MR imaging of acute abdominal pain in pregnancy

Abstract

Abdominal pain in pregnancy is a diagnostic challenge with many potential aetiologies. Diagnostic imaging is a valuable tool in the assessment of these patients, with ultrasound commonly employed first line. MRI is an excellent problem-solving adjunct to ultrasound and has many advantages in terms of improved spatial resolution and soft tissue characterisation. This pictorial review aims to outline the role of MRI in the work up of acute abdominal pain in pregnancy and provide imaging examples of pathologies which may be encountered.

Figure 1.

Coronal (a) and axial (b) HASTE T₂ -weighted MRI of the abdomen demonstrating a dilated fluid-filled retrocaecal appendix (white arrows) with surrounding oedema. There is mural thickening (white arrow, (b) and an appendicolith is present (b, arrowhead).

Figure 2.

Axial T₂ -weighted MRI (a) of the abdomen demonstrating a thickened oedematous gallbladder wall (white arrow, (a). Coronal MRCP (b) shows a dilated common bile duct and gallstones within the gallbladder lumen (white arrow), (b).

Figure 3.

Coronal (a) and axial (b) T2 sequences of the abdomen in cases of Crohn’s disease exacerbation. Thickened oedematous bowel loops can be seen in the right flank and right upper quadrant (white arrow, (a). Free fluid can be seen in the pelvis. 3b demonstrates an example of a flare of Crohn’s disease complicated by perforation and abscess formation in the right upper quadrant (white arrow, (b).

Figure 4.

Axial (a) and sagittal (b) T₂ -weighted MRI of the abdomen shows left-sided hydronephrosis (white arrow), (a) and a low signal oblong-shaped renal calculus in the proximal third of the left ureter (white arrow), (b).

Figure 5.

Coronal T₂ -weighted MRI of the abdomen in a patient with small bowel obstruction demonstrates dilated fluid filled small bowel loops. Free fluid is present above the gravid uterus.

Figure 6.

Coronal (a) and axial (b) T₂ -weighted MRI of the abdomen showing an intramural fibroid with cystic degeneration (white arrows). There are smaller fibroids inferiorly in figure A which are identified by their low signal (white arrowheads). Figure C is an axial T₂ -weighted MRI showing a large fibroid with central necrosis (white arrowhead). There is right-sided hydronephrosis (black arrow) secondary to mass effect from the gravid uterus and fibroid.

Figure 7.

Coronal (a) and axial (b)T₂ -weighted MRI through the pelvis shows an enlarged left ovary with central high signal (white arrows). Free fluid which is confirmed as haemorrhagic with signal above that of normal fluid on fat-saturated T₁ -weighted imaging (c). The presence of haemorrhagic free fluid implies rupture.

Figure 8.

Coronal T2 HASTE sequence demonstrating a large thin walled right adnexal lesion. Note the fine internal septations (black arrow). Differential diagnosis includes a simple cyst and a serous or mucinous cystadenoma.

Figure 9.

Axial T₂ -weighted MRI shows a simple left sided adnexal cyst. No complex internal features – septations, solid components, fat or haemorrhagic contents.

Figure 10.

Incidental right suprarenal mass found on CTPA for pleuritic lower thoracic back pain. This was further evaluated with an MRI adrenal protocol. The lesion was found to be T1 isointense (a), mildly T2 hyperintense (b) and did not demonstrate signal drop out on out-of-phase imaging (c).

Figure 11.

Follow up adrenal MRI 4 months later demonstrates resolution of the right adrenal mass in keeping with a resolved spontaneous adrenal haemorrhage.