With the current level of expertise in pediatrie surgery, anesthesia, and neonatal intensive care, the majority of surgically significant congenital anomalies are readily correctable in the newborn period with very low morbidity and mortality, providing prompt and accurate diagnosis is made. Some conditions present in the immediate neonatal period as life-threatening emergencies (eg, omphalocele, gastroschisis, diaphragmatic hernia). Others may evade diagnosis at birth because of lack of clinical symptoms. These latter lesions may eventually become life threatening as silent destruction of various organ systems progresses (eg, obstructive uropathy). The diagnosis of most internal anomalies comes largely from the recognition of certain clinical features frequently confirmed by diagnostic imaging studies. Delays and/ or errors in each of these two steps, added to the inherent risks of transporting a sick neonate to a center for appropriate surgical care, may contribute significantly to neonatal surgical morbidity and mortality.
Recent technological advances in ultrasonography have increased the applications and diagnostic abilities in the obstetrical field. The increasing use of maternal sonography as a means of non-invasively following pregnancy has provided a large data base for the study of normal and abnormal fetal anatomy from 12 weeks gestation onward.1'2 Among the increasing number of indications for maternal sonography (Table 1) the most common are placental localization for genetic amniocentesis, evaluation of intrauterine growth retardation, and evaluation of inappropriate size for dates. This experience has led to the sonographic description of increasing numbers of both correctable and noncorrectable fetal abnormalities in utero (Table 2).'"? The advance knowledge of many of these conditions early in pregnancy can benefit perinatal management. The fetus has achieved recognition as a patient.6 The complex moral and philosophical issue of termination of pregnancy related to antenatal detection of abnormalities will demand increasing attention from members of many subspecialties. The determination that a given set of anatomic defects discovered Jn utero is incompatible with extrauterine life will now need input not only from the geneticist and the obstetrician, but also from the surgical specialist and the sonographer. The accurate diagnosis of many of these anomalies in utero requires a high degree of sonographic expertise.
Prenatal diagnosis of correctable fetal abnormalities can potentially benefit both obstetrical and surgical care. The risks and delays involved in transporting a sick neonate can be completely eliminated if the pregnant mother can be delivered at an institution where appropriate facilities for immediate surgical care of the newborn infant are available. Further, delays in postnatal diagnosis can be completely eliminated. When a lesion likely to be associated with dystocia at the time of vaginal delivery is discovered, elective caesarean section at a center where the child can be cared for immediately may improve chances for infant survival.1'"
It is clear that most surgically correctable congenital anomalies are best handled after normal term vaginal delivery with prompt repair of the defect. There are two conditions, however, in which prenatal in utero intervention in the form of repair or palliation may be justified. The combination of severe obstructive uropathy. oligohyd ramni os, and pulmonary hypoplasia is usually fatal. In utero palliation of such obstructive uropathy by the percutaneous placement of a catheter through the maternal abdominal wall into the fetal bladder (such that it drains into the amniotic space) has the potential of relieving the urinary obstruction and providing amniotic fluid to prevent pulmonary hypoplasia.7'8 Definitive correction of the obstruction can then be performed after birth. Congenital diaphragmatic hernia most commonly is associated with severe pulmonary hypoplasia resulting in death shortly after birth in spite of satisfactory repair of the hernia defect. Pulmonary hypoplasia is most likely related to the compressive effect of the displaced abdominal viscera during the time of lung development. An experimental model for prenatal repair of the fetal defect has shown that pulmonary hypoplasia is preventable in animals, if the timing of repair is appropriate.9^ ' ' Both of these conditions are areas for future investigation.
INDICATIONS FOR MATERNAL ULTRASONOGRAPHIC EXAMINATION
SONOGRAPHIC SCANNING TECHNIQUES
Maternal sonography is best performed with mild distention of the maternal urinary bladder, which provides a natural acoustic window for optimal visualization of the lower uterine segment. Real-time scanning is utilized initially to quickly survey the entire uterine contents to document fetal viability, position of the fetus and placenta in relation to the axis of the uterus, measure the biparietal diameter of the fetus, and to note the relative amount of amniotic fluid. More detailed examination is performed with static B- m ode scans with orientation toward the longitudinal and transverse axes of the fetus itself. There are several normal sonolucent masses within the fetus which must be identified. These include the fetal heart, the stomach, loops of bowel, and the urinary bladder. By carefully noting the position of these normal masses, the position and origin of abnormal sonolucent or sonodense masses may be determined.2
PRENATAL FETAL DIAGNOSIS BY ULTRASONOGRAPHIC EXAMINATION
SPECIFIC PRENATAL SONOGRAPHIC DIAGNOSES
The list of conditions that can be diagnosed antenatally by maternal sonography is rapidly expanding (Table 2). Examples of the more clearcut ones will demonstrate the value of these techniques. The well-established diagnostic aspects of fetal neural tube defects, other central nervous system anomalies, and cardiac anomalies are excluded from this discussion.
Figure 1. Transverse scan of a 16-week gestation for gestational age demonstrates a large echo-free mass (arrows) projecting from the lateral region of the fetal head (FH). Further scans demonstrated a lateral neck origin. Spontaneous abortion confirmed the presence of a cervical cystic hygroma. (Reprinted with permission from Canty, Leopold & Wolf.')
Figure 2. Longitudinal scan performed on a toxemic female at 36 weeks gestation for increased uterine size shows hydramnios (A)1 fetal ascites (F), and a cystic mass in the left chest (M) (FH = fetal head). Surgery at birth confirmed cystic adenomatoid malformation. Left lower lobectomy was performed. (Reprinted with permission from Canty, Leopold & Wolf.')
Figure 3a. Transverse scan of normal 27-week fetal abdomen shows the tubular lucent umbilical vein (arrow), the fluid-filled stomach (S), and the spine (Sp) casting an acoustic shadow. Figure 3b. Transverse scan of normal 22week fetal abdomen demonstrating kidneys (arrows) adjacent to the spine (Sp). Figure 3c. Longitudinal scan of normal 22-week fetal abdomen shows fluid-filled bladder (B), stomach (small arrow), and heart (curved arrow). (Reprinted with permission from Canty, Leopold & Wolf.2)
Cystic lesions in the region of the fetal neck can be readily visualized sonographically in utero. The accurate diagnosis of these masses depends upon orientation of the mass in relation to the fetal axis. Cervical meningocele or myelomeningocele appears as a cystic mass protruding posteriorly from the fetal neck. Further detailed examination of the fetal brain may reveal associated hydrocephalus.4 A mass protruding laterally from the fetal neck is typical of cervical cystic hygroma (Figure I).2 Enlargement of these cystic lesions can be followed during the course of pregnancy and may dictate changes in obstetric management. When the size of the lesion is such that dystocia may occur at the time of delivery the possible necessity for caesarean section can be planned in advance. Although these two lesions are not necessarily life threatening immediately after birth, prenatal knowledge may allow for better planning for both obstetric and surgical management.
The antenatal diagnosis of diaphragmatic hernia can be made as early as 13 weeks gestation when the fetus begins to swallow significant amounts of amniotic fluid. Normally the only sonolucent structure within the fetal thorax is the heart, which can be easily identified by its movement on real-time sonographic examination. A second fluid-filled mass (stomach) in the thorax is typical of diaphragmatic hernia.5 Other possibilities include other fluid containing pulmonary cystic lesions (eg, cystic adenomatoid malformation, Figure 2).
After the 20th week of gestation many of the abdominal organ systems can be demonstrated sonographically. The fetal aorta, inferior vena cava, umbilical vein, and the fetal spine are visualized readily and used as landmarks in relation to other structures within the fetal abdomen. The normal fluid-filled stomach and loops of bowel can be seen as well as the echodense liver and spleen. The kidneys are identifiable adjacent to the fetal spine. The fluid-filled bladder is identified in the caudal portion of the abdomen (Figures 3a, b, c). Abnormalities of size or position of these fluid-filled structures form the basis for diagnosis of gastrointestinal and urinary tract abnormalities.2
Obstructing lesions of the GI tract are most commonly recognized in utero because of the dilated fluid-filled stomach and/ or loops of bowel and associated hydramnios. Duodenal atresia presents with hydramnios and a sonographic "double-bubble" lucency quite similar to the double-bubble seen in conventional radiography postnatally (Figures 4a, b). Although the double-bubble does not differentiate between the various types of duodenal obstruction, duodenal atresia is the most common. Prenatal diagnosis is of importance in that duodenal atresia may not be clinically obvious at birth and the infant may be fed. Persistent vomiting with either aspiration or electrolyte imbalance may further delay appropriate surgical correction. The prenatal knowledge allows for mobilization of the appropriate teams from pediatrie surgery, anesthesia, and neonatal intensive care at the onset of labor. Appropriate therapy can then be initiated soon after birth before complications ensue.
Upper small bowel atresia has a similar sonographic appearance with several dilated fluid-filled masses and hydramnios (Figure 5). Prenatal diagnosis can eliminate delays in postnatal diagnosis and treatment. Other abnormalities of the GI tract have also been identified in utero such as duplication cysts, etc.; however, their precise diagnosis is often more elusive.5 The prenatal knowledge of an abnormal cystic mass alerts the physician to further evaluate the child postnatally.
Defects in the abdominal wall (eg, gastroschisis, omphalocele) are detected sonographically when portions of the GI tract or other abdominal viscera are seen to lie outside the abdominal wall. Gastroschisis most commonly appears as multiple fluid-filled loops of bowel with no apparent confining sac lying anterior to the fetal abdominal wall. An unruptured omphalocele appears as a smooth-walled sac anterior to the abdominal wall. If it should contain liver, this echodense structure can be traced from the abdominal cavity to the contents of the sac (Figures 6a, b). Both of these conditions require immediate surgical correction after birth at a center equipped with sophisticated monitoring techniques and vemilatory support. Antenatal diagnosis allows for delivery of the infant at a center where immediate surgical and neonatal intensive care are available.1
Many anatomic lesions of the urinary tract cause obstruction. This group, often lacking in clinical symptoms, may elude diagnosis for months or years postnatally. The resulting increased size of normal fluidfilled spaces allows for sonographic diagnosis in utero. Appropriate localization of the "abnormal" fluid-filled mass in relation to the fetal spine and/ or pelvis helps to pinpoint the level of obstruction though this may not always be possible. Ureteropelvic junction obstruction (UPJ) appears as a solitary fluid-filled mass in the region of the involved kidney (Figure 7). The multicystic dysgenetic kidney has a typical in utero sonographîc appearance of a collection of cystic structures in place of the kidney at the same transverse level of the normal contralateral kidney (Figure 8). Uretero-vesical obstruction and occasionally reflux, leads to dilatation of the ureters. Severe urethral obstruction (eg, posterior urethral valves, urethral atresìa) can result in massive dilatation of the entire urinary tract, including the bladder, and oligohydramnios (Figure 9). Continued urinary tract dilatation, renal parenchyma! damage, and oligohydramnios associated with pulmonary hypoplasia, may result in fetal demise or neonatal death.1'''8 In this group fetal intervention may be justified and has been successfully attempted.718 The appropriate time for treatment to prevent or reverse fetal pulmonary hypoplasia is not precisely known.7
Figure 4«. Transverse scan of a 35-week gestation evaluated for clinical hydramnios shows the sonographic "double-bubble" sign of two fluid-filled masses (M) typical of duodenal atresia. At onset of labor the mother was transferred. The infant was evaluated after normal vaginal delivery at 37-weeks gestation (Sp = spine). Figure 4b. X-ray taken one hour after birth of child in Figure 4a showing radiographie "double-bubble" sign of duodenal atresia. At five hours of age the infant underwent repair of duodenal atresia and was discharged ten days later. (Reprinted with permission from Canty, Leopold & Wolf.1)
Figur· 5. Longitudinal scan of a 25-year-old prima gravida taken for increased uterine size at 33 weeks gestation demonstrates hydramnios (H) and a fluid-filled sonoJuceni structure (arrow) in the abdomen. More detailed scanning revealed several large dilated loops of bowel. Spontaneous vaginal delivery of a healthy male infant occurred at 34 weeks; surgery at four hours of age confirmed jejunal atresia. The infant was discharged at seven days of age. (Reprinted with permission from Canty, Leopold & Wolf.')
Figure 6a. Transverse scan of 1 7-year-old girl for gestational age reveals a 34-week gestation fetus with multiple fluid-filled loops of bowel anterior to the abdominal wall (arrows), typical of gastroschisis, and hydramnios (H). Immediate primary repair of gastroschisis was performed after term delivery (F = fetal abdomen). Figura 6b. Transverse scan of a 25-year-old female for gestational age aemonsiraies an extra-abdominal solid mass (M) anterior to the abdominal wall (F) typical of an omphalocele containing liver. Following transfer at onset of labor at term, primary repair was performed at three hours of age (E = extremity). (Reprinted with permission from Canty, Leopold & Wolf.1)
Figure 7. Transverse scan in a 28-year-old female for gestational age reveals a 34-week gestation fetus with a normal right kidney (RK) and a single sonolucent mass in the region of the left kidney (M) (Sp = spine). UPJ obstruction was confirmed shortly after birth and repaired at two months of age. (Reprinted with permission from Canty, Leopold & Wolf.1)
Figure 8. Transverse scan in a 29-year-old female for gestational age reveals multiple sonolucent masses (arrows) adjacent to the spine (Sp) (St = stomach). At term delivery sonography confirmed the presence of a multicystic mass in the right renal fossa. A multicystic dysgenetic kidney was removed. (Reprinted with permission from Canty, Leopold & Wolf.1)
Fetal ascites is recognized sonographically by displacement of the fluid-filled loops of bowel centrally, surrounded by the echolucent fluid. Although ascites is a nonspecific finding, it can raise suspicion for RH incompatibility, in utero congestive heart failure, or urinary tract obstruction.1'2 Ovarian cysts and choledochal cysts have also been visualized antenatally.12'13
Conjoined twins have been diagnosed antenatally by sonography (Figure 1O).12'13 This antenatal diagnosis is important to perinatal management. In most cases elective caesarean section would be the delivery method of choice to avoid dystocia and allow for planned, careful handling of the infants. Postnatal management of conjoined twins is complex and depends on the nature and location of the shared organ systems. The preparation for possible successful surgical separation requires a great deal of planning and anatomic evaluation. Sonography is an invaluable aid in both the antenatal diagnosis and postnatal evaluation.
Figure 8. Transverse scan in an 18-week gestation for genetic amniocentesis shows severe oligohydramnios and a large distended urinary bladder (B) occupying the majority of the fetal abdomen. Abortion was elected. Autopsy of the fetus demonstrated posterior urethra! valves. (Reprinted with permission from Canty, Leopold &Wolf.')
Maternal ultrasound is commonly used for the evaluation and followup of pregnancy. Increasing experience in this field has led to the accurate sonographic description of both normal and abnormal fetal anatomy and to the antenatal diagnosis of increasing numbers of surgically correctable conditions. Antenatal diagnosis has the potential of greatly benefiting obstetrical care, the counseling and advising of parents, and perinatal surgical management. The use of intrauterine fetal surgery and, or manipulation may provide increased salvage of fetuses with diaphragmatic hernia and obstructive uropathy in the future. With the known safety and noninvasiveness of maternal sonography it may become a useful screening procedure for all pregnancies.
Figure 10. Transverse scan of a 28-week gestation taken for increased uterine size reveals an unusual configuration of fetal head (FH), (upper photo) abdomen (A) and timbs (lower photo). Hydramnios (H) is also present. At 37 weeks an eight-limbed, two faced conjoined monster was delivered. (Reprinted with permission from Canty, Leopold & Wolf/)
1. Cutty TG. Leopold GR. Wolf DA: Maternal uhrasonography for the antenatal diagnosis of surgically significanmconatal anomalies. Ann Surg 1981; 194:353-365.
2. Caniy TC. Leopold GR. Wolf DA: Vllrasonography of Pediatrie Surgical Disorders. New York. Gruñe ?. Sl rati on, 1982. pp 9-36.
3. Dünne MG. Johnson ML The ultrasonic demonstration of fetal abnormalities in utero. J Reprod Med 1979: 23:195-206.
4. Hobbins JC. Grannum PAT. Berk o wit z RL, et al: Ultrasound in the diagnosis of congenital anomalies. AmJ Obsiei Grnecol I979; 1 34:33 1 -345.
5. Toulikian RJ. Hobbins JC: Maternal ultrasonography in lhe antenatal diagnosis of surgically correctable fetal abnormalities. J Pediair Surg 1 980; 15:373-377.
6. Harrison MR. Golbus MS. Filly RA: Management of the fetus with a correctable congenital defect. JAMA 1981: 246:79.
7. Canty TG. Cousins LM. Leopold GR. et al: Préñala! in utero décompression of obstructive uropaihy. unpublished data.
8. Golbus MS. Harrison MR. Filly RA. et al: In utero treatment of urinary tract obstruction. Am J Obstet Gynecol 1982; 142:383-388.
9. Harrison MR. Jester J A. Ross NA: Correction of congenital diaphragmatic hernia in utero. I. The model: lntrathoracic balloon produces fatal pulmonary hypoplasia. Surgery 1980; 88:174-182.
10. Harrison MR. Bressack MA. Churg AM, et al: Correction of congenital diaphragmatic hernia in utero. II. Simulated correction permits fetal lung growth with survival ai birth. Surgen 1980: 88:260-268.
11. Harrison MR. Ross NA. De Lo rumer AA: Correction of congenital diaphragmatic hernia in utero. III. Development of a successful surgical technique using abdominoplastv to avoid compromise of umbilical blood flow. J Pediair Surg 1981: 16:934-942.
12. Dew bun KC. Aluwihare APR. Bin h SJ. et al: Prenatal ultrasound demonstration of a chokdochal cyst. Br J Radial 1980; 53:906-907.
13. Valenti C. Kassner EG. Y er ma k ov V. et al: Antenatal diagnosis of a fetal ovarian cyst. Am J Obstet Cynecol 1975; 123:216-217.
14. Wilson RL. Shaub MS. Cetrulo CJ: The antepanum findings of conjoined twins. Journal of Clinical L'lirasound 1977; 5:35-39.
INDICATIONS FOR MATERNAL ULTRASONOGRAPHIC EXAMINATION
PRENATAL FETAL DIAGNOSIS BY ULTRASONOGRAPHIC EXAMINATION