April 19, 2014

RLQ pain in pregnancy


The list of potential badness in the pregnant patient with right lower quadrant pain is long and distinguished, but it often comes down to a simple question…

“Does this patient have appendicitis?”

Subtext: “Is this patient going to need a CT scan?”

Nobody likes ordering am abdominal CT on a pregnant patient because, no matter how low the statistical risk of damage to the fetus, there is still potential harm from ionizing radiation.

Listen to this podcast to discover that the risk of immediate maternal and fetal harm is far greater than the long term risk of ionizing radiation exposure.


Interview with Ingrid Lim MD at ACEP 2011

Risk of mortality with appendicitis in pregnancy:

In a pregnant patient with unperforated appendicitis, fetal loss is 3-5%. With perforation, fetal loss skyrockets: -30% in trimesters 1 and 2 -70% in trimester 3

Maternal mortality is 1% without  perforation and 4% with perforation


  • Step 1: Ultrasound- more sensitive in the 1st vs. 3rd trimester. Even though it may be inconclusive as far as appendicitis, ultrasound can give valuable information about the fetus, uterus, ovaries, kidneys and gallbladder. If ultrasound doesn’t give the answer….
  • Step 2: MRI without contrast DO NOT USE GADOLINIUM:CONTRAINDICATED IN PREGNANCY If no MRI available…
  • Step 3: CT with or without contrast depends on your local radiologist. Contrast (IV or PO) is considered safe in pregnancy. Research has shown that contrast does not harm fetal thyroid

RADIATION PRIMER for CT Appy protocol 

  • Fetal background radiation exposure during 9 months of pregnancy 0.1 rad (1mGy) Teratogenesis threshold: 5 rad (50mGy)
  • Estimated fetal radiation exposure from CT Appy protocol:
  • Trimester 1: 2.4 rad (24mGy)
  • Trimesters 2 and 3: 3 rad (30mGy)


  • Fetal death, malformation or developmental delay from in utero radiation exposure.
  • The threshold for a <1% teratogenesis risk is 5 rad (50mGy).
  • The highest risk period is 3-15 weeks.
  • The amount of radiation absorbed from a CT appy protocol is less than the 5 rad teratogenic threshold.
  • Even with exposure to 10 rads,  there is a 99% chance of no fetal teratogenic effects.


  • Most worrisome for childhood cancers such as leukaemia.
  • The baseline risk of dying from childhood cancer is  1 in 2000.
  • A 5 rad exposure is believed to increase that risk to 2 in 2000.
  • While that is a doubling of the relative risk, it is still small compared the rate of fetal loss from a ruptured appendix.

Bonus section: Ectopic Pregnancy and HCG levels

Traditional teaching holds that if the HCG does not double in the first 48 hours, consider ectopic. But many patients do not follow this curve. With the development of more sensitive assays, a minimum rise of 53% over 48 hrs is acceptable. 3% of ectopic pregnancies can have a negative serum HCG

Two theories:

  1. Have to have a viable trophoblast to produce HCG, no trophoblast…no HCG
  2. Ectopic died then ruptured

Bottom line.. if patient looks sick and there is a lot of free fluid in the pelvis – go to surgery

Written Summary:  Justin Arambasick MD (Akron General Medical Center) and Rob Orman MD (ERCAST.org)

Additional Resources


Related posts:

About Rob Orman

Deceptively tall.
Podcaster to the stars, father of many, lover of few


  1. Hi Rob, Casey here again with my routine difficult question…
    Has anybody looked at he risk of CT vs. a quick GA / exploratory laparoscopy (or mini laparotomy). We go GAs on pregnant women a lot with not too much downside.
    Is this crazy, or too simple ? Casey

    • Casey, I think your idea is spot on, but in the US, it’s rare to find a surgeon who will operate on a pregnant patient without a confirmed diagnosis unless she is in extremis. I could find no recent RCTs on the exploratory laparoscopy in this scenario. Keep fighting the good fight, brother.


  1. [...] if you’ve got 20 minutes to spare, check out my conversation with Rob over at ERCast. The first half is educational; round about 19:30 is where the bromance [...]

  2. [...] few weeks ago Rob Orman (ER Cast) did a great interview with Dr Ingrid Lim at ACEP which looked at the diagnosis of the possible appendicitis in pregnant women.  Go and check out [...]

  3. [...] DocsRLQ pain in pregnancy (the sequel) — Casey follows up Rob Orman’s recent ERCast on the same topic with more pearls based on the experience of a medical MacGyver in remote [...]

  4. [...] with a vengeance! He’s returned from the Essentials of EM with a massive podcast titled RLQ pain in pregnancy. Bonus track: the return of Zdoggmd. This one is in two parts. The first is an excellent discussion with with Ingrid Lim  on RLQ pain [...]

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