SonoNews: New Guidelines- reduce risk of premature diagnosis of non-viable pregnancy #FOAMed

In a meeting of 15 members of the radiology, Ob/Gyn, and emergency medicine communities, new criteria were set that was published in NEJM Oct 2013 so that we dont prematurely state that a pregnancy is non-viable. This is pretty important, and a subject that I posted about earlier as well when discussing the usefulness (…or useless ness) of the beta hCG. Can you imagine what was done, and I remember this algorithm – you have a patient with 1st trimester pain or vaginal bleeding, no IUP seen on US, low beta Hcg, and OB was called and the patient was given methotrexate??? Well, there have been cases where those patients actually had a viable IUP that showed up a week later… and then the lawsuit happens….scary stuff. It’s different now where we dont care too much about the beta hCG, or whether there is not an IUP, but whether we see anything around the ovary….and even then, very close follow up and rechecks may be considered. Below is the Eurekalert and the AuntMinnie articles on it too:

Medical experts recommend steps to reduce risk of inadvertent harm to potentially normal pregnancies

New criteria aim to prevent misdiagnoses of nonviable pregnancies

A panel of 15 medical experts from the fields of radiology, obstetrics-gynecology and emergency medicine, convened by the Society of Radiologists in Ultrasound (SRU), has recommended new criteria for use of ultrasonography in determining when a first trimester pregnancy is nonviable (has no chance of progressing and resulting in a live-born baby). These new diagnostic thresholds, published Oct. 10 in the New England Journal of Medicine, would help to avoid the possibility of physicians causing inadvertent harm to a potentially normal pregnancy.

“When a doctor tells a woman that her pregnancy has no chance of proceeding, he or she should be absolutely certain of being correct. Our recommendations are based on the latest medical knowledge with input from a variety of medical specialties. We urge providers to familiarize themselves with these recommendations and factor them into their clinical decision-making,” said Peter M. Doubilet, MD, PhD, of Brigham and Women’s Hospital and Harvard Medical School in Boston, the report’s lead author.

Among the key points made by the expert panel:

  • Until recently, a pregnancy was diagnosed as nonviable if ultrasound showed an embryo measuring at least five millimeters without a heartbeat. The new standards raise that size to seven millimeters
  • The standard for nonviability based on the size of a gestational sac without an embryo should be raised from 16 to 25 millimeters
  • The commonly used “discriminatory level” of the pregnancy blood test is not reliable for excluding a viable pregnancy

The panel also cautioned physicians against taking any action that could damage an intrauterine pregnancy based on a single blood test, if the ultrasound findings are inconclusive and the woman is in stable condition.

Kurt T. Barnhart, MD, MSCE, an obstetrician-gynecologist at the Perelman School of Medicine at the University of Pennsylvania and a member of the SRU Multispecialty Panel, added, “With improvement in ultrasound technology, we are able to detect and visualize pregnancies at a very early age. These guidelines represent a consensus that will balance the use of ultrasound and the time needed to ensure that an early pregnancy is not falsely diagnosed as nonviable. There should be no rush to diagnose a miscarriage; more time and more information will improve accuracy and hopefully eliminate misdiagnosis.”

Michael Blaivas, MD, an emergency medicine physician affiliated with the University of South Carolina and one of the panelists, emphasized that “These are critical guidelines and will help all physicians involved in the care of the emergency patient. They represent an up-to-date and accurate scientific compass for navigating the pathway between opposing forces felt by the emergency physician and his/her consultants who are concerned about the potential morbidity and mortality of an untreated ectopic pregnancy in a patient who may be lost to follow-up, but yet must ensure the safety of an unrecognized early normal pregnancy.”

Aunt Minnie article :

“In addition, the authors emphasized that the commonly used “discrimination level” of the pregnancy blood test is not reliable for excluding a viable pregnancy. They also cautioned physicians against taking any action that could damage an intrauterine pregnancy based on a single blood test, if the ultrasound findings are inconclusive and the woman is in stable condition.

“The guidelines presented here, if promulgated widely to practitioners in the various specialties involved in the diagnosis and management of problems in early pregnancy, would improve patient care and reduce the risk of inadvertent harm to potentially normal pregnancies,” the authors wrote.

Not stringent enough

Research over the past two to three years has shown that previously accepted criteria for ruling out a viable pregnancy are not stringent enough to avoid false-positive results, but it has been difficult both to disseminate this information to practitioners and to implement standardized protocols.

The challenge is that physicians from multiple specialties — including radiology, obstetrics and gynecology, emergency medicine, and family medicine — are involved in the diagnosis and management of early-pregnancy complications, according to the authors.

“As a result, there is a patchwork of conflicting, often outdated published recommendations and guidelines from professional societies,” they wrote.

To address the problem, SRU in October 2012 organized the Multispecialty Consensus Conference on Early First Trimester Diagnosis of Miscarriage and Exclusion of a Viable Intrauterine Pregnancy. At the conference, researchers reviewed the diagnosis of nonviability in early intrauterine pregnancy of uncertain viability and, separately, in early pregnancy of unknown location. They focused mainly on the initial or only ultrasound study performed during the pregnancy.

The conference participants developed the following guidelines for transvaginal ultrasound diagnosis of pregnancy failure in a woman with an intrauterine pregnancy of uncertain viability.

Findings diagnostic of pregnancy failure:

  • Crown-rump length of ≥ 7 mm and no heartbeat
  • Mean sac diameter of ≥ 25 mm and no embryo
  • Absence of embryo with heartbeat ≥ 2 weeks after a scan that showed a gestational sac without a yolk sac
  • Absence of embryo with heartbeat ≥ 11 days after a scan that showed a gestational sac with a yolk sac

Findings suspicious for but not diagnostic of pregnancy failure:

  • Crown-rump length of < 7 mm and no heartbeat
  • Mean sac diameter of 16-24 mm and no embryo
  • Absence of embryo with heartbeat 7-13 days after a scan that showed a gestational sac without a yolk sac
  • Absence of embryo with heartbeat 7-10 days after a scan that showed a gestational sac with a yolk sac
  • Absence of embryo ≥ 6 weeks after last menstrual period
  • Empty amnion (amnion seen adjacent to yolk sac, with no visible embryo)
  • Enlarged yolk sac (> 7 mm)
  • Small gestational sac in relation to the size of the embryo (< 5 mm difference between mean sac diameter and crown-rump length)

Pregnancy of unknown location

The panel also determined diagnostic and management guidelines related to the possibility of a viable intrauterine pregnancy in a woman with a pregnancy of unknown location.

For the finding of no intrauterine fluid collection and normal (or near-normal) adnexa on ultrasonography, the authors provided the following key points:

  • A single measurement of human chorionic gonadotropin (hCG), regardless of its value, does not reliably distinguish between ectopic and intrauterine pregnancy (viable or nonviable).
  • If a single hCG measurement is < 3,000 mIU/mL, presumptive treatment for ectopic pregnancy with the use of methotrexate or other pharmacologic or surgical means should not be undertaken, in order to avoid the risk of interrupting a viable intrauterine pregnancy.
  • If a single hCG measurement is ≥ 3,000 mIU/mL, a viable intrauterine pregnancy is possible but unlikely. The most likely diagnosis is a nonviable intrauterine pregnancy, so it is generally appropriate to obtain at least one follow-up hCG measurement and follow-up ultrasonogram before undertaking treatment for ectopic pregnancy.

If ultrasound had not yet been performed, the researchers offered the following key point: “The hCG levels in women with ectopic pregnancies are highly variable, often < 1,000 mIU/mL, and the hCG level does not predict the likelihood of ectopic pregnancy rupture,” they wrote. “Thus, when the clinical findings are suspicious for ectopic pregnancy, transvaginal ultrasonography is indicated even when the hCG level is low.”

Panel member Dr. Kurt Barnhart, an ob/gyn at Perelman School of Medicine at the University of Pennsylvania, said in a statement that the guidelines represent a consensus that will balance the use of ultrasound and the time needed to ensure that an early pregnancy is not falsely diagnosed as nonviable.

“There should be no rush to diagnose a miscarriage; more time and more information will improve accuracy and hopefully eliminate misdiagnosis,” he said in the statement.

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