A male baby at term is delivered using forceps. There had been Type 2 dips on the fetal heart rate tracing during the labour, and the baby was born covered in meconium. He did not breathe. The neonatologist arrived to resuscitate the baby, but after 20 minutes the baby still only had a heart rate of 60 per minute and was only giving occasional gasps. Apgar scores at 1, 5, and 10 minutes were 0, 1 and 1.
He was attached to a ventilator and transferred to the neonatal intensive care unit. Regular respirations were established and he required no further ventilation after 12 hours. However, he remained very jittery with a high-pitched cry and the nurses reported that he felt floppy. On the 2nd day he was noticed to have tonic-clonic convulsions and apnoeic attacks. Blood glucose at the time was 3mmol/l. He required ventilation again but the tonic-clonic convulsions continued despite large doses of phenobarbitone. An urgent MRI scan showed possible areas of infarction of both cerebral hemispheres and evidence of periventricular leucomalacia, indicating a poor prognosis. The neonatologist arranged to talk to the parents about the prognosis, and to discuss continuation of life support with them.
Objectives 1. Terms: APGAR scoring, Type 2 Dips, Periventricular leucomalacia 2. What are the normal foetal and neonate vital parameters and what assessments of the neonate are made at birth? 3. What are the causes and implications of a diagnosis of foetal asphyxia? 4. What is the clinical relevance of meconium staining and what risks are associated with it? 5. What assisted vaginal delivery options are available and when are they indicated? 6. What is the prognosis of this neonate?
1.) Terms APGAR scoring- A method of assessing neonates in the immediate postnatal period, to ascertain the need for resuscitation and long term CNS prognosis. It is commonly performed at 1 and 5 mins after birth. APGAR refers to the mnemonic used to remember the five steps performed in carrying out the test, each individual letter will be explored in detail in Objective 2. Type 2 dips: Also known as late decelerations, these are falls in the foetal heart rate that are deemed to be pathological, associated with a maternal uterine contraction. These decelerations are greater than 40 beats per minute from the baseline rate and the lowest rate occurs around 1-2 minutes after the peak of the uterine contraction.
Periventricular leucomalacia: Literally means a softening and whitening of the tissue surrounding the ventricles of the foetal brain, commonly seen on MRI imaging of the head.1 The periventricular areas are often at high risk of ischaemia as they have one of the poorest blood supplies of the brain, with the thalamus most commonly affected. The prognosis is poor, with a risk of cerebral visual impairment as the lateral geniculate nucleus that relays visual impulses from the retina to the cortex is commonly damaged.2
Image 1: Periventricular leucomalacia 2.) What are the normal foetal and neonate vital parameters and what assessments of the neonate are made at birth? Normal foetal parameters include a heart rate that ranges from 120-160bpm baseline rate, with accelerations greater than 40bpm of the basal rate concordant with movement, with no late decelerations and a good baseline variability rate of at least 15bpm.
The neonate’s normal parameters are listed in table 1 below. Interpretation of the score is important. Any score that is three or less indicates the need for full resuscitation by a neonatologist, often requiring Intermittent Positive Pressure Ventilation via endotracheal tube and possibly external cardiac massage if the heart rate falls below 80 beats per minute. A score of under six at five minutes indicates a poor CNS prognosis. A normal APGAR score is seven or greater, with the neonate spontaneously breathing within three minutes of complete delivery.
Once the neonate is breathing spontaneously with an acceptable heart rate, a paediatrician will perform a set of checks within the neonatal period. Many congenital defects can be noticed immediately after birth with a quick general inspection that can be carried out by a midwife or a paediatrician. Starting with the face, the neonate may have typical features of trisomy 21, such as low set ears, wide set eyes and a protruding tongue. This may correlate with single simian palmar creases. Common defects are cleft lips/palates, neural tube defects and meningoceles developing on the spinal column or neck.
Continuing downwards, herniation of the umbilicus may present as an exomphalos or a protrusion of the gut as a gastroschisis, both which require extra caution in terms of infection control and urgent surgical repair to prevent gut herniation and strangulation. A gastroschisis has an incidence of 1:3000 with a tendency towards mothers under 20 and exomphalos comes with an incidence of 1:500 in mothers over 40 years of age.
Image 2: An example of a large exomphalos with a covering sac Ending with the perigenital area and the limbs, common defects are imperforate openings of the anus, requiring surgical intervention to prevent bowel blockages and hypospadias in the male infant, where the urethra opens in the ventral or dorsal aspect of the penis rather than the glans. The limbs may show polydactyl (extra digits) or webbing between the digits of the hand or feet.
A heel prick test is commonly performed within the first week of birth. This tests for phenylketonuria, a disorder of phenylalanine metabolism that occurs in 1:10,000 births, leading to mental retardation if phenylalanine containing foods are fed and levels build up. Secondly, congenital hypothyroidism is also checked for, with an incidence of 3:10,000 babies. This leads to signs of infantile hypothyroidism, causing impaired physical and mental development.