Situs Inversus: When Your Organs Get Mirror-Flipped Inside You

In a plot twist worthy of House, MD, the answer turned out to be simple – just unexpected. Osmond did indeed have appendicitis, but “[it] was overlooked because he experienced pain on the left, rather than the normal location, on the right,” wrote Adam Taylor, Professor and Director of the Clinical Anatomy Learning Centre at Lancaster University, in a 2024 article for The Conversation. 

But “in some people, all the abdominal and thorax contents can be flipped to the opposite side,” Taylor explained. “This is known as situs inversus totalis.”

Osmond’s not the only one: the actress Catherine O’Hara also has the condition, as does Enrique Iglesias. You may unwittingly have it yourself – there’d be no reason for you to find out unless, like young Donny, your organs need unusual attention at some point. So, what’s going on?

What is situs inversus?

Put your hand on your chest, slightly left of center. Assuming you’re like most people, you should feel a heartbeat – but every so often, things aren’t exactly where they ought to be.

“Nearly all of the organs in your chest and abdomen develop in your body in a left-right formation,” explains Cleveland Clinic – but “in situs inversus, your organs develop in a right-left formation.”

“For example, the left atrium of your heart and your left lung may be on the right side of your chest. In your abdomen, your liver and gallbladder may be on the left side of your body instead of your right side,” it continues. “Your stomach and spleen may be on the right side of your body instead of your left side.”

It’s a congenital condition, meaning it’s present at birth – reassuring, really, since the alternative would be your organs flipping across your body at some point through your life – and it’s the result of genetic mutations. 

We say “mutations” plural because, well, there’s no one single cause of situs inversus: it’s been linked to more than 100 different genes, as well as having environmental risk factors. You’re more likely to develop back-to-front in this way if your mom has diabetes, for example, or if she smokes or uses cough medicine during pregnancy. It’s also connected to a family history of cardiac and non-cardiac anomalies, and – as is the case with so many health problems – low socioeconomic status. 

There’s even some evidence to suggest that a COVID-19 infection in early pregnancy could raise the risk of organs developing like this, proving that there’s literally nothing about life that the pandemic hasn’t impacted.

But here’s the thing: even if you do have situs inversus, there’s a fair chance you’ll never even know about it. 

What are the dangers of situs inversus?

Besides the main one – that is, your organs being in the wrong place – there’s a decent chance situs inversus can go completely undetected.

“Although your organs are reversed, they’re often still functional,” notes the Cleveland Clinic. “So you wouldn’t notice any signs or complications.”

In fact, we’re not even really sure how rare the condition is: estimates range from one in 1,400 to one in 50,000. That’s not surprising, since a whole lot of cases are, like Mr Osmond, only discovered incidentally, or even at autopsy. 

If that’s the case, the only “treatment” you may need is a medical alert bracelet to let health workers know of your condition in case of emergency – so that if, say, you need an emergency splenectomy, the surgeons don’t cut into the wrong side of your body. Such procedures are more problematic than a simple swip-swap might suggest: “As most surgeons are right-handed, [situs inversus] operations can cause difficulties,” points out one 2022 clinical review of the condition, since “handling the instruments with their left hand or the pedals with their left foot can be uncomfortable. Organ, especially liver[,] transplantation represents an extraordinary surgical challenge.”

Other than that, however, those with situs inversus totalis – that is, a mirror-image transposition of all organs – have gotten off quite easy. It’s when some of the organs move, and others don’t – or even, when parts of organs turn up where they shouldn’t – that things can get really problematic.

Called situs ambiguus, the spectrum between “totally normal” and “complete reversal” is “almost invariably associated with complex cardiovascular malformations,” notes one 2006 medical review, “as well as anomalies of the spleen and the gastrointestinal system.” 

“Over 80 percent of children with situs ambiguus present with complex congenital heart disease,” it adds. 

Danger in ambiguities

It’s perhaps unusual that a condition is worse when it’s less extreme, but it makes sense in this case. You can think of your body as being like a puzzle: it doesn’t just need the right pieces, it needs them to be connected to each other in the right way – and if some of them are misplaced, or facing the wrong direction, then the picture as a whole gets a bit messed up.

So, for example, kids with situs ambiguus are hospitalized more often than those with situs inversus totalis or neither condition; they also have worse nutritional outcomes and more pulmonary issues compared to their peers. Even worse, the mismatch can be extremely specific – organs like the heart, for example, are chiral, meaning they aren’t symmetric, and situs ambiguus can result in malformations like two right atria developing instead of one right and one left.

For whatever reason, the cilia throughout the body often seem to be affected – that can cause problems with your lungs, where cilia are responsible for clearing out mucus and bacteria from your respiratory tract. At best, their dysfunction means year-round coughs and congestion; at worst, it can impair your ability to breathe entirely.

That same ciliary dyskinesia, as it’s known, can cause a perhaps unexpected symptom too: infertility. For women, that’s because the fallopian tubes rely on cilia to transport ova to the uterus – if they aren’t working properly, then the egg simply doesn’t get to its baby-producing destination. In men, it results in malformed sperm, whose tails can’t motor the little guys about properly to find the egg at all.

The real kicker for situs ambiguus though? No two cases are the same. “The spectrum of cardiac malformations that is seen in heterotaxia includes transposition of the great arteries (TGA), double outlet right ventricle (DORV), double inlet left ventricle, atrioventricular septal defects and total anomalous pulmonary venous connection,” notes the 2006 paper. 

“Besides the cardiac anomalies, situs ambiguus is often associated with gastrointestinal manifestations as a right-sided stomach, a midline liver, biliary tract anomalies, intestinal malrotation and poly- or asplenia.”

Treating it, therefore, is kind of an exercise in medical improv, with each prognosis and prescription dependent on the unique situation of that one case. Sometimes it requires heart surgery within the first weeks of your life; sometimes it’s IVF; occasionally it’s a full-on lung transplant.

Whatever the situation, though, it’s worth noting that situs inversus is usually pretty harmless – and even when it causes symptoms, it’s still rare that it reduces your life expectancy. For many of those who have it, it’s just a fun little piece of personal trivia – and for most, they probably never even know about it at all.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.