Lower Abdominal Pain in Females Radiating to Thighs
In reproductive-age women presenting with lower abdominal pain radiating to the thighs, obtain a pregnancy test immediately and perform transvaginal ultrasound as the initial imaging study to evaluate for gynecologic causes, particularly ectopic pregnancy, ovarian torsion, and pelvic inflammatory disease. 1, 2
Immediate Diagnostic Priorities
Rule Out Life-Threatening Conditions First
Ectopic pregnancy must be excluded before pursuing other diagnoses in all women of reproductive age with lower pelvic pain—obtain β-hCG measurement before any imaging to avoid radiation exposure to a potential embryo and to narrow the differential diagnosis 1, 2
Ovarian torsion requires urgent diagnosis as delayed recognition increases morbidity and can result in ovarian loss—this occurs across all age groups, including postmenopausal women, though it's less commonly considered in older patients 3, 4, 5
Pelvic inflammatory disease (PID) requires immediate empiric treatment if you find cervical motion tenderness, adnexal tenderness, or lower abdominal tenderness on examination—do not delay antibiotics waiting for culture results, as this reduces risk of tubal infertility and chronic pelvic pain 1, 2
Initial Imaging Approach
For Reproductive-Age Women
Transvaginal or transabdominal pelvic ultrasound is the recommended first imaging study when gynecologic etiology is suspected or β-hCG is positive 1, 6
If ultrasound is non-diagnostic and patient is not pregnant, proceed to CT abdomen/pelvis with IV contrast, which has 74-95% sensitivity for adnexal torsion and changes diagnosis in 51% of cases 6, 2
For Postmenopausal Women
CT abdomen and pelvis is first-line imaging in postmenopausal women due to broader differential diagnosis, as ovarian cysts account for one-third of gynecologic pain cases, followed by uterine fibroids 1, 2
Ovarian torsion remains in the differential despite advanced age, particularly when associated with ovarian masses that carry higher malignancy risk 3
Common Gynecologic Causes
Pain Radiating to Thighs: Key Etiologies
Pelvic inflammatory disease presents with lower abdominal tenderness, adnexal tenderness, and cervical motion tenderness—empiric broad-spectrum antibiotics covering N. gonorrhoeae, C. trachomatis, anaerobes, and gram-negative bacteria should be initiated immediately 1, 2
Ovarian cysts and torsion cause acute unilateral pain that may radiate—ultrasound shows enlarged ovary with peripheral follicles and absent or decreased Doppler flow in torsion 1, 4, 5
Uterine fibroids are the second most common cause in perimenopausal/postmenopausal women, causing acute pain from torsion of pedunculated fibroids, prolapse, or acute degeneration 1
Endometriosis can cause chronic pain but is rare as a cause of acute pain in postmenopausal women 1
Non-Gynecologic Differential
Must-Consider Diagnoses
Appendicitis has 95% sensitivity and 94% specificity on CT with IV contrast—presents with right lower quadrant pain, fever, and anorexia 6, 2, 7
Diverticulitis has >95% sensitivity on CT and is diagnosed by pericolonic fat stranding, bowel wall thickening, and diverticula—most common in left lower quadrant 1, 6, 7
Abdominal wall pain is frequently overlooked—suspect when pain is unrelated to eating/bowel function but related to posture, with positive Carnett's sign (tenderness unchanged or increased when abdominal muscles tensed) 8
Treatment Algorithm
For Suspected PID
Begin empiric antibiotics immediately without waiting for cultures—minimum criteria requiring treatment: lower abdominal tenderness AND adnexal tenderness AND cervical motion tenderness 1, 2
Additional supporting criteria include oral temperature >38.3°C, abnormal cervical/vaginal discharge, elevated ESR or CRP, or laboratory documentation of cervical infection 1
Reassess within 72 hours—if no clinical improvement, hospitalize for parenteral antibiotics 2
For Suspected Torsion
Surgical consultation should be initiated immediately when torsion is suspected on ultrasound to preserve ovarian viability 4, 5
In postmenopausal women with torsion, full malignancy evaluation is required due to higher risk of ovarian cancer 3
Imaging Protocol Selection
CT Abdomen/Pelvis Indications
CT with IV contrast is preferred for nonlocalized abdominal pain as it provides comprehensive evaluation of all abdominal organs and detects complications like abscess, perforation, and fistula 1, 6
CT changes management in 25% of patients and alters diagnosis in 51% of cases with abdominal pain 6
MRI Considerations
MRI without contrast is preferred in pregnant patients after non-diagnostic ultrasound, with 97% sensitivity and 95% specificity for appendicitis while avoiding radiation 1, 6
MRI is an alternative when radiation exposure is a concern in reproductive-age women, though limited by cost and availability 1, 6
Critical Pitfalls to Avoid
Do not rely on conventional radiography (X-ray) for diagnosis of lower abdominal pain—it has limited diagnostic value and rarely changes management 6
Do not assume negative ultrasound rules out serious pathology—ultrasound is operator-dependent and has variable sensitivity compared to CT for many conditions 1, 6
Do not delay empiric PID treatment waiting for definitive diagnosis—early treatment prevents long-term sequelae including infertility and chronic pain 1, 2
Do not forget pregnancy testing before CT in reproductive-age women to avoid unnecessary fetal radiation exposure 1, 6
Do not dismiss ovarian torsion in postmenopausal women—delayed diagnosis is common in this age group and increases morbidity due to higher malignancy risk 3