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ORIGINAL RESEARCH |
From the Departments of Radiology, Obstetrics and Gynecology, and Surgery, Massachusetts General Hospital, Boston, Massachusetts.
Address reprint requests to: Patrick M. Rao, MD, Department of Radiology, Massachusetts General Hospital, Boston, MA 02114, E-mail: rao.patrick{at}mgh.harvard
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Abstract |
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Methods: One hundred consecutive nonpregnant women suspected of having appendicitis or an acute gynecologic condition prospectively had helical CT. Interpretations were correlated with surgical and pathologic findings (41 cases) and clinical follow-up for at least 2 months (59 cases). The accuracy for confirming or excluding both appendicitis and acute gynecologic conditions was determined. The effect on patient care was determined by comparing pre-CT plans with actual treatment.
Results: Thirty-two women had appendicitis, 15 had acute gynecologic conditions, 27 had other specific diagnoses, and 26 had nonspecific abdominal pain. For diagnosing appendicitis or acute gynecologic conditions, CT had 100% and 87% sensitivity, 97% and 100% specificity, 94% and 100% positive predictive value, 100% and 98% negative predictive value, and 98% and 98% accuracy, respectively. After CT was done, 36 planned hospital admissions, 25 planned hospital observations, and six planned appendectomies were deferred; six women had alternative surgical procedures on the basis of CT results. One patient had an unnecessary appendectomy on the basis of CT findings.
Conclusion: Helical CT is an excellent imaging option for differentiating appendicitis from most acute gynecologic conditions.
The clinical differentiation of appendicitis from acute gynecologic conditions can be difficult, because they often present similarly. Appendicitis is overlooked initially in up to 33% of women, and a presumed acute gynecologic condition accounts for 40% of the initial misdiagnoses.1 Up to 48% of women have a normal appendix removed at appendectomy, and an acute gynecologic condition is diagnosed eventually in 56% of these patients.2 These conditions include ovarian cystic disease, ovarian torsion, and pelvic inflammatory disease (PID).
Helical computed tomography (CT) is 94–98% accurate for confirming or excluding appendicitis.3,4 However, its usefulness for diagnosing or excluding acute gynecologic conditions has not been well evaluated. The purpose of this investigation was to determine the accuracy and clinical effect of helical CT in differentiating appendicitis from acute gynecologic conditions.
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Materials and Methods |
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Each woman presented with two or more clinical signs or symptoms associated with appendicitis or acute gynecologic conditions (Table 1
).5,6 Twenty-eight patients had histories of one or more gynecologic condition, including, but not limited to, endometriosis, ovarian cystic disease, dysmenorrhea, ectopic pregnancy, and fibroid disease. Eighteen women in this investigation had pelvic ultrasound that was non-diagnostic before CT. All eligible subjects referred for this investigation agreed to CT, and none were lost to follow-up.
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Helical CT scans were done according to a recently described focused appendiceal CT technique.4 All patients received initially contrast material administered through the colon but not intravenously (IV). Additional scanning was performed in 32 patients after the initial, focused CT examination: 14 had scanning of the upper abdomen; 16 had decubitus CT scanning; and two had scanning after IV contrast material administration. Most CT examinations were completed within 15 minutes.
Computed tomography scans were interpreted immediately by residents or staff members of our Emergency Radiology Division. These interpretations were the official study results and the official reports of our Radiology Department in all but one case in which a staff member’s final interpretation differed from a resident’s initial interpretation. All scans were interpreted as positive or negative for appendicitis and acute gynecologic conditions; alternative conditions were noted when present. Scan results were given immediately to the referring clinicians.
Interpretations were negative for appendicitis if the appendiceal lumen filled completely with contrast material, air, or both, or was collapsed.7 When the appendix could not be seen at CT, appendicitis was excluded only in the absence of specific signs.7 Interpretations were positive for appendicitis if a distended (7 mm or larger in diameter), unopacified appendix was seen with adjacent inflammatory changes. When the appendix was not visualized at CT, appendicitis was diagnosed only in the presence of specific signs.
Interpretations were positive for acute gynecologic conditions if signs of ovarian disease (cyst rupture, torsion, tumor) or PID were present.8 Ovarian cyst rupture appears on CT as an ovarian cyst with free fluid in the pouch of Douglas or paracolic gutter; this fluid might be low (cyst fluid) or high (hemorrhage) density. Ovarian torsion appears on CT as ovarian enlargement, heterogeneity of ovarian density (if hemorrhagic), engorgement of adjacent vessels, and free fluid in the pouch of Douglas or paracolic gutter. Ovarian tumors appear as predominantly solid, cystic, or mixed-density masses. Pelvic inflammatory disease appears as a fluid-filled uterine cavity or fallopian tubes, and a thick-walled adnexal mass with adjacent fat-stranding and fluid in the pouch of Douglas or paracolic gutter.9 In the 35 patients who had appendectomies and six who had other surgeries, CT interpretations were correlated with surgical and pathologic findings. In the 59 women who did not have surgery, CT interpretations were correlated with clinical follow-up, including out-patient clinic visits and phone calls at least 2 months after CT examination.
After CT, actual patient treatment was recorded and compared with the preliminary care plans made by referring clinicians before CT. Potential treatment alterations included avoided hospital admissions, hospital observation periods, and appendectomies as well as altered surgical approaches.
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Results |
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) on pathologic examination of the appendix (Table 2). Sixty-eight had appendicitis excluded (Figure 2), either at appendectomy and pathology (three patients) or by establishment of an alternative condition or symptom resolution during a 2-month clinical follow-up period (65). Fifteen had acute gynecologic conditions, either right ovarian cystic disease (eight) (Figure 3), PID (three), ovarian torsion (two), benign cystic teratoma (one), or hematometra (one).
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For diagnosing or excluding acute gynecologic conditions, there were 13 positive CT interpretations (13 true positives) and 87 negative CT interpretations (85 true negatives and two false negatives). For diagnosing or excluding acute gynecologic conditions, helical CT had 87% sensitivity (95% CI 60.0, 98.3), 100% specificity (95% CI 95.8, 100), 100% positive predictive value, 98% negative predictive value, and 98% overall accuracy.
Specific clinical diagnoses were identified in 27 of 53 patients (51%) who had neither appendicitis nor acute gynecologic conditions (Table 2
). Computed tomography identified specific alternative diagnoses in 23 of 53 patients (43%), which was 23 of 27 (85%) who had specific alternative diagnoses other than appendicitis or acute gynecologic conditions (Figure 4).
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Discussion |
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Despite attempts to use clinical scoring systems and periods of hospital observation, negative appendectomy rates have remained between 20% and 30% for all patients and at up to 50% for young women.11,12 Attempts to use ultrasonography have had mixed results, with reported accuracies between 71% and 95% and positive predictive values between 86% and 91%.3,13
Computed tomography is 93–98% accurate for confirming or excluding appendicitis in all patients.3,4,13 Focused techniques can lower most patients’ CT radiation exposure to only about 300 mRad, which is the yearly radiation exposure of an average individual in the United States, and about the same radiation exposure as a plain abdominal radiograph.14 Techniques that include colon contrast material are highly accurate for diagnosing appendicitis, even without IV contrast material use; administration of contrast material through the colon has been proven safe in patients with suspected appendicitis.3,4,15
In this investigation, helical CT confirmed or excluded appendicitis or acute gynecologic conditions in 98% of patients. Readily identified acute gynecologic conditions included ovarian cyst rupture, ovarian torsion, ovarian dermoid, and hematometra. Overlooked conditions included two cases of nonsurgical PID.
In our investigation, 73% of patients had their planned treatment improved by the CT findings. Women with appendicitis avoided planned hospital observation periods, whereas those without appendicitis avoided planned appendectomies. Alternative conditions were diagnosed at CT, allowing for alternative surgical procedures or immediate medical treatment for nonsurgical conditions. In two recent similar investigations, CT was shown to improve patient treatment in 58–59% of patients with clinically suspected appendicitis.16,17
One of the main limitations of this study was that there were relatively few (15) cases of acute gynecologic conditions. We suspect this was because most women suspected of having acute gynecologic conditions are imaged initially with ultrasound. Also, our study was conducted in a large academic center with helical CT and emergency radiologists available in the Emergency Department; it is not yet known how generalizable the study results will be. This investigation was a descriptive and not a comparative study between present diagnostic methods and a new technique; future investigation could include a randomized, comparative study.
We believe that women in whom acute gynecologic conditions are diagnosed versus appendicitis should have initial ultrasound evaluation. When ultrasound is normal or nondiagnostic, helical CT is an excellent second imaging option. In women in whom appendicitis is diagnosed versus acute gynecologic conditions, helical CT should be the initial imaging method.
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Footnotes |
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Received July 16, 1998. Received in revised form August 31, 1998. Accepted September 17, 1998.
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References |
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2. Nakhgevany KB, Clarke LE. Acute appendicitis in women of childbearing age. Arch Surg 1986;121:1053–5.[Abstract]
3. Rao PM, Boland GL. Imaging of acute right lower abdominal quadrant pain. Clin Radiol 1998;53:639–49.[Medline]
4. Rao PM, Rhea JT, Novelline RA, Mostafavi A, Lawrason JN, McCabe CJ. Helical CT combined with contrast material administered only through the colon for imaging of suspected appendicitis. AJR Am J Roentgenol 1997;169:1275–80.
5. Bongard F, Landers DV, Lewis F. Differential diagnosis of appendicitis and pelvic inflammatory disease; a prospective analysis. Am J Surg 1985;150:90–6.[Medline]
6. Najem AZ, Barillo DJ, Spillert CR, Kerr JC, Lazaro EJ. Appendicitis versus pelvic inflammatory disease. Am Surg 1985;51:217–22.[Medline]
7. Rao PM, Rhea JT, Novelline RA. Sensitivity and specificity of the individual CT signs of appendicitis: Experience with 200 helical appendiceal CT examinations. J Comput Assist Tomogr 1997;21: 686–92.[Medline]
8. Langer JE, Dinsmore BJ. Computed tomographic evaluation of benign and inflammatory disorders of the female pelvis. Radiol Clin North Am 1992;30:831–42.[Medline]
9. Wilbur A. Computed tomography of tuboovarian abscesses. J Comput Assist Tomogr 1990;4:625–8.
10. O’byrne JM, Dempsey CB, O’Malley MK, O’Connell FX. Non-specific abdominal pain in pre-menopausal women. Ir J Med Sci 1991;160:344–6.[Medline]
11. Izbicki JR, Knoefel WT, Wilker DK, Mandelkow HK, Muller K, Siebeck M, et al. Accurate diagnosis of acute appendicitis: A retrospective and prospective analysis of 686 patients. Eur J Surg 1992;158:227–31.[Medline]
12. Dunn EL, Moore EE, Elerdin SC, Murphy SR. The unnecessary laparotomy for appendicitis—can it be decreased? Am Surg 1982; 48:320–3.[Medline]
13. Balthazar EJ, Birnbaum BA, Yee J, Megibow AJ, Roshkow J, Gray C. Acute appendicitis: CT and US correlation in 100 patients. Radiology 1994;190:31–5.
14. American College of Radiology. Radiation risk: A primer. ACR Commission on physics and radiation safety. Reston, Virginia: American College of Radiology, 1996.
15. Shust N, Blane CE, Oldham KT. Perforation associated with barium enema in acute appendicitis. Pediatr Radiol 1993;23:289–90.[Medline]
16. Rao PM, Rhea JT, Novelline RA, Mostafavi AA, Lawrason JN, McCabe CJ. Effect of computed tomography of the appendix on treatment of patients and use of hospital resources. N Engl J Med 1998;338:141–6.
17. Shuler JG, Shortsleeve MJ, Goldenson RS, Perez-Rossello JM, Perlmutter RA, Thorsen A. Is there a role for abdominal computed tomographic scans in appendicitis? Arch Surg 1998;133:373–6.
This article has been cited by other articles:
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 L. Neumayer and A. Kennedy Imaging in Appendicitis: A Review With Special Emphasis on the Treatment of Women Obstet. Gynecol., December 1, 2003; 102(6): 1404 - 1409. [Abstract] [Full Text] [PDF]
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