1. Harry Holdorf PhD, MPA, RDMS, RVT, LRT(AS), CCP
“Other” imaging techniques in Obstetrics & Open Fetal Surgery Obstetrical Sonography 2 Lecture 23
Harry Holdorf
PhD, MPA, RDMS, RVT, LRT(AS), CCP

2. CT scan and MRI

3. Q: Why should we be concerned with “Other” imaging techniques in Obstetrics?
A: There are CT risks during pregnancy. If the abdomen or pelvis is not being imaged, such as in chest or head CT, then there is no risk to the baby. If the CT scan includes the abdomen or pelvis, then there may be a slight risk to the baby.

4. Who is the patient?
Diagnostic imaging for staging pregnant patients with cancer is a challenging task that must be addressed by a multidisciplinary team of physicians. As a first step, the team has to consider the possible benefits imaging may provide the individual patient for overcoming her disease. The multidisciplinary team must make the most useful choice of imaging modalities, to obtain information needed to offer the patient the most effective treatment for the disease stage.

5. The radiologist is a crucial player in this process, as she must guide the choice of imaging modalities in such a way that will accurately answer the clinicians’ questions, keeping in mind that not only the patient, but also the unborn child, must be protected from excess radiation and risk. Finally, the team of physicians should involve and counsel the patient in such a way that she does not have to fear harm to herself or the fetus from single, well-planned imaging studies.

6. Under what circumstances can MRI be used safely in the pregnancy patient?

7. When the patient presents with possible Appendicitis or other potentially surgical conditions (i.e. Non-bone conditions).

8. How can MRI and CT be helpful in staging diseases for the obstetrical patient?

9. Gynecological malignancies, especially that of the ovaries
Gynecological malignancies, especially that of the ovaries. Also, MRI and CT can be useful in staging cancers from other primary sites.

10. Give Several reasons why CT would be the exam of choice while treating the pregnant patient.

11. CT: Plus: Use of contrast agents can serve as a “light bulb”, illuminating certain tumors that ordinarily would not be detected with MRI.
CT: Plus: readily available.
CT: Plus: Less motion artifact.
CT: Plus: Faster
CT: Plus: Less likely for patient to be sedated.
CT: Plus: Less chance of a magnetic problem.
CT Plus: Cheaper.

12. Give Several reasons why MRI would be the exam of choice when treating the pregnant patient.

13. MRI Plus: No Radiation.
MRI Plus: MRI can be repeated within a short time.
MRI Plus: MRI is good for tumors of the brain.

14. Provide an argument as to why MRI should be the exam of choice for evaluating the first trimester pregnancy patient.

15. No harmful effects of MRI on the fetus have been demonstrated.
No radiation.
Can provide more diagnostic information than CT.
Can facilitate open fetal surgery.

17. Provide an argument as to why MRI should not be the exam of choice for evaluating the first trimester pregnancy patient.

18. Concerns in pregnancy with heating and noise.
Concern for the use of contrast agents that are known to cross the placenta and enter the fetal bloodstream.

19. What is there to worry about?
Carcinogenesis: The effect of radiation that does not result in a loss of tissue function, but does result in DNA mutation.
Termination of Pregnancy: Because of the risk of carcinogenesis after radiation doses of up to 100 *mGy, termination of a pregnancy would be justified.
*Radiation dosimetry: mSv & mGy. The millisievert and milligray are measures of radiation dose and exposure.

20. Projection radiography: If the fetus is not directly within the region to be examined, fetal radiation exposure is generally negligible and a pregnancy should not alter the decision to perform an indicated examination.

21. CT: The fetal does in CT exams of the maternal head, neck and extremities results from scatter radiation and is negligible. The dose increases tremendously when the fetus is in the field of view.
Iodinated contrast agents: A single layer of chorionic epithelium serves as an interface between the maternal and fetal circulation in the placenta. Iodine- based contrast agents are limited in their ability to cross the placenta. Nevertheless, measurable amounts of contrast agents have been detected in the fetus after intravenous administration of typical clinical doses to the mother.

22. Other modalities to worry about
Mammography
Positron Emission Tomography: PET/CT exposures the fetus to a relatively high radiation does due to the combination of two imaging methods involving radiation.

23. What if the Mother’s cancer has spread?
Metastatic Mediastinal lymphadenopathy
Bone Metastases
Brain Metastases
Breast Cancer
Cervical Cancer
Melanoma
Ovarian Cancer
Thyroid Cancer

24. The role of MRI and CT in the management of the obstetrical patient
Summary:
MRI and CT can be useful tools in the management of the obstetrical patient when maternal health is at risk. In addition, an MRI or CT scan may be indicated if the benefits of these examinations far out weigh the possible risks of radiation exposure or magnetic /heat exposure to the fetus, specifically if open fetal surgery may be a viable option.

25. Define Open Fetal Surgery

26. Open fetal surgery involves completely opening the uterus to operate on the fetus.

27. What are the three main priorities of open fetal surgery?

28. Maternal safety
Avoiding preterm labor
Achieving the aims of the surgery

29. Open fetal surgery should not be attempted prior to how many weeks of gestation?

30. Open fetal surgery should not be attempted prior to 18 weeks of gestation.

31. Open fetal surgery should not be attempted past how many weeks of gestation?

32. Open fetal surgery should not be attempted past 30 weeks of gestation.

33. What are the primary indications in which open fetal surgery may be indicated?

34. Congenital Diaphragmatic Hernia
Congenital Cystic Adenomatoid Malformation (CCAM)
Congenital Heart Disease
Pulmonary Sequestration
Sacrococcygeal Teratoma

35. Minimally Invasive Fetal Surgery
Twin-to-Twin Transfusion Syndrome
Laser ablation of vessels
Amnio-infusion
Amnio-infusion refers to the instillation of fluid into the amniotic cavity. This procedure is typically performed during labor through an intrauterine pressure catheter introduced trans-cervically after rupture of the fetal membranes

36. Endoscopic fetal surgery for Twin-to-Twin Transfusion Syndrome

37. The two open fetal surgeries most often performed…
CDH
Myelomeningocele

38. Spina Bifida MOMS trial
Management of Myelomeningocele Study
The MOMS trial is a clinical trial which began in to evaluate what was the best treatment for myelomeningocele — fetal surgery or surgical repair after birth.

39. The clinical trial results showed prenatal surgery significantly reduced the need to divert, or shunt, fluid away from the brain; improved mental development and motor function; and increased the likelihood that a child will walk unassisted.
The MOMS trial has proved that some of the factors causing problems like Chiari II malformation and hydrocephalus are in fact those that develop during the second half of pregnancy. Closing the fetus’s back early may allow some nerve function to be restored in pregnancy, and actually reverse the development of this serious condition.

40. Open fetal surgery for CDH
Tracheal occlusion technique using a catheter-based detachable balloon that is placed through the side channel of a fetoscope.

41. FINAL EXAM EXTRA CREDIT:
Describe the Tracheal Occlusion technique and what outcomes are to be expected for the babies undergoing the procedure?
Good paper = 2 points
Bad paper = no points
Explain the open fetal surgical procedure for the MOMS trial.
Good Paper = 2 points
Bad paper = 0 points

42. FIN