Normal MRI abdomen in pregnancy

Case contributed by Dr Vikas Shah

Presentation

18/40 pregnant. Lower abdominal pain.

Patient Data

Age: 25 years
Gender: Female

Intrauterine pregnancy confirmed but not interrogated in detail. The appendix is identified in a retrocecal position, with normal thickness and no luminal distension. There is no surrounding edema or free fluid. Incidental note is made of right-sided physiologic hydronephrosis caused by compression of the ureter between the uterus and the right psoas muscle, and distension of the right ovarian vein.

Case Discussion

The appendix may not be clearly identified on MRI in pregnancy for a number of reasons, including the limited spatial resolution compared to CT, and the alteration in anatomy caused by the gravid uterus. In this case, it is seen posterior to the displaced cecum. The absence of ancillary signs of acute appendicitis such as edema and fluid in the region of the cecal pole is helpful in confirming that there is no acute appendicitis. The pregnancy progressed to term with no requirement for surgical intervention.

This study also demonstrated two tubular structures in the right retroperitoneum that may be mistaken for each other, or for the appendix; the engorged right ovarian vein and the distended right ureter. Both structures are seen here as high signal on the gradient echo images, but of variable signal on different slices of the SSFSE images; likely reflecting the sensitivity of this sequence to the presence of flow. 

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