Service de Gynécologie obstétrique I -CHU Hassan II Fès Maroc
A 22-year old primigravida, 36 weeks of gestation was referred to our service for the management of gestational diabetes.
Obstetric ultrasound showed marked bilateral pleural effusions on the right, without any other findings.
A female baby was born at 37 weeks of gestation, Apgar 8 / 10, 10/10 at the 5th min with 2800gr.
The neonatal examination discovered a cyanotic and hyporeactive respiratory distress respiratory score of Selverman 6/10 without further detectable malformation. Radiography and thoracic ultrasound showed an important pleural effusion. The cytobacteriological and chemical study of the pleural fluid showed that it was an exudative chylous fluid with 26 g/L albumin, a high triglyceride level of 5.59 g/L, predominantly lymphocytic (75%) and the culture was sterile.
The white blood cell (WBC) level was 66,000 and the C-reactive protein (CRP) at 0.6 mg / L.
Abdominal ultrasound and echocardiography were normal.
Treatment was conservative (pleurodesis) with cessation of digestive intake and total parenteral nutrition for five days. Evolution was favorable. The control chest x-ray revealed a clear regression of pleural effusion
Images 1 and 2: 2D cross-sectional ultrasound at the level of the fetal thorax showing bilateral pleural effusion.
Image3: Postnatal X-ray confirmed bilateral pleural effusion.
Image 4: Normal control X-ray.
Discussion: The case shows sonographic diagnosis of chylothorax in a fetus at 36 weeks of gestation.
Definition: The word chylothorax refers to the presence of chyle in the pleural cavity. Chyle is lymph containing the products of intestinal digestion of fats; its composition is characterized by its richness in triglycerides and lymphocytes; It is conveyed from the intestine to the venous circulation through the thoracic duct. 
Etiology: They are unknown. Genetic origin seems to be excluded. People with light skin have more risk.  There are no known foods or medications ingested during pregnancy or activities that would be a risk factor. [2,3]
Pathogenesis: The presence of chyle in the pleura indicates a wound in the thoracic duct or, more often, in one of its collateral branches. These can either be injured during intrathoracic surgical procedures, or they may spontaneously rupture during an overdistension at their level by obstacle on the thoracic duct, atresia or valvular incontinence of the latter. Its mechanism, notably the integrity of the thoracic duct, can only be specified by lymphography. 
Diagnosis and sonographic findings: The progress of ultrasound allows, at present, an easy diagnosis of hydrothorax. It appears as an anechoic zone surrounding the heart and lungs .  In front of a hydrothorax, the antenatal diagnosis of chylothorax is difficult to establish, but the negativity of the balance makes it possible to evoke the diagnosis of chylothorax. The certainty is obtained in post-natal by the evolution under adapted nutrition. 
Differential diagnosis:The differential diagnosis is mainly with other pleuropulmonary effusions of infectious, malformative or congenital origin.
Associated anomalies: Hydrothorax is a rare condition that can be associated with chromosomal abnormalities or other malformation or genetic abnormalities. These associations require an effective antenatal exploration before offering a therapeutic. 
Prognosis: Some spontaneous resolutions have a good prognosis. The survival rate for those with persistent effusion is better in the absence of anasarca, the whole literature is in favor of a pleuro-amniotic shunt placement in severe effusions with hydrops or progression by Teams trained. 
Management: The management trying to harmonize all this information could propose
- 1) in the presence of an effusion in the second quarter, therefore high risk of pulmonary hypoplasia, but which can also regress spontaneously, carrying out an ultrasound assessment as advised by Hagay et al, but by supplementing it immediately with an amniocentesis with karyotype and an infectious assessment.
- 2) In the absence of associated abnormality, ultrasound control before 2 weeks of evolutions.
- 3) Continuous drainage in front of the persistence or aggravation of the effusion on the ultrasound control.
- 4) Therapeutic abstinence and ultrasound monitoring only if ultrasound monitoring shows signs of regression.
- 5) In the presence of an effusion appearing or discovered in the 3rd trimester, therapeutic decision according to the evaluation of the signs of gravity according to the attitude prostrate by Longaker et al.
- 6) In immediate prepartum, in the absence of a pleural drain, it is possible to puncture an effusion to facilitate postnatal resuscitation. 
 Longaker MT, Laberge JM, Dansereau J, Langer JC, Crombleholme TM, Callen PW, et al. Primary fetal hydrothorax: natural history and management. J Pediatr Surg 1989 ; 24 : 573-6.
 Carroll B. Pulmonary hypoplasia and pleural effusions associated with fetal death in utero: Ultrasonic findings. Am J Roentgen 1977; 129: 749-750 .
 Rustico MA, Lanna M, Coviello D, et al. Fetal pleural effusion. Prenat Diagn 2007;27:793-9
 Aubard Y, Derouineau I, Aubard V, Chalifour V, Preux PM. Primary fetal hydrothorax: A literature review and proposed antenatal clinical strategy. Fetal Diagn Ther 1998; 13: 325-333
 Mussat P, Dommergues M, Parat S, Mandelbrot L, Gamarra E Dumez Y, et al. Congenital hylothorax with hydrops: postnatal care and outcome following antenatal diagnosis. Acta Paediatr1995 ; 84 : 749-55.
 Thompson PJ, Greenough A, Nicolaides KH. Respiratory function in infancy following pleuroamniotique shunting. Fetal Diagn Ther 1993 ; 8 : 79-83
 Chemaou A. et al. Chylothorax idiopathique chez un nourrisson. Prise en charge et évolution .Archives de Pédiatrie 2012;19:711- 713