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Pelvis

Also called the pelvic girdle, the pelvis is a basin-shaped group of bones that links the torso and the legs and houses the intestines, bladder, and internal reproductive organs(1). 

The pelvis supports the muscles that balance and move the trunk, hips, and legs(2).

In newborns, the pelvis, which is narrow, cannot support the child. As an infant begins to walk, their pelvis widens and tilts, and their lower back’s lumbar curve develops(3).

Aside from carrying a person’s upper body weight, the pelvis transfers upper body weight to the lower limbs. The basin-shaped group of bones also serves as an attachment point for the lower limb and muscles of the torso(4).

These bones also protect the pelvic and abdominopelvic viscera(5). The abdominopelvic viscera include the stomach, liver and biliary system (the biological system that secretes and stores bile), intestines, pancreas, kidneys, spleen, ureters, and suprarenal glands (glands near the kidneys)(6).

The human pelvis is made up of the pelvic cavity, the bony pelvis, the pelvic floor, and the perineum(7). 

The Pelvic Cavity

The pelvic cavity refers to the space inside the pelvic bones. It is divided into two regions: the lesser pelvis and the greater pelvis(8). 

The greater pelvis is called the false pelvis, as it is part of the abdomen. Meanwhile, the lesser pelvis, which is a part of the pelvis, is referred to as the true pelvis(9).

The pelvic cavity serves as housing space for the human urinary bladder, the colon, internal sex organs, and the rectum. It also houses internal structures and tissues, such as nerves, muscles, arteries, veins, and the pelvic connective tissue(10).

The Bony Pelvis

The pelvis consists of paired hipbones: the pubic symphysis and the sacrum. The hipbones are made up of three bones(11):

  • The blade-shaped ilium, which accounts for the wideness of the hips
  • The ischium, where the weight falls when a person sits
  • The pubis, which is placed in front of the pelvis

The three bones meet at a triangular suture in the socket called the acetabulum, which forms at the hip joint with the thighbone or femur(12).

The Pelvic Floor

The pelvic floor refers to the inferior muscular layer of the true pelvic cavity. This muscular sheet divides the pelvic cavity from the perineum, the area which lies inferior to the pelvic floor(13).

It serves as a boundary of the abdominal cavity and the pelvis(14). 

The pelvic floor supports the weight of some internal organs, such as the urinary bladder, rectum, and anus. In females, the pelvic floor also holds the weight of the uterus and vagina(15). 

The pelvic floor helps in the regulation of rectal, urinary, and genital openings. It also supports the contractions of the bladder and anal sphincter(16). 

When a person coughs or lifts heavy objects, the pelvic floor helps maintain intra-abdominal pressure(17).

Dysfunction of the pelvic floor may cause the following disorders(18):

  • Cystocele, anterior vaginal wall prolapse (drooping of the organ)
  • Cystourethrocele or the prolapse of the bladder and urethra
  • Rectocele or the prolapse of the rectum into the vagina
  • Uterine prolapse or the prolapse of the uterus into the vagina
  • Urethrocele or the prolapse of the urethra
  • Enterocele or the prolapse of the small intestine into the vagina

The Perineum

The perineum is the area between two openings on the pelvic floor: the urogenital hiatus and the rectal hiatus(19). 

The urogenital hiatus refers to the urethra and the vagina in females. Meanwhile, the rectal hiatus refers to the anal canal(20). 

The perineum is a diamond-shaped area that spans the anus to the vagina in females and the anus to the scrotum in males(21).

Possible Causes of Pelvic Pain

Although medical conditions are uncommon, pelvis-based abnormalities are present in various patient populations(22).

The pelvis supports and protects several internal organs, which are vulnerable to developing abnormalities. Below are possible causes of pelvic pain(23):

  • Appendicitis
  • Sexually transmitted diseases (STDs)
  • Bladder disorders
  • Kidney infection
  • Psychogenic pain (pain caused by psychological traumas)
  • Nerve abnormalities
  • Intestinal disorders
  • Bone fracture

Below are possible causes of pelvic pain in women only(24):

  • Ovulation
  • Miscarriage
  • Pregnancy
  • Ectopic pregnancy (growth of a fertilized egg outside the uterine wall)
  • Pelvic inflammation
  • Menstrual cramps
  • Ovarian cysts
  • Fibroids (abnormal growths in the uterus)
  • Cancer 

Diagnosing Causes of Pelvic Pain

A physician may recommend any of the procedures below to treat or diagnose the causes of pelvis pain(25):

  • Abdominal and pelvic X-rays
  • Blood tests
  • Pregnancy tests in females
  • Vaginal or penile cultures to diagnose for STDs, like gonorrhea and chlamydia
  • Urine tests
  • Hysteroscopy (a procedure to examine the uterus)
  • Diagnostic laparoscopy (a procedure to see internal structures in the pelvis and abdomen)
  • Stool guaiac test (stool sample examination for the presence of microscopic blood)
  • Colonoscopy (insertion of a lighted tube to examine the rectum and colon)
  • Ultrasound
  • Computed tomography (CT) scan of the abdomen and pelvis
  1. Encyclopedia Britannica. Pelvis. Retrieved from https://www.britannica.com/science/pelvis
  2. Ibid
  3. Ibid
  4. Chaudhry, S., Nahian, A., & Chaudhry, K. (2020) Anatomy, Abdomen and Pelvis. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK482258/
  5. Ibid
  6. O’Rahilly, R., Müller, M., Carpenter, S., & Swenson, R. (2004) BASIC HUMAN ANATOMY A Regional Study of Human Structure. https://www.dartmouth.edu/~humananatomy/part_3/chapter_17.html
  7. S. Chaudhry, et al. Op cit.
  8. Ibid
  9. Ibid
  10. Ibid
  11. Encyclopedia Britannica. Op cit.
  12. Ibid
  13. S. Chaudhry, et al. Op cit.
  14. Ibid
  15. Ibid
  16. Ibid
  17. Ibid
  18. Ibid
  19. Ibid
  20. Ibid
  21. Ibid
  22. Ibid
  23. Cleveland Clinic. Pelvic Pain: Possible Causes. Retrieved from https://my.clevelandclinic.org/health/symptoms/12106-pelvic-pain/possible-causes
  24. Ibid
  25. Cleveland Clinic. Pelvic Pain: Care and Treatment. Retrieved from https://my.clevelandclinic.org/health/symptoms/12106-pelvic-pain/care-and-treatment

Retrograde Urethrogram

Pelvis / By

Retrograde urethrogram (RUG) is a diagnostic procedure that employs contrast dye to X-ray the urethra. X-rays are used to monitor the flow of the dye back down the urethra and into the bladder.

Voiding Cystourethrogram (VCUG)

Pelvis / By

The voiding cystourethrogram (VCUG) test produces pictures of the urinary system. An X-ray and an ultrasound are two medical imaging procedures that can produce images for the voiding cystourethrogram. There are numerous variations of VCUG to improve disease visualization while minimizing radiation exposure. While a VCUG procedure is generally safe, some individuals may experience adverse …

Voiding Cystourethrogram (VCUG) Read More »

MRI of the Female Pelvis

This webpage presents the anatomical structures found on female pelvis MRI. Magnetic resonance imaging or MRI of the female pelvis offers a unique display of the pelvic anatomy, including a woman’s ovaries, uterus, and fallopian tubes.  MRI is a valuable technique in diagnosing or staging anomalies or conditions in the female pelvic region. Unlike sonography …

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Male Pelvis Magnetic Resonance Imaging

This webpage presents the anatomical structures found on male pelvis MRI. Radiologists have historically imaged the male pelvis using many methods. Modalities range from conventional cystography, excretory urography, and retrograde urethrography to computed tomography and sonography(1). However, in the study, the initial expectations of each method exceeded the long-term results. Thus, experts believe that the …

Male Pelvis Magnetic Resonance Imaging Read More »

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