- Fetal chromosomal abnormalities are associated with 5% to 10% of late fetal losses.
- Since amniocytes can survive for several weeks following a fetal demise, amniocentesis can be used to obtain material for karyotyping.
- Once the patient delivers, a careful gross examination of the fetus, cord, membranes, and placenta should be documented in the chart, even if an autopsy is planned.
- Perinatal autopsy continues to play an important role in determining the cause of death, yielding new information in more than 25% of cases.
- providing the family with information about the cause of death, as well as emotional guidance;
- determining whether a loss is likely to recur and suggest possible ways to decrease the risks; and
- minimizing the care provider’s liability exposure.
To ensure all these goals are met, a systematic protocol, such as the one described in this article, is vital.
The history and other clues
Once the diagnosis of fetal death is confirmed, and the woman and her family are prepared to move for ward, it is critical to obtain a thorough history. Suggested questions include: “Has the patient felt normal over the preceding 24 to 48 hours?” “Has she experienced any recent gastrointestinal (GI) or febrile illnesses?” If either answer is yes, the cause of death may be related to listerosis, chorioamnionitis, or other infectious processes. See TABLE 1 for a complete list of questions and their rationales.
Fetal chromosomal abnormalities are associated with 5% to 10% of late fetal losses.1 With fetal tissue, there is a relatively high rate of post-delivery cell culture failure due to autolysis or contamination. Since amniocytes can survive for several weeks following a fetal demise, consider amniocentesis for karyotyping prior to induction of labor.2 If amniocentesis is unacceptable to the patient, pass an intrauterine pressure catheter after amniotomy to obtain an amniotic fluid sample as a backup in case the fetal biopsy specimen fails to grow.
If invasive testing is not feasible or acceptable, other tissue may be used, although it likely will have a lower rate of successful cell culture. If the fetal demise occurs within 24 hours of delivery, obtain for karyotyping a heparinized sample of the fetal cord blood or a blood sample by fetal cardiac puncture. Other acceptable tissue samples include 1 cm2 of fetal skin, Achilles tendon, or retro-patellar cartilage. Fetal tissue should be sent, refrigerated, in isotonic saline to the cytogenetic laboratory.
Fetuses with structural abnormalities face a higher risk of intrauterine death than normal fetuses. If the patient will allow it, a complete sonographic evaluation of the fetus for anatomic evaluation is important, especially if one was not done earlier in the pregnancy. Ultrasound also may help determine the approximate time of the demise. For instance, a recent demise would not yet demonstrate overlapping cranial sutures or postmortem skin edema.
Look closely for evidence of fetal growth restriction, which may provide clues to the cause of death. Long bone measurements may be more reliable measures of fetal size than head and abdominal measurements, due to postmortem soft tissue changes.
Potential screening questions and their rationales
|1. Has the patient felt normal over the preceding 24–48 hours? Has she had any GI or febrile illnesses recently?||Listerosis, chorioamnionitis, or other infectious processes|
|2. Has she had blurred vision, headaches, right upper quadrant pain, or abnormal facial or hand swelling?||Preeclampsia with uteroplacental insufficiency|
|3. Has she been hit, kicked, slapped, or fallen? Has she been in even a minor automobile accident?||Domestic violence or other trauma|
|4. Has she had any vaginal bleeding or leakage of fluid?||Abruption, amnionitis, or cord prolapse|
|5. When did she notice decreased fetal movement, if at all?||A clue to timing of the event|
|6. Has her pregnancy been uncomplicated until now?||Clues to placental problems: elevated maternal serum alpha-fetoprotein, growth problems, smoking, diabetes, hypertension|
Laboratory and autopsy studies
An often overlooked cause of fetal death is fetal-maternal hemorrhage. To evaluate for this, obtain a Betke-Kleihauer test or flow cytometry study prior to amniocentesis or induction of labor. Other laboratory analyses useful in determining the etiology of fetal demise include a urine drug screen and creatinine and hemoglobin A1C levels. For a complete list of potential tests and their rationales, see TABLE 2.