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Don't Let the Abdominal Wall Stand Between You and the Diagnosis
By Frank W. Ling, MD, Clinical Professor, Department of Obstetrics and Gynecology, Vanderbilt University School of Medicine, Nashville, is Associate Editor for OB/GYN Clinical Alert.
Dr. Ling reports no financial relationship to this field of study.
Yes, we've all heard this tongue-in-cheek summary of why surgery is used to determine what is wrong with a patient. Supposedly, an operation gets to the patient's underlying problem. The message is not subtle.
Actually, I am using it in this case to encourage the reader to think of the abdominal wall as the potential source of the problem rather than something that is in the way of getting to the problem. To start the discussion, I'm summarizing a short case report that highlights the abdominal wall as the source of the patient's problem.1
Case. A painful mass in the right lower quadrant appeared 2 weeks after a woman's cesarean delivery. Over the next 6 years, the mass gradually grew in size to 3 cm. Her symptoms were not cyclic. Eventually, it was excised from the lateral margin of the Pfannenstiel incision and pathology confirmed a diagnosis of endometrioma involving the dermis and subcutaneous tissue.
Commentary. It is likely that exposure of the subcutaneous tissue to endometrial tissue at the time of the cesarean delivery was the mechanistic pathway of development. Interestingly, it has been reported that having a cesarean delivery prior to the onset of labor actually increases the risk of developing an abdominal wall endometrioma.2 The incidence following cesarean delivery is less than half a percent3 and the interval from the last surgery until presentation can range from 1 month to 20 years.4 Even though common things occur commonly, and endometriomas of the abdominal wall are not common, they should certainly be in the differential diagnosis when considering the likely causes of a mass of the abdominal wall.
My personal experience with endometriomas of the abdominal wall is not published, but, because I have seen at least half a dozen cases, it did surprise me, when reading this recent case report, that it was reportable. It's a lot less common than I thought or there are a lot of folks like me who haven't reported seeing it relatively often. I can't say why I have seen so many, but there is nothing in the literature that tells me that the patient population that I have served over the past 32 years is unique or unusual.
Cyclic symptoms. Even though you would think that the mass would mimic endometriosis and have cyclic symptoms, that is true only about half the time. Also, attempts to treat such masses with medical therapy are only partially successful. This should not surprise us since medical treatment of endometriomas in the pelvis are invariably not successful. Surgery is certainly needed in those cases. Needless to say, other causes for masses of the abdominal wall would also not respond to medical/hormonal therapy, e.g., stitch granuloma, abscess, hematoma, or hernia.
Mechanical irrigation. The use of mechanical irrigation at the end of both cesarean delivery as well as gynecologic surgery for endometriosis may well reduce the potential risk of subsequent endometrioma formation. Since irrigation has been shown to reduce infection of the subcutaneous tissue layer, it may well be that a second reason to perform this irrigation is to reduce the risk of a possible endometrioma.
Plans for surgery. Another tip involves the plans for surgery once the diagnosis has been made. Because wide local excision is the appropriate surgical approach, the surgeon should be prepared to remove an area of tissue approximately twice the size of the suspected mass. Again, for the experienced gynecologic surgeon, it comes as no surprise that there is significant scarring in the abdominal wall surrounding the endometrioma, similar to the dense scarring encountered in the pelvis with extensive endometriosis. Planning to remove an area significantly larger than the palpable mass or the imaged mass will minimize the "surprise" factor for the closure once the wide local excision is accomplished.
Pain: Abdominal Wall
Far too often, gynecologists look right past the problem, both literally and figuratively. Admittedly, the example of the endometrioma makes an obvious point, i.e., a mass in the abdominal wall does not necessarily have to have intra-abdominal pathology associated with it. Beyond the issue of masses, we see many patients whose problems are assumed to be deeper than they really are.
This is particularly true with pelvic and abdominal pain. We allow that old adage in the title to lure us to a surgical approach, looking for the intra-abdominal source of pain. In the past, laparotomy of an "exploratory" nature was widely accepted. Today's version of that is diagnostic laparoscopy, with well-meaning attempts to see endometriosis, adhesions, or other potential causes of pain. In fact, our laparoscopic camera may be taking us right past the source of the problem, namely the abdominal wall. Figuratively, the surgeon is thinking intra-abdominal sources of pain and, thereby, goes right past the abdominal wall. Our trocars and scopes literally do the same thing. What are we missing? Maybe a lot.
If the clinician would routinely consider the abdominal wall as the potential source of pain, several conditions come into play. Certainly, those patients with abdominal incisions, particularly Pfannenstiels, may have an entrapped nerve or even a hyperirritable muscle bundle (trigger point) at either end. Indeed, trigger points can occur anywhere in the abdominal wall muscles, but the most common abdominal wall trigger points are reported to occur at the lateral margins of the rectus muscles in both lower quadrants. Injections to tender sites on the abdominal wall can eliminate pain in up to half of patients.5
Not only can there be trigger points in the muscles of the abdominal wall, but the muscles themselves may be the source of pain. Physical therapy modalities provided by a therapist with manual therapy expertise can prove beneficial.6
Spigelian hernias lie lateral to the rectus abdominis muscles and medial to the semilunar line. They occur at or below the arcuate line, probably because of a lack of a posterior rectus sheath. They may not produce any noticeable mass or swelling but can be a cause of pain and even bowel entrapment. Ultrasound can establish the diagnosis, but CT scan is more sensitive and specific. Surgical correction is recommended because of the risk of bowel compromise.
There is also a poorly defined proportion of patients who may have neuropathic pain manifest by abdominal wall tenderness. These patients may or may not ultimately be found to have some form of fibromyalgia. Both fibromyalgia and neuropathic syndromes may respond to various medical interventions that can include both antidepressants and anticonvulsants.
How best to avoid missing the abdominal wall? It's probably better done on physical examination than by history. First, have the patient point to the exact place where she hurts. Ideally, she can be instructed to use just one finger, rather than allowing her to wave her entire hand over a large area. Once the area of pain is found, superficial palpation can sometimes recreate the pain. If so, then the abdominal wall is a likely suspect. If superficial palpation does not recreate her pain, have her raise her head (like an abdominal crunch) then raise both her legs without bending her knees (like a leg lift). Gentle pressure on the tensed muscles may recreate her pain suggesting the abdominal wall as the painful source. If the pelvic examination is non-tender, then the focus should definitely turn to the abdominal wall. Caution should be used in performing the pelvic since a bimanual examination of the adnexa might make the examiner think that it is the intra-abdominal organs that are painful. A one-handed examination of the pelvis, not exerting abdominal wall pressure from above, is a key way to distinguish pelvic from abdominal wall tenderness. Also, the astute clinician knows that the normal ovary is normally tender, so if adnexal tenderness is found, the question should be asked of the patient, "Is that the pain that is bothering you?" Not infrequently, the patient can state emphatically that the pain on physical examination is or is not the chief complaint. This, again, helps focus attention on either the pelvis or the abdominal wall.
Whether the busy clinician ever makes the correct diagnosis of abdominal wall pain or not, it is similar to the example of the endometrioma of the abdominal wall that we used to start this discussion. The battle is won if the abdominal wall is given a fair shot within the differential diagnosis. As long as we don't routinely look past the abdominal wall, but, instead, look at it and consider it a potential source of the problem, our patients will be subjected to a minimal amount of surgery that could have been avoided.