Patients with chronic abdominal pain- with a component of abdominal wall pain- are often treated with trigger point injections. This study will help to determine if a block within the transversus abdominis plane (TAP) will provide superior analgesic benefit to a trigger point injection as therapy for these patients.

Only patients referred to the Pain Clinic for abdominal trigger point injections for abdominal wall pain will be considered for study recruitment.

Following informed consent, patients will complete a baseline questionnaire in the Pain Clinic which gathers basic demographic data, pain scores and functional scores. Patients will be randomized to receive either a TAP injection or a TPI. Because the TAP injection involves a larger area to be anesthetized, a larger volume of medication will be used.

Thirty minutes after the injection, a sensory exam will be performed on the patient to determine the level of block. At one week, one month, three months and six months after the injection, a staff member will telephone the patient to assess how they are doing. The call will take approximately 10 minutes and will consist of relaying a pain score as well as daily functioning and sleep questions.

Subjects are responsible for all clinical costs associated with the injection.

There is no remuneration offered for study participation.

Inclusion Criteria:

Only patients referred to Pain Clinic for a trigger point injection.

• Non-cancer pain greater than 3 months duration.
• Unilateral abdominal pain.
• Positive Carnett's sign (A test in which acute abdominal pain remains unchanged or increases when the muscles of the abdominal wall are tensed.)
• An identifiable abdominal trigger point.

Exclusion Criteria:

• History of chronic psychotic disorder.
• History of dementing illness.
• Active abdominal visceral disease as a known contributor of the pain.
• Abdominal surgery in the past 6 months.
• More than one trigger point.
• Abdominal wall hernias.
• BMI>40.