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Imaging the pregnant patient with right lower quadrant pain

Imaging the pregnant patient with right lower quadrant pain. Julia R. Fielding, M.D. Julia_fielding@med.unc.edu RSNA 2010. Ultrasound is test of choice. First trimester With bleeding exclude ectopic pregnancy renal stones -Without bleeding ovarian pathology. Ectopic Pregnancy.

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Imaging the pregnant patient with right lower quadrant pain

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  1. Imaging the pregnant patient with right lower quadrant pain Julia R. Fielding, M.D. Julia_fielding@med.unc.edu RSNA 2010

  2. Ultrasound is test of choice • First trimester • With bleeding exclude ectopic pregnancy renal stones -Without bleeding ovarian pathology

  3. Ectopic Pregnancy • No IUP and positive pregnancy test • 1/3 of those with ectopic pregnancy will have a normal US exam • Those with a simple adnexal cyst have a 10% likelihood of ectopic pregnancy • A complex non-ovarian mass has a sensitivity of 84%, specificity 99% and positive predictive value of 96% for ectopic pregnancy • Complex fluid/blood is often present Dighe M et al, J Clin Ultrasound 2008;36:352-366

  4. ECTOPIC PREGNANCY Courtesy Dr. D. Brown, Mayo Clinic

  5. Renal stones Incidence of 1/1500 pregnancies Stones that are >5mm, located in the proximal ureter and of irregular shape usually will require treatment US will identify hydronephrosis Ureteral jets indicate an incompletely obstructed ureter and may spare the patient a stent

  6. HYDRONEPHROSIS BLADDER STONE

  7. Right mid ureteral stone SCOUT 10 MINUTE

  8. Differential diagnosis ovarian pathology • Corpus luteum cyst • Usually 2-5cm, can be up to 10cm in size • Regresses week 11-16 as placenta develops • Simple cyst/hemorrhagic cyst/endometrioma/dermoid • Torsion – 70% cases with abnormal adnexa • Cancer very rare

  9. Simple Cyst Courtesy Dr. D. Brown, Mayo Clinic

  10. Ovarian torsion

  11. Use of CT increasing N Engl J Med 2007;357:2777-84

  12. What are the numbers? • 62 million CT scans annually, 4 million in children • University of North Carolina ER data: • 2000-2005, pediatric admissions increased 2%, chest CT increased by 435%, abdominal CT by 49% (EmergRadiol 2007;14:227-32) • Brown University, Rhode Island Hospital data: • Number of pregnant women scanned increased 89% in 10 years with only a 7% increase in admissions (RSNA 2007)

  13. Why do we worry? • In general, fetal absorption is 40% that of maternal abdomen • Ex: Maternal pelvic CT dose is 4cSv, fetal dose is 1.6 -1.8 cSv (1cSv =1 rem) • This is well below the 10cSv level for teratogenic effects • However…. Invest Radiol 2000;35:527-533

  14. Why do we worry? • Young children (and presumably those in utero) are most susceptible to radiation damage and therefore at higher risk for development of cancers later in life • Organs involved are brain, digestive tract, bone marrow (leukemia)

  15. N Engl J Med 2007;357:2277-84

  16. N Engl J Med 2007;357:2277-84

  17. What can we do?Have a plan! 1.Balance risks/benefits – talk over the procedure with the referring physician and make sure CT is needed and is the test of choice. 2. Let the referring physician discuss and document the need for the CT scan in the medical record

  18. What can we do? 3.Get written and oral informed consent for use of radiation (see new ACR guidelines) 4.Avoid multiple CT scans – radiation effects are cumulative 5.Use best scanning techniques – automatic dose reduction is useful, beware dropping the maS so low that the scan is not diagnostic

  19. What are the indications for CT scan in pregnancy? • 1. Renal stones when US is indeterminate particularly in 2nd/3rd trimester • 2. Appendicitis – MR is now test of choice, CT appropriate for IBD, obstruction • 3. Cancer staging – substitute MR if possible • 4. Lung disease – PE studies and V/Q scans yield similar radiation doses • 5. Trauma – use your routine protocol, most common cause of fetal death is maternal death • 6. Intracranial hemorrhage

  20. What is the radiation dose to the fetus? • For CT examination of head, extremities and chest, minimal <10 mSv • For CT of the abdomen/pelvis, moderate 1.6-1.8 cSv

  21. Is there a risk to the use of IV contrast agent? • Very minimal risk of depression of fetal thyroid function by free iodide • Water-soluble contrast agents (100cc) contain 5 micrograms of free iodide, less than 1/10th the level known to cause thyroid dysfunction in neonates • Exception would be maternal renal failure when free iodide not excreted back across placenta EurRadiol 2005;15:1234-1240 Radiology 2010;256:744-750

  22. Flank pain/obstructing ureteral stone • Choice 1: Ultrasound with hydronephrosis, severe pain, stent placed prophylactically under ultrasound guidance • Choice 2: <24 weeks, limited IVU • Choice 3: >24 weeks, helical CT

  23. HYDRONEPHROSIS SINGLE LEFT JET

  24. RIGHT HYDRONEPHROSIS

  25. DIILATED URETER

  26. COMPRESSED URETER

  27. Lower abdominal pain with suspicion of appendicitis • Ultrasound, followed by • Choice 1: MRI of the abdomen and pelvis • Choice 2: Contrast-enhanced helical CT

  28. 27 year old woman, 33 weeks pregnant with negative ultrasound Courtesy Dr. E. Lazarus, Rhode Island Hospital

  29. Cancer staging of the abdomen and pelvis • Choice 1: MRI of the abdomen and pelvis, judicious use of Gd-DTPA • Choice 2: Contrast-enhanced CT of the abdomen/pelvis

  30. Jejunal adenoCA with SBO I+ CT

  31. Recurrent gastric cancer

  32. TRAUMA • Use your routine protocol • Intravenous contrast agent always necessary, oral contrast agent varies by institution

  33. Ruptured splenic artery aneurysm

  34. When do we use MRI in pregnancy? • 1. The information requested from the MR study cannot be acquired using US • 2. The data are needed to affect the care of the patient or fetus during the pregnancy • 3. The referring physician does not feel is is prudent to wait until the patient is no longer pregnant to obtain these data.

  35. When do we use MRI during pregnancy? • In general, when the information to be obtained is absolutely essential to the well being of the mother or child • Specifically, • RLQ pain, suspicion of appendicitis/bowel disease • Characterization of an adnexal mass • Cancer staging • Choledocholithiasis • Head and back injuries • Fetal/placental abnormalities

  36. Safety issues • Present data have not conclusively documented any deleterious effects of MR imaging exposure on the developing fetus • All pregnant women should understand and sign a consent for the performance of MRI

  37. What about Gd chelates and fetal renal development? • Gd chelates do pass through the placenta and remain in the amniotic fluid • Because of our lack of knowledge regarding contrast/fetal kidneys, avoid Gd chelates in pregnant women unless absolutely necessary - cancer staging/vascular issues such as aneurysm, AVM

  38. Basic protocol for maternal abd/pelvis • Sagittal/axial/coronal ultrafast T2 weighted images (HASTE/SSFSE) using large FOV and torso coil if possible. Axial T2W series performed with fat saturation. • Ax T1 weighted image with fat sat through pelvis (to locate blood) • Patient supine or in left lateral decubitus position

  39. Appendicitis • Incidence 1:1500 pregnancies • Graded compression US is impractical after the first trimester • MRI is test of choice – excellent NPV for appendicitis in those patients with a normal US (94%) • Alternative is CT (fetal dose 1.8cGy) • Appearance on T2WI: Tube >6mm, often vertical, just below TI with adjacent high signal edema

  40. Case 1

  41. Case 2

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