Ultrasound in the diagnosis of fetal malformation

Ultrasound in the diagnosis of fetal malformations Implications Edgar

for obstetric

0. Horger

Charleston,

South

management

III, M.D., and G. Shashidhar

Pai, M.D.

Carolina

The prenatal diagnosis of congenital malformations through ultrasonography leads to major considerations regarding subsequent pregnancy management. These diagnoses are useful in reaching decisions concerning elective abortion, planning the time and method of delivery, and arranging for appropriate support personnel. Although the possibility of fetal anomaly must be considered in all obstetric ultrasonograms, review of 56 malformations diagnosed prenatally found that 31 were studied because of uterine size incompatible with gestational age. Polyhydramnios was associated with 24 of these cases. Multiple fetal abnormalities were found postnatally in 24 of the 51 cases in which one or more malformations were diagnosed through ultrasonography, emphasizing the need for careful counseling and follow-up examination. (AM. J. OEISTET. GYNECOL. 147:163, 1983.)

Improvements in ultrasound equipment and greater experience in scanning allow the study of many details of fetal anatomy. The subsequent recognition of anatomic abnormalities has led to the diagnosis of congenital malformations which heretofore have eluded prenatal detection. Malformations involving the fetal head, spine, chest, abdomen, heart, kidneys, gastrointestinal tract, and extremities have been discovered through ultrasonography. Publication of case reports documenting the prenatal diagnosis of single malformations has yielded to review articles listing those abnormalities found in large series of ultrasonograms.‘~ ? This report will evaluate the conditions under which ultrasonic scanning is most likely to demonstrate fetal malformations and the usefulness of these diagnoses to both physicians and patients. Clinical

material

From September 18, 1974, through November 17, 1982, ultrasound studies of 12,186 pregnancies were performed at the Medical University Hospital. Uhrasonic scanning of obstetric patients is not performed routinely in this area. Most of these studies were done only after an indication had developed during pregnancy. These patients arose primarily from the preFrom the Section of Maternal-F&l Medicine, Department of Obstetrics and Gynecology, Department of Radiology, and Gweticr-Birth DeJech Center, Department qf Pediatrics, Medical University of South Carolina. Presented at the Forty-fifth Annual Meeting of The South Atlantic Association of‘ Obstetricians and Gynecologists, Hot Springs, Virginia, January 30-February 2, 1983. Reprint requests: Edgar 0. Horger III, M.D., Department of Obstetrics and Gynecology, Medical University qf South Carolina, I71 Ashley .4zle., Charleston, South Carolina 29425.

natal clinics at the Medical Llniversity of South Carolina and obstetric practices in the immediate area, but some were referred to the Ultrasound Unit because of suspicious findings on clinical examination or ultrasonography done elsewhere. Although many of these diagnoses were based on a combination of real-time and static scanning, permanrznt sonographic documentation of each of the malformations was obtained by static scanning. Results Fifty-six congenital malformations were diagnosed in 51 fetuses (Table I). Scanning revealed each of five fetuses to have twoseparateabnormalities: hydrocephalusmeningomyelocele, hydrocephalus-omphalocele, anencephaly-spina bifida, meningomyelocele-omphatocele, and microcephaly-spina bifitia. Indications for the initial ultrasound study also are shown in Table I. Although most of the studies were done because of abnormalities in uterine size, 15 patients were referred simply for “routine” screening or because of uncertainty of estimated date of’ confinement (EDC). Other indications for scanning included suspected fetal death (2), bleeding (I), maternal diabetes (I), advanced maternal age (1). twins (1). and previous neural tube defect (1). Abnormalities in amniotic fluid volume were noted in association with 34 malformations in 3 1 pregnancies (Table I). Polyhydramnios was noted especially in association with fetal anencephaly, large teratomas, and omphaloceles. Oligohydramnios was found commonly in pregnancies in which fecal urine production 01 excretion was restricted. Only eight malformations were discovered prior to 20 weeks’ gestation, and half of the diagnoses were 163

164 Horger and Pai

Table

I. Fetal malformations

September Am. J, Obstet.

diagnosed I

by ultrasonography* I Indication

.MalJormation Yeural

diagnosed

NO.

15, 1983 Gynecol.

Routine

Determine EDC

for ultrasonography Polyhydramnios

LGA

SGA

Miscel1aneou.s

tube:

Anencephaly Spinal defect Encephalocele Cranial: Hydrocephalus Sllcrocephal> Abdominal

8 5 2

1 1

12 3

1 1” 1

3

2” 1

lh 1

3

2h

2 1”

1’ 3ce

6

2

1 1e

2

2d

wall:

Omphalocele Gastroschisis

10 1

1

1

Rellal:

Bilateral renal agenesis Multicystic dysplastic Hydronephrosis Infantile polycvstic Renal tumor

2 2 2 1 1

1

1 2

1

1

1

1

.\liscellaneous:

Cystic hygroma Sacrococcygeal teratoma Cranial teratoma Intestinal cyst I-Ma1

3 2 1 2 56

1

1

1

2 1 4

1 12

10

14

7

* I‘he number of malformations exceeds the number of fetuses because of the diagnosis of two separate malformations fetuses. indicated by the letters a. b, c, d, and e. made in the third trimester (Table I). This timing may be related particularly to late clinical recognition of abnormalities of uterine grolvth which led to many of the initial scans. Eleven of the 27 malformations detected before the end of the second trimester were in the 15 pregnancies scanned simply to determine EDC or for routine screening. Spontaneous abortion occurred in three pregnancies and 14 elective abortions resulted from the diagnosis of 16 fttal malformations (Table 1). Twenty-five infants were livehorn, and 12 of these survived. Postmortem examination was performed on 31 of the 39 fetuses ~110 failed to survive. Comment CXnical polyhydramnios prompted ultrasonography in nine of .?I1 pregnancies and was found by ultrasound in these nine cases and I :< additional pregnancies. Since trtal malformations are found in approximately 20% of pregnancies complicated by po1yhydramnios.l. ” this finding mandates a careful search for anomalies. In addition to the nine patients with clinical polyhydramnios, 14 others were scanned because of uterine size large for gestational age (LGA). Six of these could be explained by large feral hydrocephalus. and two were due LO massive distention of the fetal body b) hydronephrosis. Another four of these LGA uteri were

9 in five

caused by unsuspected polyhydramnios. Uterine size small for gestational age (SGA) led to the initial ultrasonogram in six pregnancies. Fetal growth retardation is known to accompany many congenital malformations.-’ The early diagnosis of fetal malformations offers distinct advantages. Previous reports have shown that some anomalies are amenable to correction or palliation in utero. Both serial cephalocenteses” and ventriculoamniotic shunts” have been used to drain cerebrospinal fluid and relieve intraventricular pressure in the hydrocephalic fetus. Urinary- shunts have been placed between obstructed fetal bladders and the amniotic cavity to prevent obstructive renal dysplasia and features of Potter syndrome.’ Fetal chylothorax has been drained successfully.’ However, these approaches to fetal malformations are still experimental and certainly are not yet practical for general use.” Prenatal diagnosis of certain malformations is of great value in parental counseling. Knowledge of some fetal abnormalities aids in reaching a decision regarding elective abortion or in planning for long-term care of a compromised infant. This advance knowledge also may provide for a period of emotional adjustment prior to the reality of delivering an anomalous baby. Diagnosis of a fetal malformation incompatible with survival, such as anencephaly or bilateral renal agene-

Volume Number

Ultrasound

147 2

Amnioticjuid

volume PO&Vdramnios 8’ 1C

Gestational diagnosis

age (wk)

2= 2

2” 1

It? 2e

tih

2

dramnios

ZG20

20-28

28-34

2d

Perinatul 34-40

5c 2c

1 286

2 le 1

4

4ah

4 3’

3bd 1

1

2” 1

4

3

2

1

1

2

of fetal

malformations

Spontaneous abortion

Elective abortion

Antepartum stillbirth

tic 3Cd 1

1

2d

Intrapartum stillbirth

Neonatal death

1

1 1

1 1’

6ab 1

3 2’

1 1

4b

2

1

1

1

2 2

1 1

1

1

2 2 1 __ 24

Survival

1= 1 2

1

outcome

2 2

165

at

OligohyNormal

in diagnosis

1

3

2

1

2 1 - 1 22

sis, may warrant

- 10

pregnancy

- 8

%--

termination

-16

1

1

15

__ 1 13

1 1 13

at any stage of

gestation.

Pregnancy mangement often is influenced by these prenatal diagnoses. The timing, route, and location of delivery all may be affected directly. One may plan delivery of a hydrocephalic fetus as soon as maturity is confirmed to allow prompt shunting for relief of the increased intracranial pressure. Cesarean delivery may be planned for the fetus with omphalocele to prevent rupture of the omphalocele sac due to birth trauma. Maternal transport to tertiary centers may ensure the availability of neonatologists, surgeons, and other appropriate personnel.” On the other hand, these prenatal diagnoses may precipitate other problems. While anencephaly and bilateral renal agenesis are uniformly fatal, the ultimate prognoses for the other conditions listed in Table I are uncertain. Ultrasound cannot predict the likelihood of perinatal survival or the chance of functional handicaps. One may question the usefulness to the parents of these early diagnoses. Does this knowledge truly provide for a period of’ psychological adjustment prior to delivery or does it merely engender a long period of emotional distress in anticipation of giving birth to an abnormal infant? Some pregnancies may be aborted electively because of the unknown prognosis for the infant. The current study includes 14 elective abortions. In only one case, that of a fetus with om-

-

3

__ 16

-

6

3

-

phalocele, did postmortem examination judge the anomaly to have been compatible with survival and the abortion possibly urljustified. Three fetuses aborted spontaneously and are included in the 24 fetuses with 26 anomalies incompatible with life (Table II). Assuming ideal management, perinatal survival was judged to have been possible for 27 fetuses with 30 malformations. This judgment assumes early diagnosis and prompt shunting of fetal urine to prevent obstructive renal dysplasia and earl) shunting of fetal hydrocephalus to maximize the potential for brain growth and development. The availability of expert surgical care for immediate closure of open neural tube defects and omphaloceles also is understood. Quality of life is not addressed in this assessment. The assignment of all 12 hydrocephalic fetuses to the potentially salvageable group may be overly optimistic. Some hydrocephalus IS accompanied by developmental abnormality of the brain and an ultimately fatal outcome.‘” The diagnosis of fetal malformation directly affected the management of 28 of the 31 pregnancies. Elective abortion was performed in 14 pregnancies involving 16 diagnosed anomalies. Anticipated labor dystocia due to hydrocephalus (4), sacrococcygeal teratoma (Z), or marked hydronephrosis (1) led to seven cesarean deliveries. Three fetuses with omphalocele were delivered abdominally to avoid fetal injury. Four fetuses

166

Horger and Pai

September 15, 1983 Am. J. Obstet. Gynecol.

Table II. Assessment of perinatal risk based on fetal malformations diagnosed by ultrasonography* Malformnrion

Incompatible .5urvival

dia
with

8’ 3‘” 2

Cmnrnl. H~drocephalus hlirwcephalv

0 0

Ahdomrurtl ~crll: Ornphalocelr

4

6”

I

0

2 I) 1 1 0

0 2 1 0 1

3 0

II 2

1 0

0 1

Rena/: Bilateral renal agenesis Multicysticdysplastic Hytlronephrosis Infantile polvc-Yqtic Renal tumol ‘~lisi-rllcLnPourt (:ystic hyqoma Sacrocorc~geal teratoma <:ranial trratoma Inlestinal c\\t

0 2,” 0

III. Associated in malformed Malformation diagnosed by ultrasound

SalvngrnblP

h’eural luh,: Anencephaly Spinal defect Encephalocele

Gasrrosc-hisis

Table birth

abnormalities fetuses

NO.

after

by ultrasound*

Associated

abnormalities

Anencephaly

8 ‘I.

Meningomyelocele

3 ^I. Hydrocephalus

Spina bifida 2. Meningomyelocele

“2.

Omphalocele, bladder exstrophy, sirenomelia 3. Infantile polycystic kidneys

1‘p 3

“The number of. malformations exceeds the number of tetuses be~ausr ot the diagnosis of two separate malfin-mations in five l’etllsr. indicated by the letters a. b. c. cl, and C.

discovered

diagnosed

Spina

bifida

2

Encephalocele

2

Hydrocephalus

12

Microcephaly

3

Omphalocele

IO

‘1. ‘2.

Microcephaly Anencephaly

I. Castroschisis, thoracoschisis, Interventricular septal defect “1. 2. 3. “4.

Meningomyelocele Meningomyelocele Meningomyelocele Omphalocele, tetralogy of Fallot 5. Tetralogy of Fallot, cleft palate 6. Cleft palate

“1. Spina bifida 2. Encephalocele 1. 69,XXY 2. Trisomy

triploidy 13. tetralog?

Of Fdht

with hvdrocephalus had cranial decompression during labor to allow vaginal deliver), In other cases, the prenatal diagnosis of major abnormalities allowed a /nl.(sez fuir~ approach to labor management and warnings to the nursery staff. about mulitcystic dvsplastic kidneys and a renal mass which proved to be’s mesonephroma. In I5 pregnancies with 17 malformations, the prenatal diagnosis played no role in management. Only one antepartum fetal operation was pert’ortncd. Needle aspriation of 1,090 ml of urine from an enormorlsly distended fetal bladder was done at 30 weeks’ gestation. Following cesarean delivery at 32 week?’ gestation, the infant was found to have megac!istis-I,licl-ocr)lon-ll!poperistalsis syndrome and died of. complications at 19 weeks. Since no objective measurements are available regarding the value of parental counseling, this paramrter is not included in assessing the usefulness of these prenatal diagnoses. It is the authors’ opinion that such counseling was vel-y helpful to the parents in reaching decisions

about

abortion

or care

of their

in

only

five

fetuses,

(;astroschisis

1

1. Imperfordte palate

2

1. Sirenomelia

Hydronephrosis

2

I. Megacystis-microcolonhypoperistalsis syndrome

Infantile polycystic kidneys

1

1. Meckel-Gruber drome

Cystic

3

1. Cleft palate, gut malrotation 2. Horseshoe kidney

Bilateral

renal

hygroma

agenesis

*Dual malformations diagnosed the letters a. b. c. d, and e.

prenatally

anus,

cleft

syn-

are indicated

by

infants.

The finding of a single malformation demands a thorough search for other abnormalities.” The frequency of multiple anomalies found in the nursery and at postmortem examination is shown in Table III. While ultrasonography detected more than a single malf-ormation

z. . Tracheoesophageal fistula, interventricular septal defect 4. Interventricular septal defect h5. Hydrocephalus, tetralogy of Fallot “6. Meningomyelocele, bladder exstrophy. sirenomelia 13 7. Trisomy

postnatal

studies

found 24 fetuses to have two or more abnormalities. This finding emphasizes the limitations of current techniques and the need for careful counseling regarding a guarded prognosis for even the treatable malformations. Omphaloceles commonly are associated with chro-

Volume Number

Ultrasound

147 2

mosomal abnormalities, malformation syndromes, and other anomalies.g* I1 Four of the IO infants with omphalocele had major congenital heart defects, none of which were diagnosed prenatally. Chromosomal studies were done on seven of these infants and found to be abnormal in three: two of these had trisomy 13 and one had 69 XXY triploidy. Trisomy 18 infants also often have omphalocele. ‘. *’ The diagnosis of fetal omphalocele may warrant anmiocentesis for fetal karyotype in the thorough evaluation of possible associated abnormalities. Association has been reported between 45 X0 karyotype and cystic hygroma,‘? but chromosomal studies were not done on any of the cystic hygroma fetuses in this series. The wide range of indications for ultrasound studies which detected fetal malformations in this and other series indicates that the possibility of anomalies must be considered in the performance, interpretation, and reporting of all obstetric ultrasonograms. A careful search for fetal malformations may be even more important when the size of the pregnant uterus is clinically either too large or too small for the gestational age, especially when this discrepancy is due to polyhydramnios or oliogohydramnios. Prenatal diagnosis of fetal malformations is of value in parental counseling where decisions regarding elective abortion or long-term care of a possibly handicapped child are crucial. This knowledge may assist the obstetrician in planning the time and method of delivery and in arranging for the presence at delivery of appropriate personnel to care for the infant. Techniques for treatment of congenital malformations in utero are being developed and in the future may offer more hope for successful perinatal outcome.

REFERENCES

J. C.. Grannum, P. A. T., Berkowitz, R. L., Silverman, R., and Mahoney, M. J.: Ultrasound in the diagnosis of congenital anomalies, AM. J. OBSTET. GYNECOL.

1. Hobbins,

134:331,

1979.

Kurjak, A.. Kirkinen P., Latin, V., et al.: Diagnosis and assessment of fetal malformations and abnormalities by ultrasound, J. Perinat. Med. 8:219, 1980. 3. Queenan. .J. T., and Gadow, E. C.: Amniography for detection of congenital malformations, Obstet. Gynecol. 2.

351:648. 4.

1970.

Van den Berg, B. J., and Yerushalmy. J,: The relationship birth

of the rate of intrauterine weight to mortality,

growth morbidity,

of infants of low and congenital

anomalies, I. Pediatr. 69:531, 1966. Birnholz. J-C., and Firgoletto. F. D.: Antenatal treatment of hydrocephalus. N. Engl. J. Med. 303:1021. 1981. 6. Clewell, W. H.. Johnson, M. L.. Meier, P. R., et al.: A surgical approach to the treatment of fetal hydrocephaIus,-N. Er$. J. Med. 306:1320, 1982. 7. Golbus. M. S.. Harrison. M. R.. Fillv. ,. R. A.. et al.: In utero treatment of urinary tract obstruction, AM. J. OBSTET. 5.

GYNECOL. 8.

142:383,

1982.

Petres, R. E., Redwine, F. O., and Cruikshank, D. P.: Congenital bilateral chylothorax: Antepartum diagnosis and

9. 10. 11. 12.

in diagnosis

of fetal

malformations

167

successful intrauterine surgical management, J. A. M. A. 248:1360, 1982. Harrison, M. R., Golbus, hf. S., and Filly, R. A.: Management of the fetus with a correctable congenital defect, J. A. M. A. 246:774, 1981. Mealey, J., Jr., Gilmor, R. L., and Bubb, M. P.: The prognosis of hydrocephalus overt at birth, J. Neurosurg. 39:348, 1973. Seashore, 1. H.: Congenital abdominal wall defects, Clin. Perinatol.%:61, 1978: Singh, R. P., and Carr, D. H.: The anatomy and histology of X0 human embryos and fetuses, Anat. Rec. 155:369, 1966.

Discussion DR. ANDREW R. CRACKER. Wilmington, North Carolina (Official Guest). It would be difficult to overemphasize the impact that the development of the ultrasound has had on the practice of obstetrics. With it we are able to study the developing fetus and to ascertain its normalcy of growth and development. Dr. Horger has discussed the use of the ultrasound in the diagnosis of fetal malformations. Congenital malformations continue to represent a significant and growing problem in perinatal morbidity and death. Since there does not seem to be any practical way to prevent these problems, the only realistic approach seems to be one of early diagnosis. Although congenital malformations are present in only 2% to 4% of all births. they are associated with 20% to 25% of all perinatal deaths. Therefore it would seem that careful evaluation of the fetus during routine sonography is essential. The diagnosis of certain congenital anomalies guides the obstetrician in formulating an intelligent approach regar-ding the proper conduct of delivery with the adoption of appropriate measures to deal with medical and surgical treatment of the newborn infant. It would also seem extremely important to confirm the presence of a normal pregnancy in patients of high risk for recurrent congenital anomalies, thereby relieving them of a great deal of’ emotional burden and stress. Dr. Horger states that most of the scans reported in his paper were done because of a discrepancy in uterine size and gestational age. ;it least half of the scans performed in the practice wirh which I am associated are done because of an uncerrain EDC, and are therefore done in the late first trimester or early second trimester. Many of our scans are done at the patient’s request. Approximately five hundred women are delivered yearly through our practice. Over the last year we have found two cases of anencephaly, one cardiac malformation which turned out to be tricuspid atresia, a case of fetal ascites which remains undelivered, and five cases of multiple pregnancy. Only one of these women had previously borne an abnormal infant. It is known that 90% of malformed babies are the first affected individuals of the family. The only realistic aproach seems to be routine screening of the entire obstetric population at least once during the pregnancy.

168

Table

Horger

and Pai

I. Occurrence Lyrct

September Am. J. Obstet.

and recurrence

risk for some congenital

or syLdrom~

Neural tube defects Hydrocephalus Microcephaly Gastroschisis Omphalocele Renal

agenesis

Tetralogy of Fallot Trisomy 13 Meckel

anomalies*

Risk cf ocCU,-rPNCV

Risk

211.000 (USA) 2/1.000 ; 1/20.00b-30,000 116,000

of recurrence

3% AR = 25%, X = AR = 25% 3 i

0.1%

50'%t

?

111,000 115.000

syndrome

15, 1983 Gyned.

2.7%3.2%) I% 25%

>

*Selected information compiled from Bergsma.’ = Autosomal recessive; X = X-linked.

+AR

Hobbins and associates’ found a 2.8% incidence of polyhydramnios in 2,548 ultrasound scans performed on high-risk patients. In this segment he found an 18% incidence of various anomalies. Amniotic fluid is in part cleared from the uterine cavity by fetal swallowing. Therefore, conditions which compromise this function may result in polyhydramnios. Such conditions include central nervous system abnormalities such as anencephaly and meningomyelocele or an obstruction of the fetal gastrointestinal tract proximal to the ileum. Anencephaly is usually not too difficult to diagnose as it is generally possible to discern a poorly formed cranium b>; the fifteenth week of gestation. As this anomalv is incompatible with extrauterine survival, we also recommend termination of pregnancy whenever such a diagnosis is made. This diagnosis may be further corroborated by the demonstration of an increased amniotic fluid alpha-fetoprotein. In the condition of hvdrocephalus the lateral ventricles apparently become dilated before there is a change in rhe outer skull outline. Scans done in early pregnancy may therefore reveal a normal BPD but show an extension of the lateral ventricles past a point which is midway between the falx and the outer skull outline. In the third trimester the diagnosis of hydrocephalus is not as difficult to make, since the head circumference can be \ery large. As mentioned by Dr. Horger, this information may be very useful in the patient’s management. With improved shunting techniques, neurosurgeons can now offer a life of reasonable quality to some patients with hydrocephalus. The thickness of the cortical tissue can be measured and the value of 0.5 cm has been suggested as a limit of poor prognosis.’ Vaginal delivery with decompression of the fetal head should be accomplished only in those cases where the prognosis is hopeless. When there is a reasonable chance of survival cesarean section should be performed after pulmonary maturity has been demonstrated. Approximately half of all fetal abdominal masses originate from the urinary tract system and for the most part are not malignant in nature.” In severe urethral obstruction the dilated urinary bladder may fill

the entire fetal abdomen. Under this condition it may be possible to release this pressure by inserting a selfretaining catheter into the bladder so as to prevent further damage to the kidneys. It is possible that technology may progress in the future where three-dimensional imagery may become a reality, thereby enhancing our ability to diagnose other fetal anomalies. Diagnostic ultrasound has already proved to be a powerful means of preventing the birth of babies with significant defects. REFERENCES

1. Hobbins, J. C., Grannum, P. A. T., Berkowitz, R. L., Silverman, R., and Mahoney, M. J.: Ultrasound in the diagnosis of congenital anomalies, AM. J. OBSTET. GYNECOL. 13433 1, 1979. 2. Asim, K., Peritte, K., Visnja, L., and Branko, R.: Diagnosis and assessment of fetal malformations and abnormalities by ultrasound. J. Perinat. Med. 8:219, 1980. 3. Yiu-Chiu, V.. and Chiu. L.: Ultrasonographic evaluation of normal fetal anatomy and congenital malformations, C. T.

5967. 1981. DR. LEWIS H. NELSON, Winston-Salem, North Carolina (By invitation). The term serendipity is credited to Horace Walpole (c. 1754) after his tale, “The Three Princes of Serendip.“’ The term has come to mean an apparent aptitude for making fortunate discoveries accidentally. The prenatal diagnosis of congenital anomalies IS not infrequently serendipitous because of the rarity of various anomalies in the genera1 population and lack of clinical clues prior to the scans (Table I). The authors found 51 fetuses with abnormalities (0.4%) in 12,186 obstetric scans in an 8 year period in a population referred for ultrasound evaluation for obstetric indications or suspicious findings on prior ultrasonography. Fifty-five percent of the scans yielding abnormal results were performed for an incompatibility between uterine size and gestational age. This incompatibility is the most common indication (51%) for sonography in our antenatal testing laboratory. The accidental discovery of congenital anomalies at “routine” ultrasound evaluation emphasizes the need for careful evaluation of the fetus by certified, experi-

Volume

147

Number

2

enced sonographers if the physician is not present during the entire examination. Using inexperienced personnel to do scans in the hospital or office will result in unfortunate errors of omission. The authors state that their report evaluates the conditions under which ultrasonography is most likely to demonstrate fetal malformations and the usefulness of this foreknowledge. Care of neonates with some anomalies could be improved if the diagnosis could be suspected prior to delivery. A program that would have little risk to the mother or fetus and yield a significant improvement in the detection of congenital anomalies should improve obstetric care. It is interesting to speculate on the number of single defects in this series that should have resulted in elevated maternal serum alpha-fetoprotein (MSAFP). Assuming that 88% of the open neural tube defects (NTD) should have been detectable, as based on our experience with antenatal screening of 12,084 patients by MSAFP.J then 25 (43%) of the defects in the authors’ series would have been detected by an antenatal screening program. Use of IMSAFP and ultrasound should improve the accuracy of diagnosis, although this cannot be completely assessed, since the number of defects missed by LIPtrasound during the study period is not given in this report, It is imperative that any parent with a fetus with a congenital anomaly have proper prenatal counseling, as emphasized in this report by the elective termination of’ a fetus with a correctable omphalocele. The counselors should be experienced in genetics, obstetrics, pediatric surgery, and neurosurgery if applicable. All parties concerned will suffer the frustration of frequentl! not being able to predict the severity of the defect nor the quality of survival. Antenatal thorough ultrasound evaluation, chromosome analysis, and procedures such as fetoscopy, surgery, and computed tomography must be considered. Following elective or spontaneous abortion one should obtain total body roentgenography, heart blood and umbilical cord sections for chromosome analysis, and photography of the fetus to assist counseling for future pregnancies. The authors may be optimistic concerning fetal surgery. Our experience with the antenatal shunting of two hydrocephalic infants has been one death 9 hours after the shunt and one child surviving at 3 months of age after being treated for gonorrhea1 ventriculitis acquired antenatally or at delivery. While fetal surgery may be the newest threshold for obstetrics, it is still an experimental area lacking in animal studies and longterm assessment. Can the authors provide the total number of defects in each category of defect from the entire data base and the number of false positives and false negatives? If this were known. the sensitivity and specificity of ultrasound in detecting defects could be calculated. Also, do the authors have any plans for institution of an antenatal screening program using maternal serum alphafetoprotein?

Ultrasound in diagnosis of fetal malformations

Table I. Fetal malformations ultrasonography

not detected

169

by Gestational age at Scan

Malformation

hkl

Phocornelia Gastroschisis Closed thoracic neural tube defect Cystic hygroma Duodenal atresia Cleft palate Open thoracolumbar neural tube defect

15 20 28

32 3” 33

37

REFERENCES

1. Friend, J. H., and Guralnik, D. B.: Webster’s New World Dictionary of the American Language, Cleveland and New York, 19j9, The World Publish&g>ompany, p. 1330. 2. Bergsma. D.: Birth Defects ComDendium. ed. 2, New Yoruk, 19’i9, Alan R. Liss, Inc.. ’ 3. Burton, B. I(., Sowers, S. G., and Nelson, L. H.: Maternal serum alpha-fetoprotein (MSAFP) screening in North Carolina: Experience with over 12,000 pregnancies, AM, J. OBSTET.GYNECOL.

146:439,

1983.

DR. HORGER (Closing). I agree with Dr. Cracker’s statement that routine ultraqonographic screening of the entire obstetric population will lead to the diagnosis of more fetal malformations than will scanning only those with an indication. Unfortunately. the number of obstetric patients seen at the Medical University of South Carolina exceeds the number which our Ultrasound Unit can scan routinely. I also continue to have some reservation regarding routine scanning. Although all studies to date have shown no fetal hazard from ultrasound, we didn’t think there was any risk to DES in 1948 either. Dr. Nelson pointed out that many ultrasonographic diagnoses of congenital anomalies are serendipitous, and I agree completely. His comments regarding MSAFP screening are appropriate. This test is available at the Medical University of South Carolina, but we are not using it for screening and have no plans for doing so. Dr. Nelson asked also about the number of defects which were missed during the study period. Table I shows seven malformations which were overlooked and the gestational age at which chach had a single ultrasonogram. Perhaps four or fi\re of these should have been diagnosed. Detection of cleft palate in the fetus seems very unlikely, even though this diagnosis has been reported.’ Dr. Nelson and associate? previously reported the diagnosis of duodenal atresia by ultrasound and pointed out that the diagnosis will seldom be made prior to 32 weeks’ gestation. In our case there was no polyhydramnios and no double bubble finding in the fetal abdomen. The cystic hygroma in this list is confusing. Although cystic hygroma was diagnosed by the pediatrician, the pathology report called it a very small branchial cleft cyst.

Horger

and Pai

September Am. J. Obstet.

I fully agree that antenatal surgery is experimental. Our only attempt involved the fetus thought to have an obstructed bladder but later proved to have megacystis-microcolon-hypoperistalsis syndrome-an entirely different problem. We have had no experience with antenatal cephalocentesis or ventricular shunts.

15, 1983 Gynecol.

REFERENCES

1. Christ, J. E., and Meininger, M. G.: Ultrasound diagnosis of cleft lip and cleft palate before birth, J. Plast. Reconstr. Surg. 68:854, 1981. 2. Nelson, I,. H., Clark, C. E., Fishburne, J. I., et al.: Value of serial sonography in the in utero detection of duodenal atresia, Obstet. Gynecol. 59:657, 1982.

Placental injection studies in twin gestation Euan G. Robertson, Miami,

M.D., and Rare1 J. Neer, B.A., R.N.

Florida

Vascular communication between placental twin gestation. The presence of anastomotic the fetuses. A study was conducted on 278 communication in fused twin placentas and communication was found almost universally placentas. Twin-twin transfusion syndrome of cross-placental vascular communication. be avoided by determination of chorionicity OBSTET.GYNECOL.~~~:~~O.~~~~.)

vessels can occur when there is a fused placental mass in channels can lead to the twin-twin transfusion syndrome in twin pairs to determine the incidence of vascular the frequency of twin-twin transfusion syndrome. Anastomotic in monochorionic placentation and very rarely with dichorionic occurred uncommonly despite the high frequency of occurrence Misdiagnosis of intrauterine growth retardation in one twin can by inspection of the placentas of twin gestation. (AM. J.

The nature of placentation in twins varies dependent upon the 7ygosity and time and site of implantation. Both monozygous and dizygous twins may have separate placenras or a filsed single pIacenta. Where the placentas arc separate there is no risk of vascular ~ommllnicntiori between the fetuses.’ However. since mono< horionic placentas f’requently have vascular- anastomost’s, this can allow for intermingling of the circrlI;ltic,nh of the twc, fetuses. ‘The extreme situation that occur\ nndel- these circumstances is called the twintwin transfusion syndrome in which one twin is underperiu\ed and resembles a growth-retarded singleton inf:mt and the other r\\in is hypervolemic and polyc.yrhemic-. Previous reports have suggested that although \.ascular communications are almost universal in monochorionic twin pregnancies, the incidence of the rwin-twin transfusion syndrome is low.’ This srudy was conducted as part of a larger study to f’ollo~~ rhe development of twins. The intention was to determine the incidence of anastomotic communicaFrom the Perznatal Metabolic CTnit, Department of‘0bstetic.r and G?nrro/qv, C’rrivmit~ of Minmi School of Medicinr and Jackson .Mcmru~ul Hospital. Supportrd rn pnrt by N research grant (HL 19930) from The Nulitimz~ Hea?& Lung and Blood fnstitute. Pwvnted (13 Officinl Gnrst at the Forty-$@ Annual Meeting of The South Atlantic ,4ssociation of Obstetricians and Gynecologists. Hot Spring!, Virginia, January ?O-February 2, 1983. Reprint requests: Euan G. Robertson, M.D., Uniuersi~ qf Miami School of Medicine. Department of Obstetrics and Gynecolog, 1475 NW 12th Arle.. Miami, Florida 33101. 17n

Table

I. Ethnic

distribution

Black Anglo Hispanic Haitian Oriental

in twin gestation NO.

5%

139 64 36 37 2

50 23 13 13 1

tion in fused twin placentas and to determine fect this had upon the developing fetuses. Material

what ef-

and methods

This study was conducted in the Obstetric Division of Jackson Memorial Hospital, Miami. This is a Tertiary Level Perinatal Unit serving the southern part of Florida. During the 4 year period from 1977 to 1980, there were 23,810 deliveries and 278 twin pairs were delivered during that time, giving an over-all incidence of one in 86 pregnancies. A total number of seven triplet pregnancies were also delivered. Only the twin pregnancies have been considered in this study. The ethnic distribution of the mothers reflected that of the general obstetric population (Table I). The patients’ ages varied from 12 to 43 years and their parities from 0 to 14. The research team was notified of admission of every twin pregnancy and a member of the team was present for delivery of each set of twins. No attempt was made by the research personnel to interfere with the man-