Appendicitis is the most common non-obstetrical surgical problem encountered during pregnancy. The diagnosis may be disguised due to anatomic changes as well as atypical presenting sign and symptoms which occur during pregnancy. Because of this, accurate diagnosis may be delayed and these patients are more likely than the general population (up to 60% versus 4%) to present with perforation.
Since the clinical presentation is often confusing, the differential diagnosis is broad and includes ovarian pathology, urolithiasis, UTI, pelvic abscess, IBD exacerbation, and cholecystitis.
It is critical that rapid and accurate diagnosis is made in the pregnant patient presenting with RLQ pain. Selection of the appropriate diagnostic imaging examination poses an age-old dilemma for the clinician caring for these patients because of the theoretical risks of radiation induced carcinogenesis. Therefore, the modalities of choice should include those that do not use ionizing radiation such as ultrasound (US) or MRI.
Ultrasound is a good first choice modality especially in the first and second trimesters, however it becomes much less reliable as pregnancy progresses due to changes in maternal anatomy and fetal growth. The sensitivity of US is also widely variable due to to factors such as operator dependence, overlying bowel gas, and patient body habitus.
US imaging findings of appendicitis include a non-peristalsing blind ending tubular structure adjacent to the cecum, measuring > 7 mm with wall thickening and, in some cases, surrounding inflammatory changes.
- Long axis and transverse US images of pregnant woman with RLQ pain.
Shows non-compressible blind ending tubular structure measuring 8 mm with wall thickening classic for acute appendicitis.
If results are negative or indeterminate, MRI has proven to have a high sensitivity (98-100%), specificity (94%), and accuracy (95%) in diagnosing acute appendicitis. It is also useful in making alternative diagnoses and more accurately characterizing periappendiceal phlegmons initially diagnosed by US. This may help the surgeon to make the decision to treat medically versus surgically to reduce the risk of fetal loss, pre-term labor, and low birth weight.
- Long axis US on 27 week pregnant woman shows enlarged tubular structure in the RLQ (arrows). Heterogeneous appearance of periappendiceal fat (arrowheads) indicates that there is presence of phlegmon.
- Sagittal single-shot fast SE MR image more accurately shows the size of the inflammatory phlegmon (arrows) and its relationship to and mass effect on the cecum (C) and ovary (arrowheads). This allowed the surgeon to make the decision to treat with
antibiotics until the time of delivery when the patient also underwent appendectomy.
- MR coronal fat-saturated single-shot fast SE image on a 20 week pregnant woman shows an enlarged inflamed appendix (arrow) with surrounding edema (arrowheads). C=Cecum.
MRI has been used to image pregnant women for nearly 25 years and it considered very safe. There have been no reported teratogenic or carcinogenic effects to the embryo or fetus using a 1.5 T magnet. According to the ACR’s 2007 white paper for MRI safety practices, it may be used in pregnant patients at any gestational age. (3)
A single shot fast spin echo technique is used in three planes which is good for fetal and maternal motion. STIR images are sensitive to edema. The diagnostic features of appendicitis are similar to those for US although they are seen with much more clarity and the diagnosis is definitive using MRI.
In conclusion, MRI, using tailored protocols, is the most appropriate modality to image the pregnant patient presenting with RLQ pain when US is non-diagnostic or inconclusive.
- Acute appendicitis in 20 year-old pregnant patient. Axial MR STIR sequence shows dilated appendix measuring 12 mm, wall edema, and appendicoliths (arrowheads). Rim of high signal intensity indicates inflammation.
- Ruptured appendicitis in young pregnant woman. Coronal T2 weighted single shot fast spin echo MRI shows dilated appendix (arrow) with periappendiceal abscess (arrowhead) adjacent to the cecum (C).
Dr. Jill Wilkens graduated summa cum laude with a Bachelor of Science degree in Nursing from Thomas Jefferson University. She worked as an GYN Oncology nurse and then as a NICU nurse for four years before beginning medical school. She then went to the Medical College of Pennsylvania and graduated with academic and clinical honors 1993. She completed a medical internship and radiology residency at Albert Einstein Medical Center in Philadelphia. Her love for Pediatrics brought her full-circle back to the field once again and she completed a pediatric radiology fellowship at St. Christopher’s Hospital for Children in Philadelphia.
Though skilled in all aspects of radiology, her specialty areas include women’s imaging, breast health and pediatric diagnostic care. Because of her nursing background, Dr. Wilkens enjoys direct patient care and prides herself on spending quality time with her patients.
Her advanced expertise and nurturing manner allow her to perform specialized pediatric diagnostic procedures with ease, leaving patients and their families feeling comforted and knowing they made the right choice.
Dr. Wilkens has served as an associate professor of radiology at the University of Maryland Medical Center since 2000 where she is active in educating the radiology residents. She is also proud to offer pro-bono assistance to the Baltimore County Police Department Child Abuse Division.
Dr. Wilkens is a board certified Pediatric Diagnostic Radiologist who is well published and has lectured internationally.
1. Birnbaum BA, Wilson SR. Appendicitis at the Millennium. Radiology 2000; 215: 337-348.
2. Pedrosa I, Levine D, et al. MR Imaging Evaluation of Acute Appendicitis in Pregnancy. Radiology 2006; 238
3. Kanal, Borgstede, Barkovich, et al. ACR White Paper on MR Safety 2007.
4. Singh A, Danrad R, et al. MR Imaging of the Acute Abdomen and Pelvis: Acute Appendicitis and Beyond.
Radiographics 2007; 27:1419-1431.
5. Oto A, Ernst RD, et al. Right-Lower-Quadrant Pain and Suspected Appendicitis in Pregnant Women:
Evaluation with MR Imaging – Initial Experience. Radiology 2005; 234:445-451.
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