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The use of helical computed tomography in pregnancy for the diagnosis of acute appendicitis

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The use of helical computed tomography in pregnancy for the diagnosis of acute appendicitis
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  954  Acute appendicitis complicates approximately 1 of 1440 pregnancies 1 and is the most common nonobstetri-cal indication for surgical exploration of the gravid ab-domen. 2 Many more laparotomies are performed for thesuspected diagnosis (approximately 1 of 936 births). 1 It has been reported that alteration of the intra-abdomi-nal contents by the pregnant uterus can make the clinicalpresentation difficult to interpret. 3 If this surgical emer-gency is not diagnosed in a timely fashion it can result inperforation of the appendix with grave consequences forthe mother and fetus. 2, 4 Surgical exploration itself is not  without risk. A reliable, noninvasive, safe test was sought to expedite surgery for those who truly have the condi-tion and to avoid a surgical procedure in those who donot. A helical or spiral computed tomography (CT) tech-nique has been shown to be highly sensitive and specificfor the identification of acute appendicitis in the nonob-stetric population. 5, 6  We now report for the first time theuse of helical CT for a series of pregnant patients with sus-pected acute appendicitis. Material and methods  All pregnant patients at our institution who underwent helical CT for the presumed clinical diagnosis of acuteappendicitis were retrospectively reviewed. The study pe-riod was April 1997 to February 1998. Maternal demo-graphic information, pregnancy history, hospital course,and pathologic findings, if applicable, were collected.The final outcome for the index pregnancy was also ob-tained.Helical CT was performed by standard departmentalprotocol and has been described elsewhere. 5 Helical CTuses a volumetric data acquisition to obtain high-quality images free of several artifacts that can degrade conven-tional CT images. All patients received colon contrast medium, 700 to 1000 mL of a 3% meglumine diatrizotesolution (Gastrografin; Bristol-Myers Squib, Wallingford,Conn), through a rectal catheter immediately beforescanning. Two patients (cases 1 and 7) also received oralcontrast medium, up to 750 mL as tolerated, of a 2.1%  From the Departments of Obstetrics and Gynecology, a   Emergency Medi- cine, b  and Radiology, c  Massachusetts General Hospital, and the Depart- ment of Obstetrics and Gynecology, Kaiser Permanente. d  Received for publication May 18, 2000; revised September 1, 2000; accepted September 19, 2000.Reprint requests: Mary Ames Castro, MD, University of Wisconsin Med- ical School/MCC, Sinai Samaritan Medical Center, Department of OB/GYN, 5A, P.O. Box 342, Milwaukee, WI 53201.Copyright © 2001 by Mosby, Inc.0002-9378/2001 $35.00 + 0   6/1/111721 doi:10.1067/mob.2001.111721 The use of helical computed tomography in pregnancy for the diagnosis of acute appendicitis Mary Ames Castro, MD, a  Thomas D. Shipp, MD, a  Eduardo E. Castro, MD, b  Joseph Ouzounian, MD, d and Patrick Rao, MD c Boston, Massachusetts, and Baldwin Park, California  OBJECTIVE: Accurate diagnosis of acute appendicitis in pregnancy by clinical evaluation is difficult.A safe,reliable test was sought to decrease a delay in diagnosis and to avoid unnecessary invasive procedures.Ahelical or spiral computed tomographic technique has proven to be a very accurate test in the nonobstetricpopulation for the identification of acute appendicitis.We report its use in pregnant patients with suspectedacute appendicitis. STUDY DESIGN: All pregnant patients who were undergoing helical computed tomography at our institutionfrom April 1997 to February 1998 for the suspected clinical diagnosis of acute appendicitis were retrospec-tively reviewed.Helical computed tomography was performed by standard departmental protocol.A positivestudy was reported if an enlarged appendix, which did not fill with contrast material, was present with periap-pendiceal inflammatory changes.Outcomes were determined by the results of surgery and pathologic exam-ination or clinical follow-up. RESULTS: Seven patients were identified in the study period.Two patients had positive findings on helicalcomputed tomography, and acute appendicitis was confirmed at laparotomy and by pathologic inspection.There were no further prenatal complications and both patients delivered at term.Five patients had a nor-mal-appearing appendix on helical computed tomography, and all of these patients had resolution of theirpain and symptoms. CONCLUSION: Helical computed tomography appears to be a useful, noninvasive test to accurately diag-nose acute appendicitis in pregnancy.(Am J Obstet Gynecol 2001;184:954-7.) Key words: Helical computed tomography in pregnancy, acute appendicitis   Volume 184, Number 5 Castro et al955  Am J Obstet Gynecol barium sulfate suspension (SCAN-C; LPI Diagnostics, Anaheim, Calif) 30 minutes before scanning. One pa-tient (case 1) also received intravenous contrast medium. Appendix CT scans were identified as positive for appen-dicitis on the basis of an enlarged appendix (>6 mm inthe maximum diameter) and periappendiceal inflamma-tory changes, such as fat stranding, phlegmon, fluid col-lection, and extraluminal gas. 5 The arrowhead sign de-notes contrast media collecting in an arrowhead shape inthe bowel at the cecal apex and is considered to be highly suggestive of acute appendicitis because it has beenshown to be present in 30% of cases. 7  Appendix CT scans were called normal if the lumenfilled completely with contrast medium, air, or both andthe wall was 2 mm thick or less, regardless of maximumdiameter. An appendix that did not fill with air or con-trast medium but measured less than 7 mm in maximumouter diameter was also considered normal was (Figs 1 Fig 1. Helical CT of a normal appendix (arrow)  . Fig 2. Helical CT of an inflamed appendix (A)   with periappendiceal inflamation and wall thickening (arrow)  .  956Castro et al  April 2001 Am J Obstet Gynecol and 2). 5 Intravenous contrast medium was used to evalu-ate appendiceal wall thickness and enhancement, sepa-rate from lumen distension. Results Seven patients were identified during the study period. All of these patients were in the second and thirdtrimester of pregnancy (Table 1). Helical CT was per-formed because appendicitis was clinically suspected.The ages of the patients ranged from 20 to 39 years.There were 3 nulliparous women. All patients were seen with abdominal pain. All of the patients had a maximumtemperature of less than 100.5°F except case 5, who had amaximum temperature of 100.6°F. Five of the 7 patientshad no emesis, and 2 of the 7 were without nausea. Anorexia was experienced by all but case 2, a patient whohad acute appendicitis. The time from the onset of symp-toms to presentation ranged from 1 to 24 hours, with amedian duration of symptoms of 6 hours.Two patients had positive studies. Case 1 had a nonfill-ing 10-mm appendix with an enhancing wall, periappen-diceal fat stranding, and the arrowhead sign. Before theobtainment of the helical CT, acute cholelithiasis wasconsidered and excluded on the basis of normal liverfunction tests and right upper abdominal quadrant ultra-sonography. The appendix could not be visualized withultrasonography. Case 2 had a nonfilling 14-mm appen-dix with periappendiceal fat stranding and focal cecalapical thickening, with a small amount of fluid in theparacolic gutter. An obstetric sonogram was obtained be-cause abruptio placentae was also considered; however,this was normal. Both patients underwent emergent lap-arotomy with a paramedian incision, and the diagnosis was confirmed at the time of surgery and later with patho-logic inspection (gross and histologic). Case 2 was alsoconfirmed to have acute perforation and localized peri-tonitis. There were no postoperative or perinatal compli-cations. Both of these patients delivered at term with ap-propriately grown neonates.Five patients had a normal appearing appendix on he-lical CT. On the basis of these results, in-patient observa-tion was performed in lieu of an exploratory laparotomy.These patients were observed in the hospital until they clinically improved (average length of stay, 2-5 days). Allof these patients also had abdominal or renal sonogramsthat were also normal, with the exception of case 4. Be-fore the obtainment of the helical CT, case 4 was shownon a sonogram to have a small amount of complex fluidin Morison’s pouch and in the right adnexal region. CTalso showed a small amount of free fluid in Morison’spouch with CT attenuating values suggestive of blood,but no definitive source was found. These findings weresuggestive of a ruptured hemorrhagic ovarian cyst. Ab-dominal ultrasonography was also performed for cases 3to 5 in an attempt to visualize the appendix, and these were unsuccessful. The diagnosis of acute appendicitis was excluded because the patients clinically improved.There were no further perinatal complications except incase 5; this patient had premature rupture of the mem-branes and preterm labor at 34 weeks and delivered anappropriately grown infant who was discharged home 2days after delivery. All patients were discharged homefrom the index admission still pregnant except case 7;this patient went into spontaneous labor, had chorioam-nionitis, and delivered a normal term baby. Comment In this series of pregnant patients suspected of havingacute appendicits, helical CT imaging accurately diag-nosed 2 cases of acute appendicits. In the 5 other casesnegative helical CT results were confirmed on the basis of clinical follow-up, and operative intervention wasavoided.Helical CT has been shown to be highly sensitive andspecific for the diagnosis of acute appendicitis in thenonobstetric population. In a series of 100 patients aged6 to 75 years with suspected acute appendicitis who underwent helical CT, the sensitivity, specificity, and diag-nostic accuracy were each 98%. 6 This study also con-cluded that with avoidance of unnecessary appendec-tomy and allowance of discharge or immediate operationin place of inpatient observation, significant cost savings were achieved. These findings are consistent with otherreports. 8, 9 Table I. Maternal and clinical findings CaseAgeGATime (h) symptoms No.(y)G/P(wk)PainFeverN/VAnorexiaWBCto presentation  1286/324Right side of abdomen radiating to back–+/–+21.262393/223Central uterine radiating to bilateral lower quadrants––/––19123302/132Right lower quadrant––/–+10.264271/030Periumbilical radiating to right lower quadrant–+/++9.315201/029Right side of abdoment  max 100.6°F+/–+12.586263/120Bilateral lower abdomen and right flank–+/–+16.267212/038Right side of abdomen–+/++11.712 G, Gravidity; P, parity; GA, gestational age; N, nausea; V,  vomiting; WBC,  white blood cell count; t  max  , maximum temperature; –, findingnot present; +, finding present.   Volume 184, Number 5 Castro et al957  Am J Obstet Gynecol Other advantages of helical CT include a rapid exami-nation time of approximately 15 minutes. The use of rec-tal contrast alone has also been shown to be reliable inthe diagnosis of appendicitis, and it reduces the risk of systemic reactions of intravenous contrast material, cost,and patient discomfort. 10 Intravenous contrast materialuse can show wall enhancement in an otherwise border-line case; this is necessary in about 2% of cases but didoccur in case 1. Other benefits include use of a specificsmaller incision rather than a large vertical incision toallow extensive exploration when multiple diagnoses areentertained. With the use of select limited helical scan-ning, radiation exposure is approximately 300 mrad(about one third of the average abdominal-pelvic CT at our institution). This is also well below the accepted safelevel of fetal exposure (5 rad). In comparison, the aver-age exposure from a chest radiography is 0.02 to 0.07mrad and from CT pelvimetry is 250 mrad. 11 There is a need for a rapid, reliable, safe, and cost-ef-fective test for the diagnosis of acute appendicitis in preg-nancy. The diagnosis can be extremely difficult becausethese patients uncommonly present with the classic symp-toms such as anorexia, fever, nausea, vomiting, and peri-umbilical pain localizing to the right lower abdominalquadrant. The gravid uterus can displace the appendixsuperiorly and elevate the anterior peritoneum, whichcan minimize abdominal findings. The uterus can also wall off a perforation and cause preterm labor and deliv-ery before presenting as an acute abdomen. In addition,laparotomy can result in surgical complications and pre-term delivery as well. Previous studies noted a 40% nega-tive laparotomy rate and deemed this acceptable becauseof the difficulty of accurate diagnosis and the high rate of perinatal and maternal complications with delayed diag-nosis. 12, 13 The incidence of fetal mortality is increased upto 4-fold with perforation. 3, 4 In addition, survivors re-mote from term may suffer from extreme prematurity be-cause there is an increased risk of delivery within 1 weekof laparotomy. 1 Other noninvasive imaging studied in pregnancy hasbeen ultrasonography. 14, 15  As with the patients in our se-ries, limitations in visualization of the appendix with agravid uterus, especially in the third trimester, have beenencountered. A more effective imaging study is neededfor the evaluation of gravidas with abdominal pain in thelatter part of pregnancy.Several limitations of this study warrant further com-ment. First, we only performed this study on a small num-ber of patients and reproduction of these results in alarger gravid population is necessary to validate our find-ings. Second, this study was also performed in a tertiary care institution with a dedicated emergency radiology team; therefore our findings may not be universally ap-plicable.Our initial results appear very to be promising for theaccurate diagnosis of acute appendicitis in the pregnant population with helical CT. It is a safe test with high diag-nostic accuracy and a rapid turnaround time. Furtherstudies of larger numbers of patients are warranted toconfirm the utility of this test as an adjunct for the diag-nosis of appendicitis in pregnancy. REFERENCES 1.Mazze R, Kallen B. Appendectomy during pregnancy: a Swedishregistry study of 778 cases. Obstet Gynecol 1991;77:835-40.2.Hunt M, Martin J, Martin R, Meeks R, Wiser W, Morrison J. Peri-natal aspects of abdominal surgery for nonobstetric disease. Am J Perinatol 1989;6:412-7.3.Baer J, Reis R, Arens R. Appendicitis in pregnancy with changesin position and axis of normal appendix in pregnancy. JAMA 1932;98:1359-64.4.Horowitz M, Gomez G, Santiesteban R, Burkett G. Acute appen-dicitis during pregnancy. Arch Surg 1985;120:1362-7.5.Rao P, Rhea J, Novelline R, McCabe C, Lawrason J, Berger D, et al. Helical CT technique for the diagnosis of appendicitis:prospective evaluation of a focused appendix CT examination.Radiology 1997;202:139-44.6.Rao P, Rhea J, Novelline R, Mostafavi A, McCabe C. Effect of computed tomography of the appendix on treatment of patientsand the use of hospital resources. N Engl J Med 1998;338:141-6.7.Rao P, Wittenburg J, McDowell R, Rhea J, Novelline R. Appen-dicitis: use of arrowhead sign for the diagnosis at CT. Radiology 1997;202:363-6.8.Balthazar E, Megibow A, Siegel S, Birnbaum B. Appendicitis:prospective evaluation with high-resolution CT. Radiology 1991;180:21-4.9.Malone A, Wolf C, Malmed A, Melliere B. Diagnosis of acute ap-pendicitis: value of unenhanced CT. AJR Am J Roentgenol1993;160:763-6.10.Rao P, Rhea J, Novelline R, Mostafavi A, Lawrason J, McCabe C.Helical CT combined with contrast material administered only through the colon for imaging of suspected appendicitis. AJR  Am J Roentgenol 1997;169:1275-80.11.American College of Obstetricians and Gynecologists, Commit-tee on Obstetric Practice. Washington: The College; 2000 Sept.p. 103-6. ACOG Committee Opinion No.: 158.12.Tamir I, Bongard F, Klein S. Acute appendicitis in the pregnant patient. Am J Surg 1990;160:571-6.13.Al-Mulhim A. Acute appendicitis in pregnancy: a review of 52cases. Int Surg 1996;81:295-7.14.Lim H, Bae S, Seo G. Diagnosis of acute appendicitis in pregnant  women: value of sonography. AJR Am J Roentgenol 1992;159:539-42.15.Barloon T, Brown B, Abu-Yousef M, Warnock N, Berbaum K.Sonography of acute appendicitis in pregnancy. Abdom Imaging1995;20:149-51.
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