the differential diagnoses of a groin mass include inguinal hernia , round ligament varicosities ( rlv ) , mesothelial cysts , lymphadenopathy , endometriosis , subcutaneous lipoma , cyst of nuck ( persistent embryonic remnants of the process vaginalis with cyst formation ) , vascular aneurysms , soft tissue malignancies , abscess , and cystic lymphangiomas [ 1 - 5 ] . the rlv can easily be mistaken for an inguinal hernia ( especially a strangulated or incarcerated groin hernia that needs an emergency operation ) , because they share the same clinical appearance . we report a patient with rlv during pregnancy diagnosed by doppler sonography and managed with conservative therapy ( repeated sonography and obstetric practice ) . a 29-year - old woman presented at 36 weeks gestation with a palpable mass and pain in the right groin during her second pregnancy . the opinion of the obstetrician was inguinal hernia , and he transferred her to a general surgeon . the general surgeon diagnosed a right inguinal hernia , and he transferred her to our hospital . on physical examination , the mass ( 2  2 cm ) was palpable softly , but tender , and was reducible completely by supine position change ( fig . gray - scale sonography showed a mass in the right groin composed of multiple , echo - free , tubular channels . the color doppler sonography confirmed hypervascular and abundant venous flow consistent of a mass ( fig . 2 ) . there was no sonographic evidence of a herniated bowel , or thrombus , or adenopathy . based on sonographic results , we diagnosed round ligament varicosities , and performed repeated sonography and obstetric practice . the patient had an uncomplicated vaginal delivery at 40 weeks , and by two weeks postpartum , the mass subsided . the most common diagnosis of a female groin swelling during pregnancy is an inguinal hernia . however , inguinal hernias during pregnancy are relatively rare , with a reported incidence of 1 in 1,000 to 3,000 pregnant women . a thorough literature search revealed only 16 cases internationally of rlv during pregnancy reported in the last 53 years . the rlv was first reported in 1941 by verovitz and first reported in korea in 2010 by jung et al . . the rlv are prominent veins within the round ligament and are more common in pregnancy because pregnancy promotes increased venous return and reduced venous tone . the varicose vein formation of the round ligament during pregnancy have several mechanisms , including progesterone - mediated venous smooth muscle relaxation , a raised cardiac output causing increased venous return from the limbs and leading to engorgement of venous tributaries , and most importantly , pelvic venous obstruction by the gravid uterus [ 1 - 3,5 ] . the clinical manifestation of rlv usually includes swelling and tenderness in the groin region , which can be provoked by increased intra - abdominal pressure in cases of coughing or valsalva maneuver . a clue that might suggest rlv is the coexistence of vulvar or lower limb varicosities . our case , however , absence of vulvar or lower limb varicosities did not exclude rlv . the characteristic sonographic findings include a prominent venous plexus with accompanying dilated draining veins and the typical " bag of worms " appearance of smaller veins . color doppler imaging can confirm venous flow and augmentation of this flow with valsalva maneuver . according to mckenna et al . , ultrasound criteria that may be used in the diagnosis of rlv includes : multiple dilated veins passing through the inguinal canal , absence of bowel or lymph nodes in the inguinal mass , and veins seen to drain into the inferior epigastric vein . the differential diagnoses of rlv include inguinal hernia , lymphadenopathy , endometriosis , subcutaneous lipoma [ 1 - 5 ] . the sonographic findings of inguinal hernia are a superficial , well - delineated echogenic mass that appears adjacent to , yet distinctly separate from , the uterine wall . the sonographic findings of lymphadenopathy are hypoechoic round or oval masses of varying size in the region of the inguinal area . the characteristic sonographic appearance of endometrioma is that of a well - defined unilocular or multilocular , predominately cystic mass containing diffuse homogeneous , low - level , and internal echoes . the sonographic findings of lipoma show a homogeneous , and echogenic mass that is surrounded by a thin echogenic capsule . after a correct diagnosis of rlv , a wait - and - see policy is justified . after delivery , when pelvic venous obstruction by the gravid uterus is relieved , spontaneous resolution will occur in most patients [ 2 - 5,9 ] . however , rlv requires close monitoring during pregnancy as rupture of varices and acute variceal thromboses have been reported . rupture and thrombosis of the rlv may occur and give an intense painful swelling groin , in which case emergency surgical exploration is recommended . this recommendation comes first of all to rule out a strangulated hernia , and secondly to reduce pain or discomfort caused by the inguinal mass . when a pregnant patient with an inguinal mass visits our hospital , we have to know that rlv is a part of the differential diagnosis of an inguinal mass during pregnancy , and we must perform a diagnosis using duplex sonography . if the rlv is diagnosed by sonography with the absence of a herniated bowel , or thrombus , we manage it conservatively ( repeated sonography and obstetric practice ) . however , if rlv presenting with rupture of varices and variceal thromboses are observed , emergency surgical exploration is recommended .