Case based Discussion on Late on-set FGR
Samrakshan is a National Initiative of the Indian Radiological and Imaging Association (IRIA) that addresses safe motherhood and issues related to fetal growth and pregnant women in India. Fetal Growth Restriction (FGR) or suboptimal growth of the fetus is a major problem in India with short and long-term consequences on health. Samrakshan conducted a National Fetal Growth Restriction Awareness Week 2022 jointly organized by IRIA Preventive Radiology and IRIA Kerala in association with Journo Med and MedPiper Technologies. These were a series of educational webinars that discussed clinical practice based on actual clinical cases.
The third educational webinar focused on the theme- Case-based Discussion on Late-onset FGR and understanding the concept of FGR in AGA Fetuses. Under the Samrakshan program, the focus is towards growth disorder programs because radiologists can delve into the details of growth disorders, the physiology of abnormal placentation and how to monitor, deliver and aim for better perinatal outcomes.
Dr Shilpa Satarkar, the national coordinator of Samrakshan IRIA for 2022 highlighted the Samrakshan Program, and the sensitization towards the pre-eclampsia and fetal growth restriction (FGR) screening. She also emphasized the babies with genetic abnormalities and aneuploidies. The radiologists perform pre-eclampsia (PE) and fetal growth restriction (FGR) screening, and they aim to cover 757 districts in India.
Dr Meenakshi Goyal explained about late-onset FGR. Late-onset FGR is the inability of the fetus to reach its maximum growth potential and it is usually diagnosed after 32 weeks of gestation. Late-onset FGR that remains undetected before birth increases the risks of adverse perinatal outcomes. The placental physiology and the gestational age cut-off vary from early to late-onset FGR. Though there are no solitary criteria to qualify for fetal growth restriction (FGR), a drop in the fetal weight or crossing centiles of more than two quarters is a commonly used criterion. The doppler value, uterine artery PI and MCA PI centile values are taken into consideration.
Dr Anjali Gupta, a Radiologist from Agra discussed the three daily case scenarios, scanned reports were gathered as per the Samrakshan Protocol, doppler scans were performed, the values were obtained in percentiles, the comparisons of previous scans were attempted for assessing the interval growth was optimum or not. The outcomes were obtained. She also explained about fetal growth restriction (FGR) which is the failure to reach genetically pre-determined growth potential.
The proxy for growth potential = size= weight= 10-90 percentile = AGA. FGR manifesting after 32 weeks of late-onset FGR. Any fetus which falls between 10-90th percentile doesn’t necessarily grow well. She explained the growth potential of the babies and as well as SGA fetuses. Even the biological parameters and the outcome of the cases, like how vaginal delivery was performed were well explained. She also elaborated on the cases based on Delphi’s consensus.
Dr Chitra Janu Chahar explained the different growth charts which determine fetal growth. There are different types of growth charts i.e., standard, reference or population growth charts or customized growth charts. The logic for the growth chart is every population has a different growth pattern. The growth charts help us to plot the growth of the fetus and give a visual explanation of the growth patterns of the fetus. The growth charts pick up changes in the centile of the weight which helps to identify growth restriction.
Dr Chitra Janu Chahar explained how late-onset FGR is different from early-onset FGR. Late-onset FGRs are challenging and the problems that arise with the late-onset FGR diagnosis are difficult. In late FGR, the placenta is normal and problems such as placental dysfunction are mild and that’s why the fetal weight remains normal. Late-onset FGR can be easily missed.
Why is late-onset FGR different?
The placental disease is mild, the umbilical artery is usually normal.
The fetal size is not much reduced.
There is no cardiovascular maladaptation in the fetus.
The brainstem bears the brunt.
The mature brainstem is very susceptible to hypoxia. That’s why respiratory function is compromised in late-onset FGR. So, one may have abnormal CPR and MCA PI.
Very short natural history and rapid progress and hence quick action are required. In late-onset FGR, usually, the placental affection is less than 30% and the umbilical artery may not show any changes adding to the difficulty in diagnosis.
Dr Mansi explained the ultrasound markers of late FGR, the placental disease burden, the fetal size and the criteria required for FGR cases. It is important to observe the placental disease and umbilical artery. Even the cerebral placental ratio must be measured and checked if it is less than the 5th centile. The centiles are required at the time of delivery or in surveillance and checked along with a biophysical profile i.e., fetal movements, fetal breathing, fetal heart rate and liquor and NST. So, the doppler changes and the fetal movements are observed. The gynaecologist or neonatologist needs to have a closer examination of both mother and the fetus.
The pathophysiology of FGR and the adaptation of the fetus were explained in detail. Dr Chitra Janu Chahar explained why efforts must be made to diagnose late-onset FGR. The fetal weight is normal. The brainstem becomes more susceptible to hypoxia. Complications of the hetero placental redistribution, neurodevelopmental, and diametabolic diseases like diabetes, hypertension, and cardiovascular maladaptation arise. If late FGR is treated early, stillbirths can be avoided in most cases. Careful monitoring is required for these babies as the window of opportunity is small and the survival rate is low if untreated.
Dr Shubhra Goyal explained the impact of FGR on diagnosis, planning management and delivery. When the fetus is nearly 37 weeks, the risk of prematurity is not very high this week. As compared to the risk of perinatal morbidity, one would like to deliver the baby, the reason for delivery is also based on NST and bishop score, a PV examination and the guidelines that need to be followed. The patient should be called at least twice a week for follow-up if one waits till 38 weeks. Otherwise, 37 weeks is also good if there is a good bishop score for the patient.
Additional factors to consider include
- The mother has high-risk factors.
- Abnormal NST.
- Biophysical profile and Doppler results
There can be spontaneous decelerations in the umbilical artery and these spontaneous decelerations are always associated with doppler changes. Usually, spontaneous decelerations are observed with an absence in the diastolic flow and with a reversal in the diastolic flow. It has to be correlated to the doppler findings.
Dr Shubhra Goyal explained how frequently they monitor and deliver the babies. Dr Sunil Kumar Agarwal explained his experience towards short-term and long-term outcomes of growth-restricted babies. He also discussed FGR.
Post Natal Complications
Short-term complications: Perinatal mortality, hypoxia, hypoglycemia, hypothermia, polycythemia, meconium aspiration, NEC, hypoxic-ischemic encephalopathy, IVH.
Long-term complications: Poor neurodevelopmental outcome (CP), learning disabilities, cardiovascular maladaptation, neuropsychiatric issues, metabolic syndrome, DM.
There might be minor neurocognitive morbidities and learning disabilities, more common in late pre-term babies. More cardiovascular risk factors, hypertension, and cardiac morbidities occur later on. These pre-term babies have high risks of morbidity and mortality.
Access the growth velocity closely and importance must be given to CPR values and emphasize monitoring of the patient. A weekly follow up required from an obstetrician or a gynaecologist.
AGA FGR Fetus Monitoring
For late-onset FGR, monitor with CPR, DFKC, fetal breathing and CTG. A weekly or biweekly doppler test is required. Deliver the baby by 38-39 weeks if CTG is less than P5 and shows falling trends. Deliver the baby between 36-38 weeks if UA PI is greater than p95.
Monitoring and Management
Counsel the patient to observe the daily fetal kick count. Call the patient again for a doppler. CTG monitoring and repeat scan. No role of expectant management.
Dr Mansi Jain explained that it takes about 2 minutes to save a life, 2 mins for doing pre-eclampsia and FGR screening and 2 mins of integrating fetal doppler with every growth scan. A growth scan is incomplete without growth studies and fetal dopplers. CPR and low MCA PI are the most important parameters which need to be taken into consideration.
The integration of fetal Doppler studies will help provide information for early detection of late-onset FGR and thus help to reduce perinatal mortality including stillbirths. The Doppler studies will add only 2 to 5 minutes to the examination time and is a painless, non-invasive procedure.