LETTERS TO THE EDITORS Editors ' note: Readers may note we are publishing more Letters to the Editors
in an effort to reduce the backlog and improve the publication time.
Definition of primiparas To the Editors: I write in reference to the letter (Gooden MD. Defining "primiparas" [Letter]. AM J OBSTET GyNECOL 1989; 161: 1417) and reply (Thomson M. Repl y [Letter]. AM J OBSTET GYNECOL 1989; 161 :1417) that appeared in the November 1989 issue of the JOURNAL. I agree with Dr. Goodman that the term "primipara" should be used as it is defined obstetrically. I trust that Dr. Thomson would not refer to the patient in question as being para 1 but will call them" 1 para" by using the term primipara. Those who are and hold themselves to be educated professionals are held to a higher standard than generic dictionary writers. I urge the editors of the AMERICAN JO URNAL OF OBSTETRICS AND GYN ECOLOGY to avoid the misuse of the term "primipara" within the covers of the JOURNAL. Herbert S. Gates, Jr., MD
other features that indicate the twin-to-twin transfusion syndrome, rescue of one or both twins may be possible. Isaac Blickstein, MD Department oj Obstetrics and Gynecology, Kaplan Hospital, Rehovot, Israel 76 100
REFERENCES I. Blickslein I, Lancet M. The growth discordant twin. Obstet Gynecol Surv 1988;43 :509-15. 2. Bebbington MW, Wittmann BK. Fetal transfu sion syndrome : alllenatal factors predicti ng outcome. AM J OBSTf.T GVI\[COL 1989; 160:9 13-5. 3. Gerson AG, Wallace DM , Bridgens NK, Ashmead GG, Weiner S, Bolognese RJ. Duplex Doppler ultrasound in the evaluation of growth in twin pregnancies. Obstet Gynecol 1987;70:419-23. 4. B1ickstein I, Friedman A, Caspi B, Lancet M . Ultrasonic prediction of growth discordancy by intertwin difference in abdominal circumference. IIll.J Gynecol Obstet 1989; 29:121-4.
Department of Obstetrics and Gynecology, East Carolina Univenity School oj Medicine, Greenville, NC 27858-4354
Reply Twin-to-twin transfusion syndrome To the Editors: Drs. Danskin and Neilson should be con-
gratulated for reevaluating the diagnosis of the twinto-twin transfusion syndrome (Danskin FH, NeilsonJP. Twin-to-twin transfusion syndrome: What are appropriate diagnostic criteria? AM J OSSTET GYNECOL 1989; 161 :365-9). Their study focused on the posthoc situation after the delivery of a growth discordant pair (>20%) with or withou t hemoglobin difference of ~5 gm/dl. They concluded correctly that neither permits a definitive diagnosis of the syndrome. Twin-to-twin transfusion syndrome is a rare cause of intertwin growth disparity,' which mainly results from environmental rather than genetic factors . The findings of Danskin and Neilson are therefore unsurprising. The twin-to-twin transfusion syndrome is an important and dangerous complication that must not be left for postpartum diagnosis. Bebbington and Wittman1 listed the ultrasonographic criteria including (I) intertwin growth discordancy, (2) amniotic sacs of divergent size, (3) signs of hydrops in either twin or congestive heart failure in the recipient, (4) same sex of twins, (5) single placenta, and (6) separate cords differing in size and number of vessels. In addition , percutaneous umbilical cord sampling may disclose highly divergent hemoglobin levels. Finally, Doppler velocimetry has been claimed to diagnose twin-to-twin transfusion. ; In our experience, intensive and possibly invasive evaluations may be indicated in highly discordant twins as revealed by ultrasonography.' When combined with
To the Editors: I appreciate the interest of Dr. Blickstein
in our article. I am well aware of the ultrasonographic features of Aorid twin-to-twin transfusion syndrome. They are not subtle and they were described in our article . However, the question that we have been addressing (and to which this article contributes) is whether the presence of vascular anastomoses in monochorionic placentas contributes to a spectrum of adverse outcome (i.e., less unmistakable manifestations of twin-to-twin transfusion syndrome). Such studies require that appropriate criteria are established for diagnosis of the condition after birth. Dr. Blickstein may not be surprised that the finding of a hemoglobin difference >5 gm/dl plus a birth weight difference >20% is not definitive proof of twin-to-twin transfusion syndrome, but I suspect others will be surprised. Varying reports of the pattern of Doppler umbilical artery Aow velocity waveforms in apparent twin-to-twin transfusion syndrome undoubtedly reAect a lack of satisfactory diagnostic criteria -thus concordant waveforms, '. 2 discordant waveforms,' cyclically discordant waveforms: and no consistent pattern' have all been reported . Clearly, it is vital that the type of placentation be reported in any publication on the subject of twin-totwin transfusio n syndrome, but this is frequentl y not the case. We have found that vascular anastomoses in monochorionic placentas do not, in the absence of rare Aorid twin-to-twin transfusion syndrome, exert a strong inAuence on fetal growth or umbilical artery Aow velocity waveforms. 6 The management of twin pregnancy is perhaps the example par excellence in obstetrics of uncontrolled
677
in an effort to reduce the backlog and improve the publication time.
Definition of primiparas To the Editors: I write in reference to the letter (Gooden MD. Defining "primiparas" [Letter]. AM J OBSTET GyNECOL 1989; 161: 1417) and reply (Thomson M. Repl y [Letter]. AM J OBSTET GYNECOL 1989; 161 :1417) that appeared in the November 1989 issue of the JOURNAL. I agree with Dr. Goodman that the term "primipara" should be used as it is defined obstetrically. I trust that Dr. Thomson would not refer to the patient in question as being para 1 but will call them" 1 para" by using the term primipara. Those who are and hold themselves to be educated professionals are held to a higher standard than generic dictionary writers. I urge the editors of the AMERICAN JO URNAL OF OBSTETRICS AND GYN ECOLOGY to avoid the misuse of the term "primipara" within the covers of the JOURNAL. Herbert S. Gates, Jr., MD
other features that indicate the twin-to-twin transfusion syndrome, rescue of one or both twins may be possible. Isaac Blickstein, MD Department oj Obstetrics and Gynecology, Kaplan Hospital, Rehovot, Israel 76 100
REFERENCES I. Blickslein I, Lancet M. The growth discordant twin. Obstet Gynecol Surv 1988;43 :509-15. 2. Bebbington MW, Wittmann BK. Fetal transfu sion syndrome : alllenatal factors predicti ng outcome. AM J OBSTf.T GVI\[COL 1989; 160:9 13-5. 3. Gerson AG, Wallace DM , Bridgens NK, Ashmead GG, Weiner S, Bolognese RJ. Duplex Doppler ultrasound in the evaluation of growth in twin pregnancies. Obstet Gynecol 1987;70:419-23. 4. B1ickstein I, Friedman A, Caspi B, Lancet M . Ultrasonic prediction of growth discordancy by intertwin difference in abdominal circumference. IIll.J Gynecol Obstet 1989; 29:121-4.
Department of Obstetrics and Gynecology, East Carolina Univenity School oj Medicine, Greenville, NC 27858-4354
Reply Twin-to-twin transfusion syndrome To the Editors: Drs. Danskin and Neilson should be con-
gratulated for reevaluating the diagnosis of the twinto-twin transfusion syndrome (Danskin FH, NeilsonJP. Twin-to-twin transfusion syndrome: What are appropriate diagnostic criteria? AM J OSSTET GYNECOL 1989; 161 :365-9). Their study focused on the posthoc situation after the delivery of a growth discordant pair (>20%) with or withou t hemoglobin difference of ~5 gm/dl. They concluded correctly that neither permits a definitive diagnosis of the syndrome. Twin-to-twin transfusion syndrome is a rare cause of intertwin growth disparity,' which mainly results from environmental rather than genetic factors . The findings of Danskin and Neilson are therefore unsurprising. The twin-to-twin transfusion syndrome is an important and dangerous complication that must not be left for postpartum diagnosis. Bebbington and Wittman1 listed the ultrasonographic criteria including (I) intertwin growth discordancy, (2) amniotic sacs of divergent size, (3) signs of hydrops in either twin or congestive heart failure in the recipient, (4) same sex of twins, (5) single placenta, and (6) separate cords differing in size and number of vessels. In addition , percutaneous umbilical cord sampling may disclose highly divergent hemoglobin levels. Finally, Doppler velocimetry has been claimed to diagnose twin-to-twin transfusion. ; In our experience, intensive and possibly invasive evaluations may be indicated in highly discordant twins as revealed by ultrasonography.' When combined with
To the Editors: I appreciate the interest of Dr. Blickstein
in our article. I am well aware of the ultrasonographic features of Aorid twin-to-twin transfusion syndrome. They are not subtle and they were described in our article . However, the question that we have been addressing (and to which this article contributes) is whether the presence of vascular anastomoses in monochorionic placentas contributes to a spectrum of adverse outcome (i.e., less unmistakable manifestations of twin-to-twin transfusion syndrome). Such studies require that appropriate criteria are established for diagnosis of the condition after birth. Dr. Blickstein may not be surprised that the finding of a hemoglobin difference >5 gm/dl plus a birth weight difference >20% is not definitive proof of twin-to-twin transfusion syndrome, but I suspect others will be surprised. Varying reports of the pattern of Doppler umbilical artery Aow velocity waveforms in apparent twin-to-twin transfusion syndrome undoubtedly reAect a lack of satisfactory diagnostic criteria -thus concordant waveforms, '. 2 discordant waveforms,' cyclically discordant waveforms: and no consistent pattern' have all been reported . Clearly, it is vital that the type of placentation be reported in any publication on the subject of twin-totwin transfusio n syndrome, but this is frequentl y not the case. We have found that vascular anastomoses in monochorionic placentas do not, in the absence of rare Aorid twin-to-twin transfusion syndrome, exert a strong inAuence on fetal growth or umbilical artery Aow velocity waveforms. 6 The management of twin pregnancy is perhaps the example par excellence in obstetrics of uncontrolled
677
