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The sonographic features and implications of fetal pleural effusions
ClinicalRadiology (1988) 39, 398-401
The Sonographic Features and Implications of Fetal Pleural Effusions H. ADAMS,
A. JONES*
a n d C. H A Y W A R D
Department of Radiology, University Hospital of Wales, Heath Park, Cardiff and *Royal Gwent Hospital, Newport Pleural fluid was detected by ultrasound in three fetuses as an anechoic area surrounding the echogenic fetal lung. In one fetus the underlying lung was small, immobile and of abnormal contour; death occurred in the neonatal period and the lung was found to be hypoplastic. In two other fetuses the lungs appeared sonographically normal, being mobile with normal contours. Both survived, one following spontaneous intra-uterine resolution of the effusion and the other after early neonatal intervention prompted by the antenatal diagnosis. Sonography can detect pleural fluid in utero and may permit differentiation between normal underlying lung and pulmonary hypoplasia. We recommend serial scanning to detect early adverse effects of pleural effusion upon the fetus and to plan management changes.
I s o l a t e d p l e u r a l e f f u s i o n is a r a r e c a u s e o f n e o n a t a l r e s p i r a t o r y d i s t r e s s a n d is d u e t o c o n g e n i t a l c h y l o t h o r a x in t h e m a j o r i t y o f c a s e s ( Y a n c y a n d S p o c k , 1967; C h e r n i c k a n d R e e d , 1970). T h e a e t i o l o g y o f c o n g e n i t a l c h y l o t h o r a x is n o t k n o w n . M o r t a l i t y is 15 to 2 5 % ( C h e r n i c k a n d R e e d , 1970; B r o d m a n , 1975) b u t t h e s e f i g u r e s are largely based upon early case reports when diagnosis was often delayed. Early detection should allow prompt n e o n a t a l i n t e r v e n t i o n r e s u l t i n g in a m o r e f a v o u r a b l e o u t c o m e ( V a n A e r d e et al., 1984). I s o l a t e d f e t a l p l e u r a l e f f u s i o n is a m e n a b l e to sonographic diagnosis but there have been only occasion a l c a s e r e p o r t s r e p o r t e d in t h e l i t e r a t u r e . W e p r e s e n t three cases diagnosed during a 2 year period demonstrating the principal ultrasonic features and variable outcome of the disorder.
Case2. A 41-year-old woman, gravida 5, para 3 + 1, was referred for ultrasound examination at 16 weeks gestation prior to amniocentesis. The first trimester of pregnancy had been totally uneventful. Sonography demonstrated a moderate, left fetal pleural effusion (Fig. 4). The underlying lung was normal in contour and the lung surface was seen to ripple gently with fetal movement. No other abnormality was demonstrated and in particular there was no generalised hydrops fetalis. Follow-up sonography at 28 and 34 weeks gestation showed that the effusion was no longer present (Fig. 5). Labour was induced at term because of falling maternal human placental lactogen levels, but proceeded uneventfully. A healthy female infant was delivered with Apgar scores of 8 and 10, at 1 and 5 rain respectively, and a chest radiograph in the neonatal period was normal. A presumptive diagnosis of fetal chylothorax with spontaneous intra-uterine resolution was made. Case 3. A 35-year-old woman with a history of stillbirth was admitted to hospital in the 36th week of her second pregnancy because of weight loss. Fetal ultrasound examination demonstrated bilateral pleural effusions, the left being larger than the right (Fig. 6). The lungs were normal in contour and the lung surfaces undulated gently during fetal movement. No other abnormality was seen and there was no evidence of generalised hydrops fetalis. In view of these findings and the previous obstetric history, transfer was arranged to another centre with neonatal thoracic surgical facilities. At 38 weeks gestation a female infant was delivered by elective caesarean section. Apgar scores were 7 and 10, at 1 and 5 min respectively. A chest radiograph confirmed bilateral pleural effusions which were drained. Analysis of the fluid confirmed the prenatal diagnosis of chylothorax. The infant was thriving at 6 weeks of age.
CASE REPORTS
Case 1. A 19-year-old woman, gravida 2, para 0+ 1, was referred for routine ultrasound examination at 25 weeks gestation. Sonography demonstrated a large, left-sided fetal pleural effusion with slight mediastinal shift to the right. A small, echogenic, left mediastinal mass was interpreted as a hypoplastic lung (Figs 1, 2). No other fetal abnormality was seen. There was no evidence of fetal ascites or cutaneous oedema, amniotic fluid volume was normal and the placenta was not enlarged. Follow-up scans at 29 and 39 weeks gestation showed no significant change. Labour was induced at term but fetal distress and an occipitotransverse presentation necessitated Ventouse extraction. A male infant was delivered having Apgar scores of 4 and 4, at 1 and 5 rain respectively, and assisted ventilation was instituted immediately. A chest radiograph confirmed the large, left pieurai effusion hut also showed a right pneumothorax which was drained (Fig. 3). A left intercostal drain was inserted and a considerable amount of straw-coloured fluid aspirated, analysis of which supported a diagnosis of congenital chylothorax, Despite intensive support the infant died within 24 h of birth. At post-mortem a severely hypoplastic left lung was confirmed but there was no other structural abnormality. Correspondence to: Dr H. Adams, Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF4 4XN.
Fig. 1 - Case 1. Transverse scan of the fetal thorax at 25 weeks gestation. The effusion (E) displaces the heart (H) to the right. The hypoplastic lung (arrows) lies against the mediastinum (P, placenta).
FETAL PLEURAL EFFUSIONS
399
Fig. 4 - Case 2. Transverse scan of the fetal thorax at 16 weeks gestation demonstrating a moderate pleural effusion (E, effusion; H, heart; P, placenta).
Fig. 2 - Case 1. A longitudinal scan of the fetal thorax demonstrates a hypoplastic left lung (small arrows) surrounded by the anechoic effusion (E, effusion; P, placenta; curved arrows, fetal spine).
Fig: 3 - Case 1. Chest radiograph soon after birth confirming a left pleural effusion (arrows). A n intercostal drain has been inserted for a right pneumothorax.
]:ig. 5 - Case 2. Follow-up scan at 28 weeks gestation, The effusion is no longer present (S, fetal spine; L, lung).
DISCUSSION First described by Pisek (1917), the largest review of Spontaneous neonatal chylothorax followed nearly 60 years later and included 34 cases (Brodman, 1975). In this series male infants were affected more than twice as often as females and right-sided effusions were more common than left although a small proportion were bilateral. The chest radiograph in the neonatal period
demonstrates an opaque hemithorax, often with contralateral mediastinal shift. The diagnosis of chylothorax is established by examination of the pleural fluid. Prior to commencement of feeding, the effusion is clear and straw-coloured and microscopy reveals a high proportion of lymphocytes (70 to 100%), a content resembling that of chyle. Later, following feeding, the fluid becomes turbid and adopts its characteristic lipid profile (Chernick and Reed, 1970; Van Aerde et al., 1984).
400
CLINICAL RADIOLOGY Fetal pleural effusion is readily diagnosed by ultrasound. The first reports of intra-uterine detection were by Carroll (1977) and D e f o o r t and Thiery (1978), who described fetuses with large pleural effusions and also generalised hydrops fetalis. The first description of isolated fetal pleural effusion a p p e a r e d shortly afterwards (Thomas and A n d e r s o n , 1979) and there have been occasional reports of similar cases since, s u m m a r i s e d in Table 1. The majority of cases (67%) have b e e n diagnosed during the third trimester of pregnancy. Effusions have occurred m o r e frequently in male fetuses (60%) and have been bilateral in 47% of cases described. Polyhydramnios is a c o m m o n association (53%). Five neonatal deaths have b e e n recorded following antenatal diagnosis, in three infants due to p u l m o n a r y hypoplasia and in two due to underlying congenital pulmonary lymphangiectasia. A further two infants had trisomy 21 with associated endocardial cushion defect. Congenital chylothorax is the most c o m m o n cause of isolated neonatal effusion and is likely to account for the majority of isolated fetal effusions. The most important sonographic sign of fetal effusion is an echo-free area lying between lung, chest wall and diaphragm. S o n o g r a p h y m a y also demonstrate secondary changes including p u l m o n a r y hypoplasia, mediastinal shift, hydrops fetalis and polyhydramnios. P u l m o n a r y hypoplasia is a m a j o r adverse prognostic factor; it was the cause of neonatal death in cases reported by T h o m a s and A n d e r s o n (1979) and Bovicelli et al. (1981). In the fatal case in our series, sonography
Fig. 6 - Case 3. Transverse scan of the fetal thorax at 36 weeks gestation. A large left effusion (E) outlines the fetal lung (L). A smaller right effusion was also present.
Table 1 - Fetal pleural effusion as an isolated ultrasonic abnormality: case reports
Author(s)
Gestational age ~(weeks)
Fetal sex
Lateralisation
Polyhydramnios
Nature o f fluid
Outcome~diagnosis
Thomas and Anderson (1979) Bovicelli et al. (1981) Lange and Manning (1981) Petres et al. (1982) Elser et al. (1983)
32
M
Bilateral
+
N/S
Died. Pulmonary hypoplasia
35
F
Bilateral
-
N/S
Died. Pulmonary hypoplasia
39
M
Bilateral
-
Chylous
Survived
36
F
Bilateral
+
Chylous
Intra-uterine thoracentesis. Survived
34
Bilateral
+
Chylous
Bilateral
+
N/S
+
N/S
Diagnostic intra-uterine thoracentesis. Survived Died Congenital pulmonary lymphangiectasia Died Congenital pulmonary lymphangiectasia Serial intra-uterine thoracentesis. Survived
Jouppila et al. (1983)
33
M (1 of twins) F
Kerr-Wilson et al. (1985)
33
M
Left
Benacerraf and Frigoletto (1985) Meizner et al. (1986) Benacerraf et al. (1986) Foote and Vickers (1986)
19
M
Left
38
M
Right
+
Chylous
Survived
16
F
Left
-
Chylous
34
M
Right
+
N/S
28
M
Left
+
N/S
M F F
Left Left Bilateral
Intra-uterine thoracentesis. Survived Down's syndrome, endocardial cushion defect. Outcome not stated Down's syndrome, endocardial cushion defect. Outcome not stated Died. Pulmonary hypoplasia Spontaneous resolution. Survived Survived
Foote and Vickers (1986)
Adams et al. 25 Adams et al. 16 Adams et al. 36 N/S, Not stated or unknown.
Chylous
Chylous N/S Chylous
FETAL PLEURAL EFFUSIONS
demonstrated that the hypoplastic lung was small and rigid with an abnormal rounded contour. However, in our two survivors, normal pulmonary configuration was preserved and the lungs undulated gently within the effusions during fetal movement suggesting pliability. These features may allow differentiation between the fetus with established pulmonary hypoplasia and a poor prognosis, and the fetus with potentially normal pulmonary development and a favourable prognosis. Complete disappearance of the effusion was demonstrated sonographically in our second fetus. This has not been reported before although there has previously been a report of partial resolution of chylothorax in utero (Jouppila et al., 1983). An important differential diagnosis of congenital chylothorax is serous pleural effusion due to hydrops fetalis. In hydrops there are invariably other sonographic features including cutaneous oedema, ascites, pericardial effusion and placental enlargement (Mahony et al., 1984). Diagnosis is more difficult when the mass effect of fetal chylothorax causes either direct cardiac compression or obstruction of venous return leading to secondary hydrops fetalis. Several such cases have been reported (Carroll, 1977; Defoort and Thiery, 1978; Schmidt et al., 1985). Hydrops may also result for the same reasons from other fetal thoracic anomalies including congenital diaphragmatic hernia and cystic adenomatoid malformation of the lung, conditions also characterised by a predominantly transonic fetal hemithorax (Chinn et al., 1983; Comstock, 1986; Fitzgerald and Toi, 1986). With widespread screening it is likely that fetal chylothorax will be diagnosed more frequently. However, several important points of management arise. Because of the recognised association between congenital pleural effusion and Down's syndrome (Yoss and Lipsitz, 1977; Van Aerde et al., 1984; Foote and Vickers, 1986) amniocentesis should be performed to exclude chromosomal abnormality when an effusion is detected during the second trimester of pregnancy. Sonography offers a means of monitoring the variable course of fetal chylothorax. Since pulmonary hypoplasia appears to indicate a poor prognosis, its detection in early pregnancy should lead to parental counselling and consideration of therapeutic termination. For the fetus with apparently normal lungs, serial scanning at intervals of not more than 2 weeks would seem advisable. Intra-uterine thoracentesis under ultrasound guidance is a therapeutic option when the fetus is not yet mature enough to allow early delivery (Petres et al., 1982; Benacerraf and Frigoletto, 1985; Benacerraf et al., 1986) and if performed in the second or early third trimester may prevent the development of hydrops fetalis and pulmonary hypoplasia. Thoracentesis can also be performed in the immediate anrepartum period to improve fetal condition at the time of delivery. Because of the generally favourable prognosis of fetal chylothorax, thoracentesis should be reserved for cases where the effusion is increasing in size on serial scans or where there is sonographic evidence of adverse effect upon fetal well-being. For the pregnancy nearing term, ultrasonic evaluation will enable optimal timing and mode of delivery, and prompt assessment of the neonate by the forewarned paediatrician to ensure the best chance of survival. This is well exemplified by the third case in our series.
401
In conclusion, fetal pleural effusions are readily demonstrated sonographically. In a minority of cases they are due to congenital pulmonary lymphangiectasia, or associated with established pulmonary hypoplasia and have a poor prognosis which is unlikely to be significantly influenced by intra-uterine diagnosis. In the remainder the prognosis is favourable, particularly if early neonatal intervention is instituted. REFERENCES Benacerraf, BR & Frigoletto, FD (1985). Mid-trimester fetal thoracentesis. Journal of Clinical Ultrasound, 13, 202-204. Benacerraf, BR, Frigoletto, FD & Wilson, M (1986). Successful midtrimester thoracentesis with analysis of the lymphocyte population in the pleural effusion. American Journal of Obstetrics and Gynecology, 155, 398-399. Bovicelli, L, Rizzo, N, Orsini, LF & Calderoni, P (1981). Ultrasonic real-time diagnosis of fetal hydrothorax and lung hypoplasia. Journal of Clinical Ultrasound, 9, 253-254. Brodman, RF (1975). Congenital chylothorax: recommendations for treatment. New York State Journal of Medicine, 75, 553--557. Carroll, B (1977). Pulmonary hypoplasia and pleural effusions associated with fetaI death in utero: ultrasonic findings. American Journal of Roentgenology, 129, 749-750. Chernick, V & Reed, MH (1970). Pneumothorax and chylothorax in the neonatal period. Journal of Pediatrics, 76, 624-632. Chinn, DH, Filly, RA, Callen, PW, Nakayama, DK & Harrison, MR (1983). Congenital diaphragmatic hernia diagnosed prenatally by ultrasound. Radiology, 148, 119-123. Comstock, CH (1986). The antenatal diagnosis of diaphragmatic ano7 malies. Journal of Ultrasound in Medicine, 5, 391-396. Defoort, P & Thiery, M (1978). Antenatal diagnosis of congenital chylothorax by gray scale sonography. Journal of Clinical Ultrasound, 6, 4748. Elser, H, Borruto, F, Schneider, A & Schneider, K (1983). Chylothorax in a twin pregnancy of 34 weeks sonographically diagnosed. European Journal of Obstetrics, Gynecology and Reproductive Biology, 16, 205-211. Fitzgerald, EJ & Toi, A (1986). Antenatal ultrasound diagnosis of cystic adenomatoid malformation of the lung. Journal of the Canadian Association of Radiologists, 37, 48--49. Foote, KD & Vickers, DW (1986). Congenital pleural effusion in Down's syndrome. British Journal of Radiology, 59, 609-610. Jouppila, P, Kirkinen, P, Herva, R & Koivisto, M (1983). Prenatal diagnosis of pleural effusions by ultrasound. Journal of Clinical Ultrasound, 11, 516-519. Kerr-Wilson, RHJ, Duncan, A, Hume, R & Bain, AD (1985). Prenatal pleural effusion associated with congenital pulmonary lymphangiectasia. Prenatal Diagnosis, 5, 73-76. Lange, IR & Manning, FA (1981). Antenatal diagnosis of congenital pleural effusions. American Journal of Obstetrics and Gynecology, 140, 839-840. Mahony, BS, Filly, RA, Callen, PW, Chinn, DH & Golbus, MS (1984). Severe non-immune hydrops fetalis; sonographic evaluation. Radiology, 151,757-761. Meizner, I, Carmi, R & Bar-ziv, J (1986). Congenital chylothorax prenatal ultrasonic diagnosis and successful post partum management. Prenatal Diagnosis, 6, 217-221. Petres, RE, Redwine, FO & Cruikshank, DP (1982). Congenital bilateral chylothorax. Journal of the American Medical Association, 248, 1360-1361. Pisek, G (1917). Report of a chylothorax. Archives of Pediatrics, 34, 929-937. Schmidt, W, Harms, E & Wolf, D (1985). Successful prenatal treatment of non-immune hydrops fetalis due to congenital chylothorax. British Journal of Obstetrics and Gynaecology, 92, 685-687. Thomas, DB & Anderson, JC (1979). Antenatal detection of fetal pleural effusions and neonatal management. Medical Journal of Australia, 2, 435-436. Van Aerde, J, Campbell, AN, Smyth, JA, Lloyd, D & Bryan, MH (1984). Spontaneous chylothorax in newborns. American Journal of Diseases of Children, 138, 961-964. Yancy, WS & Spock, A (1967). Spontaneous neonatal pleural effusion. Journal of Pediatric Surgery, 2, 313-319. Yoss, BS & Lipsitz, PJ (1977). Chylothorax in two mongoloid infants. Clinical Genetics, 12, 357-360.
The Sonographic Features and Implications of Fetal Pleural Effusions H. ADAMS,
A. JONES*
a n d C. H A Y W A R D
Department of Radiology, University Hospital of Wales, Heath Park, Cardiff and *Royal Gwent Hospital, Newport Pleural fluid was detected by ultrasound in three fetuses as an anechoic area surrounding the echogenic fetal lung. In one fetus the underlying lung was small, immobile and of abnormal contour; death occurred in the neonatal period and the lung was found to be hypoplastic. In two other fetuses the lungs appeared sonographically normal, being mobile with normal contours. Both survived, one following spontaneous intra-uterine resolution of the effusion and the other after early neonatal intervention prompted by the antenatal diagnosis. Sonography can detect pleural fluid in utero and may permit differentiation between normal underlying lung and pulmonary hypoplasia. We recommend serial scanning to detect early adverse effects of pleural effusion upon the fetus and to plan management changes.
I s o l a t e d p l e u r a l e f f u s i o n is a r a r e c a u s e o f n e o n a t a l r e s p i r a t o r y d i s t r e s s a n d is d u e t o c o n g e n i t a l c h y l o t h o r a x in t h e m a j o r i t y o f c a s e s ( Y a n c y a n d S p o c k , 1967; C h e r n i c k a n d R e e d , 1970). T h e a e t i o l o g y o f c o n g e n i t a l c h y l o t h o r a x is n o t k n o w n . M o r t a l i t y is 15 to 2 5 % ( C h e r n i c k a n d R e e d , 1970; B r o d m a n , 1975) b u t t h e s e f i g u r e s are largely based upon early case reports when diagnosis was often delayed. Early detection should allow prompt n e o n a t a l i n t e r v e n t i o n r e s u l t i n g in a m o r e f a v o u r a b l e o u t c o m e ( V a n A e r d e et al., 1984). I s o l a t e d f e t a l p l e u r a l e f f u s i o n is a m e n a b l e to sonographic diagnosis but there have been only occasion a l c a s e r e p o r t s r e p o r t e d in t h e l i t e r a t u r e . W e p r e s e n t three cases diagnosed during a 2 year period demonstrating the principal ultrasonic features and variable outcome of the disorder.
Case2. A 41-year-old woman, gravida 5, para 3 + 1, was referred for ultrasound examination at 16 weeks gestation prior to amniocentesis. The first trimester of pregnancy had been totally uneventful. Sonography demonstrated a moderate, left fetal pleural effusion (Fig. 4). The underlying lung was normal in contour and the lung surface was seen to ripple gently with fetal movement. No other abnormality was demonstrated and in particular there was no generalised hydrops fetalis. Follow-up sonography at 28 and 34 weeks gestation showed that the effusion was no longer present (Fig. 5). Labour was induced at term because of falling maternal human placental lactogen levels, but proceeded uneventfully. A healthy female infant was delivered with Apgar scores of 8 and 10, at 1 and 5 rain respectively, and a chest radiograph in the neonatal period was normal. A presumptive diagnosis of fetal chylothorax with spontaneous intra-uterine resolution was made. Case 3. A 35-year-old woman with a history of stillbirth was admitted to hospital in the 36th week of her second pregnancy because of weight loss. Fetal ultrasound examination demonstrated bilateral pleural effusions, the left being larger than the right (Fig. 6). The lungs were normal in contour and the lung surfaces undulated gently during fetal movement. No other abnormality was seen and there was no evidence of generalised hydrops fetalis. In view of these findings and the previous obstetric history, transfer was arranged to another centre with neonatal thoracic surgical facilities. At 38 weeks gestation a female infant was delivered by elective caesarean section. Apgar scores were 7 and 10, at 1 and 5 min respectively. A chest radiograph confirmed bilateral pleural effusions which were drained. Analysis of the fluid confirmed the prenatal diagnosis of chylothorax. The infant was thriving at 6 weeks of age.
CASE REPORTS
Case 1. A 19-year-old woman, gravida 2, para 0+ 1, was referred for routine ultrasound examination at 25 weeks gestation. Sonography demonstrated a large, left-sided fetal pleural effusion with slight mediastinal shift to the right. A small, echogenic, left mediastinal mass was interpreted as a hypoplastic lung (Figs 1, 2). No other fetal abnormality was seen. There was no evidence of fetal ascites or cutaneous oedema, amniotic fluid volume was normal and the placenta was not enlarged. Follow-up scans at 29 and 39 weeks gestation showed no significant change. Labour was induced at term but fetal distress and an occipitotransverse presentation necessitated Ventouse extraction. A male infant was delivered having Apgar scores of 4 and 4, at 1 and 5 rain respectively, and assisted ventilation was instituted immediately. A chest radiograph confirmed the large, left pieurai effusion hut also showed a right pneumothorax which was drained (Fig. 3). A left intercostal drain was inserted and a considerable amount of straw-coloured fluid aspirated, analysis of which supported a diagnosis of congenital chylothorax, Despite intensive support the infant died within 24 h of birth. At post-mortem a severely hypoplastic left lung was confirmed but there was no other structural abnormality. Correspondence to: Dr H. Adams, Department of Radiology, University Hospital of Wales, Heath Park, Cardiff CF4 4XN.
Fig. 1 - Case 1. Transverse scan of the fetal thorax at 25 weeks gestation. The effusion (E) displaces the heart (H) to the right. The hypoplastic lung (arrows) lies against the mediastinum (P, placenta).
FETAL PLEURAL EFFUSIONS
399
Fig. 4 - Case 2. Transverse scan of the fetal thorax at 16 weeks gestation demonstrating a moderate pleural effusion (E, effusion; H, heart; P, placenta).
Fig. 2 - Case 1. A longitudinal scan of the fetal thorax demonstrates a hypoplastic left lung (small arrows) surrounded by the anechoic effusion (E, effusion; P, placenta; curved arrows, fetal spine).
Fig: 3 - Case 1. Chest radiograph soon after birth confirming a left pleural effusion (arrows). A n intercostal drain has been inserted for a right pneumothorax.
]:ig. 5 - Case 2. Follow-up scan at 28 weeks gestation, The effusion is no longer present (S, fetal spine; L, lung).
DISCUSSION First described by Pisek (1917), the largest review of Spontaneous neonatal chylothorax followed nearly 60 years later and included 34 cases (Brodman, 1975). In this series male infants were affected more than twice as often as females and right-sided effusions were more common than left although a small proportion were bilateral. The chest radiograph in the neonatal period
demonstrates an opaque hemithorax, often with contralateral mediastinal shift. The diagnosis of chylothorax is established by examination of the pleural fluid. Prior to commencement of feeding, the effusion is clear and straw-coloured and microscopy reveals a high proportion of lymphocytes (70 to 100%), a content resembling that of chyle. Later, following feeding, the fluid becomes turbid and adopts its characteristic lipid profile (Chernick and Reed, 1970; Van Aerde et al., 1984).
400
CLINICAL RADIOLOGY Fetal pleural effusion is readily diagnosed by ultrasound. The first reports of intra-uterine detection were by Carroll (1977) and D e f o o r t and Thiery (1978), who described fetuses with large pleural effusions and also generalised hydrops fetalis. The first description of isolated fetal pleural effusion a p p e a r e d shortly afterwards (Thomas and A n d e r s o n , 1979) and there have been occasional reports of similar cases since, s u m m a r i s e d in Table 1. The majority of cases (67%) have b e e n diagnosed during the third trimester of pregnancy. Effusions have occurred m o r e frequently in male fetuses (60%) and have been bilateral in 47% of cases described. Polyhydramnios is a c o m m o n association (53%). Five neonatal deaths have b e e n recorded following antenatal diagnosis, in three infants due to p u l m o n a r y hypoplasia and in two due to underlying congenital pulmonary lymphangiectasia. A further two infants had trisomy 21 with associated endocardial cushion defect. Congenital chylothorax is the most c o m m o n cause of isolated neonatal effusion and is likely to account for the majority of isolated fetal effusions. The most important sonographic sign of fetal effusion is an echo-free area lying between lung, chest wall and diaphragm. S o n o g r a p h y m a y also demonstrate secondary changes including p u l m o n a r y hypoplasia, mediastinal shift, hydrops fetalis and polyhydramnios. P u l m o n a r y hypoplasia is a m a j o r adverse prognostic factor; it was the cause of neonatal death in cases reported by T h o m a s and A n d e r s o n (1979) and Bovicelli et al. (1981). In the fatal case in our series, sonography
Fig. 6 - Case 3. Transverse scan of the fetal thorax at 36 weeks gestation. A large left effusion (E) outlines the fetal lung (L). A smaller right effusion was also present.
Table 1 - Fetal pleural effusion as an isolated ultrasonic abnormality: case reports
Author(s)
Gestational age ~(weeks)
Fetal sex
Lateralisation
Polyhydramnios
Nature o f fluid
Outcome~diagnosis
Thomas and Anderson (1979) Bovicelli et al. (1981) Lange and Manning (1981) Petres et al. (1982) Elser et al. (1983)
32
M
Bilateral
+
N/S
Died. Pulmonary hypoplasia
35
F
Bilateral
-
N/S
Died. Pulmonary hypoplasia
39
M
Bilateral
-
Chylous
Survived
36
F
Bilateral
+
Chylous
Intra-uterine thoracentesis. Survived
34
Bilateral
+
Chylous
Bilateral
+
N/S
+
N/S
Diagnostic intra-uterine thoracentesis. Survived Died Congenital pulmonary lymphangiectasia Died Congenital pulmonary lymphangiectasia Serial intra-uterine thoracentesis. Survived
Jouppila et al. (1983)
33
M (1 of twins) F
Kerr-Wilson et al. (1985)
33
M
Left
Benacerraf and Frigoletto (1985) Meizner et al. (1986) Benacerraf et al. (1986) Foote and Vickers (1986)
19
M
Left
38
M
Right
+
Chylous
Survived
16
F
Left
-
Chylous
34
M
Right
+
N/S
28
M
Left
+
N/S
M F F
Left Left Bilateral
Intra-uterine thoracentesis. Survived Down's syndrome, endocardial cushion defect. Outcome not stated Down's syndrome, endocardial cushion defect. Outcome not stated Died. Pulmonary hypoplasia Spontaneous resolution. Survived Survived
Foote and Vickers (1986)
Adams et al. 25 Adams et al. 16 Adams et al. 36 N/S, Not stated or unknown.
Chylous
Chylous N/S Chylous
FETAL PLEURAL EFFUSIONS
demonstrated that the hypoplastic lung was small and rigid with an abnormal rounded contour. However, in our two survivors, normal pulmonary configuration was preserved and the lungs undulated gently within the effusions during fetal movement suggesting pliability. These features may allow differentiation between the fetus with established pulmonary hypoplasia and a poor prognosis, and the fetus with potentially normal pulmonary development and a favourable prognosis. Complete disappearance of the effusion was demonstrated sonographically in our second fetus. This has not been reported before although there has previously been a report of partial resolution of chylothorax in utero (Jouppila et al., 1983). An important differential diagnosis of congenital chylothorax is serous pleural effusion due to hydrops fetalis. In hydrops there are invariably other sonographic features including cutaneous oedema, ascites, pericardial effusion and placental enlargement (Mahony et al., 1984). Diagnosis is more difficult when the mass effect of fetal chylothorax causes either direct cardiac compression or obstruction of venous return leading to secondary hydrops fetalis. Several such cases have been reported (Carroll, 1977; Defoort and Thiery, 1978; Schmidt et al., 1985). Hydrops may also result for the same reasons from other fetal thoracic anomalies including congenital diaphragmatic hernia and cystic adenomatoid malformation of the lung, conditions also characterised by a predominantly transonic fetal hemithorax (Chinn et al., 1983; Comstock, 1986; Fitzgerald and Toi, 1986). With widespread screening it is likely that fetal chylothorax will be diagnosed more frequently. However, several important points of management arise. Because of the recognised association between congenital pleural effusion and Down's syndrome (Yoss and Lipsitz, 1977; Van Aerde et al., 1984; Foote and Vickers, 1986) amniocentesis should be performed to exclude chromosomal abnormality when an effusion is detected during the second trimester of pregnancy. Sonography offers a means of monitoring the variable course of fetal chylothorax. Since pulmonary hypoplasia appears to indicate a poor prognosis, its detection in early pregnancy should lead to parental counselling and consideration of therapeutic termination. For the fetus with apparently normal lungs, serial scanning at intervals of not more than 2 weeks would seem advisable. Intra-uterine thoracentesis under ultrasound guidance is a therapeutic option when the fetus is not yet mature enough to allow early delivery (Petres et al., 1982; Benacerraf and Frigoletto, 1985; Benacerraf et al., 1986) and if performed in the second or early third trimester may prevent the development of hydrops fetalis and pulmonary hypoplasia. Thoracentesis can also be performed in the immediate anrepartum period to improve fetal condition at the time of delivery. Because of the generally favourable prognosis of fetal chylothorax, thoracentesis should be reserved for cases where the effusion is increasing in size on serial scans or where there is sonographic evidence of adverse effect upon fetal well-being. For the pregnancy nearing term, ultrasonic evaluation will enable optimal timing and mode of delivery, and prompt assessment of the neonate by the forewarned paediatrician to ensure the best chance of survival. This is well exemplified by the third case in our series.
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In conclusion, fetal pleural effusions are readily demonstrated sonographically. In a minority of cases they are due to congenital pulmonary lymphangiectasia, or associated with established pulmonary hypoplasia and have a poor prognosis which is unlikely to be significantly influenced by intra-uterine diagnosis. In the remainder the prognosis is favourable, particularly if early neonatal intervention is instituted. REFERENCES Benacerraf, BR & Frigoletto, FD (1985). Mid-trimester fetal thoracentesis. Journal of Clinical Ultrasound, 13, 202-204. Benacerraf, BR, Frigoletto, FD & Wilson, M (1986). Successful midtrimester thoracentesis with analysis of the lymphocyte population in the pleural effusion. American Journal of Obstetrics and Gynecology, 155, 398-399. Bovicelli, L, Rizzo, N, Orsini, LF & Calderoni, P (1981). Ultrasonic real-time diagnosis of fetal hydrothorax and lung hypoplasia. Journal of Clinical Ultrasound, 9, 253-254. Brodman, RF (1975). Congenital chylothorax: recommendations for treatment. New York State Journal of Medicine, 75, 553--557. Carroll, B (1977). Pulmonary hypoplasia and pleural effusions associated with fetaI death in utero: ultrasonic findings. American Journal of Roentgenology, 129, 749-750. Chernick, V & Reed, MH (1970). Pneumothorax and chylothorax in the neonatal period. Journal of Pediatrics, 76, 624-632. Chinn, DH, Filly, RA, Callen, PW, Nakayama, DK & Harrison, MR (1983). Congenital diaphragmatic hernia diagnosed prenatally by ultrasound. Radiology, 148, 119-123. Comstock, CH (1986). The antenatal diagnosis of diaphragmatic ano7 malies. Journal of Ultrasound in Medicine, 5, 391-396. Defoort, P & Thiery, M (1978). Antenatal diagnosis of congenital chylothorax by gray scale sonography. Journal of Clinical Ultrasound, 6, 4748. Elser, H, Borruto, F, Schneider, A & Schneider, K (1983). Chylothorax in a twin pregnancy of 34 weeks sonographically diagnosed. European Journal of Obstetrics, Gynecology and Reproductive Biology, 16, 205-211. Fitzgerald, EJ & Toi, A (1986). Antenatal ultrasound diagnosis of cystic adenomatoid malformation of the lung. Journal of the Canadian Association of Radiologists, 37, 48--49. Foote, KD & Vickers, DW (1986). Congenital pleural effusion in Down's syndrome. British Journal of Radiology, 59, 609-610. Jouppila, P, Kirkinen, P, Herva, R & Koivisto, M (1983). Prenatal diagnosis of pleural effusions by ultrasound. Journal of Clinical Ultrasound, 11, 516-519. Kerr-Wilson, RHJ, Duncan, A, Hume, R & Bain, AD (1985). Prenatal pleural effusion associated with congenital pulmonary lymphangiectasia. Prenatal Diagnosis, 5, 73-76. Lange, IR & Manning, FA (1981). Antenatal diagnosis of congenital pleural effusions. American Journal of Obstetrics and Gynecology, 140, 839-840. Mahony, BS, Filly, RA, Callen, PW, Chinn, DH & Golbus, MS (1984). Severe non-immune hydrops fetalis; sonographic evaluation. Radiology, 151,757-761. Meizner, I, Carmi, R & Bar-ziv, J (1986). Congenital chylothorax prenatal ultrasonic diagnosis and successful post partum management. Prenatal Diagnosis, 6, 217-221. Petres, RE, Redwine, FO & Cruikshank, DP (1982). Congenital bilateral chylothorax. Journal of the American Medical Association, 248, 1360-1361. Pisek, G (1917). Report of a chylothorax. Archives of Pediatrics, 34, 929-937. Schmidt, W, Harms, E & Wolf, D (1985). Successful prenatal treatment of non-immune hydrops fetalis due to congenital chylothorax. British Journal of Obstetrics and Gynaecology, 92, 685-687. Thomas, DB & Anderson, JC (1979). Antenatal detection of fetal pleural effusions and neonatal management. Medical Journal of Australia, 2, 435-436. Van Aerde, J, Campbell, AN, Smyth, JA, Lloyd, D & Bryan, MH (1984). Spontaneous chylothorax in newborns. American Journal of Diseases of Children, 138, 961-964. Yancy, WS & Spock, A (1967). Spontaneous neonatal pleural effusion. Journal of Pediatric Surgery, 2, 313-319. Yoss, BS & Lipsitz, PJ (1977). Chylothorax in two mongoloid infants. Clinical Genetics, 12, 357-360.