The Abdomen Part III: The Right Lower Quadrant

The Right Lower Quadrant

The abdomen can be separated into four quadrants:

  • LUQ (left upper quadrant)
  • LLQ (left lower quadrant)
  • RLQ (right lower quadrant)
  • RUQ (right upper quadrant)

The right lower quadrant The right lower quadrant (RLQ) contains the following:

  • Right ureter
  • Right ovary
  • Right fallopian tube
  • Appendix
  • Small intestines
  • Ascending large colon


The paired ureters (one in the LLQ and one in the RLQ) drain collected urine from their respective kidneys and travel under the floor of the abdomen to the pelvis, where they drain into the bladder. Drain is not the right word, because they exhibit undulating musculature that “milks” the urine down the line, which is known as peristalsis, and spits urine into the bladder every few moments.

Like all structures covered with the lining of the abdomen (peritoneum), this lining is very sensitive to distension, be it from a bubble distending a baby’s colon in colic or a distending ovarian cyst (see below). Two things can cause a painful distending sensation in the ureter:

  • Ureteral spasm—This can be caused by a urinary tract infection, but it is more typically is produced by a kidney stone.                    
  • Obstruction from a stuck kidney stone trying to pass.

This RLQ pain is colicky, sharp, severe, and intermittent. It is painful enough to cause collapse, and the ER is needed. The pain originates on the one side and radiates downward; this pain is more dramatically when a kidney stone is traveling. The urine is often blood-tinged.

As with any pain presenting on the right side, the appendix must be considered (see below).


Ovarian cyst:

The ovary on the right is the counterpart to the one on the left. In a normal monthly cycle, a follicle ripens in preparation for release of an egg, a process known as ovulation. If that follicle becomes exaggerated in size and grows to more than two centimeters, it is then deemed a cyst. This measurement is more than just an arbitrary dividing line because it is the size beyond which its peritoneum covering, which is sensitive to distention, becomes painful. Such cysts usually dissolve away spontaneously, but if they persist, as with menstrual cycle irregularities, ovarian tumors, or bleeding into themselves, they will require more aggressive evaluation, which is usually done with an ultrasound or a CT scan. An ovarian cyst can be caused by a pre-ovulatory cyst (a follicular cyst) or a post-ovulatory cyst (a luteal cyst).

The pain from an ovarian cyst is sharp, one sided, and specifically isolated enough such that a woman can point to it with one finger. When an ovarian cyst ruptures, the pinpoint pain suddenly stops, but this relief is quickly replaced with a vague, spreading dull ache across the pelvis. This development represents the sudden release of the distension via cyst rupture but the beginning of pain from the leaking of bloody fluid into the pelvis.


Another source of pain on or around the ovary is endometriosis, which is an unfortunate implantation of menstrual-like tissue that can cause a sharp burning or aching sensation on the side it resides. Since this is hormonally active tissue, just like the lining of the uterus, its flares are timed with the menstrual cycles, giving a crucial clue to the source of the pain and the diagnosis. Endometriosis is often tamed (but not cured) with the hormonal suppression that comes with oral contraceptives (birth control pills).

Fallopian tube

Each fallopian tube can transport an unfertilized or fertilized egg from the ovary into the uterus, which is midline in the pelvis. Two sources of fallopian tube pain are the following:

Ectopic pregnancy:

If a fertilized egg gets stuck in the tube on its journey to the uterus, an embryo will begin developing there in a condition known as an ectopic pregnancy. The tube doesn’t lend itself well to distension, and this becomes the case of an unstoppable force meeting an immoveable object. The tube’s distension is painful and is similar to what occurs with an ovarian cyst, as it reaches a point of critical mass that results in rupture. Like a ruptured ovarian cyst, the sharp isolated spot of pain is suddenly relieved but is replaced by a vague burning sensation across the pelvis. The problem is worse, however, because the bleeding is worse, and it can sometimes be so severe as to be a life-threatening hemorrhage. Such a hemorrhage is a surgical emergency. If an ectopic pregnancy is caught before it goes on to rupture, medications can be given to shrink the pregnancy without surgery.

Salpingitis: This condition refers to the inflammation of the fallopian tubes and occurs due to infection. The most common culprits are gonorrhea or chlamydia. Treatment of this condition is with antibiotics, but if it is in the form of an abscess, it may require surgical drainage. If there is no abscess, the patient can be treated as an outpatient via one of several treatment regimens: one involving the use of ceftriaxone and doxycycline and another involving the use of probenecid, doxycycline, and an injection of cefoxitin.

These treatment regimens cover both gonorrhea and chlamydia since half of all persons with a STD typically have a second STD. If trichomonas is present as well, metronidazole (Flagyl) can be added.

Large bowel

Diverticulosis: This is a weakness in the bowel wall that causes a sac-like protrusion, which is known as a diverticulum, that can get infected (diverticulitis) and cause pain, usually from its very location in the LLQ. If hard fecal pieces cause blockage, the diverticulum can rupture. Usually, diverticulitis can be treated medically with antibiotics and a change in the diet, but in some cases, surgical removal of the diseased segment is required.

Treatment with antibiotics can be with ciprofloxacin and metronidazole, trimethoprim-sulfamethoxazole, and amoxicillin/clavulanate (Augmentin).

Appendicitis: This condition is mentioned because the worm-like (vermiform) appendix hangs off the beginning (cecum) of the ascending large colon. See below for the section on the appendix, which deserves its own subheading in respect to the RLQ.

Small bowel

Infections of the abdomen, adhesions (see below), or cancer can cause obstructions, and the RLQ is no exception, because the small intestines are primarily in the lower abdomen.

Crohn’s disease: This is an inflammatory condition of the wall of the intestines (small and large) that can lead to strictures and obstruction. It can happen anywhere in the gastrointestinal tract, so the abdominal pain is not limited to the RLQ.


What is limited to the RLQ, however, is the appendix. Weird genetic conditions like situs inversus, which is where the normal anatomy is reversed, can put the appendix in the LLQ, which understandably results in missed and misdiagnosis, but that is very rare. The life-saving caveat has always been:

RLQ pain is always appendicitis till proven otherwise.

Often thought of as an evolutionary holdover, the appendix is an immunological organ. Thankfully, the body can do fine without it, which is all the more important because sometimes it needs to go. Indeed, its thinness allows things, such as fecaliths, to get stuck in the GI tract, promoting infection. If such an infection inflames the entire appendix, it is deemed appendicitis. Because of a strange referred pain phenomenon, appendicitis begins as pain around the navel, and then over a day, the pain migrates to the RLQ. It is accompanied by a mild fever and nausea. Although antibiotics might lower the intensity of the infection, the inflamed appendicitis is removed to prevent a recurrence, which is likely. Mild appendicitis that spontaneously resolves can leave behind baggage, such as adhesions (see below), but a rupture is a life-threatening emergency.


Adhesions are abnormal connections between abdominal tissues and the abdominal wall or even organs. The abdomen is very vigilant with infection and inflammation, stimulating bowel fat to migrate toward an afflicted area to wall it off from the rest of the body. When this area heals, unfortunately, the two areas can be stuck together, which can sometimes create a kink in the bowel that can make the passage of bowel contents more difficult than is normal. This can distend the bowel to create a colicky, sharp pain.

With the right ovary so close to the appendix, inflammation or infection of either can cause these two structures to adhere together. This creates confusion when trying to differentiate between an ovarian process or appendicitis.


Usually fleeting in its painful presentation, adhesions (or fibrotic scarring from Crohn’s disease) can occasionally cause an obstruction that becomes a surgical emergency. Partial obstructions are treated with a liquid diet so as to not challenge the area. Adhesions are not exclusive to the LUQ and can occur anywhere in the abdomen, including in the RLQ.

The right lower quadrant in women is highly susceptible to disease in the reproductive organs; men, on the other hand, are usually susceptible to issues with the colon, which are primarily appendicitis or diverticulitis. Otherwise, kidney stones are likely. GI symptoms such as diarrhea may suggest an inflammatory bowel disease, such as Crohn’s disease.

In all these situations, the most confusing condition is RLQ pain in women because of the possibility of either an ovarian cyst, appendicitis, or both. Adhesions can make these conditions infectious bedfellows. The cyst is often a non-surgical condition, but the notorious appendix, with its appendicitis, is always a surgical condition. With both of these occurring on the right side, the drama of uncertainty builds. A CT scan or laparoscopy can be of crucial help in differentiating between these.

Lest we forget, pregnancy, with its expanding and rising central uterus, will shove the things that normally sit in the RLQ into the RUQ (right upper quadrant). One can only imagine the challenge that this would present when appendicitis, the most common cause of acute abdomen pain in pregnancy, is confused with gall bladder or life-threatening liver complications of pregnancy!