The round ligament of the uterus is a fibromuscular cord that runs from each side of the uterus, through the inguinal canal, and into the groin, helping hold the uterus in its forward-tilted position. Most people first hear about it during pregnancy, when stretching of the ligament produces a sharp, distinctive pain in the lower abdomen or groin. But the round ligament has a surprisingly rich anatomy, a debated endpoint, and a role in several clinical scenarios beyond pregnancy discomfort.
Anatomy and Course
The round ligament begins at the upper corner of the uterus, near where the fallopian tube attaches. From there it crosses the pelvis, passes through the deep inguinal ring (the internal opening of the inguinal canal), travels through the inguinal canal itself, and exits at the superficial inguinal ring.1PubMed. Anatomy, Abdomen and Pelvis: Uterus Round Ligament Classic anatomy textbooks describe it ending by fanning out into the tissue of the labia majora and mons pubis, but cadaveric research has challenged that picture. A dissection study found three distinct patterns of distal attachment: in more than half of cases the ligament ended just after the external inguinal ring, in roughly a quarter it ended before the internal ring, and in about a fifth it attached under the pubic bone. None of the specimens showed the ligament reaching the labia majora at all.2Morphologie. The round ligament of the uterus: Questioning its distal insertion That finding suggests the textbook description of a clear path into the labia is an oversimplification, or at least not universal.
The ligament’s route through the inguinal canal is the same corridor that the spermatic cord takes in males. This shared anatomy is not a coincidence. During embryonic development, a tissue bridge called the gubernaculum forms between the developing gonad region and the body wall at around six and a half weeks of gestation.3PubMed Central. The Development of the Human Female Reproductive Tract. Part 1: Uterine Tube and Uterus In males, the gubernaculum guides the testes down into the scrotum and becomes part of the scrotal ligament. In females, it becomes the round ligament.4PubMed. The female gubernaculum: role in the embryology and development of the genital tract and in the possible genesis of malformations The gubernaculum also appears to play a role in the proper development of the reproductive tract more broadly, so abnormalities in its formation may contribute to certain congenital malformations of the uterus and tubes.
What the Round Ligament Is Made Of
The round ligament is not just a passive rope of connective tissue. Microscopic studies reveal that it has a central core and an outer layer composed primarily of smooth muscle fibers, woven through with connective tissue and threaded with a rich network of nerve fibers.5BJOG: An International Journal of Obstetrics and Gynaecology. The Microscopic Anatomy of the Round Ligament The presence of smooth muscle means the ligament can contract, and the dense nerve supply helps explain why it can be such an effective source of pain when irritated or stretched.
The smooth muscle content is not identical from person to person, and research suggests that variation may matter clinically. In women with uterine prolapse, the smooth muscle fraction of the round ligament is significantly decreased compared to women without prolapse.6PubMed. Smooth muscle fraction of the round ligament in women with pelvic organ prolapse: a computer-based morphometric analysis Whether the reduced muscle content is a cause or a consequence of prolapse remains debated, but it points to the ligament’s role as more than a static anchor.
What the Round Ligament Actually Does
Functionally, the round ligament works alongside the broad ligament to maintain the uterus in its normal anteverted, anteflexed position, tilted slightly forward over the bladder, and to limit lateral displacement.7Asian Journal of Urology. Biomechanical analysis of female pelvic floor anatomy: A novel integrative framework It is not the primary support for the uterus; that job falls mainly to the pelvic floor muscles and the uterosacral and cardinal ligaments. Think of the round ligament as more of a positioning tether than a weight-bearing structure. It pulls the upper body of the uterus forward and prevents it from tipping too far backward or sideways.
This relatively modest mechanical role is part of why surgeons have historically been comfortable cutting the round ligament during certain procedures, a point that becomes relevant during hernia repair and hysterectomy.
Round Ligament Pain in Pregnancy
The most common reason anyone looks up “round ligament” is pregnancy-related pain. As the uterus grows, the round ligaments stretch and thicken significantly to keep pace. That stretching, combined with the increased blood flow and hormonal changes of pregnancy, can produce sharp or dull pain in the groin-to-hip region, often triggered by sudden movements like rolling over in bed, coughing, sneezing, or standing up quickly.8Indian Journal of Physiotherapy and Occupational Therapy – An International Journal. DEMYSTIFYING ROUND LIGAMENT PAIN IN PREGNANCY: A NARRATIVE REVIEW The pain can be unilateral or bilateral, and it may temporarily interfere with daily activities.
Round ligament pain is considered benign and self-limiting, and it tends to peak during the second trimester when the uterus is growing most rapidly relative to its starting size. It usually resolves after delivery, though it can be intense enough to cause real distress. Practical management typically involves slow position changes, warm compresses, gentle stretching, and rest. If the pain is severe, persistent, or accompanied by other symptoms like fever, bleeding, or painful urination, it warrants medical evaluation to rule out other causes.
One thing that catches people off guard is how much the pain can feel like a pulled muscle or even appendicitis when it occurs on the right side. Knowing the pattern (sudden onset with movement, quick resolution with rest, no fever or other systemic symptoms) helps distinguish it from more serious problems.
When a Groin Lump During Pregnancy Is Not a Hernia
A rarer but clinically important pregnancy complication involves the veins of the round ligament swelling into varicosities. These dilated veins can produce a visible, palpable lump in the groin that looks and feels remarkably like an inguinal hernia.9PubMed Central. Round ligament varicosities mimicking inguinal hernia in pregnancy The resemblance is close enough that misdiagnosis has led to unnecessary surgery. In one reported case, a pregnant woman was operated on at 22 weeks based on the clinical suspicion of a painful inguinal hernia; surgical exploration revealed varicosities of the round ligament instead.10PubMed. Bilateral round ligament varicosities mimicking inguinal hernia during pregnancy
The key to avoiding that scenario is ultrasound. A Doppler scan can distinguish between a hernia (which would show bowel or omental tissue) and varicosities (which show tortuous venous channels with a characteristic “bag of worms” appearance on grayscale imaging and increased venous flow during a Valsalva maneuver).11American Journal of Case Reports. A Rare but Noteworthy Diagnosis for “Lumps in the Groin” During Pregnancy: Round Ligament Varices Round ligament varicosities typically resolve on their own after delivery. The clinical takeaway is straightforward: any new groin swelling during pregnancy should get an ultrasound before anyone considers surgery.12Radiology Case Reports. Round ligament varices mimicking inguinal hernia during pregnancy
Endometriosis and Tumors of the Round Ligament
Outside of pregnancy, the round ligament can be the site of two uncommon but clinically confusing conditions: endometriosis and smooth muscle tumors (leiomyomas).
Round ligament endometriosis accounts for roughly 0.3 to 0.6 percent of all endometriosis cases.13PubMed Central. Laparoscopic surgery for endometriosis of the round ligament: A case of a patient with right-sided inguinal pain It typically presents as groin pain that worsens with the menstrual cycle, without any visible bulge. Because the pain is in the inguinal region, it can initially be mistaken for a hernia, a musculoskeletal strain, or a nerve problem. Imaging with ultrasound and MRI, combined with the cyclical timing of the pain, can raise clinical suspicion, but definitive diagnosis usually requires histological examination of tissue removed during surgery.14PubMed Central. Endometriosis of extra-pelvic round ligament, a diagnostic dilemma for physicians
Leiomyomas of the round ligament are even rarer. These benign smooth muscle tumors tend to present as a firm mass in the groin that mimics an irreducible inguinal hernia.15PubMed Central. A rare inguinal mass: Round ligament leiomyoma They can occur at any age, including after menopause.16PubMed. Leiomyoma of the round ligament in a postmenopausal woman: A rare case report Surgical excision is the standard treatment. The theme across all of these conditions is that anything producing a lump or unexplained pain in the groin region of a woman should prompt consideration of round ligament pathology, not just hernia.
The Surgical Debate Over Dividing the Round Ligament
During laparoscopic inguinal hernia repair in women, surgeons face a practical question: should the round ligament be preserved or divided? Cutting the ligament makes the operation technically simpler and faster, because the ligament passes through the same canal the surgeon needs to access and repair. Preserving it requires more careful dissection around the structure. During laparoscopic hysterectomy, division of the round ligament is a routine early step that opens up the surgical field.17Global Library of Women’s Medicine. Laparoscopic total hysterectomy: a low-cost minimally invasive surgical approach
For hernia repair specifically, the evidence is reassuring for both approaches. A study following women after round ligament transection during laparoscopic hernia repair found no increase in painful intercourse, menstrual pain, chronic pelvic pain, or uterine prolapse, while the operation itself was faster.18PubMed. Objective follow-up after transection of uterine round ligament during laparoscopic repair of inguinal hernias in women: assessment of safety and long-term outcomes A meta-analysis comparing the two approaches confirmed that preserving the round ligament requires a longer operating time, with no clear advantage in short-term or long-term complications. The meta-analysis also noted that there was no clear evidence on whether division causes infertility or uterine prolapse, meaning the question is not definitively closed.19PubMed Central. Comparison of outcomes between preservation or division of the uterine round ligament in laparoscopic groin hernia repair in females: a meta-analysis and trial sequential analysis
A separate review found that dividing the ligament was common practice and not associated with increased complications or recurrence, though it acknowledged that some evidence of decreased pain at six months needs to be weighed against potential functional consequences that have not been fully studied.20PubMed. Round Ligament Management in Female Patients Undergoing Inguinal Hernia Repair: Should We Divide or Preserve? In practice, many surgeons still prefer to preserve the ligament when technically feasible, particularly in younger women who have not completed childbearing, on the principle that keeping an intact anatomical structure is better than removing one when the evidence is a wash.
Groin Pain and the Nerve Supply
The round ligament’s passage through the inguinal canal places it in close company with several important nerves, including the ilioinguinal nerve and the genital branch of the genitofemoral nerve. These nerves can become sources of chronic groin pain in their own right, whether from entrapment, surgical injury, or other causes. Importantly, pain originating from these nerves can be referred to areas well beyond the groin itself, including the pelvic organs and the inner thigh.21PubMed. Surgical management of groin pain of neural origin
This shared neuroanatomy means that round ligament pain, nerve-related groin pain, and hernia pain can all present similarly. In someone with chronic inguinal discomfort and no obvious hernia on imaging, the differential diagnosis can include round ligament pathology, nerve entrapment, endometriosis, musculoskeletal strain, or referred pain from the hip. Sorting through these possibilities typically requires a combination of imaging, clinical history (does the pain follow the menstrual cycle? Was there a previous surgery in the area?), and sometimes diagnostic nerve blocks.
The Liver’s Round Ligament
The term “round ligament” also refers to an entirely different structure in the abdomen: the ligamentum teres hepatis, or round ligament of the liver. This is the remnant of the fetal umbilical vein, which carried oxygenated blood from the placenta to the fetal liver before birth. After delivery, the vein collapses and turns into a fibrous cord that runs along the free edge of the falciform ligament, connecting the navel to the underside of the liver.
The liver’s round ligament is normally a dormant, functionless structure. But it retains latent potential. In conditions that cause portal hypertension, such as advanced liver disease, the collapsed umbilical vein can recanalize, reopening as a functioning blood vessel to provide a pressure-relief bypass for congested portal blood flow. Surgeons performing major liver resections have documented this recanalization by Doppler ultrasound and cross-sectional imaging in patients who developed transient portal hypertension after the operation.22PubMed Central. Preservation of the round ligament to accommodate transient portal hypertension after major hepatectomy That finding has led some surgical teams to advocate preserving the liver’s round ligament during hepatectomy when possible, to leave this safety valve available.
The Hip’s Round Ligament
A third structure called the “round ligament” exists in the hip joint: the ligament of the head of the femur, sometimes called the ligamentum teres femoris. This is a short band of connective tissue that runs from a small pit on the femoral head (the fovea) to the bottom of the hip socket. For decades, anatomy classes treated it as a vestigial structure of little importance, but more recent work has revised that view.
Histological studies show the ligament has three distinct layers and contains patent blood vessels and nerve fibers, including pressure-sensing receptors.23PubMed Central. Neurovascular structures of the ligament of the head of femur The blood vessel density is highest at the foveal end, suggesting the ligament may play a nutritive role in supplying blood to the femoral head, at least in some individuals. The presence of nerve receptors also indicates it contributes to pain perception and proprioception in the hip joint, adding to its mechanical stability in ways that are still being characterized.24PubMed. Ligament of the head of femur: A comprehensive review of its anatomy, embryology, and potential function How much mechanical stabilization the ligament provides, and under what hip positions, remains an open question in orthopedic research. It is thought to become taut in certain extreme positions of the hip, but the evidence supporting a strong stabilizing role is still limited.
Despite sharing a name, the hip’s round ligament has no developmental or functional relationship to the uterine round ligament. The shared nomenclature is purely descriptive, referring to the rounded cross-sectional shape of each structure. The uterine version derives from the embryonic gubernaculum, while the hip version develops from mesenchymal tissue within the joint capsule. Their only real common ground is that both have been historically underestimated in terms of what they do.