Abdo: non-obstetric/traumatic abdo pain in pregnancy

Key Points:

• US first line test
• MRI is safe in pregnancy
• Contrast is not usually required
• DWI is important
• Retroperitoneal pitfalls: Ureter and ovarian vein
• No appendix seen + no oedema / restricted diffusion = likely no appendicitis

Acute Appendicitis on MRI: (DWI and F/S images are key)

• Diameter > 7 mm
• Wall thickness > 2 mm
• Luminal fluid
• Adjacent oedema / fluid
• Phlegmon
• (Appendicoliths)

Bowel obstruction: US can be used to look for fluid filled bowel loops. but limited in finding transition point etc.

Cases 1-4: Identify normal appendix. If unable to, find inflammatory changes

• 1: Retrocaecal appendix
• 2: Subcaecal appendix
• 3: Unable to find appendix, no inflammatory change
• 4: Unable to find appendix, no inflammatory change

Cases 5-10: Acute appendicitis

• 5: unable to find appendix, inflammatory changes seen. Confirmed on surgery.
• 6: Dilated appendix with inflammatory changes seen.
• 7: Acute appendicitis with local perforation
• 8: Acute appendicitis with phlegmon
• 9: Acute appendicitis with collection; subsequent abscess
• 10: Acute appendicitis with perforation into right perinephric space

Cases 11-12: Bowel Obstruction

• 11: Closed loop small bowel obstruction from adhesions?
• 12: Sigmoid volvulus

Cases 13-20: Gynaecological Causes

• 13-14: Carneous Degeneration of Fibroid
• 15-17: Ruptured ectopic / heterotopic pregnancy (heterotopic also has normal preg)
• 18: Ovarian torsion
• 19: Ovarian dermoid cyst
• 20: Ovarian hyperstimulation

Cases 21-22: Urologic causes

• 20: Physiologic hydronephrosis compressing against psoas. If transition well above or below, think of stones more.
• 21: Pyelonephritis: Use DWI to look for areas of signal changes more easily.