Causes of Right Side Abdominal (Stomach) Pain

Pain on the right side of the abdomen can be either in the upper part (RUQ ~ right upper quadrant) or lower part (RLQ ~ right lower quadrant). Abdominal pain is a non-specific symptom that can be attributed to a host of conditions. Therefore the presence of other signs and symptoms in association with the pain is important to consider in the differential diagnosis. Modalities may include pain that commences, worsens or eases with change in position, eating, hunger, changes in bowel movements and movement.

The final diagnosis should be done my a medical professional after a thorough case taking and additional diagnostic investigations like an abdominal ultrasound, x-ray, CT scan or MRI. Blood tests and specialized investigative techniques like an endoscopy, colonoscopy or barium enema may also be needed. Broadly, right sided abdominal pain can be attributed to the right lung, diaphragm, kidney, liver, gallbladder, head of the pancreas, small intestine, cecum, ascending colon or transverse colon of the large intestine and peritoneum. The pelvic organs and structures should also be considered in lower right sided abdominal pain. Pain in the abdomen may not originate from this area and can be referred or radiate from the chest, pelvis and back.

UPPER Right Abdominal Pain

Pain in the upper right abdominal region may be superficial or deep. Superficial causes may be attributed to the abdominal wall (skin and muscles), peritoneum, liver and gallbladder. Deeper pain may be due to the liver, bile ducts, stomach, duodenum and kidneys.


Pain may be associated with the lung tissue itself (rare), lining of the lung (pleura) or space around the lung (pleural space). Lung and pleural diseases that may causes right sided abdominal pain include :

  • Pneumonia (bacterial or viral) of the lower lobe of the right lung.
  • Pleurisy or pleuritis (inflammation of the lung membrane) from infection, trauma and so on.

Signs and symptoms may include difficulty breathing, coughing, and pain upon breathing/moving.


The liver is an important consideration in upper right abdominal pain as it occupies most of this region. As a large organ with diverse functions, and the central processing unit of nutrients, the liver is prone to a variety of disorders. Liver conditions that may cause right sided abdominal pain include :

  • Enlarged liver due to heart failure, hepatitis, fatty liver, lymphoma, leukemia, etc.
  • Liver cancer or metastases of other cancer into the liver.

Signs and symptoms may include changes in bowel movements and consistency of stool, nutrient deficiencies, jaundice, changes in appetite and weight loss.


The gallbladder stores bile that is produced in the liver. This fluid contains various compounds, particularly waste substances and fats, and can emulsify fats in the gut to allow for digestion and subsequent absorption. Bile is passed through the biliary tracts which communicates with the pancreatic duct before emptying into the duodenum, the first part of the small intestine. Conditions of the gallbladder and biliary tree that may causes right sided abdominal pain includes :

  • Gallstones or bile duct stones
  • Gallbladder inflammation (cystitis), mostly due to gallstones.
  • Inflammation or blockage of the biliary tree (cholangitis) (cystic, or common bile duct).
  • Gallbladder and biliary cancer are rare.

Signs and symptoms may include jaundice, fatty stools and episodes of pain that are intense (colicky) and generally arise after eating.


The duodenum is the first part of the small intestine and an important site for digestion. It receives the partially digested food mixed with gastric acid and enzymes from the stomach and then bile and digestive enzymes from the pancreas. It is often affected with the same pathologies that afflict the stomach, often a combination of infection and the presence of gastric acid in the duodenum for prolonged periods. Some of the conditions of the duodenum that may cause right sided abdominal pain include :

  • Duodenal ulcer
  • Duodenitis – inflammation of the duodenum similar to gastritis (stomach).

Signs and symptoms include severe pain after eating, although the pain may sometimes ease slightly with food, change in bowel movements, excessive belching and bloating.


The abdominal muscles comprise several groups of muscles that protect the abdominal contents, stabilize the trunk during movement and help with changes in position. Since the abdominal cavity lacks an extensive skeletal protection like the thoracic cavity, the abdominal muscles have to contend with significant impact in trauma. Some conditions affecting the abdominal muscles that may cause right sided abdominal pain includes :

  • Strained muscles – common cause.
  • Hernia
  • Blunt force trauma
  • Rectus sheath haematoma
  • Psoas abscess

Signs and symptoms generally include pain when moving and tenderness on palpation of the affected area.


The kidney is responsible for filtering the blood and forming urine. Electrolytes and water are reabsorbed as necessary and the urine is directed down the ureter to the bladder. The kidney is tucked behind and slightly below the liver on the right side of the abdomen to lie shielded by the back part of the ribcage. Some conditions affecting the kidney and ureter that may cause right side abdominal pain includes :

  • Pyelonephritis (infection of the right kidney).
  • Kidney/urinary stones
  • Renal carcinoma

Signs and symptoms include changes in the urine color and composition, alterations in urinary habits and additional signs like blood in the urine (hematuria).


The diaphragm is the large concave muscle that separates the thoracic and abdominal cavities. It is the major muscle of respiration and on the right side, it houses the liver immediately beneath it. When contracted, the diaphragm pushes down the abdominal contents to expand the chest cavity. Some of the conditions of the diaphragm that may cause right sided abdominal pain include :

  • Abscess under diaphragm

LOWER Right Abdominal Pain

Lower right abdominal pain may be due to some of the same causes discussed under upper right abdominal pain. With the lower abdominal regions, the continuation with the pelvic cavity means that pathologies of the pelvic organs or structures may also be a cause of pain.


The appendix are a small outpouching from the cecum of the large intestine. It is believed to be a reservoir for the normal intestinal flora (good bowel bacteria). It can become inflamed, obstructed and or infected. This may be related to the surrounding parts of the intestine or other abdominal structures or occur independently. Some of the conditions of lower right sided abdominal pain include :

  • Appendicitis (inflammation of appendix)


The small intestine comprises the duodenum, jejunum and ileum. It is the major site of digestion and absorption. Waste products and undigested material pass into the large intestine. The small intestine is also the longest part of the gastrointestinal tract and prone to various conditions that may be a continuation of pathology in the stomach or large intestine. Conditions affecting the small intestine that may cause right sided abdominal pain include :

  • Crohn’s disease affecting the last part of the small intestine, called terminal ileum.


The colon is the main part of the large intestine and has been discussed above. The most prominent part lying on the lower right side includes the cecum and ascending colon.

  • Volvulus twisting of the cecum (starting part of large intestine), rare.


Gynecological causes of right sided abdominal pain are an important and common cause. It should always be taken into consideration especially if the pain appears to be associated with ovulation or menstrual cycle or there are any menstrual changes that accompany the onset of the pain. A slight discomfort with ovulation and menstruation and mild, short lived pain during pregnancy is normal.

  • Ovulation (mid-cycle pain, Mittleschmerz)
  • Twisted or ruptured ovarian cyst
  • Ectopic pregnancy
  • Miscarriage
  • Endometriosis
  • Polycystic ovarian syndrome – PCOS; usually affecting both right and left ovary


Disorders of the male reproductive are unlikely to cause lower right sided abdominal pain with pain in the pelvis or genitalia. Some conditions to consider include :

  • Spermatic cord disorders
  • Testes disorders


The blood vessels in the abdomen include the large aorta and inferior vena cava, with the various branches and tributaries. These blood vessels are prone to a host of diseases that may be isolated to the cardiovascular system or part of a systemic condition. Some of these conditions include :

  • Hereditary angioedema
  • Henoch-Sch√∂nlein-purpura
  • Atherosclerosis of arteries that supply the intestine


  • Porphyria
  • Sickle Cell Disease


Conditions affecting the skin may be responsible for upper and lower right sided abdominal pain. Skin lesions or deformities may be present, including a rash, swelling and/or redness. Most skin diseases present with itchiness but pain may be seen in the following conditions.

  • Herpes zoster
  • Dermatitis (eczema) when the skin is broken or there is an infection.


The peritoneum mainly envelopes the gastrointestinal tract in the abdomen and peritoneal fluid keeps the organs lubricated when making contact with each other. Inflammation, infection and swelling may be associated with peritonitis.

  1. Read more here for a detailed description of right upper (RUQ) abdominal pain.
  2. Read more here for a detailed description of right lower (RLQ) abdominal pain.
About Jan Modric (249 Articles)
Health writer

Please note that any information or feedback on this website is not intended to replace a consultation with a health care professional and will not constitute a medical diagnosis. By using this website and the comment service you agree to abide by the comment terms and conditions as outlined on this page

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  • Hi MIchelle. Hopefully you have instituted the dietary changes advised after your gallbladder was removed. Failing to do so can cause most of the symptoms you have described, especially after meal time. It may be advisable to follow up with the surgeon who operated on you. This could be a sign of adhesions which does sometimes form after abdominal surgery. However, further diagnostic investigations are necessary to confirm whether this is due to adhesions or some other cause.

  • Michelle Pilote

    Thank you..I have maintained & normally do have a great diet…but these days everything hurts. I do understand the importance of maintaining a balanced diet once your gallbladder has been removed. I will ask about adhesions. …this has always been an an ongoing red flag because I’ve had over 25 surgeries most of which are in the abdominal area. I appreciate your advice. I, however, still suffering greatly with no anwers.

  • Hi Michelle. With 25 procedures (we assume that it is all abdominal) the risk of adhesions is very high. Surely this should have been suspected as a possible cause by one of your health care practitioners. Maybe there were already investigations done to confirm or exclude its existence. Unfortunately pain on its own does not give much indication of what the problem can be. We would strongly advise that you seek answers from a medical professional. You could spend long periods of time (wasted) looking for answers online but without further investigations it would be pretty much anybody’s guess. The longer you wait to seek one-on-one medical attention the worse the prognosis may be. If it is indeed adhesions there is nothing than can be done without further surgery to remove it. Hope you find answers soon.

  • Sabrina Matthews

    Jamie , I have had this same type pain this past week. Have you seen a doctor?

  • Lee

    If your getting pain in your upper right shoulder, color bone area its your gall bladder sure of it! I had it too and when my gallbladder was removed it felt better immediately and the pain stopped completely. I am not the only one that has experienced that shoulder area pain. Talk to your doctor.

  • Hi Lee. Thank you for your input. As you can read from our article it clearly states that the location of gallstone pain can be the right shoulder. It is a common symptom that may people with gallstones or other gallbladder problems do experience. However, this is not the only cause of shoulder pain. Sometimes even a heart problem can lead to right shoulder pain, although left sided pain is more typical. Please refer to the date on comments before commenting. While input it appreciated, it may not longer be relevant for a person. This question was answered a year ago.

  • Cliffany Reed

    I have been told i have a hernia but nor sure. today im having symptoms of my right side being swollen and feeling like somering is boldging out and feels wierd and slightly painful. Feels like i have a baby pushing on the lower right side of my stomach and thats impossible because i am a male.. i have had my apendix removed August of 2014, would that have antthing to do with it? This started just 30 mins ago after eating..

  • joydas

    I fell and a blunt corner hit my lower abdomen right side did USG doctor told internal wall injury but internal organs okay still abdomen pains after 2 months please suggest.its urgent

  • justine

    Hi I’ve been having mild pulling sensation on groin on right side for few months now also very noisey tummy docs done exam andbloods came back ok. Ive had 2 ectopic pregnancies could this be scar tissue?

  • Hi Cliffany. You should have your doctor confirm whether it is really a hernia. It does sound like it. If so then you will need to speak to your doctor about the possible treatment options. Surgery is usually necessary for an abdominal hernia. Don’t ignore it. Hernias can worsen over time and may eventually trap a portion of your bowel with serious and even life-threatening complications. Your doctor will advise you further.

  • Hi Justine. Scar tissue is a possibility but it is not wise to assume. There are many other conditions could be responsible. The pulling sensation and tummy noises may be unrelated to each other. It is advisable that you consult with a gynecologist if you have not already done so or seek a second opinion from another gynecologist if necessary.

  • angel

    I had my gallbladder removed October 14th 2014 and I’ve been having abdominal pain ever since and today I threw up green bile after starting off by waking up with the same headache from the day before and nausea all I did was go up stairs where the two little kids I babysit was told them to get ready for the day and went back down the stairs just to rush to the bathroom to throw up the nasty green bile go my friend to come home which then brought me home I took a nausea pill then went to sleep I at dinner and had a little of beef and nacho cheese tonight what should I do ?? I should add its not on the right side that I’m having abdominal pain its all the way across to the left side and it makes it uncomfortable for me to sleep

  • Hi Angel. Hopefully it has resolved by now. The odd episode of vomiting that lasts for a day or two is not always a cause for concern. It often arises with food poisoning and tummy bugs. However, if it is persisting then you need to see a doctor. There is really not much else we can advise online. Don’t take nausea pills to suppress the symptoms unless your doctor says so.

  • Ellen Corwin

    Hi. 3 years ago i had my right kidney removed due to stage 3 (pT3A,Nx,Mx) kidney cancer, NED since. Now on rare occasions when I’m moving my bowels I get a severe pain to the right side of my navel extending an inch or two down and an inch or two up from navel (but all on right side). Prior CT scans consistently show a stricture in the ascending colon. Could that be causing this pain? I have regular CT scans next month but just thought I’d ask what you thought. The pain is pretty severe and lasts a minute or two, then goes away. Can anything be done about it?

  • Hi Ellen. Yes, it could possibly be the cause of the pain but this is a question best answered by the doctor who is overseeing your case. With regards to treatment options, it really depends on the nature and severity of the stricture and other aspects of your medical history. You should speak to your supervising doctor about your treatment options.

  • Alissa Rosenbaum

    For the past 5 months my body has not been the same . I been with my boyfriend for that long but known him way before . I am sexually active and i have tried to get pregnant with the same guy . My period is normal comes every month but i have been feeling this pain in the right lower side of my stomach next to my belly botton its like if i pulled a muscle but i dont remember doing anything to cause that . Im not a physical active person i hate running and all that but lately its been hurting for 2 months already and i havent gone to a doctor and this month i started my period on july 9th and the smell and color of it is awful . The color has been black not brown its been black . I know when you’re ending youre period the after blood comes and its a brownish color but this is like 2nd day blood its been like this for already 3 – 4 days with this awful stench like rotten meat . So i have no idea what to do i turn 20 in a cupple of days and i just need help

  • Mariem

    Hi, so i’m 18 and for at least the past two years i’ve been having this pain on my lower right abdomen by the iliac bone (i think that’s what it’s called) it feels as if there’s smothing noded or a stone stuck in there or something so i got an ecography but there was nothing also i don’t know what triggers it exactly, i mean the pain is ”random” it could stay for 3 to 4 days then nothing for a couple of months. Any idea what can it be?

  • ac

    Look up Nephroptosis. I’ve had the Full Hysterectomy as well and found out in Feb right side pain was a Dropping Kidney … Surgery corrected and All is Better!!

  • ac

    Nephroptosis… You can Google symptoms and see if they fit?

  • Leeca

    Consider seeing a GI specialist. It could be a stone in the CBD (common bile duct) and if ends up completely blocking the duct it’s an emergency that requires immediate surgery. Better to find out and have it removed before it reaches that point

  • Leeca

    Please. Go to the Emergency Room. Immediately.

  • Edna ibe

    in April this year i noticed i had serious pain in my chest and at the right side of my tummy. although the pain was mild but it became worst with each passing day. i lost every desire to eat, i was depressed and always anxious. my heart keeps skipping beats every minute. after 2 months i went to see the doc but when i got there he just said i have ulcer without running a test or carrying out any examination and i complained of a growing bump in the right side of my tummy but he said he couldnt see it. i took the drugs but now i notice heaviness in my chest, i cant take a deep breath, i cant breath easily without feeling some strains in my chest. the pain at my right side of my tummy is still there. sometimes i feel so weak and exausted even without lifting a pin. most night i wake up to my heart racing very fast and skipping beats and my hands shaking. my tummy gets bloated at any little food i eat. pls whats going on, what do i do? i need help sir..

  • Amit Sharma

    Hi, I am feeling little discomfort or sort of streched muscles under my ribs on right side of uper portion of abdomnal. I have travelled a lot in last one month and have driven a lot. I am feeling this discomfort or stretched feeling in excess, especially when I am driving or sitting in a particular posture. There is no pain in that area…….but some times in past as well I had cramps on the sameside……..Please guide

  • Hi Amit. As you have mentioned you have been quite physically active recently. Even prolonged sitting when driving can strain muscles. It could very well be muscular but it is always better to be safe than sorry. Speak to your doctor about your symptoms and let him/her run further tests if necessary. Given the number of different organs in this part of the body, pain may be the first sign of some underlying internal disease.

  • CeCe

    My DD is 17 had has been suffering with severe pain in her upper stomach above the belly button since she was 11. Only since last year have the doctors taken me seriously with prior diagnoses from hospital, gp and walk in centres as being constipation, gas, psychological etc.. Although these do not match her symptoms. She has daily bowel movements no blood and no pain when going etc… The pains are getting worse and are daily from the minute she wakes till she goes to sleep, it even wakes her up in the night as the pains, so bad! She can only take paracetamol and is is on buscopan and omeprazole daily, none have helped her symptoms. I’m at my wits end, I cannot see her suffer no more, the pain she is in is unbearable it has had a huge affect on her daily life. She no longer goes out and has been sacked from her apprenticeship and part time job because she had to keep taking time off with the pain! The hospital have done scans blood tests and a breath test nothing showed up, only inflammation showed up once on her bloods and low vitamin D? A few weeks ago a scan showed she had polycystic ovaries but apparently this can’t be confirmed until she sees a specialist in January next year!! We have been told that condition would not cause the pain she’s experiencing?! She’s also been getting severe head pain we have been referred to a neurologist and are waiting for an appointment date to no avail!! The hospital seem to think she may have benign intercranial hypertension which is linked to polycystic ovaries!? Our gp will not give her pain relief and tells us to try yoga or meditation, it does not help! ! The specialist at the hospital thinks it maybe gastritis but the medication is not helping so I have my doubts!! Does anyone have any idea what this could be?? I can’t take this no more its heartbreaking to see my baby going through this daily….

  • Tom Taco

    ….All my life I thought poop was supposed to be black. Turns out it should be…..brown?

    At this point should I do anything? I mean, it’s not like black poop has done all that much damage to me. I mean, sometimes when I eat too much chipotle my dumps are extra hard and I tear up the anus a bit, but otherwise my poops are usually pretty good!

  • Hi Tom. While the black stool could be due to food, if it is persisting for years as you describe then it is more likely that it is due to other conditions, like bleeding within the gut. This would need to be treated. Even though a minor bleed may not cause any major complications, it can lead to iron-deficiency anemia. However, this is assuming that the black stool is degraded blood. There may be other factors that need to be considered here and you should consult with a gastroenterologist.

  • Eric Gordon

    Hi People,
    Male 40 something looking for some advice. For a number of months I’ve had abdominal pain. It’s on my right hand side at the front, just above the pelvis and usually at the back behind my ribs. Usually bad in the morning and occasionally I’m sick first thing. It seems to “flare up” every couple of weeks, but never goes away. Normally eases as the day goes on. On a good day this can be from lunchtime, normally it’s from early evening onwards but at its worst it can be all day.
    I’ve had various scans and tests. The only thing they found were a number of kidney stones in both kidneys, but all less than 5mm. I had 3 stones removed six months ago from the right kidney but it hasn’t helped unfortunately. Kidney surgeon said he didn’t think the stones were the cause of the pain. Scopes were all clear. Heart scan was OK.

    Sometimes the pain is all round my right flank, across my lower back and down to my groin.
    Other health problems that may or may not be related. High BP that they can’t seem to get under control despite being on 3 different meds. Also suffer from acne, which seems to have gotten worse along with the abdominal pain. Mostly back and thighs. Fatigue, and sometime joint and muscle pain.

    When I press quite hard in my stomach I get a really sharp pain, which made me think appendix but I don’t know if the other symptoms would fit.

    Oh, another thing. In the morning I feel like a zombie. trouble getting out of bed, brain fog and my eyes seem a funny colour.

    Every day seems like ground hog day and I don’t know where to turn now.
    Any help appreciated,

  • Daisy

    Intermittent severe RLQ pain (seemingly when constipated), off and on for two years, along with abdominal distention (pretty much consistently). Additionally, intermittent numbness in right leg (from right hip to tip of toe), when standing, approx. three months now. Pain is made worse by moving around or lying down, however numbness noticed only when standing. Blood in urine microscopic as well as hematuria off and on for three years did cystoscopy X 3 but found nothing. Any advise or help would be greatly appreciated. Thank You-

  • Sarahistic

    Hello. I am girl and 17. From past 3 4 days I’ve been feeling pain on kidney area. The right side. I took a pain killer. It decreased. But now it has increased. Now it’s on left also sometimes. After drinking water I feel fullness. And frequent urination. And pain in right side while urinating. Pain while I walk. . And also the problem of constipation That comes and goes.. help!!!!!!

  • YB

    HI, starting last night I am feeling a pain just below the rib cage in the upper right abdominal area when I breath and change sleeping position while I’m on my bed. I would like to know what causes this? Any advice?

  • Zenia

    I have been having pain on the upper right side that feels like a Charlie horse – it sometimes radiates to the left side and I get “stuck”! I don’t know what it is but it scares me! When it happens I have to lay flat or stay in the position where it doesn’t hurt. What could the cause be? I don’t have my gallbladder. I’ve recently started to feel nauseated with the pain which is something new. Any feed back will be appreciated.

  • Yatt

    hi, recently i keep getting nausea, vomiting & headache. I also having throbbing stomach. I don’t know what to do. I keep getting pain at right side of lower part of my stomach. Nearby waist. I also having pain at right side at lower side of my diaphragm.
    Even it feels painful when I want to urinate.

    What should I do?

  • Hi Yatt. Firstly the stomach is more on the left and high up where it is almost completely tucked under the ribcage. From what you are describing this is more likely to be a urinary tract problem, possibly even a urinary tract infection (UTI). However, it could also be a gallbladder problem but that usually does not present with urinary pain. At thsi point you need to speak your doctor. Most likely there will be further tests needed and then a diagnosis can be reached.

  • Yatt

    Hi HealthHype. Thanks for your info. Yes indeed it was the same result told by the doctor.
    At first I didn’t want to go to hospital. But now I am taking antibiotic for urinary tract infection.

  • Hi Yatt. We are glad that our response was helpful and that you doctor confirmed the diagnosis. Please follow through with the antibiotic course as prescribed by the doctor to ensure that the infection is eradicated. Don’t forget to follow up with your doctor thereafter.

  • Karen

    HI and i sure hope you answer,i am a 61 year old female,was never really sick and most people couldnt believe i had so much get up and go,very active all the time. i was having chest pains one day went to emergency roon. long story short,they found a mass turned out to be lung cancer. March 16th i had a lobectomy,half my lung removed,now i felt fine before i had this done,i had complications afterword with my oxygen way to low nothing bringing it up well 3 weeks later and my family all there thinking i was gonna die,it started to come up. im sorry this is so long but you needed to know. any way i was in ICU for 3 weeks and spent a little over a month. It is now Aug,10th and ive only had two bowl movements in the last month,i will feel like i really have to go and it goes away, or i sit for a very long time. Ive tried lax. ennemas,i have told my DR”s about it and they dismiss it,now across the whole top of my stomach is so tender,i sometimes get a very sharp pain right under my right breast and on my upper right side,and my lower right back always hurts, i have been telling all my Dr about these and there just not doing anything, Should i find new dr Im scared. Thank You so much if you take time to read this

  • Hi Karen. The strict definition of constipation is less than 3 bowel movements in a week with the passage of hard stool that is often difficult to pass out and requires some degree of straining. Two bowel movements in a month would definitely be considered as constipation. It may occur for a host of different reasons and could be related to your recent medical history. It definitely needs to be investigated further and treated to prevent complications like fecal impaction. This further investigation and the prescription of the appropriate treatment needs to be done by a doctor. If you are not receivng the attention your require from your current doctor(s) then you will need to see another doctor. If possible, consulting with a gastroenterologist at this point would be highly recommended.

  • dymeisha scrutchins

    I turned the wrong way or something at work the other day now my side hurt when I move a certain way what can it be

  • Hi Dymeisha. It’s difficult to say with so little information and other symptoms present. As you can see from the article above there are many possible causes for abdominal pain. However, from what you describe this is most likely muscular. One or more of the muscles may have been strained and are in spasm at the moment. Therefore movements involving this muscle or opposing it may cause pain. If the pain is still persisting, you should see a doctor as soon as possible.

  • Lara

    I usually sleep on my left side, but for the last couple of weeks I have been getting extremely sharp pains in my lower right abdomen area while sleeping. The pain usually wakes me up and then it is difficult to move and change to a more comfortable position. The pain dulls when I turn to the right side, but when I get up its back again. I thought it might be my appendix at first, but considering its been going on for weeks I doubt it. Also don’t have any other symptoms like fever, constipation, runny tummy, chills, etc. What could this possibly be?

  • Hi Lara. The abdominal cavity has many different organs and it is difficult to isolate a cause for pain on its own without any other symptoms. Appendix would be a logical assumption but as you so rightly pointed out, it is unlikely to be the cause. It is not only digestive problems that could be a cause but even gynecological, muscular, urinary problems and so on could be a cause. There is really no way to say for sure unless you consult with a doctor who can perform the necessary diagnostic conditions to identify a cause.