In the last year and a half, I’ve been able to go to Africa 4 times and Haiti once, for which I give thanks that the world still produces abundant fossil fuels. That much airplane travel does make me feel a bit guilty, even though I’m not actually vacationing.

Going to far away places to practice medicine has always been something I hankered after, and it turns out that knowing how to do and teach ultrasound is a good way to get invited to exotic places. I think if I could do cleft palate surgery or eye surgery or had a traveling dentistry practice I could also be useful in foreign lands, but as an internist it is more difficult to find something that I can do well in a hit and run fashion which actually benefits people. Bedside ultrasound, particularly teaching it, fits the bill.

Forgive me for repeating myself if you’ve already heard the story, but when I quit my regular primary care practice, I learned to do bedside ultrasound. I fell quickly in love with the ability to see inside people, sharing with patients their living anatomy, quickly making appropriate diagnoses and designing appropriate management, following patients’ response to therapy. I learned how to ultrasound the heart, lungs, liver, gallbladder, kidneys, bladder, spleen, intestines, great vessels, and also how to teach other people. It’s been exciting and time-consuming and tons of fun, and has become an integral part of my practice as an internist and hospitalist. I’ve written many blogs about how ultrasound has changed my practice, but I still get the question, “What’s it good for?”

What it’s good for varies according to the setting. A bedside ultrasound is usually done with a machine that is small enough to carry in one hand. Mine, a GE Vscan, is about a pound and has a screen that is just a few inches across. It gives surprisingly good pictures, but they are nowhere as good as the big ultrasound machine in the radiology suite. If that big machine was pocket sized, I’d be like the doctor on Star Trek. Because the bedside machines are smaller and less expensive than the full-size ones, their resolution is a little bit worse, so they are best for asking relatively simple questions.

Also, bedside ultrasound is performed by doctors who also do things other than imaging and haven’t spent the extensive amount of time radiologists have in learning subtleties of reading radiological images. At my hospital in the U.S. I can answer questions with my small ultrasound machine like, “Is there fluid in the peritoneum?” or “Are there gallstones?” or “Is the heart squeezing OK?” or “Are the kidneys/ureters blocked?” I can feel confident about whether the bladder is overfull or whether there is fluid or infection in the bases of the lungs. I can see pulmonary edema and amounts of pleural fluid that are too small to be seen on x-ray. I can follow the course of intestinal distress such as gastroenteritis or obstruction.

Sometimes I can’t see enough to say anything, most often if the patient is hugely fat or is plastered with bandages or stickers that I can’t remove. If I need to really know what is going on inside a patient who I cannot image with a bedside ultrasound, I can order a radiological study and usually get my answer in a reasonable time period. When I can look myself, though, my treatment decisions are more fluid and timely.

In the developing world, there are fewer x-rays and CT scans available, fewer official ultrasounds, and having the ability to do bedside ultrasound is pretty magical. There are many ultrasound machines in these out of the way places, and what is mostly needed is training. There could be more machines, of course, and when it becomes clearer how useful the technology can be, more resources may be focused in that direction. I have ultrasounded in Tanzania and South Sudan and the island of La Gonave, off the coast of Haiti, and the procedure, quick, painless and free, was profoundly influential. Last month, while I was in South Sudan there was a war on nearby, and there were freshly and not so freshly wounded soldiers, which was a new thing for me. Here are a few cases of exactly what ultrasound has been good for in the developing world:

1. Young man with a gunshot wound to the leg. Is it broken? Is there a pus collection? Ultrasound is really good for ruling out long bone fractures and finding subcutaneous fluid collections. The wound was only in the muscle, and a little cleaning and bandaging did the trick. No need to transfer this one to a higher level of care.

2. Different young man was injured in the face with shrapnel. He is unable to see out of one eye. Is the retina damaged? (A bad sign.) Ultrasound is quick and efficient as a tool for looking at the eye, especially if the patient is unable to open it for an exam. This guy did have a thickened and abnormal retina with evidence of blood in the posterior chamber and a metallic foreign body. He is not likely to get his sight back in that eye.

3. Little boy shot in the chest and short of breath. Is it a punctured lung? A burst blood vessel bleeding into the chest? Is the heart damaged? For this boy, it was none of these things, but a contusion of the lung, which looks a bit like pneumonia on ultrasound. A chest tube would have further compromised that lung and the boy avoided this procedure. Where is the bullet? It would have been great to have an x-ray to find that out!

4. A young woman with vaginal bleeding after three months of thinking she was pregnant. Is she having a threatened miscarriage or is this just an irregular period? Ultrasound is wonderful for seeing a uterus and whether there is a baby hiding inside. We saw many of these cases. Sometimes there was a baby, sometimes not. The treatment, bed rest vs. normal activity, was very different and knowing which was indicated could profoundly impact the whole family.

5. A little baby with an enlarging lumpy area on the lip. I could just imagine all of the creepy things it could be. The ultrasound showed it to be made up of blood vessels, so it is a cavernous hemangioma, which is a common benign tumor in infancy and usually goes away or shrinks by itself, and sometimes requires medications to help it go away.

6. A young man has been getting weaker, with swollen legs and a barrel chest. Is it heart disease? Perhaps something he was born with? These might be treatable with medications. Unfortunately, it was not. There was a huge tumor obstructing blood flow to the heart and lungs. Good to know, though heart-wrenching.

7. An old man, failing to thrive. He has back pain. Ultrasound shows he has a large bladder tumor which is blocking his kidney. Caught this late, and in a war zone, this is not treatable. Knowing helps his family to make plans.

8. An uncharacteristically pudgy woman with recurrent abdominal pain. Is it an ulcer? Actually no, her gallbladder is full of stones and is tender to push on. Surgery will help, and this lady lived in a place where that was safe and available.

9. A young woman with pelvic pain. Is it a tubal infection? A bladder infection? It is not hard to visualize the abdomen and pelvis with ultrasound, and this person had a ruptured ectopic pregnancy with blood loss into the abdomen. She will die without surgery, and she will likely do fine with it. She was rushed, appropriately, to surgery.

10. A woman with a full term pregnancy: she hasn’t been feeling the baby move. Is it in trouble? Ultrasound is absolutely wonderful for looking at babies since they float around in a big balloon of water. This woman’s baby looked healthy. Good news.

11. A woman acutely short of breath, with some chest pain: Is it asthma (common) or her heart? Strangely enough, her heart wasn’t squeezing very well, and her lungs looked wet. She responded well to medications for pulmonary edema and was fine the next day. I have no idea what that was about, and can’t find out further because I’m home, and she is probably lost to follow-up.

12. Pyomyositis: People get collections of pus in their legs and sometimes arms for no obvious reason. Then they get very sick, and if the pus is not drained, they die. When a leg is swollen up, it’s pretty hard to know where to cut to release the pus unless something like an ultrasound tells you where it is. We doctors love draining pus. The young man in question, a retired child soldier, had relief of his condition and will get well.

13. A soldier, clearly sick after being shot in the belly: Has the bullet injured a blood vessel or vascular organ? Is there a significant amount of free air to suggest a major intestinal perforation? The FAST scan (focused assessment with sonography in trauma) looks for fluid, usually blood, in the belly and can determine whether a patient needs emergency surgery, if available, to avoid bleeding to death. Lots of free air looks like air anywhere, with air artifact and multiple parallel horizontal lines. This young man had peritonitis, with thickened bowel walls, fluid-filled bowel loops and small amounts of fluid between the intestinal loops. He was transferred to a higher level of care after receiving antibiotics and fluids.

Also, babies with loud heart murmurs, young men with testicular swelling, the worried well …

Ultrasound in the developing world is great.

Janice Boughton is a physician who blogs at Why is American health care so expensive?