Hydrops fetalis

Question 1

Definition of hydrops.

Answer 1

Accumulation of interstitial fluid 2 or more body cavities (peritoneum, pleural space, pericardial space, skin oedema)

Question 2

2 broad types of hydrops

Answer 2

• Immune
• Non-immune

Question 3

What causes immune hydrops?

Answer 3

• HDFN - alloimmunisation of the mother against the fetal blood group (usually due to rhesus incompatibility) resulting in fetal haemolytic anaemia

Question 4

What are the causes of non-immune hydrops?

Answer 4

Any condition that interferes with the fetal body’s ability to manage fluid, due to:

●Obstructed lymphatic drainage in the thoracic and abdominal cavities

●Increased capillary permeability

●Increased central venous pressure

●Decreased osmotic pressure

• Hematologic causes: Alpha-thalassemia (HbBarts is commonest cause), and leukemias
• Chromosomal anomalies: Turner syndrome (50%), Down syndrome (25%), and Edward syndrome, patau syndrome
• Lymphatic causes: Congenital lymphatic dysplasia
• Cardiac causes: Paroxysmal supraventricular tachycardia, complete heart block, hypoplastic left heart, endocardial cushion defects, and congenital pulmonary airway malformation
• Infections: Parvovirus B19, CMV, HSV and syphilis
• MCDA twins: twin-to-twin transfusion syndrome (TTTS), TRAP
• Metabolic diseases: Niemann-Pick disease type-C (NPC), Gaucher disease type 2, and beta-glucuronidase enzyme deficiency
• Tumors: Teratoma (sacrococcygeal teratoma), hepatic tumors, and neuroblastoma
• Maternal diseases: Diabetes mellitus and hyperthyroidism
• Urinary causes: Congenital nephrosis and prune belly syndrome
• Digestive causes: Volvulus and meconium peritonitis
• Disorders of red blood cell (RBC) metabolism: Glucose phosphate isomerase deficiency, pyruvate kinase deficiency, and glucose-6-phosphate dehydrogenase (G6PD) deficiency
• Disorders of RBC production: Congenital dyserythropoietic anemia, Diamond-Blackfan syndrome, and Fanconi anemia
• Disorders of RBC membrane: Hereditary spherocytosis, hereditary elliptocytosis, hereditary pyropoikilocytosis, and hereditary stomatocytosis syndromes

Question 5

What is the commonest type of hydrops?

Answer 5

Non-immune - accounts 80-90% cases

Question 6

In utero investigations for hydrops.

Answer 6

Maternal tests:

• Maternal FBC +/- high performance liquid chromatography to detect haemoglobinopathy +/- carrier screening partner
• Maternal blood group and antibodies
• Maternal TFTs (Graves disease)
• Maternal HbA1c
• TORCH screen incl. parvovirus, CMV, syphilis HSV

Fetal tests:

• Tertiary level anatomy scan
• fetal echo
• USS MCA-PSV
• Amniocentesis - karyotype, microarray, viral screen, AFP (congenital nephrotic syndrome)
• Fetal paracentesis

Question 7

Survival rate for hydrops.

Answer 7

10%

Question 8

What is Mirror syndrome?

Answer 8

Mirror syndrome (also called Ballantynes syndrome) refers to a condition of generalized maternal edema, often with pulmonary involvement, that “mirrors” the edema of the hydropic fetus and placenta. Although usually associated with NIHF, it can also occur with immune-mediated hydrops. The pathogenesis has not been firmly established, but at least in some cases, the hydropic placenta increases production of soluble fms-like tyrosine kinase (sFlt1), which is an important mediator of maternal endothelial and vascular abnormalities in preeclampsia

Question 9

What is the criteria for skin oedema?

Answer 9

Oedema >5mm

Question 10

What are the commonest causes of hydrops?

Answer 10

<24 weeks

• aneuploidy

>24 weeks

• Cardiac (most common - 40%)
• pulmonary
• haematological
• infection

Question 11

What types of cardiac condition cause hydrops?

Answer 11

• structural anomalies
• vascular anomialies
• tachyarythmias
• bradyarythmias

Question 12

What would you test if fetal bradyarythmia detected during detailed fetal scanning?

Answer 12

• Maternal anti-Ro and anti-La abs for neonatal lupus

Question 13

Some fetal sequelae of hydrops.

Answer 13

• Preterm birth (iatrogenic or spontaneous)
• Hypoplastic lungs
• Bowel obstruction
• Stillbirth
• Neonatal death
• Shoulder dystocia and birth trauma

Question 14

Timing of delivery for hydrops.

Answer 14

• Dependent on cause
• Early onset and poor prognosis may opt for termination of pregnancy
• New onset or worsening hydrops - consider delivery from 34 weeks
• Stable/managed hydrops - consider delivery 37-38 weeks
• Most by vaginal delivery - CS for obstetric reasons, but be aware high risk for birth and shoulder dystocia of hydropic fetus

(uptodate)