- Email: [email protected]
Reply to: Fetal adaptation to shortage of supplies
1478
Letters
May 1994 Am j Obstet Gynecol
umbilical/cerebral pulsatility index ratio can provide a useful indication of when compensatory mechanisms begin to operate. Days or weeks can be gained with a reasonable safety for the fetal brain, until fetal heart rate changes supervene, indicating that compensation has been overwhelmed. But if placental insufficiency begins very early in gestation, neonatal outcome is directly linked with gestational age. Claudine Amiel-Tison, MD, MichHe Uzan, MD, Girard Briart, AID, and Emile Papiernik, AID Po7t-Royal-Baudelocque, 123 Bld. de Port-Royal, 75014 Pans, France REFERENCES I. Hack M, Horbar JD, Malloy MH, Tyson JE, Wright E, Wright L. Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Network. Pediatrics 1991; 87: 587-97. 2. Phelps DL, Brown DR, Tung B, et al. 28-Day survival rates of 6676 neonates with birth weights of 1250 grams or less. Pediatrics 1991; 87: 7-17. 3. Cynober E, Uzan M, Uzan S, Breart G, Sureau C. L'index diastolique carotidien: facteur pr6dictif de la souffrance foetale aigue. j Gynecol Obstet Biol Reprod 1990; 19:53-9.
4. Snidjers Numeric
RJM,
Mulder EJH. LSM, Visser GHA, in intrauterine analysis of heart rate variation fetuses: a longitudinal growth-retarded study. A.%ij OBSFEr GYNECOL 1992; 166: 22-7. Ribbert
5. Divon MY, Hsu HW. Maternal and fetal blood flow velocity waveforms in intrauterine growth retardation. Clin Obstet Gynecol 1992; 35: 156-71.
Reply To the Editors: We thank Amiel-Tison et al. for their comments on our article. Our study had an observational design. Patient care took place according to departmental standards by the attending obstetrician blinded for the Doppler data. Clinical management and decisions to intervene during pregnancy were based on fetal heart rate tracings and neonatal risk as assessedby the attending neonatologist. The relationship between Doppler data and fetal heart rate tracings were not an object of our study. Arduini et al. ' and Samo et al.' have examined this important subject. We did not study the applicability of the umbilical/cerebral pulsatility index ratio as a new diagnostic test for fetal distress. Becausethe incidence of important intracranial abnormality is especiallyhigh between 25 and 33 weeksof gestation,' patient entry was limited to this interval. All patients in this cohort were entered consecutively. In II casesit wasdecided to refrain from an obstetric
intervention, and these fetuses died in utero. Another 22 infants died neonatally before reaching term age.The is follow-up (97%) calculated of neurologic percentage on the surviving infants reaching term age. It should not be based,as suggestedby Amiel-Tison et al., on the total number of fetusesincluded in the study (73%). In the analysiswe divided our cohort by the presence or absence of an antenatally observed physiologic adinto by "retrospective" small subdivision a aptation, not basis for the of on age gestational and appropriate "flawed" birth weight statistics. Gestational age is not equally distributed among the different umbilical/cerebral pulsatility index ratio for design However, this the corrected study groups. difference by performing the neurologic examinations with a standardized technique. It seemsparadoxical that thosevery small infants who nearly all needed a cesarean section to- survive and who, as we all know, represent a do to group prove sowell neonavery-high-risk clinically tally, as we suggest becauseof and not in spite of the intrauterine adaptation to minimal conditions. The relative risk and confidence interval of a raised umbilicaVcerebral pulsatility index ratio for an abnormal neurologic outcome is given in Table L The power of the study is calculated (a = 0.05 and P=0.80) considering a 25% reduction in the incidence of neurologic abnormalities. The number of patients required to find a statistical significant difference is also given. Contrary to our initial expectations, the study showed very clearly that neurologic outcome for the survivors is not inferior in the "brain-spared" group compared with the non-"brain-spared" group. There is a tendency for infants with a raised umbilical/cerebral pulsatility index ratio to have a better outcome during the first year: less severe intracranial hemorrhages, less severe periventricular echo densities (Table 111,original article), and fewer neurologic disturbances (Prechtl,' Touwen'; Table IV, original article). The relative risks are all < 1; at 12 months the confidence interval does not even include 1. In regression models R' gives the proportional reduction in variation. It describes the strength of the associationbetween the prediction and the response.A measure with generalized R' in the case of models for categoric responsesis given by Nagelkerke.' SzccoScherjon,PhD,"- 'Joke Kok, PhD,' Hans Zondervan,PhD,' and Hans Oosting,Phly ' and ClinicalEpidemiology Departments Neonatology, of Obstetnes, ' Academic MedicalCentre,Unwersityof Amsterand Biostatistics, dam,1105AZ Amsterdam, TheNetherlands a
Table 1. Relative risk and confidence interval of raised umbilical/cerebral pulsatility index ratio for abnormal neurologic outcome Neurologic outcome Precht14 'I'ouwen-" (6 mo) 'rouwen' (12 mo)
I
Relative risk 0.85 0.75 0.70
I
95% Confidence interval 0.60-1.20 0.50-1.10 0.53-0.93
*Number of patients required to find a statistically significant difference.
I Power 0.38 0.48 0.82
No. 308 232 103
Volume 170, Number 5, Part I Am j Obstet Gynecol
REFERENCES 1. Arduini D, Rizzo G, Romanini C. Changes of pulsatility index from fetal vessels preceeding the onset of late decel79: 1992; fetus. Gynecol Obstet in growth-retarded erations 605-10. Dopp2. Sarno AP, Brar HS, Phelan j P, Platt LD. Intrapartum fluid volume, and fetal heart rate ler velocimetry, amniotic OBSTET distress. j fetal Am subsequent of as predictors GVNECOL 1989; 161: 1508-14.
3. Szymonowicz W, Schafler K, Cussen Lj, Yu VYH. Ultrain hemorrhage sound and necropsy study of periventricular preterm infants. Arch Dis Child 1984; 59: 637-42. 4. Prechtl MFR. The neurological examination of the full term newborn infant. In: Clinics in developmental medicine. London: Heinemann, 1977. 5. Touwen BCL. Examination of the child with minor neurological dysfunction. In: Clinics in developmental medicine. London: Heinemann, 1979. 6. Nagelkerke NID. A note on a general definition of the ýetermination. Biometrika 1991; 78: 691-2. coefficient of
Numerators without denominators: Again? To the Editors: I read the thought-provo king case report by Gleeson et al. (Gleeson NC, Nicosia SV, Mark JE, Hoffman MS, Cavanagh D. Abdominal wall metastases from ovarian cancer after laparoscopy. Am j OBSTET GYNECOL1993; 169: 522-3) with interest but also with concern. The implantation of tumor in trocar tracts used during laparoscopy is an undeniable possibility that must be considered when protocols for laparoscopy in the management of ovarian carcinoma or ovarian cysts are devised. However, without knowing the frequency of this event it is not possible to determine whether this disadvantage offsets the advantages of laparoscopy over laparotomy or is itself offset by them.
The publication by Maiman et al. ' refer-red to by the authors set a dangerous precedent for the quality of scientific reporting in this field. It was a case series based on a survey with a poor response rate that established no denominators for the outcome of interest. Other than documenting that patients with ovarian cancer are sometimes mismanaged, a fact we might have surmised without the survey,it provided no information that helped define the indications for laparoscopy in this diseaseor to design protocols that might determine its role. All it did was to invite the conclusion that, becausesomeone had misused the laparoscope in some cases of ovarian cancer, any use of the laparoscope in this disease could be ipso facto regarded as misuse, a line of reasoning not at all conducive to clear thought in an area already rife with high emotion and patent bias. Gleeson et al. also provide no denominators for their heterogeneous cases,and their proscription of the use of laparoscopy should have been tempered by this fact. Tbe thoughts they provoked about tumor implants are important and relevant. It was therefore disappointing to hear the authors attribute the fact that this almost never occurs in a laparotomy scar after surgery in the presenceof ascitesto irrigation of the wound, a proposition that has not one iota of evidence to support it that I am awareof. I certainly do not irrigate the wound and have never seen a cutaneous implant in a lap-
Letters
1479
if Moreover, the authors surgery. arotomy scar after believe that and that there are restraints on tumor growth within the peritoneal cavity, why not suggest irrigation of the trocar site and closure of the peritoneum below it, or even removal of the tumor through, say, the vagina, rather than condemn a very promising technique out of hand? If we can prevent implants in laparotomy scars, why can't we do so at a trocar site? The authors state that "the contraindications to laplike " I to should established. are well aroscopic surgery hear what these are and why? Presumably ascites is one of them. However, up to 10% of women with ascites have no bulk disease - the so-called ovarian cancer with find laparotomy I an personally normal-sized ovaries. unedifying ritual in this situation and could envisage by laparoscopy. better being served much patients Gleeson et al. have given me food for thought but certainly no data that I would regard as a proscription. Nicholas Kadar, MD JerseyShoreMedicalCenter,1945 Oncology, Directorof Gynecologic Route33, Neptune,NJ 07753 REFERENCE Maiman M, Seltzer V, Boyce J. Laparoscopic excision of be found to malignant. subsequently ovarian neoplasms Obstet Gynecol 1991; 77: 563-5.
Reply To the Editors: We agree with Kadar that all published for incidence fails this date to an to provide work We laparoscopy. are of complication unfortunate OBSTETRICS JOURNAL AMERICAN AND the OF that pleased GYNECOLOGY published our case reports at a time when "protocols for laparoscopy in the management of ovarian carcinoma" are being considered, because abdomifor is distressing complication nal wall metastasis a very the patient and the possibility of its occurrence even low tumor malignant potential must of with epithelial be appreciated. We hope that the adverse outcomes the Maiman by temper will et a]. and ourselves reported use of the instrument until the results of such trials are in As stated our Comment, our cases are available. judgment. The indictments of poor surgical principally majority of gynecologic oncologists would not perform laparoscopy in the presence of obvious ascites and laparoscopic staga tumors consider and would ovarian ing procedure inadequate. Cancers with minimal inbulky have upper volvement of the ovaries can often abdominal disease. At this time no procedure considered essential in the staging of ovarian carcinoma should be omitted at the primary surgery.
Kadar states that he has never seen a cutaneous implant in a laparotomy scar; this is our experience too. Our suggested mechanisms for tumor growth at lapinPerhaps the aroscopy trocar sites are speculative. from tense or intraabdominal ascites pressure creased by forcing maligpneumoperitoneurn also contributes be difficult It to would the track. along nant ascites irrigate such a small incision effectively, especially beinserted obliquely laparoscopic trocars often are cause laparoirrigation If the of through the abdominal wall.
Letters
May 1994 Am j Obstet Gynecol
umbilical/cerebral pulsatility index ratio can provide a useful indication of when compensatory mechanisms begin to operate. Days or weeks can be gained with a reasonable safety for the fetal brain, until fetal heart rate changes supervene, indicating that compensation has been overwhelmed. But if placental insufficiency begins very early in gestation, neonatal outcome is directly linked with gestational age. Claudine Amiel-Tison, MD, MichHe Uzan, MD, Girard Briart, AID, and Emile Papiernik, AID Po7t-Royal-Baudelocque, 123 Bld. de Port-Royal, 75014 Pans, France REFERENCES I. Hack M, Horbar JD, Malloy MH, Tyson JE, Wright E, Wright L. Very low birth weight outcomes of the National Institute of Child Health and Human Development Neonatal Network. Pediatrics 1991; 87: 587-97. 2. Phelps DL, Brown DR, Tung B, et al. 28-Day survival rates of 6676 neonates with birth weights of 1250 grams or less. Pediatrics 1991; 87: 7-17. 3. Cynober E, Uzan M, Uzan S, Breart G, Sureau C. L'index diastolique carotidien: facteur pr6dictif de la souffrance foetale aigue. j Gynecol Obstet Biol Reprod 1990; 19:53-9.
4. Snidjers Numeric
RJM,
Mulder EJH. LSM, Visser GHA, in intrauterine analysis of heart rate variation fetuses: a longitudinal growth-retarded study. A.%ij OBSFEr GYNECOL 1992; 166: 22-7. Ribbert
5. Divon MY, Hsu HW. Maternal and fetal blood flow velocity waveforms in intrauterine growth retardation. Clin Obstet Gynecol 1992; 35: 156-71.
Reply To the Editors: We thank Amiel-Tison et al. for their comments on our article. Our study had an observational design. Patient care took place according to departmental standards by the attending obstetrician blinded for the Doppler data. Clinical management and decisions to intervene during pregnancy were based on fetal heart rate tracings and neonatal risk as assessedby the attending neonatologist. The relationship between Doppler data and fetal heart rate tracings were not an object of our study. Arduini et al. ' and Samo et al.' have examined this important subject. We did not study the applicability of the umbilical/cerebral pulsatility index ratio as a new diagnostic test for fetal distress. Becausethe incidence of important intracranial abnormality is especiallyhigh between 25 and 33 weeksof gestation,' patient entry was limited to this interval. All patients in this cohort were entered consecutively. In II casesit wasdecided to refrain from an obstetric
intervention, and these fetuses died in utero. Another 22 infants died neonatally before reaching term age.The is follow-up (97%) calculated of neurologic percentage on the surviving infants reaching term age. It should not be based,as suggestedby Amiel-Tison et al., on the total number of fetusesincluded in the study (73%). In the analysiswe divided our cohort by the presence or absence of an antenatally observed physiologic adinto by "retrospective" small subdivision a aptation, not basis for the of on age gestational and appropriate "flawed" birth weight statistics. Gestational age is not equally distributed among the different umbilical/cerebral pulsatility index ratio for design However, this the corrected study groups. difference by performing the neurologic examinations with a standardized technique. It seemsparadoxical that thosevery small infants who nearly all needed a cesarean section to- survive and who, as we all know, represent a do to group prove sowell neonavery-high-risk clinically tally, as we suggest becauseof and not in spite of the intrauterine adaptation to minimal conditions. The relative risk and confidence interval of a raised umbilicaVcerebral pulsatility index ratio for an abnormal neurologic outcome is given in Table L The power of the study is calculated (a = 0.05 and P=0.80) considering a 25% reduction in the incidence of neurologic abnormalities. The number of patients required to find a statistical significant difference is also given. Contrary to our initial expectations, the study showed very clearly that neurologic outcome for the survivors is not inferior in the "brain-spared" group compared with the non-"brain-spared" group. There is a tendency for infants with a raised umbilical/cerebral pulsatility index ratio to have a better outcome during the first year: less severe intracranial hemorrhages, less severe periventricular echo densities (Table 111,original article), and fewer neurologic disturbances (Prechtl,' Touwen'; Table IV, original article). The relative risks are all < 1; at 12 months the confidence interval does not even include 1. In regression models R' gives the proportional reduction in variation. It describes the strength of the associationbetween the prediction and the response.A measure with generalized R' in the case of models for categoric responsesis given by Nagelkerke.' SzccoScherjon,PhD,"- 'Joke Kok, PhD,' Hans Zondervan,PhD,' and Hans Oosting,Phly ' and ClinicalEpidemiology Departments Neonatology, of Obstetnes, ' Academic MedicalCentre,Unwersityof Amsterand Biostatistics, dam,1105AZ Amsterdam, TheNetherlands a
Table 1. Relative risk and confidence interval of raised umbilical/cerebral pulsatility index ratio for abnormal neurologic outcome Neurologic outcome Precht14 'I'ouwen-" (6 mo) 'rouwen' (12 mo)
I
Relative risk 0.85 0.75 0.70
I
95% Confidence interval 0.60-1.20 0.50-1.10 0.53-0.93
*Number of patients required to find a statistically significant difference.
I Power 0.38 0.48 0.82
No. 308 232 103
Volume 170, Number 5, Part I Am j Obstet Gynecol
REFERENCES 1. Arduini D, Rizzo G, Romanini C. Changes of pulsatility index from fetal vessels preceeding the onset of late decel79: 1992; fetus. Gynecol Obstet in growth-retarded erations 605-10. Dopp2. Sarno AP, Brar HS, Phelan j P, Platt LD. Intrapartum fluid volume, and fetal heart rate ler velocimetry, amniotic OBSTET distress. j fetal Am subsequent of as predictors GVNECOL 1989; 161: 1508-14.
3. Szymonowicz W, Schafler K, Cussen Lj, Yu VYH. Ultrain hemorrhage sound and necropsy study of periventricular preterm infants. Arch Dis Child 1984; 59: 637-42. 4. Prechtl MFR. The neurological examination of the full term newborn infant. In: Clinics in developmental medicine. London: Heinemann, 1977. 5. Touwen BCL. Examination of the child with minor neurological dysfunction. In: Clinics in developmental medicine. London: Heinemann, 1979. 6. Nagelkerke NID. A note on a general definition of the ýetermination. Biometrika 1991; 78: 691-2. coefficient of
Numerators without denominators: Again? To the Editors: I read the thought-provo king case report by Gleeson et al. (Gleeson NC, Nicosia SV, Mark JE, Hoffman MS, Cavanagh D. Abdominal wall metastases from ovarian cancer after laparoscopy. Am j OBSTET GYNECOL1993; 169: 522-3) with interest but also with concern. The implantation of tumor in trocar tracts used during laparoscopy is an undeniable possibility that must be considered when protocols for laparoscopy in the management of ovarian carcinoma or ovarian cysts are devised. However, without knowing the frequency of this event it is not possible to determine whether this disadvantage offsets the advantages of laparoscopy over laparotomy or is itself offset by them.
The publication by Maiman et al. ' refer-red to by the authors set a dangerous precedent for the quality of scientific reporting in this field. It was a case series based on a survey with a poor response rate that established no denominators for the outcome of interest. Other than documenting that patients with ovarian cancer are sometimes mismanaged, a fact we might have surmised without the survey,it provided no information that helped define the indications for laparoscopy in this diseaseor to design protocols that might determine its role. All it did was to invite the conclusion that, becausesomeone had misused the laparoscope in some cases of ovarian cancer, any use of the laparoscope in this disease could be ipso facto regarded as misuse, a line of reasoning not at all conducive to clear thought in an area already rife with high emotion and patent bias. Gleeson et al. also provide no denominators for their heterogeneous cases,and their proscription of the use of laparoscopy should have been tempered by this fact. Tbe thoughts they provoked about tumor implants are important and relevant. It was therefore disappointing to hear the authors attribute the fact that this almost never occurs in a laparotomy scar after surgery in the presenceof ascitesto irrigation of the wound, a proposition that has not one iota of evidence to support it that I am awareof. I certainly do not irrigate the wound and have never seen a cutaneous implant in a lap-
Letters
1479
if Moreover, the authors surgery. arotomy scar after believe that and that there are restraints on tumor growth within the peritoneal cavity, why not suggest irrigation of the trocar site and closure of the peritoneum below it, or even removal of the tumor through, say, the vagina, rather than condemn a very promising technique out of hand? If we can prevent implants in laparotomy scars, why can't we do so at a trocar site? The authors state that "the contraindications to laplike " I to should established. are well aroscopic surgery hear what these are and why? Presumably ascites is one of them. However, up to 10% of women with ascites have no bulk disease - the so-called ovarian cancer with find laparotomy I an personally normal-sized ovaries. unedifying ritual in this situation and could envisage by laparoscopy. better being served much patients Gleeson et al. have given me food for thought but certainly no data that I would regard as a proscription. Nicholas Kadar, MD JerseyShoreMedicalCenter,1945 Oncology, Directorof Gynecologic Route33, Neptune,NJ 07753 REFERENCE Maiman M, Seltzer V, Boyce J. Laparoscopic excision of be found to malignant. subsequently ovarian neoplasms Obstet Gynecol 1991; 77: 563-5.
Reply To the Editors: We agree with Kadar that all published for incidence fails this date to an to provide work We laparoscopy. are of complication unfortunate OBSTETRICS JOURNAL AMERICAN AND the OF that pleased GYNECOLOGY published our case reports at a time when "protocols for laparoscopy in the management of ovarian carcinoma" are being considered, because abdomifor is distressing complication nal wall metastasis a very the patient and the possibility of its occurrence even low tumor malignant potential must of with epithelial be appreciated. We hope that the adverse outcomes the Maiman by temper will et a]. and ourselves reported use of the instrument until the results of such trials are in As stated our Comment, our cases are available. judgment. The indictments of poor surgical principally majority of gynecologic oncologists would not perform laparoscopy in the presence of obvious ascites and laparoscopic staga tumors consider and would ovarian ing procedure inadequate. Cancers with minimal inbulky have upper volvement of the ovaries can often abdominal disease. At this time no procedure considered essential in the staging of ovarian carcinoma should be omitted at the primary surgery.
Kadar states that he has never seen a cutaneous implant in a laparotomy scar; this is our experience too. Our suggested mechanisms for tumor growth at lapinPerhaps the aroscopy trocar sites are speculative. from tense or intraabdominal ascites pressure creased by forcing maligpneumoperitoneurn also contributes be difficult It to would the track. along nant ascites irrigate such a small incision effectively, especially beinserted obliquely laparoscopic trocars often are cause laparoirrigation If the of through the abdominal wall.