At 8 weeks embryo is 15 cm long, with nose, toes and fingers identifiable, spontaneous movements. At 12 weeks, arms are normal proportion, external genitalia are recognizable as male or female, heartbeat is detectable.
Defined as a Hb difference of at least 5 and a weight difference of at least 20%, which is obviously a postnatal definition! Antenatal USS apart from different sizes there is usually polyhydramnios around one twin and oligohydramnios of the other, grading system used. If twin to twin is suspected at midtrimester, the ultimate mortality is up to 80%; timing of the transfusion process is crucial.
Mechanism - shunts between monochorionic twins are normal, but not a problem if bidirectional and balanced, which is maybe only 2/3 of the time... But not all discordant growth is because of twin to twin transfusion, and the way of telling the difference is that SGA twin is plethoric except in twin to twin.
It is well known that twins have higher neuro disability rates, especially in monochorionic, and this is particularly true if one twin dies in utero. Twin to twin transfusion may have a role here, in terms of embolism, DIC or haemorrhage.
Amnioreduction good in early disease; laser ablation increases single survivors but at cost of reducing double survivors as well as double deaths.
For Downs, NHS has set target to improve sensitivity and specificity. Requires combination of nuchal translucency, HCG, Progesterone E3, AFP, PAPP-A and Inhibin A. New research looking at isolating fetal DNA or RNA from maternal blood stream hence avoiding need for invasive tests.
Fetal ultrafast MRI now able to image CNS and other organs without movement artefact.
Fluid collects at neck as dependent oedema. At 10 to 14 weeks lymphatics are poorly developed so more obvious. Associated with Down’s syndrome (because of abnormal, more elastic collagen), neurodevelopmental problems eg arthrogryposis (reduced movement), pulmonary problems eg congenital diaphragmatic hernia (poor breathing movement), and congenital cardiac defects. A nuchal lucency of 3mm has a positive predictive value of 10% for major abnormality; at 6 mm the ppv is 90%.
In antenatal isolated mild ventriculomegaly, a minority will have abnormal karyotypes, about half will resolve before birth (although may still have long term neuro probs...). J Perinat Med. 2005;33(3):236-40.
ie below 10th centile on antenatal scan. Goes hand in hand with reduced liquor volume and impaired umbilical artery doppler. Important to separate out constitutionally small babies (perhaps due to a syndrome) - in which case liquor volume etc normal, and prognosis better. If aneuploidy is suspected (eg coexisting fetal anomalies) amniocentesis can be done, but cordocentesis or placental biopsy is quicker eg 48 to 72 hours.
Absent or reversed end diastolic flow on umbilical artery doppler predicts perinatal mortality and morbidity in high risk pregnancies eg pre-eclampsia. In particular it is associated with necrotizing enterocolitis, and abnormalities in superior mesenteric artery blood flow persist in the first week of life. Whether doppler contributes anything in low risk pregnancies is debatable; in some studies correcting for oligohydramnios and gestation removed any predictive value. It is not recommended as routine antenatal screening.
NZ case control study found fish, carbohydrate and folate intake in pregnancy protective against SGA babies.
Arch Fet 2004; 89
SGA babies mostly catch up by 4yr else short for life. GH study in progress (high dose, low dose, vs titrated by IGF-1).
Urinary tract abnormality; premature rupture of membranes; NSAIDs. Associated with increased morbidity due to cord compression, and/or pulmonary hypoplasia.
Open fetal surgery used in CDH, meningomyelocoele, cystic adenomatoid malformations, sacrococcygeal teratomas (AV shunting leads to hydrops), obstructive uropathy. Not clear that this is better than optimal postnatal care.
For severe haemolytic disease of the newborn, Fetal Rh or Kell status can be ascertained from fetal DNA in maternal plasma. Doppler of middle cerebral artery allows timing of intrauterine transfusions without need for further amniocentesis.
Maternal immunoglobulin recommended in severe AITP (Eur collab trial, BJHaem)
Velamentous cord insertion = attached to membrane. Associated with congenital anomalies. High risk of vasa previa if lower segment. No risk of recurrence.
Managed by multidisciplinary team including Maxfax surgeon, plastics surgeon, dental surgeon, speech therapist. Beware submucous cleft palate, where mucosa overlies a defect: may look normal on inspection, else a bifid uvula, or looks indented, or bluish or white line in the middle of the soft palate. Still associated with early feeding difficulties, speech problems and ear problems.
CLAPA is the charity, lots of info.
Look for other dysmorphisms esp Pierre Robin, fetal valproate. If midline, can be associated with hypopituitarism.
Avoid separating from mother, and encourage normal feeding (breast especially). If difficulties, then try:
Repair of a cleft lip is done at 2-3/12. Palate is done at 1 yr, sometimes it needs to be a 2 stage procedure.
Folic acid reduces cleft lip and palate. Grounds for mandatory food fortification?
This work
is licensed under a Creative
Commons Attribution-Noncommercial-Share Alike 2.5 UK: Scotland License.