Achondroplasia is a genetic disorder that affects bone growth, and is the most common form of dwarfism. Individuals with achondroplasia typically have short stature, disproportionately short arms and legs, a normal-sized torso, and a characteristic facial appearance. Achondroplasia does not affect intelligence, and individuals with achondroplasia can lead healthy, fulfilling lives. Achondroplasia is not evident during a 20-week scan, but significant bone shortening becomes noticeable in the 3rd trimester. Surprisingly monogenic NIPT, for FGFR3 mutation, can detect achondroplasia as early as 10 weeks.

Acrania, a type of neural tube defect (NTD), is a condition where the top part of the baby’s skull, including the brain, does not form properly. This anomaly is often detectable in the first trimester of pregnancy, even at 10 weeks. Unfortunately, acrania is associated with exposed brain tissue and is not compatible with life. While relatively common among structural anomalies, its early detection is crucial for informed medical decisions At the London Pregnancy Clinic, we screen for acrania as early as 10 weeks, prioritising early detection of this severe structural anomaly.

Absence of Cavum Septum Pellucidum (CSP): The absence of cavum septum pellucidum refers to the lack of a small fluid-filled space in the midline of the brain, known as the cavum septum pellucidum (CSP). While some individuals with this condition may not exhibit noticeable symptoms, in some cases, it can be linked to septo-optical dysplasia. It may contribute to problems of vision, developmental issues or other conditions.

Absent nasal bone refers to the absence or underdevelopment of the nasal bone during prenatal development. Absent nasal bone does not represent structural anomaly. This anatomical variant is often identified through ultrasound imaging. While the absence of a nasal bone can be a soft marker for certain chromosomal conditions, especially Down’s syndrome, it’s essential to note that it doesn’t necessarily indicate a problem on its own. NIPT can be an excellent solution to reduce anxiety for parents worried about absent nasal bone. Alternatively, they may considered to have diagnostic invasive test.

Agenesis of the corpus callosum (ACC) is a condition where the bundle of nerve fibers connecting the two hemispheres of the brain, known as the corpus callosum, either partially or completely fails to develop. This anomaly can impact the communication between the brain’s hemispheres. While some individuals with ACC may not show significant symptoms, others might experience developmental delays or intellectual disabilities. The severity of symptoms can vary, making each case unique.

Amniotic Band Syndrome is a rare condition that occurs during fetal development when fibrous bands from the amniotic sac entangle parts of the fetus, restricting normal development. These bands can lead to various deformities, facial distortion or even amputation of fingers, extremities, or other body parts. The severity of the effects can vary widely. The severe forms of ABS are lethal.

Atrio-ventricular septal defect (AVSD) is a common congenital heart defect with a hole in the septum (wall) between the heart’s chambers, affecting all four chambers of the heart (atria and ventricles). This defect can contribute to abnormal blood flow within the heart. AVSD is often associated with Down’s syndrome. The severity of AVSD can vary, and surgical intervention is probably required to correct the defect after birth.

Bilateral renal agenesis occurs when both kidneys fail to develop during embryonic development. This anomaly leads to the absence of both kidneys, essential for filtering waste and regulating fluids in the body. The condition is strongly associated with the absence of amniotic fluid around the fetus, contributing to lung hypoplasia where the lungs may not fully develop. With a practically 100% lethality rate, bilateral renal agenesis is a severe condition.

Body-stalk anomaly is a rare and severe congenital condition where there is an abnormality in the development of the fetus, leading to the absence of the abdominal wall. This results in the exposure of internal organs outside the body. The baby is also lacking a proper umbilical cord. The condition is associated with severe deformities and is incompatible with life. 

Cleft lip and palate are congenital conditions where there is an opening or gap in the upper lip and/or roof of the mouth (palate). These openings occur during embryonic development and can vary in severity. Cleft lip and palate may impact feeding, speech, and facial appearance and can be associated with various chromosomal and genetic abnormalities.

Coarctation of the aorta is a common congenital cardiac anomaly where there is a narrowing or constriction in the aorta, the main blood vessel carrying oxygenated blood from the heart to the body. This critical condition requires urgent treatment after birth, often involving surgical intervention to correct the constriction. Generally, CoA may not be easily detectable even by specialist fetal echocardiography.

Congenital Diaphragmatic Hernia (CDH) is a congenital anomaly where there is a hole or opening in the diaphragm, the muscle that separates the chest from the abdomen. This opening allows abdominal organs to move into the chest cavity, potentially impacting the development of the lungs. It is crucial to note that diaphragmatic hernia is a severe condition, with a perinatal mortality rate ranging from 30-40%. For survivors, CDH will require surgical intervention after birth.

Duodenal atresia is a congenital condition characterized by a blockage or closure in the first part of the small intestine, known as the duodenum. This condition is strongly associated with Down’s syndrome. Detectable through prenatal screening, duodenal atresia may create a double-bubble appearance on ultrasound, and it is often linked with polyhydramnios (excess amniotic fluid). The blockage can pose challenges in feeding after birth, necessitating surgical intervention to correct the issue.

Echogenic bowel refers to an ultrasound finding where the fetal bowel appears brighter than usual. This increased echogenicity can be a soft marker in prenatal screening. It may be associated with various conditions, including intrauterine infections, chromosomal abnormalities (Down syndrome), bowel anomalies, and cystic fibrosis (CF). While often benign, it can also indicate the need for further investigation. It also can be associated with reduced fetal growth.

Exomphalos (omphalocele) is a congenital condition where the abdominal wall does not fully close, leading to organs such as the intestines, liver, or stomach protruding outside the body and being covered by a transparent membrane. This condition is strongly associated with chromosomal and genetic conditions. Exomphalos requires surgical intervention shortly after birth to place the organs back into the abdomen and close the opening. The surgical outcome will depend on the position of the liver; when the liver is outside the abdomen, some babies may experience problems with lung function.

Fetal Akinesia Deformation Sequence (FADS) is a disorder characterized by reduced fetal movements during pregnancy, leading to various physical deformities. This condition is both clinically and genetically diverse, meaning it can manifest in different ways, and its causes may involve a range of genetic factors. Severe cases of FADS are lethal. Related conditions are Pena-Shokeir syndrome (PSS), arthrogryposis multiplex congenita (AMC), multiple congenital contractures, multiple pterygium and other neuro-muscular disorders.

Fetal hydrops is a serious condition characterized by an abnormal accumulation of fluid in two or more parts of fetal body, such as the skin, abdomen, and chest. This condition can result from various underlying causes, including heart and chromosomal or genetic abnormalities. Fetal hydrops is associated with a significant risk to the health of the developing fetus and may lead to severe complications and death.

Gastroschisis is a congenital condition where an opening in the abdominal wall allows intestines to protrude outside the body. Free-floating intestines in gastroschisis may be susceptible to damage from mechanical friction and amniotic fluid toxicity. Gastroschisis requires surgical intervention shortly after birth to place the organs back into the abdomen and close the opening. The general outcome of surgery is favorable in the majority of cases. Complicated cases may involve liver herniation or result in the loss of part of the intestine.

Holoprosencephaly (HPE) is severe embryonic brain malformation. It is characterized by the incomplete separation of the embryonic brain into distinct hemispheres.  Holoprosencephaly can lead to intellectual and developmental disabilities and facial deformities. The severity of the condition can vary widely, however majority of individuals with HPE experience profound disabilities or die. At the London Pregnancy Clinic, we screen for holoprosencephaly as early as 10 weeks, prioritising early detection of this severe brain anomaly.

Hypoplastic Left Heart Syndrome is the most severe common congenital heart condition where the left side of the heart, including the left ventricle and aorta, is underdeveloped. This complex anomaly hinders the heart’s ability to pump oxygenated blood effectively. HLHS is a critical condition requiring urgent medical intervention, and after involving a series of surgeries. It is also associated with intellectual delays in affected babies. Due to the absence of the left part of the heart, creating a normal four-chamber heart, even with advanced cardiac surgery, is impossible.

Limb reduction defects are congenital anomalies characterized by the underdevelopment or absence of limbs during fetal development. These defects can affect the arms, legs, or both and vary in severity, and the causes can be genetic or environmental. Statistics from the National Congenital Anomaly and Rare Disease Registration Service in England reveal that limb defects are among the most common congenital abnormalities and, paradoxically, less detectable during prenatal ultrasound screening.

Megacystis is a prenatal condition characterized by an abnormally enlarged bladder (more than 7 mm in length) in the developing fetus, typically observed around 11-13 weeks. This condition can be associated with underlying structural or functional abnormalities of the urinary system, with the worst-case scenario being the development of lower urinary tract obstruction (LUTO). While isolated small megacystis may resolve on its own, it can also signal more complex issues, including chromosomal abnormalities.

Polydactyly is a congenital condition characterized by the presence of extra fingers or toes. This anomaly can range from a small, non-functional digit to a fully formed and functional extra digit. Polydactyly is often isolated, however, it can be associated with chromosomal abnormalities, such as trisomy 13 (Patau syndrome), and many different genetic syndromes.

Fetal renal pelvic dilatation (RPD) occurs when there’s swelling or enlargement in one or both of the kidneys. In more severe cases, this enlargement is also known as hydronephrosis. The swelling happens because urine is not draining properly from the kidney to the bladder or down from the bladder. This can be caused by various factors, such as a blockage in the urinary tract or a condition affecting the valves that control the flow of urine. In cases of severe blockage, the baby may suffer from a lack of amniotic fluid. It’s crucial to monitor and, if necessary, provide medical intervention after birth to ensure proper kidney function.

A right aortic arch (RAA) is an anatomical variant in the aorta’s structure, characterized by its position on the right side instead of the usual left. While generally asymptomatic, RAA can exert pressure on the trachea (windpipe) and oesophagus (pathway from mouth to stomach), affecting breathing and swallowing. Evaluation through detailed imaging, especially fetal echocardiography, and a comprehensive head-to-toe assessment of anatomy and associated conditions is crucial. Moreover, there’s a small chance of an association with 22qdel syndrome, a genetic disorder called DiGeordge syndrome.

Clubfoot, also known as talipes, is a common congenital condition where a baby’s foot is twisted out of shape or position. This condition can affect one or both feet. The foot may be turned downward and inward, making normal movement difficult. Clubfoot is usually treatable with early intervention, including casting, bracing, and, in some cases, surgery. In rare cases, talipes can be an early presentation of Fetal Akinesia Deformation Sequence (FADS) or other musculoskeletal disorders. 

Tetralogy of Fallot (TOF) is a common congenital heart condition. Before birth, TOF consisted of three abnormalities: a VSD (hole in the heart’s wall), narrowing of the pulmonary valve and overriding aorta (aorta positioned over the VSD). This complex condition can lead to oxygen-poor blood being pumped into the body. Tetralogy of Fallot is associated with various chromosomal and genetic conditions and structural anomalies. TOF will require surgical intervention after birth.

Thanatophoric dysplasia is severe skeletal dysplasia characterized by abnormal bone development, leading to a small ribcage, short limbs, and a disproportionately large head. The term “thanatophoric” is Greek for “death-bearing,” highlighting the severe lethal nature of the condition. Being rare, TD is the most common lethal skeletal disorder and can be diagnosed by monogenic NIPT for FGFR3 mutation.

Transposition of the Great Arteries (TGA) is a common congenital heart condition where the main arteries, the aorta and the pulmonary artery, are wrongly switched. This leads to an abnormal circulation of oxygenated and deoxygenated blood. TGA is a critical condition requiring urgent medical intervention immediately after birth. It is a congenital anomaly where prenatal detection makes an enormous difference in a baby’s life. Undetected TGA left without urgent postnatal treatment can result in neonatal death.

A Ventricular Septal Defect (VSD) is a prevalent heart anomaly characterized by a hole in the wall that separates the heart’s lower chambers (ventricles). This results in a passage for blood between the ventricles, essentially creating a “hole in the heart.” The opening size can vary, and while some VSDs may close naturally over time, others might require surgical intervention. VSD often occurs as part of more complex heart anomalies. Fetal echocardiography is essential if there are any suspicions of a VSD, providing detailed insights into the heart’s structure.

Ventriculomegaly is the enlargement of the brain’s fluid-filled spaces, known as the ventricles. This condition is often identified through ultrasound imaging around or after 20 weeks of pregnancy. Ventriculomegaly is the most common fetal brain abnormality and can be the manifestation of other more severe neurological conditions. While mild cases are benign and may not lead to any issues, severe ventriculomegaly (hydrocephaly) can be associated with neurological abnormalities and intellectual disabilities. Close monitoring and additional diagnostic tests (neurosonography, MRI, infection screen, amniocentesis) may be recommended to assess the overall health and development of the baby.