MR imaging evaluation of abdominal pain during pregnancy: appendicitis and other nonobstetric causes.

Department of Diagnostic Imaging, Warren Alpert Medical School of Brown University, Women and Infants Hospital, Rhode Island Hospital, Providence, RI, USA.
Radiographics (Impact Factor: 2.73). 03/2012; 32(2):317-34. DOI: 10.1148/rg.322115057
Source: PubMed

ABSTRACT Clinical diagnosis of the cause of abdominal pain in a pregnant patient is particularly difficult because of multiple confounding factors related to normal pregnancy. Magnetic resonance (MR) imaging is useful in evaluation of abdominal pain during pregnancy, as it offers the benefit of cross-sectional imaging without ionizing radiation or evidence of harmful effects to the fetus. MR imaging is often performed specifically for diagnosis of possible appendicitis, which is the most common illness necessitating emergency surgery in pregnant patients. However, it is important to look for pathologic processes outside the appendix that may be an alternative source of abdominal pain. Numerous entities other than appendicitis can cause abdominal pain during pregnancy, including processes of gastrointestinal, hepatobiliary, genitourinary, vascular, and gynecologic origin. MR imaging is useful in diagnosing the cause of abdominal pain in a pregnant patient because of its ability to safely demonstrate a wide range of pathologic conditions in the abdomen and pelvis beyond appendicitis.

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    ABSTRACT: Sigmoid volvulus complicating pregnancy is a rare, non-obstetric cause of abdominal pain that requires prompt surgical intervention (decompression) to avoid intestinal ischemia and perforation. We report the case of a 31-week pregnant woman with abdominal pain and subsequent development of constipation. Preoperative diagnosis was achieved using magnetic resonance imaging and ultrasonography: the large bowel distension and a typical whirl sign - near a sigmoid colon transition point - suggested the diagnosis of sigmoid volvulus. The decision to refer the patient for emergency laparotomy was adopted without any ionizing radiation exposure, and the pre-operative diagnosis was confirmed after surgery. Imaging features of sigmoid volvulus and differential diagnosis from other non-obstetric abdominal emergencies in pregnancy are discussed in our report, with special emphasis on the diagnostic capabilities of ultrasonography and magnetic resonance imaging.
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    ABSTRACT: Purpose To compare life expectancy (LE) losses attributable to three imaging strategies for appendicitis in adults-computed tomography (CT), ultrasonography (US) followed by CT for negative or indeterminate US results, and magnetic resonance (MR) imaging-by using a decision-analytic model. Materials and Methods In this model, for each imaging strategy, LE losses for 20-, 40-, and 65-year-old men and women were computed as a function of five key variables: baseline cohort LE, test performance, surgical mortality, risk of death from delayed diagnosis (missed appendicitis), and LE loss attributable to radiation-induced cancer death. Appendicitis prevalence, test performance, mortality rates from surgery and missed appendicitis, and radiation doses from CT were elicited from the published literature and institutional data. LE loss attributable to radiation exposure was projected by using a separate organ-specific model that accounted for anatomic coverage during a typical abdominopelvic CT examination. One- and two-way sensitivity analyses were performed to evaluate effects of model input variability on results. Results Outcomes across imaging strategies differed minimally-for example, for 20-year-old men, corresponding LE losses were 5.8 days (MR imaging), 6.8 days (combined US and CT), and 8.2 days (CT). This order was sensitive to differences in test performance but was insensitive to variation in radiation-induced cancer deaths. For example, in the same cohort, MR imaging sensitivity had to be 91% at minimum (if specificity were 100%), and MR imaging specificity had to be 62% at minimum (if sensitivity were 100%) to incur the least LE loss. Conversely, LE loss attributable to radiation exposure would need to decrease by 74-fold for combined US and CT, instead of MR imaging, to incur the least LE loss. Conclusion The specific imaging strategy used to diagnose appendicitis minimally affects outcomes. Paradigm shifts to MR imaging owing to concerns over radiation should be considered only if MR imaging test performance is very high. © RSNA, 2014.
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