RIVIERA MAYA, MEXICO — Expect the unexpected during a fetal ultrasound exam, and if you find it, be kind but unambiguous in describing your observations and concerns.
“The ambiguity we sometimes use to try and soften what we are saying doesn't change the message, but it can change the interpretation,” Dr. Nancy Chescheir said at a conference on obstetrics, gynecology, perinatal medicine, neonatology, and the law.
“If there is no fetal heart activity, tell the patient her baby's heart is not beating and that the fetus has died. If you see findings suggestive of a fetal anomaly, describe exactly what you see, express your concern, and refer the patient to an expert as quickly as possible,” said Dr. Chescheir, the Betty and Lonnie S. Burnett Professor of obstetrics and gynecology at Vanderbilt University, Nashville, Tenn.
Many diagnoses of fetal demise or anomaly will be discovered during a detailed anatomic scan ordered on the basis of some increased risk, including a poor past pregnancy outcome, family history of genetic disorders, or abnormal early biomarker studies. In these cases, the patient probably already has an idea that there may be a serious problem.
“The patient is already suspicious. They watch the ultrasound; they may have had scans before, and they know what fetal heart activity looks like. If you are certain of the diagnosis of fetal demise, be very kind, do it in private, but be unambiguous about what you are seeing.”
In cases of uncertainty, the 5–10–20 rules can be a help, Dr. Chescheir said. “If you have a 5-mm crown-rump length, you have to see a heartbeat or you have a dead baby. There's no need to have her come back in 48 hours for a repeat scan or to do hormone levels.”
If the fetus measures only 4.5 mm from crown to rump, however, you should ask the woman to come back for a repeat scan when you anticipate a length of 5 mm. “You will probably have to wait at least 3 days to see this growth. If at that time, you have a 5-mm length and still no heartbeat, make the diagnosis and get on with your therapeutic options.”
For a gestational sac with a mean diameter of 10 mm, you must see a yolk sac; if you don't, the pregnancy is not viable. Similarly, for a 20-mm mean gestational sac, you must see a fetal pole. The absence of one means the pregnancy is not viable, Dr. Chescheir said at the meeting, which was sponsored by Boston University.
Surveys about patient satisfaction with fetal ultrasound diagnosis agree on one thing, Dr. Chescheir said: Women don't appreciate the delay between the moment a problem is identified and the moment the doctor communicates the problem.
“They really don't like it if the sonographer is not allowed to say anything during the exam,” Dr. Chescheir said. “If the sonographer is fairly certain about a fetal demise, she should be able to say something. You may not want her making the diagnosis, but she should be allowed to tell the patient something.”
Having very clear office procedures can avert problems in this area, she said.