Bowel Diseases
Synonyms/Description
Pelvic masses related to bowel such as appendicitis, endometriosis, colon cancer, Crohn’s disease, ulcerative colitis, diverticulitis, lymphoma, sarcoma, or other bowel-specific diseases identified on a pelvic ultrasound
Etiology
There are multiple etiologies in this grouping of bowel diseases. The etiologies range from inflammatory/infectious such as appendicitis, inflammatory bowel diseases, and diverticulitis to neoplasms such as lymphomas, carcinomas, and sarcomas.
In the small bowel, neuroendocrine tumors, adenocarcinomas, sarcomas, lymphomas, and miscellaneous tumors comprise 36.5%, 30.9%, 10.0%, 18.7%, and 3.9% of malignancies, respectively. In the appendix, neuroendocrine tumors, adenocarcinomas, sarcomas, lymphomas, and miscellaneous tumors comprise 31.7%, 65.4%, greater than 1%, 1.7%, and 1.1% of malignancies, respectively. Colon tumors include mostly adenocarcinomas (93.0%), whereas sarcomas and lymphomas are relatively rare.
These entities are briefly discussed in terms of ultrasound findings because they may be encountered during a sonographic gynecologic exam. For more detailed information about any of these lesions, please refer to the suggested reading.
Ultrasound Findings
Diseases of the bowel are detectable and can be accurately diagnosed using ultrasound. Typically the sonographic evaluation of bowel abnormalities includes the appearance of the bowel wall, amount and quality of peristalsis, reaction to manual compression using the transducer, and relative “stiffness” of the bowel loop. Also there may be a nonspecific mass, which is difficult to distinguish from adnexal or uterine masses. It is crucial to identify the uterus and ovaries separate from the mass to correctly diagnose it as a bowel problem.
Endometriosis
Endometriosis of the rectosigmoid colon is covered in the section on endometriosis.
Appendicitis
The typical ultrasound findings include a distended, noncompressible tubular mass, greater than 7 mm in diameter and with relatively cystic center suggesting bowel. In the transverse view, the abnormal appendix often appears as a double ring indicating the swollen wall. Gentle compression will displace normal loops of bowel to better demonstrate the inflamed appendix, although the compression is usually uncomfortable for the patient. There can also be inflammation of the adjacent omental fat with a very echogenic characteristic appearance, sometimes with shadowing from an appendicolith. The sensitivity for ultrasound compared with computed tomography to diagnose appendicitis is 75% versus 90%, and the specificity is 86% versus 100%. Ultrasound is often the only imaging needed to make the diagnosis.
Inflammatory Bowel Diseases
These include Crohn’s disease and ulcerative colitis, which typically produce a diffuse thickening of a segment of bowel wall, with reduced peristalsis and a “stiff-looking,” relatively straight segment of bowel. There is usually a loss of the normal striated gut appearance because of the disease involving multiple layers of the bowel wall. Ulcerative colitis is found mostly in the rectum and rectosigmoid, whereas Crohn’s is typically seen in the distal ileum.
Diverticulitis
When a diverticulum becomes inflamed, it appears sonographically as a segmental area of thickened bowel wall with an inflamed outpouching (diverticulum) and inflamed surrounding pericolic fat. Diverticulitis can also result in an abscess that can be seen sonographically. The bowel wall thickening is usually asymmetric but retains its normal three layers, thus differentiating it from the appearance of inflammatory bowel disease.
Duplication Cyst
Bowel duplication cysts are rare congenital anomalies that may be asymptomatic for much of a person’s life. However, when these undergo hemorrhage, infection, or torsion, the symptoms are similar to appendicitis or ovarian torsion. Sonographically, when these cysts are symptomatic, they will show internal hemorrhage and appear similar to an endometrioma.
Lymphoma
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