1. MR Imaging of Pregnant Women with Abdominal Pain and Suspected Appendicitis: Diagnostic Accuracy and Outcomes
Indu Rekha Meesa, MD
Leena Mammen, MD
GRMEP/MSU Diagnostic Radiology Residency
Spectrum Health Dept of Diagnostic Radiology
Advanced Radiology Services, P.C.

2. Appendicitis in Pregnancy
Most common cause of acute surgical abdomen during pregnancy
Occurs 1 in 1500 pregnancies
Clinical presentation is variable and symptoms can overlap with normal pregnancy related complaints
Complications include premature labor and maternal/fetal death
Increased mortality with perforation of the appendix and with peritonitis

3. Appendicitis Imaging in Pregnancy
Ultrasound and CT have traditionally been the imaging modalities of choice
Sensitivities and specificities greater than
85% and 95%, respectively, in nonpregnant patients
Major disadvantage of CT: radiation exposure to the developing fetus
Major disadvantages of US:
Highly operator dependent, expertise needed
Decreased diagnostic performance due to:
Advanced gestational age
Obscuration of the appendix by bowel gas
Obesity/large body habitus

4. Appendicitis Imaging in Pregnancy
MRI is the recommended modality if US is inconclusive.
Recent literature on limited patient numbers:
- MRI can accurately diagnose or exclude
acute appendicitis
- MRI is useful to diagnose alternative causes of RLQ
pain (pelvic abscess, tubo-ovarian abscess,
ovarian torsion, adnexal mass)

5. Purpose of the Study
Study conducted to review our experience at Spectrum Health, including volumes and reasons for imaging pregnant patients.
Evaluate diagnostic accuracy with MRI during pregnancy and clinical outcomes over a two year period.

6. Materials and Methods Patients:
All pregnant women who underwent an abdominal/pelvic MRI at Spectrum Health between 1/2008 and 1/2010 were included.
Medical records and MRI findings retrospectively reviewed in 46 pregnant women.
Out of this group, 23 women with right lower quadrant pain and clinical concern for appendicitis were identified.
Age range: 17 – 39, mean age 28

7. MRI Imaging Technique
1.5 T GE magnet with coil selection based on size
MRI sequences: axial and coronal T2 single shot fast spin
echo, axial and coronal steady state free precession (Fiesta)with fat suppression, and axial and coronal 3D pre-contrast T1 (LAVA).

8. Materials and Methods Image Interpretation a. Radiologists:
a. expertise in abdominal MRI either by fellowship training or over five years experience in MRI interpretation.
b. Image analysis:
a. Identification of appendix
b. Size of the appendix (normal if outer diameter <7mm)
c. Overview of abdominal and pelvic viscera
d. Periappendiceal inflammatory change

10. Results and Clinical Outcomes
46 pregnant women underwent a total of 53 MRI scans
23/46 (50%) presented with RLQ pain and other signs suspicious for appendicitis (Chart 1)
Of those 23 who had RLQ pain:
A. 10/23 (43%) MRI findings positive for acute
appendicitis
1. 5/10 (50%) uncomplicated acute appendicitis by
MRI criteria, all were confirmed at surgery
2. 4/10 (50%) complicated acute appendicitis
a. 3 ruptured appendix with abscess
- 2/3 treated with surgical debridement
- 1/3 treated with percutaneous drainage by
interventional radiology
b. 1 case of appendicitis missed on the initial scan. Diagnosed on the f/u scan for ruptured
appendix with abscess, treated with surgical debridement
3. 1/10 findings suspicious for appendicitis but was discharged without surgery
or further follow up (not included in statistics)
B. 13/23 (57%) negative MRI for appendicitis
1. Managed medically and discharged

11. Results and Clinical Outcomes
23/46 (50%) cases were performed for conditions other than RLQ pain, in which a variety of abnormalities were found.

12. Table 1: Findings on MRI performed on pregnant women for conditions other than RLQ pain
Number of patients
Description 2
Placenta Previa 1
Placenta Accreta
Thinning of Lower Uterine Segment
Uterine Fibriods
Cystic Ovarian Mass
Ovarian Dermoids
ParaOvarian Cyst
Cornual Pregnancy
Sub-Septate Uterus
Left Adrenal Mass
Polycystic Kidneys
Renal Calculi
Thickened Terminal Ileum
Fetal Renal Agenesis

13. Results and Clinical Outcomes

14. Case 1: 2nd trimester with RLQ pain. MRI demonstrated a normal appendix

15. Case 2: 3rd trimester with acute retrocecal appendicitis and periappendiceal edema

16. Case 3: 3rd trimester with a dilated appendix, appendicoliths, and small abscesses near the abdominal wall.

17. Case 4: 2nd trimester with a RLQ abscess

18. Case 4: Coronal image of the RLQ abscess containing a tiny pocket of gas

19. Case 4: CT guided drain placement in RLQ abscess.

20. Case 4: MRI obtained after abscess drainage shows resolution of RLQ fluid collection.

21. Discussion
The appendix is reported to be seen at MR imaging in up to 90% of nonpregnant patients
The appendix is seen in 83-89% of pregnant patients
Normal appendiceal wall is less than 2mm thick
Normal appendiceal diameter less than 7mm
Periappendiceal inflammation/edema is well imaged by MRI

22. MRI for appendicitis during pregnancy
Cobben et al, 2004: Appendix identified in 11/13 patients (3 with appendicitis)
Oto et al, 2004: Appendix identified in 81% of the 23 patients (3 had appendicitis). 5 patients had alternative etiologies for pain: ovarian torsion, pelvic abscesses
Pedroso et al, 2006: Appendicitis in 4/51. Sensitivity 100%, specificity 94%.

23. ACR Appropriateness Criteria Right lower quadrant pain, pregnancy
1996 (revised 2005)
US, abdomen, RLQ, graded compression 8
MRI, abdomen, with or without contrast 7
CT, abdomen, with IV contrast 6
US, pelvis and endovaginal
CT, abdomen, without contrast 5
X-ray, chest 4
X-ray, abdomen, AP and upright 2
X-ray, barium enema
NUC, Gallium/WBC scan
Appropriateness Criteria Scale = Least appropriate 9 = Most appropriate

24. Conclusion: MRI for Appendicitis Evaluation during Pregnancy
Offers the clinician more confidence in clinical dilemmas
Greater impact with misdiagnosis of appendicitis during pregnancy
Greater potential complications as both mother and fetus are involved
Reduces possible psychologic pressures on the patient and repeated ED visits
Has the potential to reduce hospitalization time with a definitive diagnosis.

25. Conclusions, continued
MRI of the abdomen without contrast is an excellent alternative to CT and US
Our results are concordant with initial experiences published on this emerging imaging technique
MRI has the potential to significantly decrease negative laparotomy rates and decrease hospital time

26. Other Implications of our Study
Imaging results must be correlated closely, especially with clinical discordance. Our negative predictive value was 93%.
There is an opportunity to discover alternative etiologies for patients with abdominal/pelvic pain with the MRI examination.
We observed a novel application of MRI during pregnancy: an imaging technique to follow up abdominal and pelvic abscesses in pregnant women.

27. References
Babaknia A, Parsa H, Woodruff JD. Appendicitis during pregnancy. Obstet Gynecol 1977; 50; Cunningham FG, McCubbin JH. Appendicitis complicating pregnancy. Obstet Gynecol 1975; 45: Mourad J, Elliott JP, Erickson L, Lisboa L. Appendicitis in pregnancy: new information that contradicts long-held clinical beliefs. Am J Obstet Gynecol 2000; 182: 1027 – Ames Castro M, Shipp TD, Castro EE, Ouzounian J, Rao P. The use of helical computed tomography in pregnancy for the diagnosis of acute appendicitis. Am J Obstet Gynecol 2001; 184: Rioux M. Sonographic detection of the normal and abnormal appendix. AJR 1992; 158: Lodewijk P. Cobben, Ingrid Groot, Lucien Haans, Johan G. Blickman and Julien Puylaert. MRI for Clinically Suspected Appendicitis During Pregnancy. American Journal of Roentgenology 2004; 183: American College of Radiology Appropriateness Criteria: Right lower quadrant pain, fever, leukocytosis in the pregnant woman. Revised Oto A, Ernst RD, Shah R, Koroglu M, Chaljub G, Gei A, Zacharias N, Saade G. Right-Lower-Quadrant Pain and Suspected Appendicitis in Pregnant Women: Evaluation with MR Imaging-Initial Experience. Radiology 2005; 234: Anderson B, Nielsen TF. Appendicitis in pregnancy: diagnosis, management and complications. Acta Obstet Gynecol Scand 1999;78: Maslovitz S, Gutman G, Lessing JB, Kupdermine MJ, Gamzu R. The significance of clinical signs and blood indices for the diagnosis of appendicitis during pregnancy. Gynecology Obstet Invest 2003; 56: Nagayama M, Watanabe Y, Okumura A, Amoh Y, Nakashita S, Dodo Y. Fast MR imaging in obstetrics. RadioGraphics 2002;22: Jung SE, Byun JY, Lee JM, et al. MR imaging of maternal diseases in pregnancy. AJR Am J Roentgenol 2001; 177: