The Easiest Abdominal Pain Patient: Addressing Abdominal Wall Pain

Abbreviations

AWP

abdominal wall pain

RVU

relative value unit

Abdominal wall pain (AWP) is common in hepatology clinics and can be frustrating for patients who continue to look for help. Thirty percent of patients with chronic abdominal pain have some AWP.¹ AWP is more common in patients with persistent right upper quadrant pain, especially in those who have abdominal surgery, sports‐related injuries, and obesity.¹, ² The patient with AWP often has had numerous imaging studies and endoscopies investigating the cause of pain,³ where a simple physical examination would suffice.

We have a high index of suspicion in anyone who comes to our clinic with abdominal pain, even in our hepatology and hepatobiliary clinics. Patients may have coincident conditions, such as irritable bowel syndrome, elevated liver enzymes, and inflammatory bowel disease, all of which can present with abdominal pain. The patient’s history often offers clues: pain exacerbating by motion or an acute event. Patients often report pain when getting in and out of bed. Pain can be associated with oral intake given that the abdominal wall moves with gastric distention. Many patients will use a single finger to point to a spot of pain on their abdomens.

The examination for AWP is simple: evaluate for a positive Carnett’s sign (see Fig. 1). In our practice, we ask patients to use just one finger and point to the fingerbreadth’s area of maximal tenderness in their abdomen. We palpate there while the patient flexes their abdomen, whether through a sit‐up, flexing their neck forward, or lifting their legs up (Fig. 2). A positive test occurs when the pain worsens with flexion. A positive Carnett’s sign without a palpable hernia is pathognomonic for AWP. AWP does not cause but can present with red flag symptoms such as anemia or weight loss. These should be worked up separately (but remember to still treat the AWP!).

FIG 1.

Carnett's sign. Reproduced with permission from The American Journal of Gastroenterology.⁵ Copyright 2020, Wolters Kluwer Health, Inc.

FIG 2.

Injection site. Reproduced with permission from The American Journal of Gastroenterology.⁵ Copyright 2020, Wolters Kluwer Health, Inc.

Management

A trigger point injection leads to a 50% relief of pain after injection of a local anesthetic; its value is that it serves as a diagnostic and therapeutic procedure.⁴ We recommend lidocaine and triamcinolone as the initial injection for patients with a positive Carnett’s sign. We caution patients regarding hypopigmentation or thinning of the subcutaneous tissue, burning discomfort during the injection, and a small risk for infection given the piercing of the skin. We use the five‐point technique described as follows:

Instructions for abdominal wall injection (five‐point technique; see Fig. 2)

Mix 4 mL of 1% lidocaine with 40 mg (1 mL) of triamcinolone in a 5‐mL syringe. Attach to a narrow‐caliber (21‐gauge or less) 5/8‐ or 1‐inch needle. Mark the site of the patient’s pain on the abdominal wall and prep with chlorhexidine. Insert the needle perpendicular to the patient’s abdomen at the marked site with the goal to reach the rectus abdominus muscle; this normally requires the full length of the needle. We warn patients they may feel a “stick” or a “sting” sensation. Once the tip of the needle is at the point of maximal tenderness, inject 1 mL of the mixture. Prior to injection, we warn patients that they may feel a “burning” sensation. Withdraw the needle to the skin, redirect upward at a 45° angle, and reinsert to the needle’s maximal depth; inject an additional 1 mL of mixture. Repeat step 5 with the needle directed to the left, downward, and right, each at a 45° angle, then remove the needle while applying pressure with sterile gauze. Gently massage the injection site and apply a bandage if needed for hemostasis.

We do not use ultrasound guidance given the superficial nature of the treatment. Longer needles (1 inch) are more useful in obese patients or in the lower abdomen. We generally do not do a second injection before a 3‐month interval and do not repeat injections more than once. In those who incompletely respond, we recommend a daily oral nonsteroidal anti‐inflammatory drug or a topical analgesic (such as a lidocaine transdermal patch), but our success with these treatments is limited.

Trigger point injections for AWP must be one of the most cost‐effective procedures in gastroenterology.⁴ You can code abdominal wall trigger point injections under the 2019 ICD‐10‐CM (International Classification of Diseases, Tenth Revision, Clinical Modification) Diagnosis Code M79.1 (Myalgia) using the CPT (Current Procedural Terminology) code 20552 (Injection(s); single or multiple trigger point(s), 1 or 2 muscles) with code J1030 for the injectable triamcinolone. If your local payer uses a relative value units (RVUs)‐based reimbursement model, this correlates to an additional 0.66 RVU in combination of all codes presented according to the Medicare National Fee Schedule.

AWP is common and can be easily diagnosed with a simple physical examination finding. A positive Carnett’s sign without a palpable hernia is pathognomonic for AWP, and treatment with a trigger point injection is both safe and effective. We hope that this guide will help providers feel better about treating patients with AWP and more likely to perform trigger point injections.