesia, Secondary Drug: Bupivacaine Placebo Drug: Clonidine Placebo Drug: Bupivacaine Drug: Clonidine Not Applicable

Detailed Description:

Acute severe pain after cesarean section (CS) occurs more often than is thought and 10-15% of the women having a cesarean section develop chronic pain (Kehlet et al. 2006). With over 1.3 million cesarean deliveries per year in the US, this is bound to create a significant health problem. One way to address this health burden is to refine techniques that may help control the pain women experience after CS and ultimately reduce the potential to develop chronic pain.

The purpose of this randomized, double-blinded study is to evaluate the ability of an established anesthetic technique called the transversus abdominis plane (TAP) block to reduce the amount of hyperalgesia women develop around their incision after CS. Measuring the amount of punctuate mechanical hyperalgesia is used as a tool to assess postoperative central sensitization (Lavand'homme et al. 2005), which contributes to postoperative acute pain. Since postoperative acute pain has been shown to be predictive of developing postoperative chronic pain (Eisenach et al. 2008; Yarnitsky et al. 2008), an effective TAP block could help diminish the incidence of chronic pain after CS. In addition, blood samples will be collected for future genetic analysis and we will test preoperatively for mechanical temporal summation (mTS) to evaluate CNS (central nervous system) sensitization and nociceptive system hyperexcitability and see if this correlates with the amount of hyperalgesia women develop around their incision after surgery.

The primary aim of this study is to evaluate the benefits of two different solutions injected by TAP block technique on postoperative peri-incisional hyperalgesia.

Layout table for study information
Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 90 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Participant, Care Provider)
Primary Purpose: Prevention
Official Title: Transversus Abdominis Plane (TAP) Block for Cesarean Section
Study Start Date : November 2009
Actual Primary Completion Date : August 2010
Actual Study Completion Date : August 2012

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Cesarean Section

Arm Intervention/treatment
Placebo Comparator: Placebo
Sterile Saline used for TAP block = Bupivacaine Placebo + Clonidine Placebo
Drug: Bupivacaine Placebo
2 x 20mL 0.9% NaCl
Other Names:
  • Bupi Placebo
  • Sodium Chloride

Drug: Clonidine Placebo
2 x 1mL 0.9% NaCl
Other Name: Sodium Chloride

Active Comparator: TAP (Bupi)
2x20mL 0.375% Bupivacaine + 2x1mL of 0.9% NaCl = 150mg Bupivacaine + Clonidine Placebo
Drug: Clonidine Placebo
2 x 1mL 0.9% NaCl
Other Name: Sodium Chloride

Drug: Bupivacaine
2 x 20mL 0.375% Bupivacaine = 150 mg Bupivacaine
Other Name: Bupivacaine Hydrochloride

Active Comparator: Clo-TAP (Bupi + Clon)
2x20mL 0.375% Bupivacaine + 2x1mL Clonidine = 150mg Bupivacaine + 150µg Clonidine
Drug: Bupivacaine
2 x 20mL 0.375% Bupivacaine = 150 mg Bupivacaine
Other Name: Bupivacaine Hydrochloride

Drug: Clonidine
2 x 1ml Clonidine = 150 µg Clonidine
Other Name: Clonidine Hydrochloride

Primary Outcome Measures :
  1. Wound Hyperalgesia Index (WHA) Assessed 48 Hrs After Block Placement in the Different Groups [ Time Frame: 48hrs after CS ]
    Determine which of three different TAP formulations (Placebo, TAP, Clo-TAP) has the most beneficial effect on the postoperative area of hyperalgesia 48hrs after the start of the cesarean section. The smaller the area of WHA, assessed in cm2, the better the outcome. Area sizes may range from 0 to any size.

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

Layout table for eligibility information
Ages Eligible for Study:   18 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Female
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • non-laboring women who will benefit from and have clinically consented to a scheduled or non-scheduled cesarean delivery under spinal anesthesia
  • English speaking (UW Site) or Portuguese speaking (Brazil site)
  • aged between 18 and 45 years
  • BMI < 40
  • ASA physical status class I or II

Exclusion Criteria:

  • laboring women undergoing a non-scheduled cesarean delivery
  • non-English speaking (UW Site) or non-Portuguese speaking (Brazil site)
  • previous spinal surgery
  • contraindications for neuraxial anesthesia
  • allergy to local anesthetic, ultrasound conduction gel, or Clonidine
  • history of chronic pain
  • inability to receive intraoperative Toradol

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01015807

Layout table for location information
United States, Washington
University of Washington
Seattle, Washington, United States, 98195
Hospital e Maternidade Santa Joana
São Paulo, Brazil, 04103-080
Sponsors and Collaborators
University of Washington
Layout table for investigator information
Study Chair: Ruth Landau, MD University of Washington
Principal Investigator: Laurent Bollag, MD University of Washington

Layout table for additonal information
Responsible Party: Laurent Bollag, Assistant Professor, Department of Anesthesiology and Pain Medicine, University of Washington Identifier: NCT01015807    
Other Study ID Numbers: 36707
First Posted: November 18, 2009    Key Record Dates
Results First Posted: May 30, 2017
Last Update Posted: October 23, 2017
Last Verified: September 2017
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by Laurent Bollag, University of Washington:
transversus abdominis plane block
TAP block
cesarean section
Additional relevant MeSH terms:
Layout table for MeSH terms
Somatosensory Disorders
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases
Anesthetics, Local
Central Nervous System Depressants
Physiological Effects of Drugs
Sensory System Agents
Peripheral Nervous System Agents
Antihypertensive Agents
Autonomic Agents
Adrenergic alpha-2 Receptor Agonists
Adrenergic alpha-Agonists
Adrenergic Agonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action