What is the differential diagnosis for a left tubal mass with a central hemorrhagic component and peripheral vascularity in the presence of a normal beta human chorionic gonadotropin (hCG) level?

Differential Diagnosis for Left Tubal Mass with Central Hemorrhagic Component and Peripheral Vascularity with Normal Beta-hCG

The most likely diagnosis is a tubal ectopic pregnancy, even with a normal beta-hCG level, and this should be managed as such until definitively proven otherwise. 1

Primary Differential Considerations

Tubal Ectopic Pregnancy (Most Likely)

• An extraovarian mass with central hemorrhagic component and peripheral vascularity in the absence of an intrauterine pregnancy has a high likelihood of representing tubal ectopic pregnancy, regardless of beta-hCG level. 1
• The described appearance matches either a "tubal ring" (round/oval fluid collection with hyperechoic rim and peripheral vascularity) or a nonspecific heterogeneous mass, both classic presentations of tubal ectopic pregnancy. 1
• Ectopic pregnancies are located ipsilateral to the corpus luteum in 70-80% of cases, making left-sided location consistent with this diagnosis. 1
• Critically, pathology-confirmed ectopic pregnancy can occur with negative serum beta-hCG levels, though this is extremely rare with only documented case reports. 2
• The central hemorrhagic component suggests either blood within the gestational sac or hemorrhage from a degenerating/aborting ectopic pregnancy. 1

Corpus Luteum (Key Alternative)

• Differentiating a tubal ring from an exophytic corpus luteum is challenging because both can demonstrate peripheral vascularity on color Doppler. 1, 3
• The corpus luteum typically appears as a <3 cm cystic lesion with thick wall and may contain internal echoes or hemorrhage. 1
• The critical distinguishing feature is whether the mass is inside or outside the ovary—gentle pressure with the transvaginal transducer can help determine if the mass and ovary move together (corpus luteum) or separately (tubal pregnancy). 1
• A "claw sign" of partially surrounding ovarian parenchyma confirms ovarian origin and corpus luteum diagnosis. 1, 3
• Echogenicity helps differentiate: tubal rings are typically more echogenic than corpus luteum, which appears hypoechoic. 1
• Luteal cysts with central hemorrhagic component and peripheral vascularity are classified as O-RADS 2 with <4% malignancy likelihood. 3

Hemorrhagic Ovarian Cyst (Ruptured or Intact)

• Can present with central hemorrhagic component and peripheral vascularity, mimicking ectopic pregnancy. 1
• Rupture of hemorrhagic ovarian cyst can cause echogenic free fluid (blood) in pelvis, similar to ruptured ectopic. 1
• The "sliding sign" on transvaginal ultrasound helps confirm the mass is separate from ovary or uterus, excluding ovarian origin. 1

Chronic/Degenerating Ectopic Pregnancy

• A chronic ectopic pregnancy could explain the normal beta-hCG level if the pregnancy has been present for an extended period with declining hormone levels. 2
• May appear as heterogeneous mass with hemorrhagic component and organized blood products. 1
• This is the most plausible explanation for the rare scenario of ectopic pregnancy with normal beta-hCG. 2

Tubal Choriocarcinoma (Rare but Critical)

• Extremely rare malignancy that can present as hemorrhagic tubal mass and may have elevated or normal beta-hCG depending on tumor burden. 4
• Can be initially misdiagnosed as chronic ectopic pregnancy. 4
• Appears as hemorrhagic friable mass, potentially adherent to surrounding structures. 4
• This diagnosis underscores the importance of histopathological examination of all tubal tissue in patients presenting with suspected ectopic pregnancy. 4

Diagnostic Algorithm

Immediate Assessment

• Confirm the mass is extraovarian using the "sliding sign" technique with gentle transducer pressure to determine if mass and ovary move independently. 1
• Assess for "claw sign" of ovarian parenchyma—if present, favors corpus luteum over ectopic. 1, 3
• Evaluate echogenicity: hyperechoic rim favors tubal ring; hypoechoic appearance favors corpus luteum. 1
• Document presence or absence of intrauterine pregnancy—absence with adnexal mass creates positive likelihood ratio of 111 for ectopic pregnancy. 1

Beta-hCG Correlation

• Normal beta-hCG does NOT exclude ectopic pregnancy, though it makes it less likely. 2
• If beta-hCG is truly undetectable (<5 mIU/mL), consider chronic/resolved ectopic or non-pregnancy-related pathology. 2
• Serial beta-hCG measurements should be obtained—plateauing or declining levels suggest failing/chronic ectopic. 5
• In stable patients with beta-hCG ≤3,000 mIU/mL, repeat sonographic evaluation and serial beta-hCG should be obtained before definitive diagnosis. 1

Assessment of Free Fluid

• Evaluate for free intraperitoneal fluid—echogenic fluid suggests hemoperitoneum from ruptured ectopic or hemorrhagic cyst. 1
• More than trace anechoic free fluid is concerning for ectopic pregnancy, even without identified extraovarian mass. 1

Clinical Context Integration

• Assess hemodynamic stability—tachycardia, hypotension, or syncope mandate immediate surgical intervention regardless of beta-hCG. 2
• History of amenorrhea, pelvic pain, or vaginal bleeding increases ectopic likelihood. 5
• Risk factors include prior ectopic, pelvic inflammatory disease, IUD use, or assisted reproduction. 5

Management Approach

Given the high specificity of adnexal findings and potential for life-threatening rupture, this should be managed as probable ectopic pregnancy until proven otherwise. 1

• If hemodynamically unstable: immediate laparoscopy or laparotomy. 5, 2
• If stable with normal beta-hCG: close surveillance with serial beta-hCG every 48 hours and repeat transvaginal ultrasound in 48-72 hours. 1, 5
• Surgical pathology should be obtained on all tubal tissue to exclude rare tubal choriocarcinoma. 4
• If mass proves to be corpus luteum in premenopausal woman and <5 cm: no additional management required. 3

Critical Pitfalls to Avoid

• Never exclude ectopic pregnancy based solely on negative beta-hCG in a woman of reproductive age with adnexal mass. 2
• Do not rely on color Doppler alone to differentiate tubal ring from corpus luteum—both demonstrate peripheral vascularity. 1, 3
• Avoid misdiagnosing eccentric intrauterine pregnancy as interstitial ectopic—confirm gestational sac is completely surrounded by endometrium. 1
• Do not perform fine-needle aspiration of adnexal masses due to risk of seeding if malignancy present. 6
• Ensure histopathological examination of all surgically removed tubal tissue to avoid missing tubal choriocarcinoma. 4