Antepartum testing for vasa previa: Current standard of care

Antepartum testing for vasa previa: Current standard of care

Antepartum testing for vasa previa: Current standard of care R. H. Messer, M.D., A. R. Gomez, R.N., C.N.P., and T.J. Yambao, M.D. Amarillo, Texas Vasa...

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Antepartum testing for vasa previa: Current standard of care R. H. Messer, M.D., A. R. Gomez, R.N., C.N.P., and T.J. Yambao, M.D. Amarillo, Texas Vasa previa is a rare accident in obstetrics with high fetal mortality. There are simple tests available to distinguish fetal from maternal blood. Recently it has been called into medicolegal question whether patients with third-trimester bleeding need to be tested for fetal bleeding. We surveyed 100 community hospitals and all the medical schools in the United States in an attempt to answer the question. It appears that the standard of care in the United States does not require such testing. (AM J OBSTET GYNECOL 1987; 156:1459-62.)

Key words: Vasa previa, fetal bleeding

Velamentous insertion of the cord was described more than 100 years ago. Hemorrhage from cord vessels with loss of fetal blood and fetal death was described more than 85 years ago. With vasa previa, the umbilical vessels lie below the presenting part, unprotected by either cord or placenta, and thus are prone to tear, resulting in fetal bleeding. The m~ority of reported cases result in fetal death, and it is usually rapid. There are probably many unreported fetal deaths from this cause as well. The incidence of vasa previa is probably about 1/2000 to 115000 deliveries. There is an excellent recent review by Kouyoumdjian.' The diagnosis is sometimes made by palpating or visualizing the vessels, but it is not usually made before birth. Sometimes vasa previa is found by accident at the time of cesarean section for fetal distress. Theoretically, if fetal bleeding were discovered in time, fetal loss could be prevented. A number of ways to distinguish fetal from maternal blood exist. Tests that have been used are those of Apt and Downey! Ogita et al,S Gelsthorpe,• and Kleihauer-Betke, 5 the Fetaldex, and hemoglobin electrophoresis for fetal hemoglobin. A simple Wright stain for the normoblasts and nucleated red cells of fetal blood can be used. Unfortunately, there is a tendency for case reports that appear in the literature, sometimes even describing fetal death, to "recommend" that such testing of vaginal bleeding for fetal blood be routine. If this were standard procedure, then fetal loss could theoretically produce medicolegal liability if fetal blood testing were not done. Such a malpractice case has recently occurred (Messer RH, personal communication). Is such testing From the Texas Tech University Health Sciences Center. Presented at the Fifty-fourth Annual Meeting of The Central Association of Obstetricians and Gynecologists, Milwaukee, Wisconsin, October 9-11, 1986. Reprint requests: Robert H. Messer, M.D., Texas Tech University Health Sciences Center, Department of Obstetrics and Gynecology, 1400 Wallace Blvd., Amarillo, TX 79106.

Table I. Question 1: Is it routine to test patients with third-trimester bleeding for fetal blood in your hospital?

I . y~%

No n

89

%

Medical schools Community hospitals

18 3

16.8 5.8

47

83.2 90.4

Total

21

13.2

136

85.5

usually done in hospitals in the United States? Does it need to be done in order to conform to the reasonable and acceptable standards of care?

Method In order to answer these questions we sent a simple survey questionnaire to 103 community hospitals and 127 medical school obstetric departments. The community hospitals were selected randomly from across the United States, but each was chosen because its number of beds approximated that of a hospital in which a medicolegal case had occurred. The addresses of the medical schools were all of those listed in the most current Directory of the Association of Professors in Gynecology and Obstetrics (APGO). Three questions were asked: (1) Is it routine to test patients with thirdtrimester bleeding for fetal blood in your hospital? (2) Have you saved any babies by diagnosing vasa previa? (3) How many deliveries per year occur in your hospital? The questions were kept very simple and were restricted to one side of a postcard. Requiring simply that boxes be checked rather than a long questionnaire filled out was done on purpose to ensure the highest possible return. Results Replies were received from 107 (84%) ofthe medical schools. Fifty-two (50.5%) of the community hospitals 1459

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Am J Obstet Gynecol

Table II. Question 2: Have you saved any babies by diagnosing vasa previa? No

Yes

Don't know

n

%

n

%

n

%

Medical schools Community hospitals

42 7

39.2 13.5

41 23

38.3 44.2

22 16

22.6 30.8

Total

49

30.8

64

40.2

38

23.9

responded. The responses to question I are summarized in Table I. The responses to question 2 are summarized in Table II. The mean number of deliveries was 3046 in community hospitals and 4050 in medical school hospitals. These hospitals represent almost 600,000 annual births.

Comment There were quite a variety of miscellaneous responses to the questionnaire that were anecdotal in nature and beyond the scope of this short discussion to list. The majority of hospitals surveyed do not test for fetal blood in this circumstance. This is true of community hospitals as well as medical school hospitals. However, many hospitals report that babies have been saved. This implies that other means were used. In literature reports the diagnosis is sometimes made by palpating the presenting vessels or when a cesarean section is done for fetal distress. Because vasa previa is a rare entity, this study may seem to make a minor point. On the other hand, poor obstetric outcome is the rule with vasa previa and poor obstetric outcome is a leading cause of lawsuits in the United States at this time. This study shows very clearly that to comply with reasonable and customary national standards of care it is not necessary to routinely test for fetal blood in patients with third-trimester bleeding. Most community hospitals in this survey and most medical school hospitals do not do so. This does not address the question of the wisdom of that testing but rather current practice. Although most hospitals do not routinely do such testing, it is prudent to understand the rationale and methods used. Many of the tests for fetal blood are described as "simple" since they are based on resistance of fetal hemoglobin to alkali denaturation. However, there is no evidence that these tests are accurate in all clinical situations. Examples might be: How dilute can the fetal/maternal blood cell ratio be? What influence does amniotic fluid have on these tests? Meconium? In any case it is hoped that a medicolegal question has been answered by this study.

REFERENCES I. Kouyoumdjian A. Velamentous insertion of the umbilical cord. Obstet Gynecol 1980;56:737. 2. Apt L, Downey WS. Melena neonatorum: the swallowedblood syndrome. J Pediat 1955;47:12. 3. Ogita S, Ishiko 0, Matsumoto M, Hasegawd H, Sugawa T. Instruments and methods: a simplified method for measuring fetal hemoglobin. Obstet Gynecol 1976;48:237. 4. Gelsthorpe K. A rapid method for differentiating fetal from maternal blood. Vox Sang 1960;5:172. 5. Kleihauer E, Braun H, Betke K. Demonstration von Fetalen Haemoglobin in dem Erythrocyten eines Blutausstrichs. Klin Wochenschr 1957;35:651.

Editors' note: This manuscript was revised after these discussions were presented.

Discussion DR. EMANUEL P. GAZIANO, Minneapolis, Minnesota. Dr. Messer and his group pose a question and provide objective data on an issue that is becoming increasingly important for all clinical obstetricians-the accusation of negligence for adverse outcomes in rare events for which there are potential diagnostic and therapeutic remedies. As the title suggests, vasa previa, whose welldefined anatomy and often lethal pathophysiologic consequences have been known to thoughtful clinicians for almost 200 years, serves well to illuminate the dilemma. The major thrust of the study, though, is to define a concept of the law, standard of care, as it relates to the physician's responsibility to diagnose and treat. The discussion will focus on three areas: first, the validity of the study design; second, a review of the legal requirements for standard of care; and finally, speculation as to whether the conclusions reached by the authors effectively define standard of care as it pertains to vasa previa. The study is appealing in its directness and simplicity in addressing whether patients with third-trimester bleeding are routinely tested for the presence of fetal blood. The data would be more meaningful if it were known whether those with clinical abruptio placentae and placenta previa were tested or testing was considered only for those at greater risk, such as pregnancies with multiple gestations, and those in whom bleeding was associated with an abnormal fetal heart rate pattern. Further, this question implies that for vasa previa the sole presentation is one of bleeding, while case reports indicate that concealed hemorrhage or occlusion

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of the aberrant vessels by the fetal presenting part can occur with devastating result. 1-3 For those who answered yes to the question of routine testing, survey of the method of testing such as Kleihauer-Betke and hemoglobin electrophoresis would be pertinent. Did the methods require central laboratory facilities or was the method a bedside procedure such as fetal scalp hematocrit or the Apt or Ogita test? Again, the question relating to experience with survival would have been insightful if the diagnostic criteria were reported. For example, were amnioscopy, fetal heart rate data, palpation, and fetal scalp sampling useful for the 31% of institutions reporting survival? These details may have suggested a practice pattern that more clearly defines standard of care. A total response rate of 69% is considered good by survey researchers. However, the authors need to define who the individual respondents were, how the community and university hospital sample was drawn, and how many mailings were needed to obtain their data. Almost a quarter of the responders answered "don't know" to the survival question. It is likely that this response was based on the personal experience or knowledge of the respondents rather than a systematic review of the institution's experience. Considering the legal issues implicit in failure to diagnose, the concept of physician responsibility must be defined. According to Fineberg et al.,' "the law has created a standard of the reasonable physician of ordinary prudence who acts with reasonable and due care in a given situation." The law further requires that "the physician possess and exercise the requisite skill, care, and diligence that the particular case demands."• The legal term that refers to these physician skills or expertise is standard of care and is based on the principles of objectivity and uniformity, the references of which are the skills and experience of other physicians in that speciality. Initially, the latter applied to physician standards within a local community, but recently the courts have widened their interpretation to extend this concept to the practice standards of the "entire body of the American physician."• To apply a particular standard, the courts have looked to expert medical testimony although proof of the standard may be preceded by the in- or out-of-court admission of negligence by the defendant-physician.• Admission of textbook evidence varies from jurisdiction to jurisdiction, but in most courts text data may be used only to cross examine the medical expert. Federal courts, and some states, however, allow statements from texts, scientific journals, manufacturers, brochures, and drug information warnings to be admitted as independent evidence.• Finally, the courts agree that a choice may be made among various diagnostic and therapeutic options if these options are generally deemed "good practice" by other physicians.• The first duty of the physician therefore is to act with

reasonable and due care in a given situation. Standards of care are in a constant state of flux as new knowledge and technology become available. For vasa previa, despite its rarity and the paucity of meaningful data, a body of knowledge is emerging that will yield a reasonable and prudent set of clinical standards. For example, ultrasound makes it possible to define many cases of third-trimester bleeding as being either abruptio placentae or placenta previa. In the absence of these complications, bleeding associated with abnormal fetal heart rate data suggests vasa previa be a part of the differential diagnosis. Similarly, observations that vasa previa is 10 times more frequent in multiple than singleton gestations, that the diagnosis can occasionally be made prior to amniotomy by careful palpation, and that vascular rupture may occur with intact or ruptured membranes serve as important discriminating features.5-7 Importantly, physicians and the public must know that despite application of all current clinical knowledge and technology, adverse outcome is unlikely to be prevented in all or even most cases of vasa previa. However, despite the study's finding of a low rate of routine fetal blood testing for third-trimester bleeding, a specific charge of negligence will be answered on a case-by-case basis in the courts of law and may largely be affected by the medical expert and his clinical bias. REFERENCES I. Kouyoumdjian A. Velamentous insertion of the umbilical

. cord. Obstet Gynecol 1980;56:737. 2. Curl CW, Johnson WL. Vasa previa, antepartum diagnosis: report of a case. Obstet Gynecol1968;31:328. 3. Naftolin F, Mishell DR. Vasa previa-report of 3 cases. Obstet Gynecol 1965;26:561. 4. Fineberg KS, Peters JD, Willson JR, Kroll DA. Obstetrics/gynecology and i:he law. Ann Arbor, Michigan: Health Administration Press, 1984. 5. Tejani S, Tejani N, Weiss RR, Nathanson H. Vasa previa, diagnosis and management. NY State J Med 1970;70:772. 6. Pent D. Vasa previa. AMJ 0BSTET GYNECOL 1979;134:151. 7. Carp HJA, Maschiach S, Serr DM. Vasa previa: a major complication and its management. Obstet Gynecol 1979; 53:273. DR. PAUL G. ToMICH, Maywood, Illinois. Messer et al. have raised the question: "When patients present with third-trimester vaginal bleeding, is it necessary to test for fetal hemorrhage, to conform to standard of care and to avoid the accusation of having committed medical malpractice?" The bases for this question are: ( 1) Vasa previa is known to be a tare but catastrophic obstetric complication that theoretically can be screened for by testing for fetal hemorrhage. (2) Recently a malpractice case has occurred wherein the plaintiff's allegation was failure to test for and diagnose vasa previa, with a poor outcome. The authors sent a questionnaire to 103 community hospitals and 127 medical school obstetric departments. The overall response rate was 69% with 84% of the

1462 Messer, Gomez, and Yambao

medical schools responding and 50.5% of the community hospitals responding. Only I6.8% of the medical school obstetric departments and 5.8% of the community hospital obstetric departments routinely screen for vasa previa by performing a Fetaldex or KleihauerBetke test. Nonetheless, 40.5% and I3.5%, respectively, of the respondents were of the opinion that such testing had saved babies' lives! Although B-scan and real-time ultrasonography has facilitated placental localization with an accuracy of >90%, until recently the prenatal diagnosis of vasa previa by ultrasound had not been made. 1 The traditional method to screen for fetal bleeding was by examining the blood for fetal erythrocytes! Gianopoulos et aF have recently reported the prenatal diagnosis of a vasa previa by careful ultrasonographic evaluation and Doppler studies. 2 The patient was a maternal transport to the Loyola University Perinatal Center because of third-trimester vaginal bleeding and a partial placenta previa. The presence of a succenturiate lobe of the placenta with a persistent pulsatile echogenic pattern overlying the internal os of the cervix was noted on three separate examinations. At the time of primary cesarean section, the diagnosis of vasa previa was confirmed. Of interest, testing for fetal hemorrhage performed during the hospitalization was negative on three separate occasions. I have some questions concerning the design of the study: (I) How were the 103 community hospitals selected for the study? (2) More important, why were only I 03 such hospitals selected? (3) At each hospital or medical school obstetric department, who responded to the questionnaire? (4) Of the community hospitals, which of them have residency training programs in obstetrics and gynecology? (5) Do the authors know what percentage of those respondents who said no to questio11 I, said yes to the second question? This study does address the issue of to what extent current standard of care is affected by the frequency that physicians perform or omit a particular test. The current standard of care for the diagnosis of a vasa previa is that it is rarely tested for by performing any evaluation for fetal hemorrhage and that unfortunately the diagnosis is still most often made retrospectively after a poor outcome. Perhaps, as a quality assurance issue, we should reevaluate our current practice pattern and do screening for vasa previa. I would like to congratulate the authors for their effort in this thought-provoking study. It represents an excellent example of how the medical profession may demonstrate what is considered standard of care to the legal profession when necessary. REFERENCES I. Sanders R, James AE. Principles and practice of ultraso-

nography in obstetrics and gynecology. 2d ed. New York: Appleton-Century-Crofts, 1980. 2. G!anopou!os J, Carver T, et a!. Diagnosis of vasa previa Wlth ultrasonography. Obstet Gynecol 1986 (in press).

June 1987 Am J Obstet Gynecol

DR. DAVID G. DECKER, Rochester, Minnesota. This article covers a much broader area than vasa previa. Those of us who have retired from active practice are constantly called on to testify in legal situations. Some of us testify on one side or the other, but I prefer the defense. In attempting to defend some of the physicians who find themselves in trouble, there are three main things that trip us up. First, there is the old cliche, accurate records, and this, I think, is very evident in the presentation that has just been made. There was not an accurate evaluation of the blood loss at the time of the initial incident, a major omission. Second is communication with the patient. We experience this over and over and over again. "Well, the doctor wasn't worried." "He didn't pay any attention to what I told him." "He didn't want to talk about it." The patient's worries were not adequately addressed. You are all busy, but for heaven's sakes, if you want us to try to help you, give us something to help with. The third and final comment that I would like to make is that this association is one of the primary sources where you can hone your skills and see what your colleagues are doing and thus maintain your standard of practice. I enjoyed the article. It was brief, but it carried a great deal of "meat", and I hope that my comments may have added a bit. DR. JosEPH C. Scorr, JR. Omaha, Nebraska. Before Dr. Messer concludes, I have one final question for him. These cases can be dragged out a long time. Was there an outcome in this case? DR. MESSER (Closing). The answer to Dr. Scott's question is that the defendant physician in this case won the case. The plaintiff's case was essentially dismissed by the jury. In response to Dr. Gaziano's question, I did not ask what the source of the third-trimester bleeding was, so I do not know. I was trying to keep the questionnaire quite simple. He does have a good point in that babies can die of vasa previa even if there is no bleeding. Both he and Dr. Tomich asked how the community hospitals were selected. There is a directory of all h?~~ pitals in the United States, and what I did was pick hospitals of the approximate size of the hospital in which this case occurred. They were then selected randomly from all over the United States. As to why there were I03, I just wanted to make sure at least I 00 of the postcards were sent out. There was no magic number. To answer another question, who was the individual to whom the questionnaire was sent, I did not know which individual to select in the community hospital, so the cards were mailed to the department of obstetrics in these community hospitals. I also do not know which ones had residencies. There are some faults in the article, but I think it successftdly answered the question.