Should I be worried if the positions of my baby’s organs are reversed?

SINGAPORE – For centuries, anatomists were baffled by spleens, hearts and other major internal organs found to be on the “wrong” side of the human body, appearing mirrored from their normal position.

First recognised in medical literature in the 1600s, situs inversus, as the rare genetic condition is known, is found in one out of every 10,000 people.

In May, a foetus was diagnosed with situs inversus in Wuhan, making headlines in China. The parents of the so-called “mirror baby” boy were uncertain whether the pregnancy should be terminated.

The Straits Times answers concerns about the congenital condition and how common it is here.

Q: How do internal organs form on the ‘wrong’ side of the body?

A: More than 100 genes have been linked to defects affecting organ placement and development in the early stages of foetal growth.

This can manifest as situs inversus totalis – the complete reversal of internal organs – or situs ambiguous, also known as heterotaxy syndrome, where organs are partially transposed from their usual position.

According to a regional study of infants in the United States, patients with reversed organs were found to be more likely to have mothers diagnosed with diabetes, fathers who smoked and a family history of heart defects or other anomalies, among other factors.

But what causes the condition remains a mystery in many cases, said National University Hospital (NUH) senior consultant Chen Ching Kit, who has about 21 years of medical experience.

Dr Chen, who works at the division of paediatric cardiology, sees a case of situs inversus every three to five years.

He said: “More than 50 per cent of the time, we don’t have an answer; we test the genes and things turn out to be okay. We don’t know why the condition happens.”

Q: How common is the condition in Singapore?

A: Situs inversus is rare in Singapore. Every year, one or two cases are detected at KK Women’s and Children’s Hospital (KKH).

The condition is usually discovered when foetuses are screened via an ultrasound scan at around the 20th week of pregnancy, said Dr June Tan, a senior consultant at KKH’s Department of Maternal Fetal Medicine.

Dr Tan said parents who have babies with situs inversus are advised to get them a detailed ultrasound scan to assess for any associated complications, so they can plan for appropriate and timely care for the child post-delivery.

For instance, those with congenital heart diseases may require open-heart surgery to correct the defect.

Q: Will children with reversed organs have health complications?

A: Professor Quek Swee Chye, who heads the division of paediatric cardiology at Khoo Teck Puat – National University Children’s Medical Institute, said: “The condition generally does not have implications on the health of patients unless there are other associated conditions.”

A 2020 study of 155 children with situs inversus in China found that almost one in four had other health conditions, with many having abnormalities involving multiple systems, especially cardiovascular and respiratory problems.

Patients with situs inversus and a heart on the left side of their chest may have a slightly higher frequency of heart defects, said Prof Quek.

Those with conditions where organs are partially mirrored are more likely to have complex congenital heart anomalies, he added.

Studies have also found that some genetic conditions known to occur together with situs inversus can remain undetectable until youth or even adulthood. These include eye disorders that cause vision loss and kidney disorders.

Knowing that a patient has situs inversus is also crucial in emergencies.

Prof Quek, who chairs NUH’s medical board, said: “It is useful for doctors to be aware of the condition in these patients when performing procedures or surgery, or in making diagnosis. 

“For example, appendicitis will have left-sided abdominal pain instead of typical right-sided abdominal pain.”

Because of the condition’s rarity, most surgeons do not have much experience in dealing with such patients and require more flexibility and creativity, as well as detailed scans to adapt surgical techniques.

At KKH, records of genetic conditions associated with structural anomalies, including situs inversus totalis, detected during antenatal ultrasound scans are kept, said Dr June Tan.

Q: What can parents do if their child feels down about having a rare genetic condition?

A: Children with genetic conditions such as congenital heart defects may feel different because of their physical limitations, said Dr Chen.

He said: “To the extent that it does not harm the kid’s health, we should allow the child to do whatever the child wants in terms of activities... to show kids that despite their limitations, there are things they can still do, and they can potentially do better than other kids.”

It is also important for parents to be open about the child’s condition, as far as the child can understand it, he said, adding that when patients reach their teens, they might decide to skip medical check-ups because they are unaware of their condition.

Dr Chen said: “It’s hard to predict whether they will go into depression or will be feeling different. It’s something we need to watch out for.”